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Battery Charging at Mooring


freewheelin

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I am going to apologize in advance. I am sure this has been covered 100 times on this forum, but I tried to search and could not find anything. Basically, I keep my (new to me) boat on a mooring and I loathe running the diesel to charge the batteries. 9 times out of 10 I sail on and off the mooring, and would prefer to only have to run the engine when there is no wind and I need to get somewhere. So I am trying to figure out the cheapest, low maintenance option for solar charging of the batteries while the boat swings on the mooring. The goal is to be able to race and/or day sail every weekend without running the engine (unless I want).

A couple more details. It is a 30ft boat, with two 12 volt marine deep cycle batteries (in line for now, will rewire and isolate a starting battery this winter). Normal draw is minimal (bilge pump, speed/depth/wind, and sometimes the stereo) for day sailing or racing. I have no problem running the engine for an hour or so a day if I am out cruising for a week or weekend causing usage to increase. I would greatly prefer something modular over fixed.

Sadly I got lost quickly in the world of solar. I am sure there are others out there in the same situation, so I am looking for advice.

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When you say modular do  you mean a flexible solar panel you can roll up and stow away?

Anyway a small panel of 15-25W will be plenty. We lived on a 30' sailboat for 4 years with a 50W panel supplying all our power. We rarely had to run the engine but didn't have a refrigerator which is a huge load. 

You will also need a controller to avoid overcooking the batteries. A simple PWM type will be sufficient. Just be sure to check the 'float' voltage is not so high that it will gradually boil the batteries over many months.

And since there are lots of vendors out there - avoid the marked up marine sellers. 

 

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19 minutes ago, Zonker said:

A simple PWM type will be sufficient

Plenty good enough. I've gotten away with a simple relay with a bit of hysteresis for years. Still, given how cheap MPPT has gotten I wonder why not go that way?

Just, FWIW, in my testing I didn't see a lot of difference between MPPT that searches for panel voltage and MPPT that assumes it.  Either one made a noticeable difference when battery voltage was low. My testing was with smaller panels, lower voltages and a different battery chemistry... So, more anecdotal than not.

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I kept both my J30 and my J35 topped off with one of the cheap solar panels available at West Marine for many years. Both boats had a couple deep cycle batteries. The panel didn't create enough juice to cook off the batteries during the times I wasn't using the boat. I think I paid 45-50$ for the thing and it worked for many years.

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33 minutes ago, Zonker said:

When you say modular do  you mean a flexible solar panel you can roll up and stow away?

 

thanks, Zonker. Yeah, exactly. I don't even know if it needs to rollup if it is small enough. Just something I can leave out in the cockpit when I am cruising or away from the boat, but can disconnect and stow below when I am racing with crew or sailing with friends and need the space. That's the idea at least.

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2 hours ago, weightless said:

Plenty good enough. I've gotten away with a simple relay with a bit of hysteresis for years. Still, given how cheap MPPT has gotten I wonder why not go that way?

Just, FWIW, in my testing I didn't see a lot of difference between MPPT that searches for panel voltage and MPPT that assumes it.  Either one made a noticeable difference when battery voltage was low. My testing was with smaller panels, lower voltages and a different battery chemistry... So, more anecdotal than not.

Thanks. When looking for PWN or MPPT, what size/type should i look for?

 

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2 hours ago, Bump-n-Grind said:

I kept both my J30 and my J35 topped off with one of the cheap solar panels available at West Marine for many years. Both boats had a couple deep cycle batteries. The panel didn't create enough juice to cook off the batteries during the times I wasn't using the boat. I think I paid 45-50$ for the thing and it worked for many years.

was this one of those trickle chargers?

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1 hour ago, freewheelin said:

Thanks. When looking for PWN or MPPT, what size/type should i look for?

 

I'm no dentist... Dunno if any of this will help or is even correct but I'll type my thoughts out here and folks can correct them:

Easiest is to buy a complete package that's intended for your battery type.  You should have lots of options for what you're trying to do.

The parts of the system are the batteries, the controller and the panels. Since the controller sits between the battery and the panel(s) you need it to match both.

