Battery Recommendations - 30 ft Racer/Cruiser

[freewheelin 162]

This spring I will be replacing/upgrading my batteries. I am replacing two 12 V group 27 deep cycle wet cell batteries. The boat (30 fter) lives on a mooring during the season, and the two batteries are in parallel. I have 25 watts of solar charging them when I'm not around. My goal is as much battery life as possible between charging. I sail on and off most days, and want to minimize the need to run the engine to charge. Normal amp draw is pretty low - just instruments, running lights, and LED cabin light - but without a dedicated starting battery, having the juice left over to start the motor is important.

I know this is pretty vague, but when I look at all the battery options out there it seems to be a huge range of products and prices. But a lot of the information seems to be directed at long term cruisers drawing a lot of amps. So I am hoping someone will have experience with small banks for smaller boats focused on racing and weekending.

[Third Reef 26]

If you don’t have a dedeicated starting battery then you need a dual use battery. Suggest you shop around locally and the net for an AGM unit(s) with around 50-100 amp hours. Your biggest issue will be physically sizing. 

Are you running a solar battery regulator between the solar cells and the battery ?

A

[Moonduster 316]

The last thing I would recommend is AGM. The first question is whether you race your boat ... and whether rules compliance is a concern as it requires both sealed batteries and a separate start battery in some cases.

Do you race? Do you intend to race in any Cat 0, 1, 2 or 3 events?

 

[Third Reef 26]

7 minutes ago, Moonduster said:

The last thing I would recommend is AGM. The first question is whether you race your boat ... and whether rules compliance is a concern as it requires both sealed batteries and a separate start battery in some cases.

Do you race? Do you intend to race in any Cat 0, 1, 2 or 3 events?

 

He says he doesn’t want a dedicated starting battery.

Want do you have against one of the most commonly available batteries?

 

3R

[Moonduster 316]

Many people who race don't realize that some events require a separate start battery. He says he wants a solution for racing and cruising, it's possible he's just unaware. I doubt he wants to race and be non-compliant.

Regarding AGM, they're overpriced and fickle. Of all possible battery solutions, they are the least compatible with his low capacity, low cost desires.

 

[freewheelin 162]

23 minutes ago, Third Reef said:

Are you running a solar battery regulator between the solar cells and the battery ?

yes, I use a 20A solar charge controller. A cheap one I got off amazon, but it works.

My concern with AGM is that my alternator is stock, so i would need to add a regulator there (from my very loose understanding).

[kent_island_sailor 5,283]

First principles:

Your 25 watts of solar only provide X amp hours per day. A battery from a submarine won't give you much more usable power than you have now.

So first order of business: Get at least 50 watts and a good MPPT charge controller.

Second - reduce the demand side. Replace every light with an LED.

Third - Improve batteries. I do not like AGM for your application. They really hate not being well topped off. Gel batteries are more tolerant for your application and have around twice the cycle life. Golf cart batteries are cheap for the capacity if you have room and want rugged wet cells.

Fourth - Improve your engine charging and think about going to big house small start instead of 2 27s.

 

[freewheelin 162]

25 minutes ago, Moonduster said:

The last thing I would recommend is AGM. The first question is whether you race your boat ... and whether rules compliance is a concern as it requires both sealed batteries and a separate start battery in some cases.

Do you race? Do you intend to race in any Cat 0, 1, 2 or 3 events?

 

Thanks for the response. I do race, but only phrf and club racing. I checked our local rules and saftey requirements and they don't mention batteries. No on Cat 0-3 events.

FWIW, I am not opposed to running a dedicated starting battery. But the boat came this way because the previous owner kept it on shore power. I haven't had a problem with the current setup, but could always re-wire if necessary.

[kent_island_sailor 5,283]

What is your budget for this project?:

[Moonduster 316]

A dedicated start battery is not worthwhile, in my opinion, in your application. It's difficult to charge properly and there's no failure analysis in which it increases reliability. You're much better off with a low voltage cut out that turns off your loads (other than the starter) when the voltage falls below a programmed threshold.

Given your description, the question comes down to how you look at budget. If you want a low upfront price, then you want to get yourself a flooded lead-acid battery like this. Shopping around might save you 25% or so. Taken care of thoughtfully, it should last 3-5 seasons.

If you're instead focused on total cost of ownership and can make a bigger up front investment, then I'd recommend an LFP battery like this. Taken care of thoughtfully, it will outlast your boat.

[freewheelin 162]

5 minutes ago, kent_island_sailor said:

First principles:

Your 25 watts of solar only provide X amp hours per day. A battery from a submarine won't give you much more usable power than you have now.

So first order of business: Get at least 50 watts and a good MPPT charge controller.

Second - reduce the demand side. Replace every light with an LED.

Third - Improve batteries. I do not like AGM for your application. They really hate not being well topped off. Gel batteries are more tolerant for your application and have around twice the cycle life. Golf cart batteries are cheap for the capacity if you have room and want rugged wet cells.

Fourth - Improve your engine charging and think about going to big house small start instead of 2 27s.

 

Thanks Kent.

To answer some questions:

1) I have a PNW controller, but can add another panel to it if needed. But that is another thing to take down and stow when sailing. I only use the solar to keep the batteries topped of and/or recharge after a daysail. Anything more that that I don't mind using the alternator and running the engine.

2) Everything has gone over to LED

3) That is my concern with AGM. I want something that is low fuss. Aren't golf cart batteries 6 v?

4) It hasn't been a huge issue yet, so I don't know if i want to make a huge project. Of course now is the time.

Budget - i'd say $600 or less hopefully.

[Moonduster 316]

If you're willing to run your engine sufficiently long to recharge from each start, then your 25W panel should be sufficient to float out the battery and keep up with self-discharge. I would not consider a pair of 6V batteries, they will have too much capacity for your stated application.

Your loads, other than your engine, are dainty. You don't need a large battery bank.

