A cardinal sin???

[LagoonJim]

I've been in a similar situation myself with dying agm bank while awaiting LiFePo4 conversion(which was best thing I ever did, ignore LiFePo detractors).

As said before, you likely have one or more bad batteries, which is to say you may have a few ok.

Use of a proper load tester is best. However, steps below may give the same result.

1) place your hand on top of each battery, any that are warmer have internal shorts, drawing the rest of the bank down.(stored energy being released as heat)

2) without disconnecting from bank, use a digital volt meter to measure voltage of each battery at terminals. Ones with slightly lower voltage than the rest are bad(even if still connected to charger).

3) once removed, let a battery rest a few hours, then re-test to see if voltage drops quickly. Very likely you find a couple outright bad, and with any luck you have a few still serviceable.

If you have batteries left after tests above, load tester will tell you if they are candidates for reconditioning(desulfation).

I've reconditioned dead batteries with marginal success. That said, a battery that just has low capacity due to sulfation won't hurt the rest of the bank, they just don't help.

Getting rid of outright bad batteries, adding a fresh battery or two if necessary, is probably best approach in your situation.

[Skipper Kenny]

Originally Posted by Tracyandkimo

I believe it’s the daily cycling from 50-90% that’s aging them

Have you desulphated them?

[botanybay]

Originally Posted by OS2Dude

I take it you are not switching to LFP now because of availability? If you can get good ones now, I would not wait. If you can't, then I would do as suggested and remove the worst batteries from your bank, maybe get one or two expendable AGMs.

What else do you have running in the evening/night/early morning? As stated, the refrigerators/freezers should stay cold as long as you don't open them much (at all). If they are running that much at night, they may need attention. Try packing the freezers densely so you have a cold mass. Same for the refrigerators. If you have items you need/REALLY want from the fridge in the evenings/night, keep those in a single unit.

If you have Victron components, I just ordered a new EPOCH 300Ah V2 LFP. There is also a 460Ah version. The V2 means it can be a part of the Victron environment via the BMS.CAN bus on a CERBO.

https://www.epochbatteries.com/colle...rine-batteries

Or a few cheap golf carts. 4 would get 24v and 220ah, abuse them for 6 months and throw away.

[Dave9111]

Dont put lithium in parallel with lead acid. The batteries will fight each other.

You meed a battery isolator to combine la and li batteries.
I have such a setup.
Autohaus sells a $52 isolator on Amazon. Buy a few cheap lifepo4 12 volt,
100 ah batteries off ebay or amazon and you will be set. The lead acid gets
Charged first then the lithium. Works great. No batteries fighting each other.
I have this setup in a vehicle. The alternator charges everything.

Make sure you remove bad batteries from your existing pack or else nothing may charge up. Bad batteries never charge to full voltage which compromises your
Battery pack.

[robert sailor]

Who’s messing with our boat name? SV Cardinal Sin