The battery will do best with certain charging characteristics. Identify the type of battery you have. Flooded lead acid, gel, AGM, etc. The controller will list what it's compatible with. Many also allow custom programming.

The panel or array of panels will have characteristic power, voltage (the highest will be open circuit) and current ratings. Your controller needs to meet or exceed those values. Many panels and controllers are intended for 12 volt systems. So, you can often use the current in amps as a first cut. Do check the details before you buy.

PWM is pulse width modulation. In this context it is a scheme that switches the panels on and off based on feedback from the battery.  The panels will work at battery voltage. 

MPPT is maximum power point tracking. Generally, panels intended for 12 volt systems produce maximum power when they run at about 17 volts. If you make a circuit between the solar panel and the battery the panel will be drawn down to the battery voltage. That's going to be less than the maximum power voltage. The MPP part of an MPPT controller uses voltage converters to run the panel at 17 volts or so and provide the battery with its working voltage. The "T" part of MPPT varies the panel voltage to find the actual MPP rather than the nominal one.

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4 hours ago, freewheelin said:

was this one of those trickle chargers?

it wasn't billed as such, just a small flexible solar panel with wires that had gator clips on the end to hook up to a battery.

it was maybe 1ft by 1.5ft

 

 

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15 hours ago, weightless said:

The battery will do best with certain charging characteristics. Identify the type of battery you have. Flooded lead acid, gel, AGM, etc. The controller will list what it's compatible with. Many also allow custom programming.

Thanks for all the information. This is really helpful. The batteries are two basic 12V Deep Cycle group 27 batteries (so flooded lead acid). They are run in line, so I would use the solar to charge both. The batteries are 3 years old, but in good shape. They were kept on shore power until April when I bought the boat.

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Do you really mean "inline"? That's a specific technical term which means  the connections are set up to give you 24V electrics.  It's more common to have them connected "in parallel" to double the capacity available at 12V.

Either works but the setup would be a little different for the two cases.

Cheers,

              W.

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1 hour ago, freewheelin said:

Thanks for all the information. This is really helpful. The batteries are two basic 12V Deep Cycle group 27 batteries (so flooded lead acid). They are run in line, so I would use the solar to charge both. The batteries are 3 years old, but in good shape. They were kept on shore power until April when I bought the boat.

Excellent. That gives you lots of options. To complicate your choices allow me to suggest that you might not want to limit yourself to flexible panels. I used a setup similar to this one (actually more like the 10 watt version)

 https://www.amazon.com/ECO-WORTHY-20W-Solar-Panel-Polycrystalline/dp/B00PFGP0EA?crid=3462MWHCVOBCX&keywords=solar+panel+12+volt&qid=1533657023&sprefix=solar+panel+12+&sr=8-3&ref=mp_s_a_1_3

on a daysailor. Left it on deck at the dock. Chucked it on a berth below when sailing. Worked for years. I put some schmoo on the corners of the frame. The were a bit pointy. The goop also kept the frame off the deck for a bit better ventilation and less wobble. I used a plug connection. 

 

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Ok, thanks. That is a good point about flexible. Provided it is not too big or heavy, I guess flexible doesn't matter that much. would likely switch out the gator clips for a hard connection, and add a quick release.

What I liked about this one was the grommets made for easy tie down, allowing it to be moved around and secured easily. But I could probably rig something similar on a rigid panel i guess.

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2 minutes ago, freewheelin said:

Provided it is not too big or heavy

The small framed panels are surprisingly light. There's not really much to them. Advantages v flexible are that they're generally smaller and cheaper for a given power. They may last longer too, but either way you're looking at inexpensively produced panels so YMMV. I never tied mine down. Just put it on deck and it was fine. There's a power cord on it, of course...

Glanced at the panel you link. It looks fine.  I think the controller Amazon is suggesting for it is of the make or break type. The panel I linked has a PWM controller included. In practice, there's probably not much difference. The PWM controller should keep the battery voltage more steady. Soup to nuts the rigid setup is a good deal cheaper. In boat terms either system is practically free.