If you're a little paranoid about winding up unable to start, consider a low cost solution like this.

 

[freewheelin 162]

11 minutes ago, Moonduster said:

A dedicated start battery is not worthwhile, in my opinion, in your application. It's difficult to charge properly and there's no failure analysis in which it increases reliability. You're much better off with a low voltage cut out that turns off your loads (other than the starter) when the voltage falls below a programmed threshold.

Given your description, the question comes down to how you look at budget. If you want a low upfront price, then you want to get yourself a flooded lead-acid battery like this. Shopping around might save you 25% or so. Taken care of thoughtfully, it should last 3-5 seasons.

If you're instead focused on total cost of ownership and can make a bigger up front investment, then I'd recommend an LFP battery like this. Taken care of thoughtfully, it will outlast your boat.

Ok, good advice. I like the idea of a low voltage cutoff. I didn't think of that. 

I am not opposed to a large investment up front for something that will last. I generally lean that way. I am not sure that I understand the value of the lithium though - is it longer life between charges? based on the AH it doesn't seem that way.

By the way - does the group number indicate physical size? 

[Ishmael 10,550]

2 minutes ago, freewheelin said:

Ok, good advice. I like the idea of a low voltage cutoff. I didn't think of that. 

I am not opposed to a large investment up front for something that will last. I generally lean that way. I am not sure that I understand the value of the lithium though - is it longer life between charges? based on the AH it doesn't seem that way.

By the way - does the group number indicate physical size?

BCI Group Number	L (inches)	W (inches)	H (inches)	L (mm)	W (mm)	H (mm)
Passenger Car and Light Commercial Batteries (12 Volt/6 Cells)
21	8-3/16	6-13/16	8-3/4	208	173	222
22F	9-1/2	6-7/8	8-5/16	241	175	211
22HF	9-1/2	6-7/8	9-1/2	241	175	229
22NF	9-7/16	5-1/2	8-15/16	240	140	227
22R	9	6-7/8	8-5/16	229	175	211
24	10-1/4	6-13/16	8-7/8	260	173	225
24F	10-3/4	6-13/16	10-3/4	273	173	229
24H	10-1/4	6-13/16	9-3/8	260	173	238
24R	10-1/4	6-13/16	9	260	173	229
24T	10-1/4	6-13/16	9-3/4	260	173	248
25	9-1/16	6-7/8	8-7/8	230	175	225
26	8-3/16	6-13/16	7-3/4	208	173	197
26R	8-3/16	6-13/16	7-3/4	208	173	197
27	12-1/16	6-13/16	8-7/8	306	173	225
27F	12-1/2	6-13/16	8-15/16	318	173	227
27H	11-3/4	6-13/16	9-1/4	298	173	235
29NF	13	5-1/2	8-15/16	330	140	227
33	13-5/16	6-13/16	9-3/8	338	173	238
34	10-1/4	6-13/16	7-7/8	260	173	200
34R	10-1/4	6-13/16	7-7/8	260	173	200
35	9-1/16	6-7/8	8-7/8	230	175	225
36R	10-3/8	7-1/4	8-1/8	263	183	206
40R	10-15/16	6-7/8	6-7/8	277	175	175
41	11-3/16	6-7/8	6-7/8	293	175	175
42	9-5/16	6-13/16	6-13/16	243	173	173
43	13-1/8	6-7/8	8-1/16	334	175	205
45	9-7/16	5-1/2	8-15/16	240	140	227
46	10-3/4	6-13/16	9	273	173	229
47	9-11/16	6-7/8	7-1/2	246	175	190
48	12-1/16	6-7/8	7-9/16	306	175	192
49	15	6-7/8	7-3/16	381	175	192
50	13-1/2	5	10	343	127	254
51	9-3/8	5-1/16	8-13/16	238	129	223
51R	9-3/8	5-1/16	8-13/16	238	129	223
52	7-5/16	5-13/16	8-1/4	186	147	210
53	13	4-11/16	8-1/4	330	119	210
54	7-5/16	6-1/16	8-3/8	186	154	212
55	8-5/8	6-1/16	8-3/8	218	154	212
56	10	6-1/16	8-3/8	254	154	212
57	8-1/16	7-3/16	6-15/16	205	183	177
58	10-1/16	7-3/16	6-15/16	255	183	177
58R	10-1/16	7-3/16	6-15/16	255	183	177
59	10-1/16	7-5/8	7-3/4	255	193	196
60	13-1/16	6-5/16	8-7/8	332	160	225
61	7-9/16	6-3/8	8-7/8	192	162	225
62	8-7/8	6-3/8	8-7/8	225	162	225
63	10-3/16	6-3/8	8-7/8	258	162	225
64	11-11/16	6-3/8	8-7/8	296	162	225
65	12-1/16	7-1/2	7-9/16	306	190	192
70	8-3/16	7-1/16	7-11/16	208	179	196
71	8-3/16	7-1/16	8-1/2	208	179	216
72	9-1/16	7-1/16	8-1/4	230	179	210
73	9-1/16	7-1/16	8-1/2	230	179	216
74	10-1/4	7-1/4	8-3/4	260	184	222
75	9-1/16	7-1/16	7-11/16	230	179	196
76	13-1/8	7-1/16	8-1/2	334	179	216
78	10-1/4	7-1/16	7-11/16	260	179	196
85	9-1/16	6-13/16	8	230	173	203
86	9-1/16	6-13/16	8	230	173	203
90	9-11/16	6-7/8	6-7/8	246	175	175
91	11	6-7/8	6-7/8	280	175	175
92	12-1/2	6-7/8	6-7/8	317	175	175
93	15	6-7/8	6-7/8	354	175	175
95R	15-9/16	6-7/8	7-1/2	394	175	190
96R	9-9/16	6-13/16	6-7/8	242	173	175
97R	9-15/16	6-7/8	7-1/2	252	175	190
98R	11-3/16	6-7/8	7-1/2	283	175	190
Passenger Car and Light Commercial Batteries (6 Volt/3 Cells)
1	9-1/8	7-1/8	9-3/8	232	181	238
2	10-3/8	7-1/8	9-3/8	264	181	238
2E	19-7/16	4-1/8	9-1/8	492	105	232
2N	10	5-9/16	8-15/16	254	141	227
17HF	7-3/8	6-7/8	9	187	175	229
Heavy-Duty Commercial Batteries (12 Volt/6 Cells)
4D	20-3/4	8-3/4	9-7/8	527	222	250
6D	20-3/4	10	10-1/4	527	254	260
8D	20-3/4	11-1/8	9-7/8	527	283	250
28	10-5/16	6-13/16	9-7/16	261	173	240
29H	13-1/8	6-3/4	9-1/8	334	171	232
30H	13-1/2	6-13/16	9-1/4	343	173	235
31	13	6-13/16	9-7/16	330	173	240
Electric Vehicle Batteries (6 Volt/3 Cells)
GC2	10-3/8	7-3/16	10-5/8	264	183	270
GC2H	10-3/8	7-3/16	10-5/8	264	183	270

