Scream Power LIFEPO4 Battery Won't Hold Above 14v Charge

itsmattmp

New Member
I've been using a 320 AH Scream Power LIFEPO4 battery for a few months now. Been fine until this past week. For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls to 13.1-13.2 volts. Is this normal, or should my battery maintain at least 14v at full charge?

I'm using two 60A Renogy charge controllers, and one 100A EPEVER charge controller to charge with solar, and an Inteli-Power PD9160AL to charge with a generator.

Using a Victron Multiplus 12/3000 inverter. It's been able to run our RV AC just fine in the past, but today it started shutting off from low voltage even though voltage should have been full. Voltage would sag from 13.0-13.5 volts to 12.0 volts during a short time running the AC, and then would jump back up to 13 something volts after shutting off.

I'm afraid my battery is failing. Scream Power advertises 1 C rates - that's why I went with their battery. But maybe it can't handle it?
 

Forbisher

Փփքխմպձժճֆըվմ
I've been using a 320 AH Scream Power LIFEPO4 battery for a few months now. Been fine until this past week. For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls to 13.1-13.2 volts. Is this normal, or should my battery maintain at least 14v at full charge?

I'm using two 60A Renogy charge controllers, and one 100A EPEVER charge controller to charge with solar, and an Inteli-Power PD9160AL to charge with a generator.

Using a Victron Multiplus 12/3000 inverter. It's been able to run our RV AC just fine in the past, but today it started shutting off from low voltage even though voltage should have been full. Voltage would sag from 13.0-13.5 volts to 12.0 volts during a short time running the AC, and then would jump back up to 13 something volts after shutting off.

I'm afraid my battery is failing. Scream Power advertises 1 C rates - that's why I went with their battery. But maybe it can't handle it?
LFP battery voltage settles to 13.6V or less after a full charge.
LFP will never "maintain" an over 14V charge.
Look at the voltage chart on my avatar.

Even though LFP can be charged at 1C for longer life 0.5C is recommended.
 

MisterSandals

Participation Medalist
For some reason my chargers will quickly charge it up to 14.4-14.5 volts but the the chargers shut off and the battery voltage quickly falls
Are you sure the batteries are actually fully charged? If the current is not tapering you are likely measuring the charger/battery combined voltage (14.x).

Otherwise, measure the individual cells, that will provide more info at to what is going on with your battery. As Forbisher said, they will settle down. Some folks see 3.5v/cell while others (me!) see 3.35v/ cell.
 

itsmattmp

New Member
Are you sure the batteries are actually fully charged? If the current is not tapering you are likely measuring the charger/battery combined voltage (14.x).

Otherwise, measure the individual cells, that will provide more info at to what is going on with your battery. As Forbisher said, they will settle down. Some folks see 3.5v/cell while others (me!) see 3.35v/ cell.
My Inteli-Power charger starts at full amps (60 amps) and then tapers down to about 5 amps within about 1 minute of charging. So apparently it thinks the battery is fully charged. I have an Ammeter which I've programmed at 320AH, but I can't get it to read over 270AH now.

I used to be able to comfortably have enough power to last sun down to sun up, but now I lose power around 6 am.

I can't test the individual cells because the Scream Power battery is not "user serviceable". I understand I could cut it open, but I imagine it would void the warranty.

Is it possible that running my AC pulled too high a C rate from the battery? But shouldn't this battery have a BMS that would stop me from pulling a higher C rate than its rated for? And shouldn't a lithium battery be able to handle short surges from starting a compressor motor? What's the best way to test my battery to figure out if it's been damaged? Use a benchtop charger to fully charge, and then do a capacity test?
 
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