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21 minutes ago, kent_island_sailor said:

When I am on my mooring I put my 50 watt panel out and it keeps the batteries topped off no problem. I use a Morningstar PWM controller. I will get MPPT one day and probably gain about 30%or more charging.

Sorta depends on how you define the problem but I don't think you'll get 30% more charging with MPPT if your PWM controller is keeping your batteries topped off. "Full is full."*

*King Pedant III (or somebody else).**

**But it's complicated. Even in the case where you're topping the batteries off there might be and advantage to getting them to float voltage quicker. How much quicker MPPT might get there depends on things (factors, stuff, etc )...

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1 hour ago, kent_island_sailor said:

When I am on my mooring I put my 50 watt panel out and it keeps the batteries topped off no problem. I use a Morningstar PWM controller. I will get MPPT one day and probably gain about 30%or more charging.

Thanks. What size boat & battery bank. I am starting to worry that the 15 watt or so range that I have been looking in may be a little small, and I should go for a little more while I am going for it.

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17 minutes ago, weightless said:

Sorta depends on how you define the problem but I don't think you'll get 30% more charging with MPPT if your PWM controller is keeping your batteries topped off. "Full is full."*

*King Pedant III (or somebody else).**

**But it's complicated. Even in the case where you're topping the batteries off there might be and advantage to getting them to float voltage quicker. How much quicker MPPT might get there depends on things (factors, stuff, etc )...

Maybe I should have been more clear - when the BOAT is on the mooring. If *I* am there, we are using electricity and we usually use more power than we get from solar.

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1 hour ago, weightless said:

^^^ I should add that you can drill all the holes you want into the aluminum frames. If you want to tie the thing down it shouldn't be difficult to attach a bit of string to it.

ok, that makes sense. I am looking a little more at controllers as well, and will likely upgrade to a slightly nicer unit with a display. The cost is pretty much negligible, and that way I can plug in more solar if ever needed.

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1 minute ago, freewheelin said:

Thanks. What size boat & battery bank. I am starting to worry that the 15 watt or so range that I have been looking in may be a little small, and I should go for a little more while I am going for it.

https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Solar/dp/B00DVPPFDS/ref=sr_1_3?ie=UTF8&qid=1533667497&sr=8-3&keywords=50+watt+solar

Do NOT buy West Marine panels. Somehow they have the worst panels for the most money of anyplace.

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17 minutes ago, freewheelin said:

 I am looking a little more at controllers as well, and will likely upgrade to a slightly nicer unit with a display. The cost is pretty much negligible, and that way I can plug in more solar if ever needed.

As you're looking you might want to consider the quiescent power draw of the controllers, their efficiency and if they prevent reverse current. I wouldn't stress out over any of that. I'm pretty sure that the options you've mentioned will work fine.

 

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This might not be enough, and having a controller with displays of output, etc. would be nice, but it works for me. It's a cheap 10w system I got from Menards hardware. It claims to have built in overcharge and discharge protection, so no controller. It's small, and since I wanted to just leave it mounted while sailing, I rigged up a little tilting frame off the transom for it. It has worked well for a year, keeping my deep-cycle lead-acid battery topped up. I use the battery only for a trolling motor to get in and out of my marina if there is not enough wind or direction is problematic, otherwise I sail in and out. Obviously if you split up your two batteries you could use two of these, one for each battery. Anyway, I like the simplicity of this setup, just link the output leads to the battery terminals.

https://www.menards.com/main/electrical/generators-alternative-power-generation/solar-power/coleman-reg-10-watt-solar-12-volt-solar-panel/58025/p-1444444202237-c-6292.htm?tid=-6134962004053644418&ipos=10

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I am narrowing in on a choice. I am looking at this combo:

https://www.amazon.com/gp/product/B00W81BZTO/ref=ox_sc_act_title_1?smid=AV16HZDTPF1LD&psc=1

https://www.amazon.com/gp/product/B01MU0WMGT/ref=ox_sc_act_title_4?smid=A18M12GR6V2Z8F&psc=1

Debating between the 25 watt and 30 watt options for the panel. price is negligible, but I am wondering if the added size of the panel is really worth the extra 5 watts for my use.