[freewheelin 162]

What about 2 of these, with a booster as backup (thanks moon - great suggestion)?

https://www.batteriesplus.com/battery/marine-and-boat/na/bci-group-27m/sli27mdp

That may keep me going for a few years for less than $300.

[Ishmael 10,550]

27 minutes ago, freewheelin said:

What about 2 of these, with a booster as backup (thanks moon - great suggestion)?

https://www.batteriesplus.com/battery/marine-and-boat/na/bci-group-27m/sli27mdp

That may keep me going for a few years for less than $300.

There's a lot of truth to the saying that you buy batteries by weight. The Duracell weighs 49 pounds, the equivalent Trojan weighs 60 pounds. Heavier plates, longer life. Walmart used to sell the Duracell, you might see if they still carry them, probably save a few $.

[freewheelin 162]

2 minutes ago, Ishmael said:

There's a lot of truth to the saying that you buy batteries by weight. The Duracell weighs 49 pounds, the equivalent Trojan weighs 60 pounds. Heavier plates, longer life. Walmart used to sell the Duracell, you might see if they still carry them, probably save a few $.

ok, thanks. I will look into trojan then. any other brands worth checking out?

[Third Reef 26]

1 hour ago, Moonduster said:

The last thing I would recommend is AGM.

 

I picked up a 200Ahr AGM battery from a solar shop for $300AUD and have been running it hard on my 30' cat 3 racer/cruiser for 5 years. It still hold volts. I have a 40Watt solar panel that takes the batter to full charge between sails with motor charging from time to time. My alternator charges just below the float voltage. Running lights, radio, AIS and auto pilot, sometimes  for days at a time. I do however have a seperate starter and a battery combiner.

3R

[hard aground 78]

2 hours ago, freewheelin said:

ok, thanks. I will look into trojan then. any other brands worth checking out?

Penn, Deka, Rolls, Interstate. 

[freewheelin 162]

1 minute ago, hard aground said:

Penn, Deka, Rolls, Interstate. 

thank you!

[Ishmael 10,550]

15 minutes ago, freewheelin said:

thank you!

West Marine batteries are made by East Penn (last time I checked). They occasionally had some super battery buys, but their regular prices suck.

[toddster 922]

Looking around, it seems as if prices on (some) LiFePO4 batteries are beginning to drop.  Into the range where I don’t dismiss the idea out of hand any more.   

[kent_island_sailor 5,283]

4 hours ago, freewheelin said:

Thanks Kent.

To answer some questions:

1) I have a PNW controller, but can add another panel to it if needed. But that is another thing to take down and stow when sailing. I only use the solar to keep the batteries topped of and/or recharge after a daysail. Anything more that that I don't mind using the alternator and running the engine.

2) Everything has gone over to LED

3) That is my concern with AGM. I want something that is low fuss. Aren't golf cart batteries 6 v?

4) It hasn't been a huge issue yet, so I don't know if i want to make a huge project. Of course now is the time.

Budget - i'd say $600 or less hopefully.

You get much better charging from a good MPPT controller than PWM. This is one of my winter projects. I have one 50 watt panel that is easy enough to move around and store.

Golf cart batteries are 6 volts, thus you need two of them. Probably overkill for you. I would consider two new 27s run parallel as one big battery* and a lithium car jump-starter for the off chance you run them dead. This all would be well within your budget and pretty simple.

* the shallower the discharge, the longer they last.

[Moonduster 316]

There are several advantages to LFP:

• LA batteries can only be discharged to 50%. An LFP battery can be discharged to 80% or further. So a 100AH LA battery has 50 useable AH and could be replaced with a 60AH LFP battery at no loss of useable capacity
• LFP batteries can be charged to full capacity at a high rate, where as LA batteries can only be charged to about 80% at a high rate and then their ability to accept charge slowly tapers off. This means longer charge cycles and more engine hours
• LFP weighs about 25% of LA for the same useable capacity. 

While it's true that longevity of LA batteries is proportional to weight - provided they're cared for - the relationship is non-linear. And heavy batteries cost more, too, again with a non-linear relationship. Rolls batteries are certainly the heaviest of which I'm aware, and have a very long life properly maintained. However, they don't pay for themselves. And, since weight is the enemy of performance on a racing sail boat, I would caution about pursuing very expensive, very heavy batteries - they don't make sense in this application.

[sonofasailor4x 3]

We have a 31' Elan 31S  racer / cruiser we keep on a mooring.   The boat came with a 15 year old! (we have proof) Deka Dominator 31 Gel battery house battery that was still ticking.  Still, it seemed like we should replace it.  After MUCH research on AGM, Wet cell (rolls and trojan), and others, we decided just to replace it with the same Deka Dominator.  Here's why - Gel batteries have a low self discharge rate so can sit on a mooring for a long time without being fully discharged.  Also, they can recover better from a very low discharge that might also happen on a mooring.  So we use it has the house battery. It's great. 

