Balancing fast using just the balance wires

[parajared]

Can you balance a battery using only the balance wires?

1) why?
Why not!
I can think of a few reasons
-to be able to balance an entire 20s lifepo4 cell pack using just a 6s hobby lipo/life charger.
-balance batteries individually when you parallel several hobby lipos together: like this

In my last post connecting JST-XH to Lifepo4 I found that it's totally possible to monitor each cell in your lifepo4 pack by just connecting JST hx wires (the balance wires on hobby lipo packs) to the BMS wires.

Taking this one step further couldn't you just charge balance right down the balance wires themselves with a hobby charger: I plan to accomplish this by making the main charge wires (the fat wires that come off the battery) just first and last lead of the balance wires instead Like this:



This wouldn't be to charge the pack mind you, but to keep the cells in balance.

 

[dogman dan]

I started doing this some time ago after reading about how Ypedal was doing it.

He made a rig that converted a jst plug into a row of Anderson plugs. Selecting the correct two plugs, he could then easily and quickly single cell charge up a low cell in any pack.

Use your choice to charge, from a plain phone charger power supply, or my favorite, an RC hobby charger set to 1s and 2 amps charging.

Got a high cell, hook a turn signal light bulb to the high cell. This can be done while the whole pack is still bulk charging saving time, and discharging the high cell much faster than your RC chargers balancing function typically does it.

Here is my really complicated rig for doing it. Two bare male jst prongs attached to whatever plug you use on your charger output. I also have a turn signal light with two andersons on it. You simply stick the two prongs into the right holes on the female jst, to select the cell in the pack you want to charge or discharge.

This works with a single cell or if you wish use the jst parallel adapter of your choice, and you can charge or discharge any set of paralleled cells in the pack. I find it a real time saver to just adjust only the one cell in a large pack that needs it. A balancer will be discharging the whole pack of cells, waiting to start recharging the whole pack eventually. Why not just manually bring up that one low cell with an RC charger?

 

[Tommy L]

The BC168 charger charges thru the balance leads only. Up to 6s at 8amps per channel (cell).

I find that 8amps at 4v (around 32 watts) get the balance leads towards the hot side.
At 4amps the balance leads are just above ambient.
I have two of these and I use an HP server 600pb power supply

The video below is Hyena charging set up/explanation.

Tommy L sends.....

[youtube]ZfQ7homv_84[/youtube]

 

[dogman dan]

Good example of how all RC chargers should work.

Weed out your funky packs, and you don't need to balance very often. I have a three year old 20s 10 ah pack that is approaching 50% capacity left. But it's still staying nicely balanced on bulk charges. Amazing.

By balanced, I mean to .05 v or so. If you are fretting about .01v I pity you. Just because it can be measured does not make it matter.

 

[parajared]

Brilliant! This is why I love the sphere, there is always someone out there who has not only figured it out, but also how to make it awesome. New plan is to just hook a couple of jst wires to an Anderson power pole. Easy.

 

[Tommy L]

Good example of how all RC chargers should work.

Weed out your funky packs, and you don't need to balance very often. I have a three year old 20s 10 ah pack that is approaching 50% capacity left. But it's still staying nicely balanced on bulk charges. Amazing.

By balanced, I mean to .05 v or so. If you are fretting about .01v I pity you. Just because it can be measured does not make it matter.

Dogman.....

I know that you have been following this "STRONG" build.
This Loom is 18 gauge tapped into 4 BC168 chargers. This is sweet!

Tommy L sends....

 

[dogman dan]

Hard to beat that. I scoff at folks who fuss and whine about a lipo pack that's "out of balance" when it's only off by .01v.

But with that rig, you'd get as perfect a balance as possible every charge. Nothing wrong with that at all.