Charging without a BMS

I bought the following 4A 12S charger:

Since it is CC/CV, I should be able to charge without a BMS, right? I expect it to limit the current to 4A.

I’m not worried about balancing - I can manually balance the battery when need be.

Yes, the only thing to be careful is the trickle charging. Li-ions should not be trickle charged. Do they have a charge profile? Ask them for one. Good find for the price!

As long as you keep an eye on the balance you should be fine. I recommend getting a balance board anyways so you don’t accidentally over charge a cell if too much time goes by between balancing cycles.

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Thanks for the reply! I was unaware of the issue with trickle charging.

For anyone else reading, here is some more information about the problem of trickle charging a li-ion battery.

From “Li-ion cannot absorb overcharge. When fully charged, the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium and compromise safety. To minimize stress, keep the lithium-ion battery at the peak cut-off as short as possible.”

From "Stage 4: Charge Termination – Unlike nickel-based batteries, it is not recommended to continue to trickle charge Li-Ion batteries. Continuing to trickle charge can cause plating of metallic lithium, a condition that makes the battery unstable. The result can be sudden, automatic, and rapid disassembly. "

I couldn’t find anything definitive about why the trickle charging was bad though other than the fact that the battery is already full charged. I suspect that this charger has a potentiometer to adjust the end voltage. I wonder if I set it to say 50V rather than 50.4V, whether trickle is no longer a concern?

@PSXX Oh, I sent a message to the supplier asking for the charge profile. If they get back to me, I’ll attach it here.

Trickle charging is bad because it leaves the battery at a high voltage for a prolonged period if time.

I’m not sure they trickle charge at all as they do have a cutoff current of 5% charge current. Another thing to look for is at what voltage is charging re-enabled

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No no no no. You must use a BMS for charging. Charging without one caused this. Cc/CV is a requirement for all chargers when charging liion. The CC/CV doesn’t keep the cells balanced. It just won’t over charge the pack a s a whole. Doesn’t protect you from anything. Absolutely DO NOT charge without a BMS. image

Sorry and no offense but no. The lack of a bms did not cause that fire. Your inexperience making batteries and using them appropriately did. The BMS is a very very very important safety feature but not by any means vital.

I do not condone or suggest anyone to build a pack without a BMS but with enough experience and care, it can be done as proven by @whitepony. It just means you have to be conservative in your discharge and charge levels as well as checking your battery every once in a while for balancing.

I currently charge without a BMS with this monstrosity. I trust myself checking the balance of the cells more than I trust a BMS to do a good job of it.


It’s a 12V power supply connected to a Drok boost converter. It’s great because I can control the charge voltage (I almost never charge past 49.5V) and current. However, I wanted something more portable and less noisy. The Drok makes a surprisingly loud high pitch noise.