Recommendations for Group 31 AGM replacement with LiFPO4

[john61ct]

Originally Posted by ranger42c

What AGM batteries do you have that lasted 6 years? Under what circumstances? Typical depths of discharge? How soon re-charged (presumably often, to the extent your solar system can do it)? Periodically equalized (if recommended)? How expensive?

I'm wondering if it might be whatever you had is good enough bang for the buck...

Yes 6 years is a good run if AGM is actually required.

[Pegu Club]

Firefly group 31, more usable amps than other AGMs. Check out Mainsail’s review on “marine how to”, good info there.

Fair winds,

[Inkog]

Originally Posted by john61ct

Please link to quality LFP cells cheaper than FF that do not require importing yourself from China.

And FF are just fine, uniquely so among AGM, going to 80% DoD.

Of course LFP will accept **much** higher C-rates, but regularly going over 0.3C hurts longevity, not a great idea.

Plus of course the design/BMS must allow it, which most drop-ins don't.

AGM thrives at the highest rates the will accept, better for longevity than slow charging.

Only use 20-hour rate for comparing lead chemistries, this stuff is confusing enough mixing in other rates.

I love LFP, not trying to push FF at all, each choice has different advantages for different use cases.

According to their spec sheet (attached) 50% DOD is comparable in cycles to LiFePo, but your only getting half the useable Ah. Even the best Drop-in LifePo are $8-10/Ah useable the Fireflys look to be $11/Ah

[john61ct]

I have no interest in drop ins.

I paid around $500 per FF G-31, plus shipping was under $15 per unit for quantity orders.

Again, no problem going to lower DoD if weight is a problem.

And also again, I do not consider either to be great value unless chronic PSOC abuse is unavoidable.

Really can't beat those Deka GCs at $1/Ah, likely to outlast both.

[Inkog]

Originally Posted by john61ct

Only use 20-hour rate for comparing lead chemistries, this stuff is confusing enough mixing in other rates.

I love LFP, not trying to push FF at all, each choice has different advantages for different use cases.

You're correct, I meant to use 20h/5A rating but in my haste I quoted the 5h rating. Still, the capacity only ups from 90 to 108 in that case, and doesn't change my opinion.

[svspirited]

They're West Marines believe it or not, they were with the boat when we bought her. She sat at a marina plugged in for about 7 months before we took ownership and for another 3 or so after we took ownership before running her north. The previous owners were not shy about running the generator so I'm not sure how much the batteries were abused.

The starter battery for both the main and generator are pretty much dead and the house bank is on its way out as we have been using them pretty heavily for the past few months. We try and not discharge below 80% and we are not a power hungry boat, all LED lighting, a good balanced sail plan so the auto pilot doesn't work too hard, and we rarely run the inverter, mainly for charging up laptops, phones, and the occasional food processor. The biggest constant load is the refrigeration, it eats about 5amps for about 15 minutes every hour or so, sometimes more sometimes less. Electronics is the other but that's only when underway.

We are not hard hitters and under that usage pattern the FF is supposedly capable of >3,500 cycles. I know LiFPOs would be more efficient and last longer but if I can get even close to those numbers the added cost of upgrading all of the infrastructure to handle Lithium seems to outweigh the benefits for now. Maybe in 5 years or so when it is time to swap again the lithium tech will come down in price and I'd be more willing to upgrade the rest of the infrastructure.

Originally Posted by ranger42c

What AGM batteries do you have that lasted 6 years? Under what circumstances? Typical depths of discharge? How soon re-charged (presumably often, to the extent your solar system can do it)? Periodically equalized (if recommended)? How expensive?

I'm wondering if it might be whatever you had is good enough bang for the buck...

-Chris

[newhaul]

Calb Lfp is about the same price $5.10 per ah
https://www.electriccarpartscompany....B-SE-Batteries
And you can reduce that cost by about 1/3 by importing yourself .

Or go here and choose your own reseller
http://www.calbusainc.com/calb-buy

[john61ct]

There was a recent thread containing information about ECPC's less than immaculate record on honoring warranties.

