LiFeP04 charging

[k-harvey]

With my 2 12v 20ah LiFepo4 home made battery packs with having no 12v LiFePo4 charger I've been charging with
my 12v fully automatic 4.3a acid battery charger until shown as charged & it seems to work very well only taking more than all night to charge .
After advice from a fellow member I joined both packs in series & tried charging with my 24v lifepo4 e bike charger thereby charging the 2 packs at once. This way the LiFeP04 chargers -29v 3a (that I have many for e bikes)often show the packs as being charged when they are not & more often will not start charging. While I'm present anyway.
When I do get these packs charging in series -& shown as charged the 12v acid charger can as it seems put a lot more amps in.
& of the LiP04 chargers are too inconvenient to use as I need the fully charged for when I use them ..
Can the 12v acid fully auto ( says on charger for acid battery only)DO DAMAGE TO MY liFeP04 cells.
If smoke came from the 12v charger I would not worry but not my 2 liFep04 packs nor reduce their life..

 

[Ypedal]

Well, depending on the end voltage of your lead acid charger.... check it and report back.

do your 12v packs have BMS's ?

 

[k-harvey]

The liFep04 packs each have a BMS --also I cannot get a voltage reading from the 12v Automatic chargers as its so sensitive but on the
outside (where it reads for acid battery only it says 12vdc 4300ma )This acid battery charger cannot even be shorted out ie spark when + & -
are joined .

 

[Ypedal]

hook it up to the battery and check the voltage while it shows fully charged, report back. :wink:

Basically, you need to get the cells to at least 3.5v to get the most out of them. so x4 = 14.0 v

if the charger goes to trickle at 13.5v / 4 = 3.37v .. then you are not getting full capacity potential.

 

[999zip999]

I like having a set of sense wires for each cell for a cellog type meter. Plus don't over charge per cell 3.6v and no higher than 3.8v. as 3.5 is full.

 

[dogman dan]

Having the bms will help the lead acid charger not damage the packs. The bms will start discharging, very slowly, any cells that overcharge. So the bms should be able to keep up with the small trickle that is present when a lead charger shows finished.

Not starting to charge, that could be a flaky plug on the 24v charger. Full, and unplugged, both show the green light.

 

[Wishes]

With my 2 12v 20ah LiFepo4 home made battery packs with having no 12v LiFePo4 charger I've been charging with
my 12v fully automatic 4.3a acid battery charger until shown as charged & it seems to work very well only taking more than all night to charge .
After advice from a fellow member I joined both packs in series & tried charging with my 24v lifepo4 e bike charger thereby charging the 2 packs at once. This way the LiFeP04 chargers -29v 3a (that I have many for e bikes)often show the packs as being charged when they are not & more often will not start charging. While I'm present anyway.
When I do get these packs charging in series -& shown as charged the 12v acid charger can as it seems put a lot more amps in.
& of the LiP04 chargers are too inconvenient to use as I need the fully charged for when I use them ..
Can the 12v acid fully auto ( says on charger for acid battery only)DO DAMAGE TO MY liFeP04 cells.
If smoke came from the 12v charger I would not worry but not my 2 liFep04 packs nor reduce their life..

2 BMS usually do not like being charged in series and I have never seen it work properly. As you describe, they will either not charge, or not charge unequally resulting in at least 1 pack being not full.

Many 12v Lead Acid chargers output only 12v. Others will output up to 14v. Like other members said, you need 14.6v from your charger to get the full capacity into them. It doesn't matter how many amps your push at 12v, your packs will never fully charge. And without a lifepo4 charger, you will never top off your cells properly. And over time, it will cause enough of an unbalance to your cells that the bms will not be able to compensate. They do have limited discharge current capacity on the balancing function.


Wishes

 

[k-harvey]

Thank you all ---have managed to get voltage of an SLA acid battery at the max with this charger, it with charger connected & on, it reads 14v but now have another problem that's in another thread of 2 cells being zero volts .Have to buy LiFepo4 charger probably when buying the next BMS & cells the way things are going .Seems I like LiFePo4 problems.---but Battery device with LiFePo4 instead of SLA is proving successful
Also I did find a faulty wire from charger that could have been stopping the charger to start. Both 12v LiFePo4 when charged & left for a time are 13.7-& 13.86v. These packs are wrapped up in black wide tape so have a job getting into them .Worst case scenario they sit in a little salt water.