LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[CatNewBee]

Originally Posted by Cdn

Question for the experts. If I have a 1200amph Lithium bank charged by Balmar alternator (I am aware it will take a while and will supplementing a large solar system), can I use my electric appliances while charging via alternator? Ie, if my bank is at 80% and I run my AC, will my alternator charge the batteries while my batteries run the AC?

You can run loads while charging.
With a large LFP bank, 1200Ah is large, you have the advantage, that there is very little voltage drop when turning on heavy loads, so yes, a small A/C is not a problem at all.

With small FLA batteries the voltage would drop below 10V and further and may then overwhelm the alternator. The charge current is driven by the voltage difference between the set point and the battery voltage.

You refer to 7A, I assume it is on 220V? So your draw is about 1540W, using the inverter you may draw 130A on the battery, if you refer to 110V and 7A then around 65A.

Anyway, your Balmar outputs how many Ampere on cruising speed and how many on idle?

If it outputs more than your consumption, you may charge while cooling, if not, the battery is slowly discharging.

[Delfin]

Originally Posted by Belezar

This may have been posted here already, and I’m not going to read through 7000 posts to see, but I think it’s a shame that this run on post was done this way. There is a ton of good info here, but in this format it is extremely hard to search. And it started 8 years ago. Technology has changed so much since then. Why do I care? I just bought a boat with a LI house bank. I get that it’s your own little community but still...

I feel your pain....

The search function for the site is not terribly intuitive, but it can help a bit to get you more specific information, winnowed out from the thousands of posts.

Sorry if you already know this, but a quick primer on searching:

1. Use Advanced Search
2. Make sure you click the radio button "Show Results For Posts"
3. Enter your Search term
4. When you get the return, click on the hyperlink "Re:...…" and you'll land on that particular post

Unfortunately, if there are multiple posts with your search term you will have to plow through them one at a time. It would be very nice if the site could return in one window the posts with your search term, but as near as I can figure out, your choice is to get a return of an entire thread where your search term may be buried - completely impractical for this whopper thread - or a list of individual posts you have to click one at a time through to read.

[Cdn]

Originally Posted by CatNewBee

You can run loads while charging.
With a large LFP bank, 1200Ah is large, you have the advantage, that there is very little voltage drop when turning on heavy loads, so yes, a small A/C is not a problem at all.

With small FLA batteries the voltage would drop below 10V and further and may then overwhelm the alternator. The charge current is driven by the voltage difference between the set point and the battery voltage.

You refer to 7A, I assume it is on 220V? So your draw is about 1540W, using the inverter you may draw 130A on the battery, if you refer to 110V and 7A then around 65A.

Anyway, your Balmar outputs how many Ampere on cruising speed and how many on idle?

If it outputs more than your consumption, you may charge while cooling, if not, the battery is slowly discharging.

Thanks for the info. I have learned a lot reading your posts.

I am wondering if the best best would be to get dual CS144 alternators with external regulation and derate them to 100amps each. a 1200amph lithium battery bank would eat up the amps like candy. From reading these fourms, it seems like a CS144 is basic and easily replaced. With oversizing the alternators and drawing less power, it should help keep the heat down.

Yanmar sells a second bracket for a dual alternator setup on the 4JH series (57HP is what I am ordering).

[CatNewBee]

Sorry, i cannot help you with this, I am not familiar with the Balmar product range.

I still have the original alternators without external regulator on board. They are pretty weak and not meant to charge the LFP bank. I use to sail and not motor a lot, if i need to charge, I prefer to run the generator for 2 hours and use the shore power chargers plus the Victron Quattro, this gives me 300A charge current that corresponds with 4.2kW load on the generator. Combined with watermaker and /or hot water boiler i can pretty much squeeze about 7.5..8kVA from the Onan and use it very efficiently.

But I guess, here are a lot of Balmar fans who know the product range very well and can give you some tipps.

[john61ct]

You could have an infinity-gazillion Ah bank, but in the end your energy sources must contribute on average per day more Ah input, than what all your loads are consuming.

If you need to run the genset every day to recharge your bank anyway

then might as well run it while the aircon is going.

Then you don't **need** such a large bank, or cycling it less deeply means it will last much longer.

[john61ct]

Originally Posted by Cdn

I thought Lithium batteries could be discharges and recharged between 90% and 10% with out much damage and could be cycled about 5000 times?

The distinction between "damage" and "reducing cycle lifespan" is not cut and dried.

For every battery chemistry, drawing down to low SoC means a much shorter lifetime than shallower cycling. There are many other factors besides average DoD% that impact cycle lifetime, but that is certainly one of the major ones.

For most "lithium" chemistries, even 500 cycles is an unusually long lifespan. LFP specifically is usually rated 2-3000.


> The amp draw of a small 6000 BTU cabin AC is only about 7 amps. With an alternator providing 150 amps hot (Balmar XT), I was assuming it would charge batteries while the batteries were also providing power to the AC? Am I missing something

Better to convert to Watts for energy consumption when multiple voltages are involved.

Aircon is a huge load for off-grid living, especially if you try to run it for many hours per day.

Most cruisers without a big genset only use it when on shore power.

Even a fridge, certainly a freezer, are large loads, because they are cycling 24*7

A big winch may be more amps, but very low average Ah per 24 hours, that is the key metric when sizing your bank.