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I think that if the panel is small enough compared to the battery bank you can get away with a controller less system. That's one thing less to break and a super simple system, effectively the solar panel trickle charges the battery. Unfortunately I can't remember of the ratio between the panel output and the battery bank size for this setup to work.

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3 hours ago, freewheelin said:

I am narrowing in on a choice. I am looking at this combo:

https://www.amazon.com/gp/product/B00W81BZTO/ref=ox_sc_act_title_1?smid=AV16HZDTPF1LD&psc=1

https://www.amazon.com/gp/product/B01MU0WMGT/ref=ox_sc_act_title_4?smid=A18M12GR6V2Z8F&psc=1

Debating between the 25 watt and 30 watt options for the panel. price is negligible, but I am wondering if the added size of the panel is really worth the extra 5 watts for my use.

Seems plausible to me, FWIW. It's about twice the price of the 25 watt kit. I'd be tempted to go with the kit (also, FWIW).

The controllers look functionally the same. They're both PWM. The one you list has USB charging and a display. You might use those, but this system is for when you're not on the boat. There is probably a bit of overhead to the bells and whistles which will come out of your battery charging. The kit controller looks like it might go nicely into a project box. Its 3 amp rating is adequate for the job. They're both inexpensive Chineseium. Dunno if you're au fait on that front. I wouldn't expect great documentation...

The 30 watt panel says it'll produce 1.7 amps and the "25 watt"* 1.1 amps. Those are top line numbers. You could do a power budget. It's a hard problem to do properly. I'd go for an educated guess. An MPPT controller with the 25 watt panel might provide almost as much charging as the 30 watt panel with a PWM controller. 

* I think they may have rounded a bit aggressively to get to 25 watts.

 

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FYI - without MPPT, you will almost never get much over about 60% of rated power. I have never seen over about 2.5-2.7 amps from my 50 watt panel. Remember the power rating of a panel is usually at 18 volts or so. So 50 watts at 18 volts is 2.78 amps. The PWM controller reduces the voltage to 14, so 2.78x14=38 watts. The magic of MPPT is that it does not reduce the 18-20 volt input to 14, it converts it with a DC-DC converter circuit to provide the same power at a lower voltage.

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8 minutes ago, kent_island_sailor said:

FYI - without MPPT, you will almost never get much over about 60% of rated power. I have never seen over about 2.5-2.7 amps from my 50 watt panel. Remember the power rating of a panel is usually at 18 volts or so. So 50 watts at 18 volts is 2.78 amps. The PWM controller reduces the voltage to 14, so 2.78x14=38 watts. The magic of MPPT is that it does not reduce the 18-20 volt input to 14, it converts it with a DC-DC converter circuit to provide the same power at a lower voltage.

Yep, that's why I listed current. With a PWM controller the panel is a current source. Photons in, amps out. With MPPT the panel is a power source. Photons in, watts out.

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26 minutes ago, weightless said:

The controllers look functionally the same. They're both PWM. The one you list has USB charging and a display. You might use those, but this system is for when you're not on the boat

Good points all around. I didn't mention this before but should have. What made me interested in the display was that I currently don't have a voltmeter, and was thinking I could kill two birds that way. It seemed the display units can function in that capacity, so it seemed worth the $10-15 extra to me. Don't know if that is rational or not.

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7 minutes ago, Zonker said:

For small panels it makes more sense to buy a slightly bigger panel which is cheap compared to the cheapest MPPT controllers.

my thoughts exactly. and the system doesn't have to be perfect, just functional for my use.

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My Blue Sky MPPT's contribution is rather 'meh'. I suppose it is worth it. I have a switch to enable or bypass it. I have watched it carefully. Rarely a significant difference. One needs a regulator and it does a passable job of that. Might as well MPPT at the same time. That was for full-time cruising.  For a boat mostly idling on a mooring a $12 solar regulator would be fine.

