Practical experience with Li Batteries on raceboats?

[alctel]

Yeah please don't charge your lifepo4 bank above ~14v

Winston says 14.6 is ok but that's under factory conditions and assumes charging completely stopping (which isn't how alts tend to be set up) and holding them at 100% voltage is bad for them anyway.

At 14v they are basically 98% -100% charged anyway, any higher and you are pushing into the 'knee' where the voltages starts spiking, and you'll unbalance your cells and risk damage for no gain.

I've had a bank for around 2 years I homebrewed and did a ton of reading before I installed it

 

[Not My Real Name]

I've had a bank for around 2 years I homebrewed and did a ton of reading before I installed it

Me too.

 

[bushsailor]

someone asked how fast do they charge, Mine take about 60 amps all the way up to 99% full,  but I have no idea why they do not take the full alternator capacity. (It is a balmar 125 amp alternator. Also it does not really matter. They charge pretty quickly.

We just did a 2 and half day ocean race and charged the battery once for 45 minutes and finished with 60% capacity left. That included a fridge (no freeze dried) and full instrument system. (that has a 200 amp system)

It does make a huge difference.

 

[jack_sparrow]

someone asked how fast do they charge, Mine take about 60 amps all the way up to 99% full,  but I have no idea why they do not take the full alternator capacity. (It is a balmar 125 amp alternator. Also it does not really matter. They charge pretty quickly.

Bush if still accepting 60A they are well short of 99% SOC. If acceptance starts at 60A with a 120A Alt they are already well north of say 60% SOC. They will accept every amp that small case alternator has to the extent being small case you run the risk of cooking it.

My guess is you have a columb counting Battery Monitor that has not been set up properly so no automatic reset at your selected 100% SOC capacity/alternator "set point voltage" so its SOC reading is completely out of wack and that error increases each time you discharge/charge. If monitor SOC governed by pack voltage even more inaccurate.

The nett effect is relying on your battery monitor SOC you are only using a fraction of battery capacity and that from mostly in the top half. Fix that and your charging time will plummet when you start using the full capacity range.

Leave your LA experience/knowledge on the dock as it hinders understanding LFP.

 

[jack_sparrow]

Yeah please don't charge your lifepo4 bank above ~14v

Winston says 14.6 is ok but that's under factory conditions and assumes charging completely stopping (which isn't how alts tend to be set up) and holding them at 100% voltage is bad for them anyway.

At 14v they are basically 98% -100% charged anyway, any higher and you are pushing into the 'knee' where the voltages starts spiking, and you'll unbalance your cells and risk damage for no gain.

I've had a bank for around 2 years I homebrewed and did a ton of reading before I installed it

^^^^ This ....yes charge and use don't float noting 14.2v is absolute max on a system with really good BMS.

Best storage voltage is 40- 50% SOC or say 3.15v per cell.

 

[Moonduster]

Bush,

You say your batteries are only accepting 60A charge rate - what's the voltage during that charging? In all likelihood, if you've a Balmar alternator you've got a Balmar regulator (neither are a good choice) and it's your regulator that's limiting the rate-of-charge, possibly due to alternator temperature. 

 

[Cuffy]

I have a lfp bank on board and to save changing the whole charging systems I left a small LA for starting the engines and then a B2B charger as the only charge source connected to the lfp bank. This is full programmable for ALL voltages and and durations. It also has limits the charge current so alternators will not overheat. It does limit charge rate a bit to much, 50a, but main charge source is solar so no issues for me.

Set to 14v max with no absorbtion and then 13.2 float, which takes load once battery has discharged to 60 - 70 % with obviously nothing overnight!!

 

[nota]

cars are getting new chemistry in 2020

XNRGI battery technology. Developed over 15 years by Motorola, Intel, US Navy. Commercialising - now.

Summary (compared to present technology Lithium):

- Energy Density 3x (mass basis) 5x (volume basis)
- Safe. No thermal runaway, no dendrites
- Longer life
- Capital cost (Factory) 1/20
- Re-charging rate x2.5
- Cost approx 1/2

https://xnrgi.com/wp-content/uploads/2019/07/XNRGI-Breakthrough-Battery-Architecture-Solves-Key-Issues-Energy-Storage.pdf

sounds good but we will see

 

[jack_sparrow]

XNRGI battery technology. Developed over 15 years by Motorola, Intel, US Navy. Commercialising - now..

