Charging trouble

[Joost]

Hello electric geeks,

I want to ask for help too solve the next problem.

I have a 48V 6A lifepo4 charger that charger too a height of 58,4V.
Now is the problem that wen it hit its 'full charge' voltage it cutoff. No trickle charge will start, I know/think because the voltage drop and the charger kicked not in.

Wen I switched the charger off and on it starts......

How can I solve it?

Thanks for reading my topic!

 

[TristanP]

I have a 48V 6A lifepo4 charger that charger too a height of 58,4V.
Now is the problem that wen it hit its 'full charge' voltage it cutoff. No trickle charge will start, I know/think because the voltage drop and the charger kicked not in.

Of course it is cut off, because it is fully charged. Given a 16S pack with a charge voltage of 3.6V per cell it's even slightly overcharged. (16*3.6=57,6)

How much did the voltage drop that you think it should be charged again? Also it may not be advisable to start charging an almost fully charged pack with a (relative) dumb CCCV charger.

 

[dogman dan]

You don't solve it. that's normal. Lithium chargers never trickle. But they may cycle on and off as the pack balances. If they don't, you can manually cycle it on and off, as you said.

If you have a bms,, it's discharging some higher charged cells at that point. Re setting the charger to run again when you unplug and replug,, that's just continuing the balancing process.

So do that when you need a perfect balance. like before you store it awhile, or need a 100% discharge for a very long ride.

If you pack is really dropping voltage after you take it off the charger, then you may have some weak cells. The only way to really diagnose this, is to charge full, get it really balanced by doing the unplug thing a few times,, then check the voltage of each individual cell immediately,, then again a half hour later.

half an hour later, good healthy cells will not drop below 3.5v each. If they lose voltage from 3.6v or whatever to 3.5v,, that's just surface charge. Surface charge is a slight overcharge that lifepo4 systems do to help it balance better.

If you have cells that only hold 3.3v,, that's a weak cell. 3.45v,, that's not perfect, but still ok and usable.

 

[Joost]

Thank you all for answering.

I was thinking that it trickle automatic when it drop to the 'charge' level of the bms.
Is there a guide were I can check and setup a lifepo4/li-ion charger?
Or what are the steps to measure and set the trim pots?