Lifepo4 charger

[84bronze]

I am looking for a charger for lifepo4 24v battery I'm getting ready to build using 8 272ah cells. I have this charger that I have been using for my agm batteries and it works good. It says that it will work for lithium batteries also but not sure if it is a good idea or not.

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[MisterSandals]

Without seeing any specs its hard to make a detailed analysis. How high does it say it will charge your battery?
I'd say if you get over 27.6v you're charging 100%.

What is your use case? Charging a battery for emergency standby (twice a year), or everyday, or ???
Having great tools is one of my favorite things but sometimes good enough, is good enough!

 

[84bronze]

I get 14.4 or 28.8 open circuit voltage. It stops charging when battery is at 28.8.

I use it for my agm batteries to charge daily if no sun and it works really good for what it is. I have a 700w generator that runs it and can still use my inverter at the same time.

I'm not sure if I should try to charge a 24v lifepo4 battery with it? Does it matter what kind of charger to use as long as it does not over voltage? BMS should shut it off if it gets to high?

 

[MisterSandals]

I'm not sure if I should try to charge a 24v lifepo4 battery with it? Does it matter what kind of charger to use as long as it does not over voltage? BMS should shut it off if it gets to high?

Sounds better than fine, looks great.
Yea, BMS last line of safety for many conditions.

 

[84bronze]

Thanks. I'll give it a try instead of buying another charger first.

 

[Diysolar123]

you do realize that for an 8S 280Ah battery bank... that will charge at only 5amps (140W limit), ouch, thats going to take a loooong time to charge.
I use an MP3020 which can provide 20A at up to 30V for a single cell, or an 8S string.

if you are handy with a soldering iron you can make a very impressive power supply (50amps output) for around $80 using two DPS-800GB server power supplies in series...warning, they have very loud fans!

I find 20amps to be a good number as it means I can use 10awg cables and not worry about hot wires.

 

[84bronze]

Being off grid I don't have access to unlimited AC power. I have a small 700w (5-6 amp output) generator that runs almost 8 hours on a 1/2 gallon of gas. I just want enough to keep my batteries from going dead while still using them when no sun. I have a bigger generator that I run a 55 amp charger that will charge them faster.

With 2.2kw of solar I usually get 7-10 amps in on a cloudy day, or less on a rain day, I only need to run in the morning or evening to keep batteries going until sunlight

 

[MisterSandals]

I have this charger that I have been using for my agm batteries and it works good.

Seems you've already determined the amount of charging power (140w) is sufficient.

You sound like you are not an off grid novice and you have this under control.

 

[Ed Tech Sensei]

Thanks. I'll give it a try instead of buying another charger first.

How did that work out?

I have a similar question regarding the use of a 24v lead-acid battery charger with LiFePO4 batteries. I recently replaced two 12v 32ah AGM batteries with two 44 ah LiFePO4 batteries on my wheelchair (Quickie P110). The charger doesn't have a readout. The controller on the wheelchair has an XLR (like a mic jack) charging port and colored bars to indicate battery use and charging input. The charger states "for lead-acid batteries only" but my wheelchair is so old, I don't think LiFePO4 batteries were common back then.

I initially charged the batteries individually with a 12v/24v bench charger. I could continue to do that, but it's a pain to remove the battery boxes from the wheelchair. I could also make an XLR connector cable and connect that to my charger using the 24v setting. It would be much more convenient to use the charger that came with the wheelchair.

 

[84bronze]

I am still waiting for my batteries. I am in the process of getting everything ready. The charger works good for agm batteries and is listed as lithium also. I would hate to ruin my lifepo4 batteries when I get them although it sounds like it will work

As long as the voltage is not too high and has a way to shut off when "full" it should work. I can only speak in theory though. You can read the charger voltage with a meter open circuit and when connected to the battery