..sounds good but we will see

Price of raw lithium is a good place to gauge inroads of other battery chemistry like this. Currently pretty steady but supply origin and derivative also plays a big part not just demand. Lithium Price Bulls Were Right

 

[jack_sparrow]

someone asked how fast do they charge, Mine take about 60 amps all the way up to 99% full,  but I have no idea why they do not take the full alternator capacity. (It is a balmar 125 amp alternator.

Bush if still accepting 60A they are well short of 99% SOC. If acceptance starts at 60A with a 120A Alt they are already well north of say 60% SOC. They will accept every amp that small case alternator has to the extent being small case you run the risk of cooking it.

My guess is you have a columb counting Battery Monitor that has not been set up properly so no automatic reset at your selected 100% SOC capacity/alternator "set point voltage" so its SOC reading is completely out of wack and that error increases each time you discharge/charge. If monitor SOC governed by pack voltage even more inaccurate.

Bush,

You say your batteries are only accepting 60A charge rate - what's the voltage during that charging? In all likelihood, if you've a Balmar alternator you've got a Balmar regulator (neither are a good choice) and it's your regulator that's limiting the rate-of-charge, possibly due to alternator temperature. 

Moon if not a SOC monitor issue (as I indicate) and as you suggest either external alternator regulator is limiting charge rate (60A or 50% of rated is overkill) OR if not that it is then heat, then doesn't 60A or 50% of rated Alt output at start up, indicate that alternator of Bush's has already been cooked by LFP and is on the way out?

The concept promoted by some here that you don't have to alter LFP charge sources to match real life LFP chemistry, but rely what is in the battery suppliers brochure, is hogwash.

Moon by the way I agree with you fully about Balmar. The concept that you pay a huge premium for a small case alternator that is painted white and suddenly it is a heavy duty alternator capable of handling LFP's extended acceptance rate is nonsence. External regulation allowing you to depower it does help but that then means you are not taking full advantage of LFP.

Likewise I'm with you Moon if do have LFP, then subject to installation constraints incl room engine drive/belt imposed loads on bearings etc, then install a large case alternator that can handle the heat LFP imposes. If stuck with small case then ideally rip out the rectifier/heat source and make it external or at very least improve alternator cooling with a mechanical fan source etc.

That said what I'm suggesting there is for a long distance race boat or cruiser wanting to limit fuel supply where alternative energy sources don't exist/not suitable to their application.

Stored energy in the form of alternative battery chemistry and ability to spend money and amortised that against actual use and time is 'horses for courses". A concept many miss.

To the OP's question about LFP for racing, then if it wasn't for offshore regs imposing sealed battery chemistry, quite frankly they would for short course racing with relatively low loads, be better off with flooded LA. With sealed battery chemistry imposed, then just accept that a racing boat charging regieme murders that chemistry, and just accept that fact and throw that low cost sealed battery(s) away after a few races.

The higher capital cost of LFP inclusive of changing onboard charge source doesn't really make sence unless loads are high and you have a onboard charging regieme to take proper advantage of the battery chemistry.

As I said "horses for courses"

 

[Joakim]

You talk a lot about cooking an alternator. What is the difference of having usually a much larger lead acid deep cycle batteries vs. a rather small LFP. Both may take full alternator load for 30 minutes or even more than an hour, both certainly long enough to heat the alternator to as hot as it gets. I certainly have run mine at full 60 A many times 30+ minutes with lead acid. I have only 180 Ah, many have 300-500 Ah or even more.

I know even one boat using boiler via alternator and a big inverter, since the engine is raw water cooled. Still crazy, but hasn't cooked the alternator.

Are some alternators more prone to cooking? The newer 100+ A ones that come with VP and Yanmar?

 

[Moonduster]

If not a SOC monitor issue (as I indicate) and as you suggest either external alternator regulator is limiting charge rate (60A or 50% of rated is overkill) OR if not that it is then heat, then doesn't 60A or 50% of rated Alt output at start up, indicate that alternator of Bush's has already been cooked by LFP and is on the way out?

No. Rate of charge is not an SOC monitor issue and it's not an indication that the alternator has been cooked. Charging at 50% of the alternator's rated output is only indicative of only two things:

1. The alternator is cold rated and at operating temperature, it's output falls a lot
   
2. The alternator isn't being given sufficient field current to generate its rated output
   

With a cold rated alternator you should see closer to 80% of rated output once at temperature. The Balmar regulator is almost certainly part of the problem described and can probably be programmed to get the output higher.

What is the difference of having usually a much larger lead acid deep cycle batteries vs. a rather small LFP.

Exactly. There is no difference.

Are some alternators more prone to cooking?