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12 minutes ago, Zonker said:

For small panels it makes more sense to buy a slightly bigger panel which is cheap compared to the cheapest MPPT controllers.

The prices are dropping fast on MPPT. Caveat emptor and all, particularly if you aren't comfy looking at the guts of such things.

Name brand: https://www.amazon.com/dp/B018M88G5C/ref=sspa_dk_detail_3?psc=1&pd_rd_i=B018M88G5C&pd_rd_wg=FPqoy&pd_rd_r=KMPBJP3N57J47W04F7VM&pd_rd_w=XeW0I

Pig in a poke: https://www.ebay.com/itm/MPPT-Solar-Charge-Controller-20A-12V-24V-PV-Solar-Panel-Battery-Regulator-W-USB/112870463749?hash=item1a479a9905

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11 minutes ago, freewheelin said:

I currently don't have a voltmeter, and was thinking I could kill two birds that way. It seemed the display units can function in that capacity, so it seemed worth the $10-15 extra to me. Don't know if that is rational or not.

It can be hard to trouble shoot a system using its own displays. I'd install a voltmeter. Also, I'd pickup a cheap multimeter or two.

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22 minutes ago, daddle said:

My Blue Sky MPPT's contribution is rather 'meh'.

You're not the only person I've heard reporting that. MPPT does work in the right conditions. Those conditions are not ubiquitous when charging lead acid batteries. It works better with NiMH... Bet that helps :) 

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1 hour ago, freewheelin said:

ok, thanks. I think that was a 20 watt, that's why i got confused. I really appreciate all this info, it is quite helpful!

You're right. Sorry about that. When I looked at the listing that came up this morning I thought I saw 25 watt. I was moving quickly so maybe not, but maybe worth a quick search...

eg. https://www.amazon.com/Watts-Solar-Panel-Charger-25W/dp/B01LL7CWZG/ref=pd_sbs_86_2?_encoding=UTF8&pd_rd_i=B01LL7CWZG&pd_rd_r=XX62FFJMC8CXH6EQ6MDY&pd_rd_w=Fi1Xn&pd_rd_wg=sSx8M&psc=1&refRID=XX62FFJMC8CXH6EQ6MDY

But, just looking now and I was confusing the 20 watt with some other listing. That also explains why it looked to be over-rating its power... It looks like I did read the correct current rating though. Fee advice... But, trust me, my intentions were good :)

 

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16 hours ago, weightless said:

But, trust me, my intentions were good :)

haha no doubt about that. that's the best part about this forum - people eagerly willing to help (answer my dumb questions). I really appreciate it.

I went ahead and ordered the 25 watt panel from Amazon, with a 30 amp controller that was pretty well rated. I figure this will give me a set up that i could add another panel or two to down the road when we are able to get out cruising for longer periods. Whole package including a quick connect extension and battery cables was $75. Hope it works!

In other news, yesterday I fixed the problem that kept draining down my battery. I had an over-active bilge pump, which was luckily just a float switch issue and not a leak. So bilge pump was switching on, but not off.

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On 8/8/2018 at 9:46 AM, Panoramix said:

I think that if the panel is small enough compared to the battery bank you can get away with a controller less system. That's one thing less to break and a super simple system, effectively the solar panel trickle charges the battery. Unfortunately I can't remember of the ratio between the panel output and the battery bank size for this setup to work.

With 'trickle charging' it's about balancing heat transfer.  If you 'overcharge' a battery, the excess power just becomes heat.  If the charging rate is low enough, the heat can dissipate and not kill the battery.   I don't recommend this approach on a boat. 

 

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On 8/10/2018 at 12:48 PM, TheDragon said:

And let us know, as you can see lots of folks interested in how these systems work in practise.

Will do. I had hoped to install this weekend, but only half the packages arrived in time. Leaving town in a few days, so now I won't be able to get to for a couple weekends. I'll give an update on whether it works, and hopefully take some pictures.

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  • 2 weeks later...