For the starting battery we use a group 24 battery which is a bit lighter and cheaper.  Deka group 24 Marine Master.  Lots of amps for the size, and pretty cheap comparatively, so if it dies sooner,  so be it.  No allegiance to Deka, it just happens they had the batteries that fit our needs.

HTH.

 

 

[fufkin 641]

Freewheelin's power needs are miniscule.

If he got top of the line oversize AGM's(Lifeline)(w Pro Mariner) wired them parallel so that both batteries handle start/house and wear/and/tear simultaneously over their lifetime...how much charge would he really have to replace over the course of the week in between races? 1% or less? The weight might be down low and negligible for beercan racing. 

I'm aware of the need to top to 100% w AGMs but he'd be barely scratching the surface on weekly usage and could likely trickle charge(yeah the last 1% is the hardest). (I"m not sure what his engine based charging is). If he ran the batteries and flexed them and shore powered them on a semi regular or even once in a while basis I bet they'd last 9 years or more. The 9 years running free of hassle vs turfing inferior batteries every 3 years? Priceless.

Up front cost is the other side of it. 

[El Borracho 2,614]

4 hours ago, fufkin said:

Freewheelin's power needs are miniscule.

If he got top of the line oversize..

Except in the thread title is Racer/Cruiser. So as Moonduster points out weight should be a factor. I use the minimal size pair of Trojans. For me that is just a pair of T-105’s. Abuse them horribly with deep discharge and poor charging. They last the expected five years. Not expensive (in sailing terms) to replace anywhere in the world. I have a tiny dedicated generic start battery that is always fully charged. It lasts about ten years...like a car.

I should use lithium...but don’t think my casual habits are compatible with the fragility and complexity of the contemporary offerings. Checking electolyte level is about my limit of attention, to be honest.

[MangoCats 9]

11 hours ago, toddster said:

Looking around, it seems as if prices on (some) LiFePO4 batteries are beginning to drop.  Into the range where I don’t dismiss the idea out of hand any more.   

This ^^^ is my first thought - keep your existing system and have a Lithium backup for starting, it's one thing to read the spec sheets, quite another to lift a LiFePO4 that is capable of starting your engine - they are alarmingly light, and small, and whatever they cost may well be compensated for by those factors.

[Steam Flyer 8,388]

15 minutes ago, MangoCats said:

This ^^^ is my first thought - keep your existing system and have a Lithium backup for starting, it's one thing to read the spec sheets, quite another to lift a LiFePO4 that is capable of starting your engine - they are alarmingly light, and small, and whatever they cost may well be compensated for by those factors.

The problem with these batteries is that they need a fairly sophisticated charger and 100% unflagging adherence to the maintenance regime. You can't simply wire them in, and switch them in/out; unless you're a heck of a lot smarter and more diligent than average.

Shucks, I take good care of a set for RC model sailing, and find it a bit trying, and have killed one set.

-DSK

[fufkin 641]

2 hours ago, El Boracho said:

Except in the thread title is Racer/Cruiser. So as Moonduster points out weight should be a factor. I use the minimal size pair of Trojans. For me that is just a pair of T-105’s. Abuse them horribly with deep discharge and poor charging. They last the expected five years. Not expensive (in sailing terms) to replace anywhere in the world. I have a tiny dedicated generic start battery that is always fully charged. It lasts about ten years...like a car.

I should use lithium...but don’t think my casual habits are compatible with the fragility and complexity of the contemporary offerings. Checking electolyte level is about my limit of attention, to be honest.

Lifeline 27 and Trojan 105 both around 65 lbs. When I refer to an oversized battery it would be something like a Lifeline 31xt weighing in at 75 lbs, which boosts Ah from 105 to 125...complete overkill for his app but bullet proof. The rate of monthly self discharge for the Lifelines would be in the 1-3% range vs 5-10% for the Trojans.

 

 

[kent_island_sailor 5,283]

Gel batteries have really low self discharge. Back before I had solar or shore power, my gel batteries that sat from December to March had no issue starting the engine.

[Moonduster 316]

You say:

Freewheelin's power needs are miniscule.

If he got top of the line oversize AGM's(Lifeline)(w Pro Mariner) wired them parallel so that both batteries handle start/house and wear/and/tear simultaneously over their lifetime...how much charge would he really have to replace over the course of the week in between races? 1% or less? The weight might be down low and negligible for beercan racing. 

I'm aware of the need to top to 100% w AGMs but he'd be barely scratching the surface on weekly usage and could likely trickle charge(yeah the last 1% is the hardest). (I"m not sure what his engine based charging is). If he ran the batteries and flexed them and shore powered them on a semi regular or even once in a while basis I bet they'd last 9 years or more. The 9 years running free of hassle vs turfing inferior batteries every 3 years? Priceless.

This is a classic example self-contradictory piss poor analysis used by hacks the world over. Allow me to summarize:

Requirements: Small

Solution: Large and expensive

What on earth are you thinking? It's just inane. If ever there was an application for a single, inexpensive flooded battery, this is it. Instead you're recommending two expensive fickle batteries. It's just stupid.

 

[freewheelin 162]

8 hours ago, fufkin said:

I'm aware of the need to top to 100% w AGMs but he'd be barely scratching the surface on weekly usage and could likely trickle charge(yeah the last 1% is the hardest). (I"m not sure what his engine based charging is). If he ran the batteries and flexed them and shore powered them on a semi regular or even once in a while basis I bet they'd last 9 years or more. The 9 years running free of hassle vs turfing inferior batteries every 3 years? Priceless.

