Charging Lifepo4 battery.

[Naysayer]

I'm a newbie to Lifepo4 & got a 100ah.
I've read mention about using a regulated power supply with current limiting to charge but there never any details.
Maybe I'm over-thinking it.
If possible, I'd like to user my Astron VLS-35 for charging.
is it really as simple as setting the voltage, connecting and wait for current meter to drop?
neil

 

[W4KVW]

I'm a newbie to Lifepo4 & got a 100ah.
I've read mention about using a regulated power supply with current limiting to charge but there never any details.
Maybe I'm over-thinking it.
If possible, I'd like to user my Astron VLS-35 for charging.
is it really as simple as setting the voltage, connecting and wait for current meter to drop?
neil

Most Lithium batteries require a Lithium charger. My Bioenno came with a charger & the information says not to use a regular battery charger.

 

[sp5it]

How you gonna control CC/CV stages?
Better get proper charger.
Mike

 

[Naysayer]

How you gonna control CC/CV stages?
Better get proper charger.
Mike

That's not the same as Current Limiting and adjustable voltage on the Astron VLS-35?

 

[Shadetree Mechanic]

It should have onboard BMS (battery monitoring system) that takes care of cell balance, max charge and discharge current, battery temperature etc. so it shouldn't take anything special to charge it. The manual that came with the battery should confirm this. People with RVs replace their lead acid banks with these all the time.

 

[Naysayer]

Yes thank you. Battery came complete w/ BMS.

 

[brandon7861]

I also recommend buying one. If you get it wrong, you'll burn your house down. These things don't give you much warning.

LiPo and LiFePO4 are different chemistries and take different charging. Does it say 3.2v/cell (LiFepo4) or 3.7v/cell (LiPo)?

You can expect a constant current stage of .5 to 2 x C-rate, so if you have a 3000mAh battery, a slow charge is 1.5A, normal charge is 3A, and some support fast charging at higher rates like 2x C, but you better know what you have or it can thermally run away trying to fast charge!

After the voltage reaches 4.2v (for LiPo) or 3.6-3.65v (for LiFePO4), the charge mode is switched from constant current to constant voltage (otherwise the voltage would go up past that voltage and boom. When the charge current in this constant voltage stage drops below .05C to .1C (150 to 300mA for a 3000mAh battery), charging is stopped.

I only write this to give you an idea how it works, but if you get it wrong, or your constant voltage is just a little too high, even 4.25v for the 4.2v case, you can plate lithium damaging the battery and there is a risk of fire. This is why nobody here is going to recommend you try it yourself unless you have some good electronics experience and know EXACTLY what battery you have.

I don't plan to make anyone a schematic for this. Too much liability.

 

[Naysayer]

Thanks for the warning and thanks for saying it straight.
My first Lifepo4 experience so I'm going slow.
I already fused my psu-batt wire. From the charts 20ah is adequate but I will maintain a constant 'eye on it all' w/ temp gun in hand.

 

[Naysayer]

I needed a awhile to recognize the liability concern.
Actually doing it, drove that concern home.
I will relate my personal experience.

My new 100ah Lifepo4 came with a 40% charge. It sucked a steady 20A from my Pyramid 35A power supply (recently re-capped) for a few hours until the Bluetooth app indicated 90%. The primary hazard was the temptation to walk away / do something else, while it's charging.

Depending on the wires used, they will generate heat, 20A worth of heat so must be mindful. I connected a small fan for psu heatsink.

The next day, my 10A Lifepo4 charger was delivered and it finished off the remaining 10% where battery still reports now (3 days later.)
n2eye