Yes. This is primarily a function of cooling design and quality of heat sink and diodes. There are many sources of very competitively priced alternators that are rated for continuous duty at high temperature and will crank out their rated current for, literally, days with case temperatures well over 150ºC. There are many others that won't meet their rated output for 10 minutes and fail at much lower case temperatures.

 

[jack_sparrow]

You talk a lot about cooking an alternator. What is the difference of having usually a much larger lead acid deep cycle batteries vs. a rather small LFP. Both may take full alternator load for 30 minutes or even more than an hour, both certainly long enough to heat the alternator to as hot as it gets.

None Yes ..but Joakiim one takes full alternator load for ever..it doesn't quit after 30 minutes. That is the battery chemistry difference.

No. Rate of charge is not an SOC monitor issue and it's not an indication that the alternator has been cooked. Charging at 50% of the alternator's rated output is only indicative of only two things:

1. The alternator is cold rated and at operating temperature, it's output falls a lot
   
2. The alternator isn't being given sufficient field current to generate its rated output
   

With a cold rated alternator you should see closer to 80% of rated output once at temperature. The Balmar regulator is almost certainly part of the problem described and can probably be programmed to get the output higher.

What is the difference of having usually a much larger lead acid deep cycle batteries vs. a rather small LFP.

Exactly. There is no difference.

Are some alternators more prone to cooking?

Moon you actually have nothing at hand to come up with that summation until Bush answers your question; being voltage at 60A which he hasn't answered so you have absolutely no idea what both output voltage is or real SOC is, yet you then say it is down to alternator brand and stuff..WTF. I at least give a supporting explanation to your view Moon about alternator design, but what do you do? Go gobblygook to say basically the same thing.

Bush,

You say your batteries are only accepting 60A charge rate - what's the voltage during that charging? In all likelihood, if you've a Balmar alternator 

So a Yes and Yes maybe No conversation has now gone circular not having the full story.

No wonder people are confused about LFP with people blowing noise out of their arse with tech language most don't understand wanting to be the smartest person in the room, but informing no-one.

 

[Not My Real Name]

You talk a lot about cooking an alternator. What is the difference of having usually a much larger lead acid deep cycle batteries vs. a rather small LFP. Both may take full alternator load for 30 minutes or even more than an hour, both certainly long enough to heat the alternator to as hot as it gets. I certainly have run mine at full 60 A many times 30+ minutes with lead acid. I have only 180 Ah, many have 300-500 Ah or even more.

I know even one boat using boiler via alternator and a big inverter, since the engine is raw water cooled. Still crazy, but hasn't cooked the alternator.

Are some alternators more prone to cooking? The newer 100+ A ones that come with VP and Yanmar?

Large frame / high capacity alternators are generally better at taking heat, but even they have limits.

Some LFP's may take a pretty large chunk of C as a charge capability until they are full. This means they will pull as much power as your alternator can produce, as long as it will produce. They will demand the power from the alternator, and the alternator will spin up and run as high as it can to deliver.

Even a high output, large frame alternator will overheat eventually.

It's recommended that if you have an external regulator you de-rate the alternator to ~60-70% of max, so you don't keep it spinning up at 100% output if your batteries are discharged. Also if you set your float voltage on the regulator, you can basically keep the alternator providing your power while the engine is running without overcharging the LFP bank.

Stan Honey discusses it here:

http://www.honeynav.com/wp-content/uploads/2016/06/LFP-battery-Stan-Honey-notes.pdf

Many have observed that that small-frame alternators overheat if run continuously at full output. I selected a Balmar AT-165 which has a significantly higher rated output
than I need. It is small-frame, fits easily on a Yanmar, and uses the Denso hairpin stator which is said to be more efficient than a conventional winding. I run it at Balmar’s belt manager setting of b-9, which is 55% of full-field. This setting limits the max alternator current to about 110A which is close to 0.3C for my battery, which is the CALB recommendation for charge current. The AT-165 is able to put out 110A continuously without exceeding 220 deg F, even in the small Cal 40 engine space.

 

[Joakim]

Some LFP's may take a pretty large chunk of C as a charge capability until they are full. This means they will pull as much power as your alternator can produce, as long as it will produce. They will demand the power from the alternator, and the alternator will spin up and run as high as it can to deliver.