I will need to check the specs on the alternator, but i think it is rather small. its a 18 HP engine, so maybe a 30-40 amp?

Shore power semi-regular is not a good option for me. I can go a whole season without hooking up to shore power. If before and after hauling would be enough, then maybe. But it is sounding like AGM may be too fickle for my uses.

[freewheelin 162]

3 hours ago, El Boracho said:

Except in the thread title is Racer/Cruiser. So as Moonduster points out weight should be a factor. I use the minimal size pair of Trojans. For me that is just a pair of T-105’s. Abuse them horribly with deep discharge and poor charging. They last the expected five years. Not expensive (in sailing terms) to replace anywhere in the world. I have a tiny dedicated generic start battery that is always fully charged. It lasts about ten years...like a car.

Weight is a factor, yes. I like to keep things light on the boat as much as I can. Thanks for the t-105 recommendation. Though I dont have a dedicated starting battery so it sounds like i'll need a dual purpose.

[kent_island_sailor 5,283]

7 minutes ago, freewheelin said:

Weight is a factor, yes. I like to keep things light on the boat as much as I can. Thanks for the t-105 recommendation. Though I dont have a dedicated starting battery so it sounds like i'll need a dual purpose.

Not really. A start battery has many thin plates. These get destroyed when deep-cycled, but provide a lot of cranking current per pound/size of the battery. For starting, that is exactly what you want. Deep cycle batteries have thicker plates. These stand up to deep cycling much better, but for a given size of battery have less cranking amps and are slower to recharge. This does not mean they will not start engines and does not mean that doing so damages them. What it does mean is that they would need to be bigger and heavier than a start battery to be able to start the same size engine. Golf cart batteries will have no issue at all starting a small diesel. Golf cart batteries are made to be abused. They got run down way past 50% all the time and get banged around. They are also easy to move around by hand compared to a big 12 volt battery.

The above is for wet cells.
AGMs come in start, deep cycle, and dual purpose configurations. Gels are made just one way and are good for deep cycle use and they can start engines.

If you don't mind the drawbacks of AGMs, East-Penn Deka makes West Marine AGMs and also sells them at Sams Clulb under their label (Energizer? Duracell??) in size 31 for literally half the price

[Slick470 241]

Also have a 30 footer. Make sure that you measure where the batteries can go. Not just length and width, but height too. On our boat I can just fit two group 31 LAs in the battery bay, but they are too tall and I can't close the lid. Most golf cart batteries are also a non starter for us due to their height. 

Sealed batteries like AGMs can open up more options because they don't have to be installed upright. 

 

[sbman 25]

I've been using Wal Mart branded Group 29 'deep cycle' batteries with really good success (3+ years so far). There are only a few manufacturers that actually make batteries, they are mostly rebranded versions of the same thing. I'm not sure who is making the current batch of wal-mart batteries.  You have to look closely at the labels to get the deep cycle instead of the dual purpose.  They start small engines OK, and two in parallel will be plenty of cranking amps to start your diesel. (1200 cranking amps for dual group 27)  Their Group 27 for $82 each, Group 29 for $99.  Add an MPPT charger and a second panel for 50W and you'll be good. Even if you have to replace batteries in 3 or 4 years, you won't feel too bad about it at that price.

https://www.walmart.com/ip/EverStart-Lead-Acid-Marine-RV-Battery-Group-27DC/164242687

https://www.walmart.com/ip/Everstart-Maxx-Lead-Acid-Marine-RV-Battery-Group-29DC/131118029

Alternatively, the recommendations for dual 6V trojan golf cart batteries is also excellent advice, and they will likely have a longer lifespan.

You still want a bit more solar and a good charge controller though to make sure they are getting a good charge consistently.  Check and add water once in a while.

[MangoCats 9]

4 hours ago, Steam Flyer said:

The problem with these batteries is that they need a fairly sophisticated charger and 100% unflagging adherence to the maintenance regime. You can't simply wire them in, and switch them in/out; unless you're a heck of a lot smarter and more diligent than average.

Shucks, I take good care of a set for RC model sailing, and find it a bit trying, and have killed one set.

-DSK

Are your model batteries LiPo (polymer) or LiFePO4 (Iron Phosphate)?  LiPo are considerably shorter lived, and more finicky.   Iron Phosphate is what they're building most EV car battery packs from.  There are many on the market today kitted out as a "drop in replacement" for 12 lead acid, with the charging circuitry to make them compatible with standard alternator output.  They're small and light enough that carrying it to and from the boat and keeping it on trickle charge at home wouldn't be any more onerous than bringing a 4-pack of beers.

[weightless 699]

4 hours ago, Steam Flyer said:

The problem with these batteries is that they need a fairly sophisticated charger and 100% unflagging adherence to the maintenance regime. You can't simply wire them in, and switch them in/out; unless you're a heck of a lot smarter and more diligent than average.

Shucks, I take good care of a set for RC model sailing, and find it a bit trying, and have killed one set.

-DSK

Yep. Changing from FLA to VRLA also requires changes that have to be done correctly and completely. There's nothing particularly complex or inscrutable about managing a gel, an AGM or a LiFePO4 in theory. However,  the details matter and the risk costs and opportunity costs get bigger as you get into fancier batteries. Modifying the whole system and then leaving it on its own on a swing mooring must increase the risk of a bug destroying an expensive battery. If it were me I'd stick with FLA. I might look into a small jump start battery / power bank that I could charge at home and take to the boat. If the engine has a crank start option it might be worth having the crank aboard... Maybe.

[MangoCats 9]

2 minutes ago, weightless said:

Yep. Changing from FLA to VRLA also requires changes that have to be done correctly and completely. There's nothing particularly complex or inscrutable about managing a gel, an AGM or a LiFePo4 in theory. However,  the details matter and the risk costs and opportunity costs get bigger as you get into fancier batteries. Modifying the whole system and then leaving it on its own on a swing mooring must increase the risk of a bug destroying an expensive battery. If it were me I'd stick with FLA. I might look into a small jump start battery / power bank that I could charge at home and take to the boat. If the engine has a crank start option it might be worth having the crank aboard... Maybe.