Very useful topic.  My boat’s also on a mooring - a rather new situation.  A few weeks ago, just before leaving for two weeks of sailing, I discovered the starter battery was undercharged (despite motor having been run occasionally while sorting out engine re-installation issues at the mooring).  I always knew in back of my mind I’d need to confront the issue of putting in a small panel for the mooring.  :-). I’ve got one 12v start battery and two 6v golf carts (house loads; normally have 4; will replace entire house bank in a few years, when needed, with 4 total).

So - based on discussion here, I’ll pick up (Amazon)

—>Newpowa 25 watt panel ($43.97) (https://www.amazon.com/Monocrystalline-Newpowa-Quality-Module-Marine/dp/B01M9B6RQI/ref=mp_s_a_1_1?ie=UTF8&qid=1534946968&sr=8-1-spons&pi=AC_SX236_SY340_QL65&keywords=newpowa+25+watt&psc=1 )

—>30A controller (did you get this one below, at $15.99, or another?  30A rating to give me additional panel options in the future, as you mentioned too): https://www.amazon.com/gp/aw/d/B071ZVD7R5/ref=sspa_mw_detail_3?ie=UTF8&psc=1

-–>cables: which ones did you get, freewheelin?

 

(For a panel, since it’s only for keeping batteries topped up at mooring, I’m tempted instead to get this flexible 30W panel for a bit more, $57.99, depending on how flexible it is - I’d like any panel I get to be easily storable when sailing...and flexible seems preferable in my case.)

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I'd stick with a rigid panel. The flexis don't have enough UV durability. They're fine for the opposite use case from what you describe (always stored until sailing) but if they'll live outside most of the time they won't last. It's not hard to store a 25W panel, they're just not that big but a square form factor unit might be easier, depending on your situation.

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Mentioned elsewhere, but maybe worth repeating in this thread: I have a nominal 135W of rigid panels, and when I acquired my boat it had a basic Steca Solarix controller feeding the house 'bank' of two T-105s and an ancient Rutland windgen topping off the engine battery. I removed the annoying whirlygig and fitted a 'Morningstar SunSaver Duo' ( http://a.co/4upZjJQ ) in place of the Steca. The attraction of this 25A controller is the fact that it can divide its output across two separate batteries. It is a PWM device, but I have been advised that MPPT isn't really that important for small solar arrays. Although a bit pricey, it may be a useful solution for others - I haven't found anything similar from other manufacturers. It has worked perfectly for the last six months, and seems like a quality device.

Oh, you can also get it along with the 'remote meter' ( http://a.co/bd450wK ) that I have recently ordered separately. Going to go and collect it today and will try to install by the end of the week.

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I use a small panel and PWM controller to keep my meager house battery charged.  I recall that I also have a plug-in charger for when we're hooked up to electric at the dock.  For the life of me, I can't remember (since I haven't used it in so long) if I have to remove the PWM from the circuit before I plug in the AC supply charger.

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9 hours ago, IStream said:

I'd stick with a rigid panel. The flexis don't have enough UV durability. They're fine for the opposite use case from what you describe (always stored until sailing) but if they'll live outside most of the time they won't last. It's not hard to store a 25W panel, they're just not that big but a square form factor unit might be easier, depending on your situation.

Very good point - a classic example of trade offs!  You’re right - the 25w panel is small -only like 12” x 24” (sorry for the imperial measurements :-) )

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3 hours ago, bplipschitz said:

I use a small panel and PWM controller to keep my meager house battery charged.  I recall that I also have a plug-in charger for when we're hooked up to electric at the dock.  For the life of me, I can't remember (since I haven't used it in so long) if I have to remove the PWM from the circuit before I plug in the AC supply charger.

Unlikely that it is necessary to remove the PWM (solar) connection. Common that an engine alternator and PWM would be running at same time, for example.

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Here’s a follow-up question to keeping a battery charged on a mooring.

After installing panel, controller, cabling - should I connect to my starter battery, or my house bank (2x 6v golf carts in series)?  To share charge between the two banks, I’ve long used a Xantrex Echo Charge —which “looks at” the voltage on the house bank, where the alternator and (when it was installed) wind generator both output to, and diverts charge to the starter battery, as needed (e.g., immediately after cranking and starting engine.)

