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mgulley82 avatar image
mgulley82 asked

BMV-712 consumed amp hours off

I have a BMV-712 connected to a 450 amp hour lead acid battery bank (Trojan t-105’s). Recently When I run my battery charger to bring the batteries to a fully charged state I’ve noticed that the consumed amp hours still read 40-50 amp hours consumed when the BMV synchronizes and resets the battery to fully charged and resets consumed amp hours to 0.


in other words I’m using 100+ amp hours over night but only registering a return of about 50-60 amp hours back into the bank when I fully charge them.

Is this normal?

Both my solar and my AC-DC battery charger bring the batteries to 14.82 volts for a specific time based on previous day’s discharge and then reduce batteries to 13.5 volts with minimal amps to sustain this. I have adjusted my battery settings because before I was getting fully charged status too early.

BMV Battery Monitor
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klim8skeptic avatar image klim8skeptic ♦ commented ·

I would bump the "charged voltage" on the BMV up a bit.

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2 Answers
brainy avatar image
brainy answered ·

Hi. You should check peukert and charge efficency. Peukert will cause too much counted amp hours on type/amount of load and charge efficiency will cause that too less amp hours are counted while charging. It's not that easy to find the correct values but i bet it is a combination of both values. LiFePO4 for example have a peukert of 1.00, which means that it does not matter if you just pull out 1A or 50A or whatever and charge efficiency on them is >99%. Like i said, its very hard for find the 100% correct values

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mgulley82 avatar image
mgulley82 answered ·

I may have answered my own question


so my aims inverter/charger has a specific time it follows for absorption charge. Seems

My batteries were charging up fast enough to only trigger about 1 hour of absorption time which wasn’t actually fully charging the battery bank.

Being as we are now in winter and the batteries theoretically have a 40-50% reduced capacity I will reduce the charge current accordingly

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