Agreed, if you're just going to slap a LiFePO4 starter battery in parallel with your existing FLAs and hope for the best, that has an unacceptably high chance of ending poorly.  However, if you can hook up a bank-switch to choose starter power between the existing FLAs and the LiFePO4 and just manage the LiFePO4 charging separately, that _should_ be a straight forward setup for someone with the patience to read and understand the basic instructions.

I'm curious - are crank-start adapters for Yanmar 2GMs a common thing?  My previous boat had a pull-start 30HP outboard, because I really don't like the fuss and bother of battery maintenance.

[MangoCats 9]

This: https://www.amazon.com/Shorai-Xtreme-Rate-LifePO4-Duration-LFX14L2-BS12/dp/B008VIIWLW is the LiFePO4 tech I'm talking about.

Proceed with due care, I will not be held liable when your boat goes up like a Tesla that's been rigged to burn...

[weightless 699]

9 minutes ago, MangoCats said:

I'm curious - are crank-start adapters for Yanmar 2GMs a common thing?

I think some of them came with cranks and some didn't. I've got two that came with handles and could, in theory, be started by hand.

[Moonduster 316]

The compression ratio of diesel engines makes pull or crank start very challenging. Some models fitted with compression release levers are startable, but I'm unaware of multi-cylinder engines that can be hand started.

A start booster pack is a fine alternative to a hand crank.

[CruiserJim 112]

Question for the OP - you said "replace/upgrade".   Which do you mean?  Is your current setup working well enough for you, or are there specific things you want that make the current setup inadequate?   If what you have is doing what you need, KISS and just replace and go sailing.

 

[freewheelin 162]

3 minutes ago, CruiserJim said:

Question for the OP - you said "replace/upgrade".   Which do you mean?  Is your current setup working well enough for you, or are there specific things you want that make the current setup inadequate?   If what you have is doing what you need, KISS and just replace and go sailing.

Hey Jim,

Good question. The boat is newish to me (bought last april). The setup worked fine at first, then late season got out to the boat (after letting it sit for a over a week) and couldn't turn it over. There was no voltmeter on the boat, so i figured I hadn't charged it enough and was just dealing with discharge- so added the solar to help keep it topped off (which I planned to do anyway). Turns out the problem was one of the two batteries was flat dead, and therefore drawing down the charge. So I pulled it out of parallel and ran off the one battery for the rest of the season. Figured I would wait until spring to replace both, rather than have one sit all winter.

I realize that is a long answer for a short question. But the "replace/upgrade" meant either. If the setup I have seems best, then looking for recommendations on replacing (group 27, deep cycle). Or, if there is a better options out there for my use, I was thinking of upgrading the bank to AGM or Lithium. I didnt know much before starting this thread, and it has been quite helpful.

[kent_island_sailor 5,283]

6 minutes ago, freewheelin said:

Hey Jim,

Good question. The boat is newish to me (bought last april). The setup worked fine at first, then late season got out to the boat (after letting it sit for a over a week) and couldn't turn it over. There was no voltmeter on the boat, so i figured I hadn't charged it enough and was just dealing with discharge- so added the solar to help keep it topped off (which I planned to do anyway). Turns out the problem was one of the two batteries was flat dead, and therefore drawing down the charge. So I pulled it out of parallel and ran off the one battery for the rest of the season. Figured I would wait until spring to replace both, rather than have one sit all winter.

I realize that is a long answer for a short question. But the "replace/upgrade" meant either. If the setup I have seems best, then looking for recommendations on replacing (group 27, deep cycle). Or, if there is a better options out there for my use, I was thinking of upgrading the bank to AGM or Lithium. I didnt know much before starting this thread, and it has been quite helpful.

"Best" would cost multiple thousands of dollars.
New FLA , 50 watts, and MPPT would probably work well for you and cost around $400-$500 all in.

[weightless 699]

14 minutes ago, Moonduster said:

I'm unaware of multi-cylinder engines that can be hand started.

My 2gm20's came with hand cranks and have decompression levers. The Yanmar folks must have figured it was possible to hand start them. I haven't attempted it. Years ago I hand cranked a one cylinder Yanmar and it was a PIA. I suppose one might get the knack of it but I wouldn't attempt it if I had other options.

[CruiserJim 112]

Gotcha.  If one battery worked for you last year, then I'd say replace them both with two matching batteries, both deep-cycle.  These batteries have no problem delivering enough current to turn over the engines found in small sailboats, don't worry about "dual purpose".   Keep the batteries electrically separate, one for start, one for house.  Alternate how you use them.  Parallel them when running the engine (or get a combiner switch to do it automatically).   

Does your controller have two separate outputs?  This would be ideal, when you leave the boat the controller will direct the panel output to each battery as needed but the batteries will be kept separate so a flaw in one won't discharge the other.

Get good quality conventional flooded batteries.  Your power needs are minimal and this should do you just fine until you do something crazy like add DC refrigeration.  No need to break the bank on this one IMO.  

[Ishmael 10,550]

12 minutes ago, weightless said:

My 2gm20's came with hand cranks and have decompression levers. The Yanmar folks must have figured it was possible to hand start them. I haven't attempted it. Years ago I hand cranked a one cylinder Yanmar and it was a PIA. I suppose one might get the knack of it but I wouldn't attempt it if I had other options.

I read of one sailor who, faced with dead batteries, wrapped the mainsheet around the flywheel (?) and gybed. Got the engine going.