But I have a feeling that the solar panel would be better hooked up to the starter battery, since that one is, for sure, what you want to keep charged on a mooring, to be able to start engine. (But I can, of course, parallel the two banks with a switch.) However, not having another solar panel or wind generator (for now) hooked up to the house bank, what will keep up the charge on that bank?  The Echo Charge?  Or nothing?

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Good question. To keep things simple I would put all the chargers directly on the same bank. Presumably the Echo Charge will take care of the start battery on windy and sunny days. Regardless, the start battery should last a few months with no charge...and if you are not visiting the yacht at least that often you have bigger problems. I would not leave the boat with the switch on BOTH to prevent all being dead...which such abuse the start battery is not built for.

I should get an Echo Charge because sometimes I forget the switch to BOTH when running the engine, which very slowly runs the start battery down.

 

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On 8/7/2018 at 11:58 AM, WGWarburton said:

Do you really mean "inline"? That's a specific technical term which means  the connections are set up to give you 24V electrics.  It's more common to have them connected "in parallel" to double the capacity available at 12V.

Either works but the setup would be a little different for the two cases.

Cheers,

              W.

In parallel gives you 12v. In series gives you 24v... inline simply means connected between supply power  (battery)  and end use (appliance, light...ect)... IE inline amp meter. 

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On ‎8‎/‎22‎/‎2018 at 9:17 PM, daddle said:

Unlikely that it is necessary to remove the PWM (solar) connection. Common that an engine alternator and PWM would be running at same time, for example.

My alternator, charger, and PWM controller all coexist just fine and have done so for many years.

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On ‎8‎/‎23‎/‎2018 at 8:55 PM, Jud - s/v Sputnik said:

Here’s a follow-up question to keeping a battery charged on a mooring.

After installing panel, controller, cabling - should I connect to my starter battery, or my house bank (2x 6v golf carts in series)?  To share charge between the two banks, I’ve long used a Xantrex Echo Charge —which “looks at” the voltage on the house bank, where the alternator and (when it was installed) wind generator both output to, and diverts charge to the starter battery, as needed (e.g., immediately after cranking and starting engine.)

But I have a feeling that the solar panel would be better hooked up to the starter battery, since that one is, for sure, what you want to keep charged on a mooring, to be able to start engine. (But I can, of course, parallel the two banks with a switch.) However, not having another solar panel or wind generator (for now) hooked up to the house bank, what will keep up the charge on that bank?  The Echo Charge?  Or nothing?

I charge my house bank, not my start battery., The start battery gets charged when the engine runs and not used for anything when the engine doesn't run, so it should stay charged. I have a Blue Seas ACR that I can leave on if I want to, that way when the house bank gets enough charge it will parallel the start battery and charge that too.

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On 8/27/2018 at 4:42 PM, freewheelin said:

No more running the diesel unless i want to! Thanks for all the advice. Install was easy, and the system seems to be working great.

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I may have jumped the gun. My wife went out to check on the system (I am working offsite) and the display still read 11.8V. Looks like it is receiving solar. So I think a couple things could be going on:

1) Batteries (or one) are shot

2) Solar panel isn't working

3) Controller display isn't working

I can put a multimeter on the battery when i get home to rule out #3. Any options I am missing?

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Bummer.

The picture of the panel has it in partial shade. Maybe there's a better location for it?

While you have the multimeter out it might be worth checking the open voltage of the panel.

If your DMM has an appropriate current setting you might check the current between the panel and controller and the controller and batt.

Put a towel or similar over the panel and see if it draws current from the battery.

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17 minutes ago, weightless said:

Bummer.

The picture of the panel has it in partial shade. Maybe there's a better location for it?

While you have the multimeter out it might be worth checking the open voltage of the panel.

If your DMM has an appropriate current setting you might check the current between the panel and controller and the controller and batt.

Put a towel or similar over the panel and see if it draws current from the battery.