I can't seem to find it anymore, if anyone else can please post a link.

I assume they aren't a sponsor of this website or something?

[ranger58sb]

Originally Posted by svspirited

They're West Marines believe it or not, they were with the boat when we bought her. She sat at a marina plugged in for about 7 months before we took ownership and for another 3 or so after we took ownership before running her north. The previous owners were not shy about running the generator so I'm not sure how much the batteries were abused.

We are not hard hitters and under that usage pattern the FF is supposedly capable of >3,500 cycles.

Maybe it's just a question of doing the $$$ math, then. If you really need (want, whatever) AGMs, you can probably get the same batteries you have for less money from someplace other than WM. Compare that price to FF prices, cycles to cycles, decide whether you need to leap through any hoops or not.

-Chris

[Rough Magic]

Good discussion. I'm interested in a power supply for a home ham radio... instead of using a power supply, I thought a battery and charger would be as good, maybe better. Eventually, using solar to make an emergency power supply. Lithium vs AGM is my dilemma.

[newhaul]

Originally Posted by Rough Magic

Good discussion. I'm interested in a power supply for a home ham radio... instead of using a power supply, I thought a battery and charger would be as good, maybe better. Eventually, using solar to make an emergency power supply. Lithium vs AGM is my dilemma.

personally I would go with lifepo4 in a home shack and 200 watts solar to keep it charged ( be sure to use a charge controller that can be set for Lfp)

now depending on your setup I would say 100 to 200 ah is plenty for that .

Pm me
Rob Ka7wld

[TrentePieds]

Hello John61ct,

I have a tiny request :-) Acronyms can be a bit of a bother since we are an international forum with a lot of members whose first languages are not Henglish. I'm one of them :-).

Would you be kind enuff to spell out the whole schmeer before you default to acronyms? That would be very helpful for us who are interested in batteries and electrical systems generally, but really know nothing about them. That's another demographic I belong to ;-)

TrentePieds

[RickG]

We've been using a bank of seven G31 Fireflies purchased from Coastal Climate Control for the last two years as full-time cruisers. They were the best choice for us two years ago. We are very happy with their charge acceptance rate and PSOC behavior as well as the low self-discharge rate. If we did the upgrade now we would look very closely at the LiFePo4 options. I expect our next battery bank will be LiFePo4 when we need to replace the Fireflys in 15 years.

We run Victron solar controllers for 660 watts of solar panels and a Victron Multiplus 3000 charger/inverter. The alternator is a Balmar 110amp and the regulator is a Balmar MC-612.

Cheers, RickG

[CapnBazza]

Originally Posted by svspirited

Our current AGM battery bank is coming to the end of its useful life, they are about 6 years old now and starting to lose charge pretty rapidly, the solar is keeping things alive when it is sunny out but when the clouds roll in the bank dies off pretty quickly. The current setup is 6x96ah group 31 AGMs with a Magnum inverter/charger that works really well. I have been looking at the GreenLife brand which claims to be a drop in replacement for the battery we currently have with a simple reprogram of the charger to charge at the correct levels for Lithium. They do have an onboard BMS so I think I can buy the six batteries and drop them in to the existing boxes and in theory be good to go with a good bit more useable power and a little less weight.

Does anyone have experience with this brand? Any others you would recommend? Is the idea of a simple drop in replacement reality or marketing hype? I've done some searches on the forum and the opinions appear pretty mixed on that topic but only a few were real world examples where it appears to have worked out just fine.

My drop in LiFePO4 batteries (2 x 100ah) have been doing a sterling job for four years. They were cheap and imported from China without even a label.

[john61ct]

One would hope so.

If you are happy with the 2-3000 cycles the vendor promises, then by all means, most not-rip-off LFP will indeed deliver that, barring any catastrophic care failures.

But will they do the 12+ years a good FLA bank can? Has the price difference delivered good ROI at that point?

What about the 20-30 years I'm striving to get out of mine?