How to I balance charge a 13s with only a 6s balance charger?

ClintBX

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Hi ESFMs

I have a few batteries that are no longer charging fully. Some of them are quite new but have a cheap bms installed.

Rather than throw out perfectly good packs, I want to learn to balance them (and maybe replaced their bms with good quality ones at some stage)

I bought one of those iMax balance chargers for this purpose but because I couldn't find any for a 13s pack, I had to settle for a 6s.

How do I balance charge my 13s with a 6s? Can I even?

Clinton
 
Custom balance harness to suit with a pole for main charge in segments ( sets) using said custom harness ( with extra poles for main charge leads coming out, for said current).

There are other fancy ways but this is simple manual circuit.
 
Hobby chargers in general do a pretty poor job at balancing worn packs that have gone far out of whack, take forever and only start the job while cells are at highest SoC% which is unhealthy.

Node chargers, where every cell gets an independent 1S charge regulation circuit are better.

And then you have dedicated balancers, which balance cells against each other at any desired SoC not just at the top.

https://www.amazon.com/Equalizer-Battery-Balancer-Capacitors-Continuous/dp/B07SFCY36G

https://www.ebay.com/itm/3-6-10-16S-Li-ion-Lifepo4-LTO-Battery-Equalizer-BMS-1-2A-Energy-Transfer-Balance-/173876774436
 
Can I use my 6s balance charger on my 13s pack? And can I charge it through the bms port? I'm thinking if I can get the 14 pin jst linked up to two 6 pin connectors and just rotate them? Would it work that easily? Id it safe to do it that way? I'm very new to this
 
It's more painstaking, but I set my rc charger to 1s, and made an adaptor plug to go into each pair of holes that goes to a group in the balance plug. Most of the time you just need to bring up a few low groups, just to see if it stays balanced after that, and the rc charger will go into trying to bleed off the high groups if you have the whole thing hooked up which can take a lot longer.
Be careful even just using your multi meter on the balance plug.. I've shorted my probes together before accidently measuring two side by side tabs, and it's just enough of a spark to heat up and deform the plastic balance plug, making it not want to plug back in.
There's a big style balance plug, and a tiny style, I've gotten careful enough to do the big style reliably, but on the tiny style I just keep a probe on one end of the plug, then go down the line with the other so the probes are farther away from each other, and write down the voltages, then do the math on the numbers afterward to get the individual group voltages.
Best of luck... Pick a time when your hands feel steady.

Ps. Maybe have outdoor access.. I had a pack balancing, and my well meaning but nosy friend looked at it while my back was turned, bumped it and shorted the balance wires so there was suddenly sparks and fire, and had to chuck the flaming pack out into my shop driveway.🙄
 
You'd be best to buy 2 or 3 6s balance chargers, or spend more money and get a better charge or put 2 6s packs in parallel and hopefully you have a higher amp 6s charger.

Hyperion EOS1420i
Thunder Power made the TP1430C 14s charger

https://hobbyking.com/en_us/turnigy-reaktor-120-duo-2x120w-balance-charger-ac-dc-us-plug.html?queryID=462b53ec6cdfbe56dccaeec5bf47951a&objectID=77536&indexName=hbk_live_magento_en_us_products

https://hobbyking.com/en_us/quad-4x6s-lithium-polymer-charger-400w-dc-only.html?queryID=462b53ec6cdfbe56dccaeec5bf47951a&objectID=72755&indexName=hbk_live_magento_en_us_products

https://hobbyking.com/en_us/turbo-charger-1200w-4-300w-synchronous-balance-charger-discharger-version-2.html?queryID=462b53ec6cdfbe56dccaeec5bf47951a&objectID=67468&indexName=hbk_live_magento_en_us_products
 
markz said:
You'd be best to buy 2 or 3 6s balance chargers
NO if you use multiple lower-count chargers at once

without breaking the larger-count pack down into appropriate sized sub-packs

you need to be ** absolutely ** certain each charger is electrically isolated - very few are

otherwise big short BOOM melting burning not good.
 
Yes you can - **in theory** with the right charger and harnesses

first balance charge #1 - 6 groups

then #8 - 13 groups

then go back and do say #5 - 10

and they should end up all "pretty close" assuming your charger is pretty accurate.

But it may well take many many hours per group, days altogether, dangerous to leave unattended

really a noob should not be messing with a kludge like this.

Doing one cell at a time is probably faster.

Within 10-15 mV should be good enough.
 
Well, chances are that it's probably just one series out of balance. I know that for sure on one pack. The other 2 I haven't checked yet.

I might find a 2 pin jst connector and work it that way.

Thanks guys. I'll keep y'all posted on my progress.
 
FYI, a string means cells in series.

A group for in parallel.

So, just one group may be out of balance.