Thanks, I will try all that. Yeah, I can also move the panel back so the boom won't shade it. Do you think that shade would cause it to not charge at all? I am kind of surprised that the voltage has stayed consistent at 11.8 - neither up nor down as i would have expected if it was working or not working.

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11 minutes ago, freewheelin said:

Thanks, I will try all that. Yeah, I can also move the panel back so the boom won't shade it. Do you think that shade would cause it to not charge at all? I am kind of surprised that the voltage has stayed consistent at 11.8 - neither up nor down as i would have expected if it was working or not working.

I don't know. It seems odd. With only three parts to test it should be possible to narrow things down pretty quickly. With the battery so low, if you can keep an eye on the voltage (and ideally current) you could take the controller out of the circuit and see if you get charge. Lack of good sunlight or something odd with the controller are my first thoughts but testing will tell.

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Full shading of single cells on a panel dramatically reduces output, it limits current through the entire panel. You need the entire module in full sun for full output. With such a small panel, you'll need it to be full sun to get any charge out of it.  Some panels are designed with series / parallel strings to help mitigate this, partial shading is still a bigger reduction than you would think.

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  • 1 month later...
On 8/6/2018 at 7:39 PM, Zonker said:

Anyway a small panel of 15-25W will be plenty. We lived on a 30' sailboat for 4 years with a 50W panel supplying all our power. We rarely had to run the engine but didn't have a refrigerator which is a huge load. 

And since there are lots of vendors out there - avoid the marked up marine sellers. 

 

2

With a 30 feet boat, your options are limited. Two options a) Change by running your engine. b) Some small solar panels. What Zonker suggest should do the trick.

I would also do whatever you can to reduce your daily power needs. Change to LED, if you got a fridge, can you improve the isolation? Get an oil lamp or two gives out some nice heat and good reading lights. Geta old style outside oil lamp for the anchor light. Not kidding, it saves a few amps, just hoist the lamp at the bow. Replace your batteries to high-quality AMG with a good charger. When solar is not enough, you need to run the engine. Upgrade the alternator, check and possible upgrade the wiring from the alternator to the batteries.   

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Something is wrong.

Put the panel in full sun and measure the voltage. It should be around 18 to 24 volts, depending on the panel. Assuming that is good, next step is connect direct to the battery. It is best to be able to measure the current going in. Failing that, the voltage should rise. A small panel and a large battery will mean it won't rise very fast, but you should see something.

 

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Thanks for the tips. Something was wrong. I think that I mentioned I have two 12Vs in series. Isolating them, I discovered that one was completely dead and wont hold any charge. So it was also drawing down the other battery. I have taken it out of series, and now everything seems to be working well. The solar arrangement is holding my (now one) battery at around 13.8V.

I am hauling in a couple weeks for the winter, so I didn't bother replacing the battery. I will replace both batteries before launching in the spring, and will hopefully have no issues. I'll try to remember to post an update or a picture or two next spring. I love the peacefulness of sailing on and off the mooring.

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1 hour ago, freewheelin said:

Thanks for the tips. Something was wrong. I think that I mentioned I have two 12Vs in series. Isolating them, I discovered that one was completely dead and wont hold any charge. So it was also drawing down the other battery. I have taken it out of series, and now everything seems to be working well. The solar arrangement is holding my (now one) battery at around 13.8V.

I am hauling in a couple weeks for the winter, so I didn't bother replacing the battery. I will replace both batteries before launching in the spring, and will hopefully have no issues. I'll try to remember to post an update or a picture or two next spring. I love the peacefulness of sailing on and off the mooring.

Are you sure they were in series? You had a 24 volt system?

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On 10/17/2018 at 10:06 AM, freewheelin said:

I meant parallel. Sorry, I always get the terms mixed up.

Try to just remember the term and concept “series aiding”.   Voltages add —“aid” each other— when in series.  They’re hooked up in a ‘straight line’, + to - and so on from battery to battery so, being in a ‘straight line’, in series, the voltages add up, like numbers in a line...12v + 12v.  

Just one way to help remember it.  (Voltages in paralleled batts remain the same - they’re “parallel”, the ‘same line’).

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