First Charge/Top Balance charger issue

[JAS]

Hello all,

I purchased (4) 170AH EnerAmp batteries from Current Connected and an OverKill BMS in order to create a 12v battery pack. My plan was to put cells in series (with the BMS of course) and charge up with my Noco Genius 10A charger. Then put the cells in parallel (no bms) and do a Top Balance with this benchtop power supply: https://www.amazon.com/gp/product/B01NACT99O/ref=ox_sc_act_title_3?smid=AYFZ6BM3IGB5D&psc=1


Unfortunately, my Noco keeps going into overheat within about 5 minutes (I need to contact Noco about the warranty). Is it safe to use the power supply that I was going to use for the top balance to do the initial charge at 14.6v?

Thanks,

Jeff

 

[Bob B]

Yes .... you will be safe as long as you have the BMS set up so it can interrupt the charge if one cell goes too high.

Most of those power supplies come with really crappy leads with tiny alligator clips and too much voltage will be dropped across the leads when top balancing.

Do yourself a favor and save frustration later by replacing them with 10-12 gauge wire with ring terminals on both ends.

 

[JAS]

Thanks Bob, I did read that in other threads regarding the crappy leads.

 

[Samsonite801]

To understand how a normal battery charger works for like a lead acid 3-stage charging...

You have Bulk, which applies a CC for awhile (voltage is variable), when the voltage gets up to a certain limit, it switches to Absorb stage, which sets the charger to CV, and the current is variable, and when the current tapers off lower and lower, it hits some point where it sets the CV to a lower float voltage, and keeps it there.

So on a power supply, if you set it to CV and set it to a safe voltage limit for LiFePO4, you will essentially slow charge the battery up to full, it may take a bit longer, but it's safe...

NOTE:
On LFP you don't need Absorb, but if you bulk charge (with CC) on LFP, you have to watch the voltage, and stop it when it gets to safe limit. Of course your BMS should have some safety cutoff built-in too.

 

[JAS]

So for a 12v LiFePO4, is 14.6v safe, or should I go lower for my purposes of doing an initial charge before doing a top balance?

 

[Stepandwolf]

I did my whole charge using a PS similar to yours. It will charge 10A until, like mentioned, the amperage drops as you get nearer the voltage value you set. For the top balance, as you said, you will be in parallel mode, and will be charging at 3.65v or whatever is appropriate for your setup.