[freewheelin 162]

7 minutes ago, CruiserJim said:

Gotcha.  If one battery worked for you last year, then I'd say replace them both with two matching batteries, both deep-cycle.  These batteries have no problem delivering enough current to turn over the engines found in small sailboats, don't worry about "dual purpose".   Keep the batteries electrically separate, one for start, one for house.  Alternate how you use them.  Parallel them when running the engine (or get a combiner switch to do it automatically).   

Does your controller have two separate outputs?  This would be ideal, when you leave the boat the controller will direct the panel output to each battery as needed but the batteries will be kept separate so a flaw in one won't discharge the other.

Get good quality conventional flooded batteries.  Your power needs are minimal and this should do you just fine until you do something crazy like add DC refrigeration.  No need to break the bank on this one IMO.  

yes, controller has separate outputs, but I have not used them because the batteries have been in parallel. others on here have recommended keeping them in parallel, with a lithium booster backup just in case. I do like the idea of having a bigger house bank to draw down.

[CruiserJim 112]

If you want a bigger house bank, that will work.  Just depends on your intended usage.  I know when I switched to LED cabin and anchor lights, switching them on would not even budge my ammeter, so again your current draw is very low.  Depends how many nights you are either underway or on the hook and how much solar you get. 

I prefer to parallel the house batteries thru a battery switch when in use, but separating them when leaving the boat unattended.  Batteries can develop internal shorts, causing the bad battery to deplete the good one.  And it is possible (although very rare) for this to create a very high current draw between the batteries, which can create a lot of heat.  Happened to a friend of mine.  No fire, he just happened to stop by and check on his boat one day and smelled an electrical burning odor.  

[kent_island_sailor 5,283]

5 minutes ago, CruiserJim said:

If you want a bigger house bank, that will work.  Just depends on your intended usage.  I know when I switched to LED cabin and anchor lights, switching them on would not even budge my ammeter, so again your current draw is very low.  Depends how many nights you are either underway or on the hook and how much solar you get. 

I prefer to parallel the house batteries thru a battery switch when in use, but separating them when leaving the boat unattended.  Batteries can develop internal shorts, causing the bad battery to deplete the good one.  And it is possible (although very rare) for this to create a very high current draw between the batteries, which can create a lot of heat.  Happened to a friend of mine.  No fire, he just happened to stop by and check on his boat one day and smelled an electrical burning odor.  

You are quite right, all this can be done with the switch without any rewiring.

[Moonduster 316]

There are lots of many ways in which connecting batteries in parallel or series causes more problems than offers solutions. It's never a feature of a good installation where needs can be satisfied with a single battery and a low voltage cut off switch.

[fufkin 641]

On February 4, 2019 at 3:27 PM, freewheelin said:

This spring I will be replacing/upgrading my batteries. I am replacing two 12 V group 27 deep cycle wet cell batteries. The boat (30 fter) lives on a mooring during the season, and the two batteries are in parallel. I have 25 watts of solar charging them when I'm not around. My goal is as much battery life as possible between charging. I sail on and off most days, and want to minimize the need to run the engine to charge. Normal amp draw is pretty low - just instruments, running lights, and LED cabin light - but without a dedicated starting battery, having the juice left over to start the motor is important.

I know this is pretty vague, but when I look at all the battery options out there it seems to be a huge range of products and prices. But a lot of the information seems to be directed at long term cruisers drawing a lot of amps. So I am hoping someone will have experience with small banks for smaller boats focused on racing and weekending.

Moonduster, I'm not gonna get into a battery shitfight with you, the resident battery guru, but let me try to spell out my rationale. 

Yes he says small banks. But small is relative. He's currently running group 27 wet cell.  The weight difference between a wet cell group 27 Trojan and a group 27 AGM Lifeline is 7 pounds. I hope that doesn't fuck with his racing results. Nowhere in his initial post do I see a mention of price...but I'll get to that.

9 hours ago, Moonduster said:

You say:

Freewheelin's power needs are miniscule.

If he got top of the line oversize AGM's(Lifeline)(w Pro Mariner) wired them parallel so that both batteries handle start/house and wear/and/tear simultaneously over their lifetime...how much charge would he really have to replace over the course of the week in between races? 1% or less? The weight might be down low and negligible for beercan racing. 

I'm aware of the need to top to 100% w AGMs but he'd be barely scratching the surface on weekly usage and could likely trickle charge(yeah the last 1% is the hardest). (I"m not sure what his engine based charging is). If he ran the batteries and flexed them and shore powered them on a semi regular or even once in a while basis I bet they'd last 9 years or more. The 9 years running free of hassle vs turfing inferior batteries every 3 years? Priceless.

This is a classic example self-contradictory piss poor analysis used by hacks the world over. Allow me to summarize:

Requirements: Small

Solution: Large and expensive

What on earth are you thinking? It's just inane. If ever there was an application for a single, inexpensive flooded battery, this is it. Instead you're recommending two expensive fickle batteries. It's just stupid.

 

 

Your  group 24 Deka wet cell rates cold crank 550, 65 amp h at 20 hr, 120 minutes at 25 amps, weighing in at 44 lbs.

The smaller sizing upfront means he will draw a larger % of total capacity to start his engine a couple of times a week and use of the electronics/lights etc. He will then have to replace this larger % of total capacity at a slower acceptance than the Lifeline AGM. He will also have a faster self-discharge rate to add to his already small charging set-up. 

My approach of going for bigger, even at a group 27 Lifeline adds a hefty 18lbs per battery(over the group24, approx 6lbs over wet cell group 27)to this racer/cruiser phrf boat probably down low and near the engine, but brings a more realistic 715 cold crank, 100 amp h at 20hr, 186 minutes at 25amps. This would probably be the best bet...''oversizing' might not be necessary, but as I meant it would be going to a 31T adding a whole 2 lbs per battery and brings the #s to 750, 105 and 195 respectively. Going for the whole hog 31xt adds another 10lbs, and brings the numbers to 800, 125, and 230minutes at 25amps respectively. 

