Charging series lithium batteries

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
So I have a device I'm putting together with 4S batteries, and I'm considering charging styles. It looks like what will be easiest would be to simply do a 1S charger on a single cell and rely on the active balancer to distribute current. I'm putting the active balance in no matter what, and the 1S charging circuit is more compact. Is that a terribly bad method, or just kind of not really ideal?
 

KeithWalker

Joined Jul 10, 2017
3,030
What are the input requirements of the active balancer? They usually require a higher supply voltage than the that of the battery. A 1S charger will only supply enough voltage to charge a single cell.
 

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
What are the input requirements of the active balancer? They usually require a higher supply voltage than the that of the battery. A 1S charger will only supply enough voltage to charge a single cell.
Right, but once that one cell gets above the threshold of the balancer, it will start to move the current around until they're balanced.
 

MrSoftware

Joined Oct 29, 2013
2,169
Check out some of the hobby chargers. I know for sure they bulk charge in series. From there I'm not sure if they then use the balance wires (that go to the individual cells) to slow charge the low cells, or use load resistors to pull down the cells that are too high. But I bet the schematic for those things is online somewhere if you dig. One example is the C1-XR charger, I've got a few of these and they work really well.
 

LowQCab

Joined Nov 6, 2012
3,937
Battery-Balancers are generally NOT designed to "move" significant amounts of Power between Cells.
How long do You expect a Charging-Cycle to take ?

Charging just One Cell, for any reason, is not a good plan.

Would You please completely characterize your Battery and it's Load ?,
if You do, I'm sure you'll get much more pertinent advice.
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KeithWalker

Joined Jul 10, 2017
3,030
So I have a device I'm putting together with 4S batteries, and I'm considering charging styles. It looks like what will be easiest would be to simply do a 1S charger on a single cell and rely on the active balancer to distribute current. I'm putting the active balance in no matter what, and the 1S charging circuit is more compact. Is that a terribly bad method, or just kind of not really ideal?
Your concept of powering a multi-cell active balancer with a single cell charger will NOT work. an active balancer usually requires a supply voltage greater than the fully charged multi-cell battery voltage.
 

Externet

Joined Nov 29, 2005
2,182
If I understand well, I have charged packs of multiple lithium cells by applying 4.10 V to only one of the cells with alligator clips, then to another, then to another... using a single cell charger or a plain 4.10VDC supply. Usually left overnight. Yes, several nights to recharge a pack. But excellent results when you have no balancer circuitry. ;)
I have replaced a bunch of flashlights, tool packs, gadgets with lithiums and no balancer. End working fine by recharging cell after cell of the pack. Some may call it tedious, but if you have small alligator cables, it works ! Can do several of the pack at a time with several individual single cell chargers (or supplies).
 

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
Your concept of powering a multi-cell active balancer with a single cell charger will NOT work. an active balancer usually requires a supply voltage greater than the fully charged multi-cell battery voltage.
So maybe I'm not communicating effectively, but I will NOT be trying to power the BALANCER. I will power ONE CELL at 4.1 or 4.2V, then rely on the balancer to do its job and distribute the power to the other cells.
 

LowQCab

Joined Nov 6, 2012
3,937
You might get it to work, who knows ?
It's still a very "iffy" plan.

You been told that it probably won't work well by several professionals,
Why do You continue to ask the same question ?
The answers won't be any different.

You are considering using a piece of equipment in a manner that it was not originally designed for.

Your Batteries will probably suffer for it.

How much do new Batteries cost compared to a proper Charger ?
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Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
You might get it to work, who knows ?
It's still a very "iffy" plan.

You been told that it probably won't work well by several professionals,
Why do You continue to ask the same question ?
The answers won't be any different.

You are considering using a piece of equipment in a manner that it was not originally designed for.

Your Batteries will probably suffer for it.

How much do new Batteries cost compared to a proper Charger ?
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I'm not asking the same question. If you follow the thread, I was explaining the fact that the other person didn't understand the question I was asking and I was clarifying to make sure that we're at least on the same page.
 
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