 
Me and my friend have had many discussions on this sort of topic and would love to know what solution you come to best of luck
 
john61ct said:
FYI, a string means cells in series.

A group for in parallel.

So, just one group may be out of balance.

So, the singular form of series in this case is string? I've always felt awkward referring to one series as "series"
 
I'm still trying to figure out how I'll be hooking up my balance charger to my 13s pack. All the tutorials show that you have to connect the output plugs into the charge/discharge leads of the pack but when I do that, I get an error message "connection break". I'm assuming that its because the charger is limited to 22.2v.

How do I get around that? Can I just plug the output leads directly to 2 series through the BMS terminals? But then how do I hook up the balance charging terminals? Do I have to break my pack apart? I don't want to have to undo the nickel strips.
 
Yes a string is a set in series.

The members of that string may be a single cell, as is best if possible

if I want a 400Ah bank then ideally I buy a set if 400Ah cells.

If I want redundancy, e.g. RTW in a boat, maybe buy twice as many 200Ah cells, can then put two strings in parallel.

But with these tiny cells, say under 20Ah, people usually parallel a set (group) at the 1S level, each 3.7V nominal

and then connect those groups into a single string.
ClintBX said:
john61ct said:
FYI, a string means cells in series.

A group for in parallel.

So, just one group may be out of balance.

So, the singular form of series in this case is string? I've always felt awkward referring to one series as "series"
 
Voltron said:
Are you to where you have the balance wire plug exposed like this?
IMG_20200210_210612884.jpg

Yes.
 

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Now just make 2 probes that will fit in the holes in the balance plug (don't force anything too big in them and bend the terminals inside the plug, like a paperclip is usually too big, I've used thin solid strand insulated wire or tiny male jst 2 pin plug, but had to trim plastic off the body and thin down the terminals), attach them to your charger outs, maybe with a fuse added inline in case anything slips.
Set your charger to 1S, and make sure the amps are set right for how many cells are in a group. Since you're charging the groups one by one until the charger tops out, there won't be any actual balancing, so you won't be hooking your charger balance plug to anything.
Here's the confusing part. One end of the big plug is positive and one is negative. So if you start with the positive charger lead in the positive hole, the negative goes the next hole over. But when that one is done, and you move over one hole, the positive is now in what was the negative, and the negative is now in the third hole, etc down the line. The same hole that was the first groups negative becomes the second groups positive.
 
Voltron said:
Now just make 2 probes that will fit in the holes in the balance plug (don't force anything too big in them and bend the terminals inside the plug, like a paperclip is usually too big, I've used thin solid strand insulated wire or tiny male jst 2 pin plug, but had to trim plastic off the body and thin down the terminals), attach them to your charger outs, maybe with a fuse added inline in case anything slips.
Set your charger to 1S, and make sure the amps are set right for how many cells are in a group. Since you're charging the groups one by one until the charger tops out, there won't be any actual balancing, so you won't be hooking your charger balance plug to anything.
Here's the confusing part. One end of the big plug is positive and one is negative. So if you start with the positive charger lead in the positive hole, the negative goes the next hole over. But when that one is done, and you move over one hole, the positive is now in what was the negative, and the negative is now in the third hole, etc down the line. The same hole that was the first groups negative becomes the second groups positive.

How do I know which to connect to positive and which to negative when charging 1s this way?
 
Start at the "bottom" one, where the pack level negative return is the same "zero volts" as the negative of the first cell-group.

That group's positive will likely be at 3.something.

Serial means that positive is in circuit with the negative for group #2 and so on, each group tge same ballpark voltage.

Use a known good** accurate** DMM and confirm each pair before applying your DIY harness charger leads.
 
Yes, just put your meter on either end of the plug to figure out the polarity, and it doesn't matter which end you start from for the charging... The single red wire is probably the first positive, so if your meter agrees, then the next one over will be it's negative, and so on down the line.
On my meter, if it's reversed it shows a minus sign in front of the voltage.
16116865472732973595974762367213~4.jpg
Assuming the red is the first positive, then your probes would go here...
16116865472732973595974762367213~2.jpg
Then after the first group is done, moved over to here, etc.
16116865472732973595974762367213~3.jpg
 
How do I know when it's charging? I identified the one series that's lower than the rest and I got a couple pieces of thin wire. I've confirmed that they're making contact through my multimeter. I've selected lipo setting and charge on 1s but this charger isn't giving me any indication that's is charging. Are you sure I don't need the balance charging terminals?
 
No, on your charger I'm not. My rc charger doesn't.
Mine also has different setting for lipo vs li ion?
Any pictures of the setting screens?
What voltage is the group at?
 
I already asked you that
john61ct said:
Does that charger allow charging without the balance plug?
We are not taking the time to write just for fun.

If you don't know how to find out something so basic

I really think you should not be messing about on this path by yourself.

Find someone local to you to help might be easier.
 
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