In any of these batteries, his usage will barely scratch the surface of total capacity and topping them up between his engine and a slightly bolstered solar setup should be fine. (I'd welcome yours or anyone else's opinion on this)

If someone wants to argue the merits of AGM for this application(he says no on occasional shorepower)  fine and for a deeper discharge regime it might be different, but under sizing the battery setup for a guy that wants to replace the group 27s that came w his boat(one of which is depleted...standard clue as to previous use pattern), and stated that his main goal was to have enough juice left over to start the engine every single time? I don't know about that. My version could run his set-up after a month of neglect with just the bilge pump left-on no problem, would withstand a knockdown at the mooring no problem, and would probably withstand an imperfect charging regime with less/no need to recondition. 

So, the price part of it? Well that comes down to running costs over time and I'm pretty sure Freewheelin said he'd consider paying more upfront if it made cents.

My version of expensive is replacing inexpensive batteries every three years in an imperfect real world use regime. More expensive batteries have a better ability to withstand the abuse(to a point), and should obviously be protected by a proper setup and a smart charger. Without going into why, I'll just cite THE source for anyone(lots of you guys already have it I'm sure) who wants to go deeper into it, https://www.amazon.ca/product-reviews/0071790330/ref=pd_lpo_sbs_14_cr_0/136-9550876-1549737?ie=UTF8&refRID=N26Z8P8PFSQTC2RZ995B

Your characterization of a Lifeline battery as fickle is a good one and worth a chuckle. Expensive yes, fickle?...that's a first. 

As for this particular thread, I'll let you guys sort out the various options of a dual battery set-up and the merits of the supposedly superfluous belts and suspender approach of a third dedicated start battery required by many of the authorities that be. 

Cheers.

[Steam Flyer 8,388]

7 hours ago, weightless said:

...    ...    ...  If the engine has a crank start option it might be worth having the crank aboard... Maybe.

Another option is the spring-drive starter. They don't make them for all engines but they are available for a lot of marine engines....... huge torsion spring with a ratchet and geared-down crank, bolts on in place of the electric starter. Crank it up, which can take a hell of a lot of cranking, but then you trip the ratchet and va-va-voom, off to the races.

About the LiPo vs LiFePo batteries, have to admit I don't know. Will look and see, I have a small programmable charger/balancer that I carefully set to match what it says on the label of the battery pack.

FB- Doug

[freewheelin 162]

14 hours ago, Steam Flyer said:

Another option is the spring-drive starter. They don't make them for all engines but they are available for a lot of marine engines....... huge torsion spring with a ratchet and geared-down crank, bolts on in place of the electric starter. Crank it up, which can take a hell of a lot of cranking, but then you trip the ratchet and va-va-voom, off to the races

I appreciate the crank advice, but for my use I can't imagine a time I would use it. I probably should have clarified that starting the engine for me is not a safety concern, just a convenience to have it when I want it. If I can't start it up, I can sail back to the mooring (or anchor if out cruising) and get a booster from shore. 

[freewheelin 162]

20 hours ago, CruiserJim said:

If you want a bigger house bank, that will work.  Just depends on your intended usage.  I know when I switched to LED cabin and anchor lights, switching them on would not even budge my ammeter, so again your current draw is very low.  Depends how many nights you are either underway or on the hook and how much solar you get. 

I prefer to parallel the house batteries thru a battery switch when in use, but separating them when leaving the boat unattended.  Batteries can develop internal shorts, causing the bad battery to deplete the good one.  And it is possible (although very rare) for this to create a very high current draw between the batteries, which can create a lot of heat.  Happened to a friend of mine.  No fire, he just happened to stop by and check on his boat one day and smelled an electrical burning odor.  

Thanks for the advice on this. I do have the batteries run through a battery switch. Actually, both a selector switch and shutoff switches (bat 1, bat 2, general). Sounds like I should just be using them more effectively. I will look at the wiring diagram when I am back to the boat next. But it stands to reason that I should only be drawing one down at a time. (including when i am not on the boat) rather than leaving them in parallel.

[kent_island_sailor 5,283]

[SemiSalt 282]

I've been running my 28-footer on one battery for the last few years. My house needs are minimal: bilge pump, one instrument, VHF.  I have a small solar panel, maybe 15W, to keep the battery charged in the winter, and of course it contributes even more in the summer.

I don't know what freewheelin considers minimal engine charging. I have a half-hour run out to the starting line, and the same getting home. More than enough to replenish after turning the  engine over for 5 seconds during starting.

[bacq2bacq 250]

No one has yet mentioned carbon-enhanced lead-acid....eg http://fireflyenergy.com/

Disclosures:

1) I am running a single carbon-foam G31 in our F31 tri, 200W-faceplate solar with programmable Vmax (please don't boil your VRLA AGMs....), Yammy 9.9 4-stroke with an alternator, and not too much load, and it has sufficed for extended cruising.  Not cheap first-in cost, but over time I have grown tired of replacing premature-death batteries.

2) I am importing these into Ontario, Canada.  In case you are here and want some, you can get them at http://www.totalbattery.com/  Yeah, take out an ad, I know, I know...  In the States maybe try https://www.bruceschwab.com/advanced-energy-storage-systems/firefly-energys-oasis-group-31/

3) I don't worry anymore about keeping the battery "topped up" (flooded, with electrolyte) or "topped-up" (any traditional lead-acid, with charge)  or "balanced" (Lithium-*, better trust your BMS...)...

cheers all,
ben

[freewheelin 162]

On 2/9/2019 at 11:42 AM, SemiSalt said:

 

I don't know what freewheelin considers minimal engine charging. I have a half-hour run out to the starting line, and the same getting home. More than enough to replenish after turning the  engine over for 5 seconds during starting.

Similar to yours. Though I prefer sailing home over re-running the diesel. Twilights & cruising I prefer sailing off as well. I'm on a mooring, which makes both easy.