Charging lithium battery

[Just4Fun]

I have a 52Ah 12V Lithium Iron Phosphate (LiFePO4) battery. I charge it with a mains charger that has a LiFePO4 mode. The battery and charger are both new. When fully charged the battery is 14.1V. In use the battery has a load but no charge mechanism. Typically the voltage drops to 10-point-something volts in a single use, and then I charge it again. I have 2 questions:

1. How low can I allow the voltage to drop?
I would like to use the battery for twice as long as I have done so far. Is that possible? Safe? Bad for the battery?

2. Suitability of my charger.
It takes a long time to charge the battery. Reading the "manual" that came with the charger, it says it can charge batteries up to 20Ah and maintain the charge on any battery. 20Ah is less than half the capacity of my battery.
Is this battery & charger combination safe? I have read of fires supposedly caused by using the wrong charger to charge electric bikes. Obviously something I would like to avoid.
If it is safe, will this slow charging harm the battery?

 

[John Brown]

I'm not expert, so don't take anything I say as gospel, but;
Lifepo4 are apparently very safe, extremely unlikely to catch fire. The fires that one reads about are Li Ion, as far as I know.
The Lifepo4 battery I have(24V 100ah) has integrated Battery Management System that will prevent overcharging or over discharging.
It seems unlikely to me that a slower charge rate would damage anything. My solar charger produces anything from a fraction of an amp up to around 20a, in theory.
You can find more info on the web regarding actual voltages etc. Maybe you could give a link or more info on the make and model of your battery?

 

[Sideways]

The latest big thread on UKW that bears on LiFePO4 batteries is here:
https://www.ukworkshop.co.uk/threads/diy-powerwall-battery.148821/

You'll find this graphic in the thread

Given the voltage range of a cell, a 12v battery will be made of 4 cells in series, and possibly series strings in parallel. Check the 12v column in the table and keep the battery voltage in the green range for longer life.

I've read stuff that suggests that charging at 20% of the battery capacity is good for long life but my own commercial battery will charge and discharge at upto 6.5kW vs a 16.6kWh battery so that's about 40%

If you are using higher rates of charge or discharge, then the charger should be monitoring the temperature inside the battery pack.

Hope this helps

 

[Just4Fun]

Maybe you could give a link or more info on the make and model of your battery?

Thanks for your help. My battery is this one: https://www.westmarine.com/relion-r...e-deep-cycle-battery-12.8v-52ah-20659900.html

My charger is this one: https://fulbat.com/charger/charger/fulload-1000/

I bought these two together without even considering whether the charger was "man enough" to charge that battery, so the mis-match is totally my own fault.

 

[John Brown]

I think you'll be fine. Obviously you might want/need a faster charge, but as far as I know you're not going to hurt anything by using a lower charge rate.
At that price(assuming US dollars), I would sincerely hope the battery has a good management system built in. My 24v(actually 25.6v) 100ah battery cost me £429, and that made my eyes water.

 

[TRITON]

Only thing im aware of with batteries and charging concerning Ebikes is the charger needs to be 'married' to the battery system, and to have a cut off when full charge is achieved.

The problem with fires is cheapo chargers that dont automatically stop trying to force a charge in when the battery is full, so it overheats then Whumph, up it goes

Thee other problem is people think it is ok to leave anything on charge overnight while they are asleep. It is that kind of behavior that has cost many lives.

 

[John Brown]

Only thing im aware of with batteries and charging concerning Ebikes is the charger needs to be 'married' to the battery system, and to have a cut off when full charge is achieved.

The problem with fires is cheapo chargers that dont automatically stop trying to force a charge in when the battery is full, so it overheats then Whumph, up it goes

Thee other problem is people think it is ok to leave anything on charge overnight while they are asleep. It is that kind of behavior that has cost many lives.

Ebikes generally use Lithium Ion batteries.
The OP is asking about a Lithium Ferrous Phosphate battery. They are not known for catching on fire.
Having said which, I believe you are right, in that folk buy cheap chargers that are either cr@ppy designs, or aren't matched to the battery for charging eScooters. We all(?) charge the Li Ion batteries in our smartphones, mainly overnight (I'd guess) without problems.