[Recy]

Originally Posted by Cdn

Thanks for the info. I have learned a lot reading your posts.

I am wondering if the best best would be to get dual CS144 alternators with external regulation and derate them to 100amps each. a 1200amph lithium battery bank would eat up the amps like candy. From reading these fourms, it seems like a CS144 is basic and easily replaced. With oversizing the alternators and drawing less power, it should help keep the heat down.

Yanmar sells a second bracket for a dual alternator setup on the 4JH series (57HP is what I am ordering).

Do you have link to the Yanmar second bracket.

[rom]

Originally Posted by Recy

Do you have link to the Yanmar second bracket.

https://www.yanmarshop.com/catalogue...kit2ndoptional


I would rather upgrade the factory alt to a 28SI or similar, way less expensive than a secondary alt mount. Unless maybe you want to mix voltages, e.g. one alt 12V the other 24V.

[Cdn]

Originally Posted by Recy

Do you have link to the Yanmar second bracket.

No. If you call a Yanmar dealer they should be able to find it.

[newhaul]

New video just posted about a review of the renogy 50 amp dc to dc with mppt solar built in
https://youtu.be/JtAUrS4zNSA
It seems to pass the smell test now I am actually considering one over the 40 amp unit.

[Farang]

Cells arrive tomorrow, Bwaaa, panic stations! Due to supply issues I Received 32 x 100a/h CALB cells instead of 8 x 400a/h. Seeking pack redesign opinions from the vast pool of experience here.

I just binge read the most recent 100 pages of this outstanding thread...wish I had before I ordered.

On a 48’ catamaran I’m replacing 8 x Group31 Lifeline AGM’s @ 12v and upgrading the charging capability for 800a/h of new LiFePo cells.

Current charging system is 16 solar panels total of 1960watts, 5 x Victron Mppt’s and a Victron Multi 1600/70* powered by a 2.4kva ac genset. A Victron CCGX display and SiMarine Pico provide monitoring.

The new charging systems add 2 x 50a Victron Phoenix chargers to the genset feed and 2 x 30a Victron dc2dc chargers from the agm cca start batteries.

(*) the Multi 70a inverter/charger will be split off to the load bus but I was intending to switch it for occasional bulk charge on to the charge bus with a bluesea battery switch in between the busses. Issues?

Before the cell switch I chose a REC ABMS with Victron canbus support and 2 x Bluesea MlRBS 7700 latching relays for disconnects.

Trying to make the best of it I tell myself smaller cells are more robust, easier to handle, with some possibility of swap out redundancy. With more cells to be concerned with I ordered 2 additional Pico sensor modules now supporting 12 temp sensors + 1 from REC.

So the question to the forum is:
A). Do I stick with 8P4S and 1 REC bms. I’ll only ever get string level management. What about shorted/ runaway cells? Fuse sizing? REC tech advice was to have extra interconnects to spread the current.

B) split into 4p4s2p add a 2nd bms. Issues? REC weren’t thrilled in this. Have to get another ccgx, prob a pi with Venus.

C) downsize to 7p4s (still more capacity than the old agms) and keep 4cells as spares.

D). None of the above...sell the cells on eBay, order 400 a/h Winstons and wait another month for delivery.

I couldn’t find a “pack design” thread so I’m posting here.

I invite ALL comments particularly from those members posts I read with larger Xp4s packs like Nebster and Anjin, and CNB and AndyAlford with REC and CCGX experience, the gurus in this space Mainesail, OceanSeaSpray etc and all the other knowledgeable prolific posters out there.

[MikeFergie]

I have just finished putting together my batteries. I have 24 x CALB Ca100 batteries and have built 2 batteries made up of 12 cells each giving me a configuration of 3P4S. I have gone individual cell balancers ( one for each cell) and they are active balancers and one BMS for each battery.
This gives me 2 x batteries of 300 amp hours each @ 12v or 4100 watt hours per battery.[ATTACH]204665

[MikeFergie]

My battery size is 610mm long by 230mm wide and 300mm high

[mikedefieslife]

Originally Posted by MikeFergie

I have just finished putting together my batteries. I have 24 x CALB Ca100 batteries and have built 2 batteries made up of 12 cells each giving me a configuration of 3P4S. I have gone individual cell balancers ( one for each cell) and they are active balancers and one BMS for each battery.
This gives me 2 x batteries of 300 amp hours each @ 12v or 4100 watt hours per battery.[ATTACH]204665

I see you've gone with the Daly BMS. Did you upgrade the pitiful 6AWG wires? I wasn't happy with them on my 200a, so crudely added 50m2 instead. Of course the way around that is to just use the BMS to control a relay instead.

[Farang]

Originally Posted by MikeFergie

I have just finished putting together my batteries. I have 24 x CALB Ca100 batteries and have built 2 batteries made up of 12 cells each giving me a configuration of 3P4S. I have gone individual cell balancers ( one for each cell) and they are active balancers and one BMS for each battery.
This gives me 2 x batteries of 300 amp hours each @ 12v or 4100 watt hours per battery.[ATTACH]204665

Great reply, thanks. Can you share the cell balancer model used? I like the redundancy of 2 banks, how are they configured with the busses and disconnects?