It all comes to the sizing of the battery vs. alternator. The link showed a very unusual case of going from 180 Ah lead acid to 360 Ah LFP.  That really makes a difference on alternator load. I would say going from 180 Ah lead acid to 90 Ah LFP would be much more common due to much higher price and usable Ah of LFP. If you have a 60 A alternator a 180 Ah lead acid can take full 60 A for quite a long time depending on SOC. Mine takes full 60 A up to about 70% SOC. So if you started at 30%, that's more than an hour and about the same a 90 Ah LFP can take. So where's the difference regarding an alternator? It's another story that most lead acid batteries don't last long going to 30% SOC and not charging above 70%.

I'm also quite certain that 30 minutes is long enough to make an alternator as hot as it get. It doesn't get any hotter, if run for days.

 

[Not My Real Name]

It all comes to the sizing of the battery vs. alternator. The link showed a very unusual case of going from 180 Ah lead acid to 360 Ah LFP.  That really makes a difference on alternator load. I would say going from 180 Ah lead acid to 90 Ah LFP would be much more common due to much higher price and usable Ah of LFP. If you have a 60 A alternator a 180 Ah lead acid can take full 60 A for quite a long time depending on SOC. Mine takes full 60 A up to about 70% SOC. So if you started at 30%, that's more than an hour and about the same a 90 Ah LFP can take. So where's the difference regarding an alternator? It's another story that most lead acid batteries don't last long going to 30% SOC and not charging above 70%.

I'm also quite certain that 30 minutes is long enough to make an alternator as hot as it get. It doesn't get any hotter, if run for days.

It's not unusual at all, it's quite usual.

I went from 660Ah 24V lead-acid (264 usable) to 720Ah 24V of LFP (576 Ah usable). So more than double the usable capacity. I could have put in more, but I'm at the point now where I need to run my generator to make hot water before I need to charge my batteries so it doesn't make sense.

Going down in total is a racer thing, I suspect. We cruisers look in increase our time between charges while reducing charge times. We're less interested in saving weight which is the only reason a racer can justify the expense and complexity of LFP that I can see. You just don't use your batteries enough, otherwise.

I've also gone from ~90A charging capability to 200A. My cells will take all 200A, though I only run around 170A or so normally because of limits my AC wiring (each 100A charger is on a 16A 240V circuit).

If you run your lead-acid AGMs down to 30% you've fucked your battery life for most batteries; they don't like discharging that deep. Most L-A technology starts taper charging at 80%-85%, with the final 10% being really slow. So you should be running them from 50% - 90%, which at 60A will take under an hour until you start tapering of your charge level. Assuming your 60A alternator is the rare beast that actually delivers 60A, it will start de-rating itself within an hour.

The extended heat can cause damage, I believe. Though I won't argue the point with you as I'm not the expert that guys like Calder, Honey, etc. are. But if you replace 180 Ah lead with 180Ah LFP (which is still more common that going down, I think, because you increase usable capacity dramatically and still cut weight), then you're going to run that 60A alternator for 2-2.5 hours or so to go from 20% to 100%.

 

[Joakim]

I have VP MD2020 with it's standard 60 A alternator. It does deliver 60 A as long as I have tried. The current only drops after the regulated 14.2 V is reached. I have a flooded battery, that is 10 years old. I very seldom need to go under 60% SOC and even more seldom do I need to start the engine just for charging.

I guess it's about money and sailing region. I don't know a single boat in the Baltic Sea going to equal or bigger LFP. You can't sail more than a couple of days until you reach the opposite coast. Most cruisers sail only during daytime and motor to and from harbour, which gives enough charging. Quite often there is no wind and you motor parts of overnight legs.

My friends who have gone to LFP mostly cruise. Only one of them races actively.

 

[Moonduster]

Even a high output, large frame alternator will overheat eventually.

This is simply not true. If the alternator has been designed and speced for continuous output, it will run at full output continuously. The exist, they're light and they're affordable. They're used in all sorts of fire, ambulance and military applications. We put them on V70s, IMOCA 60s and super maxis. We run that at full field until we shut them off.

If someone tells you that their 200A alternator can only be run at 120A continuously, then you should ask them why they market it as a 200A alternator when it's clearly a 120A alternator. And you shouldn't buy it unless you're happy paying for a 200A alternator and receiving a 120A alternator. Or if you want white paint.

 

[jack_sparrow]

Even a high output, large frame alternator will overheat eventually.

Got to say never seen that happen.

 

[Miffy]

Got to say never seen that happen.

Reading thru this thread... I mean the little alternator on the Volvo 15hp pumps out 60amp at idle and 100+ at steady cruise rpm. 

Get a victron BMS that starts at about $250/€250 and call it a day. What's with the long winded clearer than mud back and forth.