Charging LiIon with a LifePo Charger

Joined
Jul 6, 2022
Messages
6
Hi,

I am aware of 3.6v <> 4.2v. This is not the topic here.

My 14s-charger died (58.8v) and I need replacement. To prolong the batteries life (by, well, just a bit) I though about this 16s LFP-charger -> https://de.aliexpress.com/item/1005003682689596.html

My question: are cc/cv charging curves of LiIon & LFP chargers the same, or should I stay away of this although the voltage is in range?
 
I'm doing a similar thing. I have a 24s LiFePO4. Max charge voltage would be 87.6, and that's what most of the 24s chargers do, at least the ones that don't let you set your own voltage. I don't want to go that high, I also want to prolong cycle life.

I ordered a 20s Li-ion charger. Max charging voltage is 84v. This is much closer to what I want my 24s LiFePO4 voltage to be. Disclaimer: I haven't used it extensively yet. But I don't see any issue, as long as you know and confirm via multimeter the max charging voltage of your charger. Both Li-ion and LiFePO4 require CC/CV. I tend to pull the plug before the charger shuts off anyway, because I like to just go to 80-90%.
 
You'd have to test if this is the case now, with whatever charger you buy, but in years past the difference between a LiFePO4 charger and a Li-Ion charger was that the LFP charger did not shut off it's output voltage once current dropped below a certain point, while the LI did.

If you look around Dnmun's posts there are a few that detail some of this, including showing what board to remove from certain brands/models of LI charger to turn them into LFP chargers.


Other than that, the chargers work the same basic way.


FWIW, many decent chargers have adjustments inside for at least the max voltage, and some also have a termination current adjustment (point at which they turn off when current drops below that), as well as a max charge current adjustment.



Note that if you intend to manually terminate charge, or have a separate device to do this (BMS, etc), and don't want the charger to turn off it's output, you can use LED PSUs like the Meanwell HLG (and ELG) series as chargers. I use the MW HLG-600H-54A to charge my EIG NMC C020 14s2p packs for the SB Cruiser trike; this version has an adjustment pot for current and for voltage.

They are also waterproof and vibrationproof, being completely sealed and potted. (mine is bolted to the bottom of the trike and has been submerged at least twice in flash floods as I rode home from work; it's been working for years without problems, and I got it well-used rather than new). (I also have a 12v MW in the 150H series up on a pole in the backyard running an LED panel; it's been there for at least a couple of years in the sun and rain and heat and cold and still works).

Just remember...they don't turn off (which a proper charger would, with the exception of chargers specifically designed not to for balancing or other reasons) when current drops below some point, so it's up to your battery's BMS or other device you install to do that.


The Cycle Satiator is also a good charger...thoroughly programmable, but it isn't cheap and only comes in a 300W size (three voltage/current combination variations, though).
 
it will work, all the chargers are cc/cv. As long as the max voltage is similar or lower than what your battery requires you will be ok. If I were you I would get one of the 100v 10a volt/amp LED meters (about 7 dollars) and connect between the charger and battery so you see the charging in realtime. I use those cheap meters on all my chargers.

a led volt amp meter.jpg

If your paranoid about making sure the battery doesn't exceed a certain voltage, you can use an overvoltage protection relay that will pull a relay to disconnect the battery if the voltage goes too high. This will save you if the charger and bms fail. I use them and they work very well. They cost about 10 dollars and measure up to 99 volts.

1 099.jpg
 
Can you provide a link to those overvoltage relays that you like to use? Looks like something I'd be interested in trying out
 
I stopped using BMSssses on my bike batteries (have 3 now, ~750Wh, ~300Wh and one with ~120Wh) because on the biggest pack the (el cheapo) BMS failed once. Glad the pack survived. So I will not fool around too much about circuits to monitor and shut off this and that.

Think I'll just go the simplest way and get a (craigslist or w/e) 2A 14S charger for a couple bucks and manually shut it off after a while charging. Everything else is just overengineering for charging a couple Wh now and then after a ride.

Other than that still good input here, thanks!
 
Back
Top