Charging/ Balancing through the balance leads only

mybike · Apr 30, 2015

I have a bulk lipo pack set-up as in the pic. I would like to balance my pack when need be but don’t want to break the pack a part to do so.
I am running 3x18.5v lipo packs in series and 6 more in 3x series then in parallel and bulk charging to 62.25v. I have wrapped the lipo in cling film as one fat pack.

Q1. Can I balance my pack using just the balance lead each pack one by one when they ever go some what out of balance and leave the pack in series and Parallel?
Q2. If the answer was yes what charger will do that? (I am from the UK).

wesnewell · Apr 30, 2015

They make chargers that charge through the balance leads, or you can make a simple adapter to charge individual packs with any balance charger.

mybike · Apr 30, 2015

Wesnewell thanks for your reply.

Just to be clear as I don’t want to miss understand this… :oops:

Are you saying I can use a JXT lead and plug it in to the balance port of my Imax charger and run the negative and positive of the main charge leads from the charger to the JXT leads as in the picture you have shown, then plug the JXT in the lipo packs individually charge and balance charge them in lilo and lipo mode and I can leave my pack in series and parallel

like in the picture below?

dnmun · Apr 30, 2015

make sure to take pictures before, during, and after.

mybike · Apr 30, 2015

dnmun said:
make sure to take pictures before, during, and after.

Im lost…what are you trying to say. :?:

wesnewell · Apr 30, 2015

Yes, that's what I'm saying. Just make sure you don't feed it more amps than the small balance wires can handle. Most are 5A max. 3A should be perfectly safe. Unlikely, but if they are 26awg, don't go over 2A. 22awg is good for 7A. I think most are 24awg which is good to 3.7A.

mybike · Apr 30, 2015

Thanks wesnewell much appreiate it helping me on this!

John Bozi · Aug 21, 2015

Hi guys,

I am going to bulk charge 9 x 4s packs as 12s 3p where they are paralleled first then in series. Although I plan to use my satiator most the time these 4s chargers are so cheap that I am interested in using for balancing occasionally without pulling apart the pack. So I'd buy 3 of these...

Do any mods need to be made to use them?
and
Could I use the satiator at the same time as using them?

I've heard somewhere something along the lines that there is a common negative problem.....

http://www.hobbyking.com/hobbyking/store/__28838__Hobbyking_174_DC_4S_Balance_Charger_Cell_Checker_30w_2s_4s_AU_Warehouse_.html

Hobbyking® DC-4S Balance Charger & Cell Checker 30w 2s~4s, simple to use Lipoly charge unit that will balance charge 2s~4s lipoly batteries via the balance lead, complete with overall & individual cell voltage display.
Features:
Sturdy alloy case
LED Display showing overall and individual cell voltage
1000m/A~1500m/A balance charge output
9v~16v (30w) input
Power lead supplied
Compact size ideal for field box
Dimensions: 80mm x 50mm x 21mm
Weight: 71g (without lead)
Suitable for JST-XH balance plugs

thanks

skoleskibe · Aug 30, 2015

There is a common ground problem, just blown up my own 3 chargers HK chargers..... Shite

dnmun · Aug 30, 2015

boost converters always have the ground of the DC input tied to the ground of the output. that cannot be changed or hacked. they are not the same as a switch mode power supply.

John Bozi · Aug 30, 2015

sorry to hear they blew up, were you doing something along the lines I described above?

I asked HK chat help a while ago about this and they said it would work, I didn't trust them as they don't know enough about seriesed packs.....

thanks for confirming that I can't do this.

SjwNz · Aug 30, 2015

wesnewell said:
Yes, that's what I'm saying. Just make sure you don't feed it more amps than the small balance wires can handle. Most are 5A max. 3A should be perfectly safe. Unlikely, but if they are 26awg, don't go over 2A. 22awg is good for 7A. I think most are 24awg which is good to 3.7A.

Also, when charging via the balance leads, if you charge current is to hi, this can cause an error in the 1st and Last cells voltage that the charger will see. The resistance of the balance lead with the charge current will cause a voltage to be formed which will add itself to the cell voltage.

dnmun · Aug 30, 2015

no, the balance current does not build up a significant deltaV over the sense wire. it can be considered identical in voltage. the sense wire is copper conductor and current is in the range of mA so the delta V is in the nanovolt range. essentially 0V.

SjwNz · Aug 31, 2015

dnmun said:
no, the balance current does not build up a significant deltaV over the sense wire. it can be considered identical in voltage. the sense wire is copper conductor and current is in the range of mA so the delta V is in the nanovolt range. essentially 0V.

Yes I agree 100%, I should of stated that the issue I was talking about is when you put the main charge current through the balance plug , So charge and Balance through the balance plug.

dnmun · Aug 31, 2015

no, you charge from each terminal of the battery. the BMS inside the balancing charger will send the proper balancing current through the sense wires. it does not charge through the sense wires in any case, only through the terminals since the sense wires can only handle the balancing current and not the charging current.

SjwNz · Aug 31, 2015

dnmun said:
no, you charge from each terminal of the battery. the BMS inside the balancing charger will send the proper balancing current through the sense wires. it does not charge through the sense wires in any case, only through the terminals since the sense wires can only handle the balancing current and not the charging current.

I know this, but this thread is about Charging/ Balancing through the balance leads only . I have done a diagram to show what I am talking about
what could happen if charging at to high current using the balance plug only. Charging via the balance plug is fine as long as you keep the current down,
MyBike just wants to balance his cells every once in a while. but because the main battery leads are connected to the other packs in series/parallel he only has access
to the balance plugs to do his balance charge.

dnmun · Aug 31, 2015

well then his laziness is just gonna make his battery even more unbalanced.

TheBeastie · Aug 31, 2015

I think the best way to build a dodgey balance charger is just via a bunch of powerpacks and dc step downs.
get a bunch of these either one for every cell in P or split your pack in half for charging and get half the amount
http://www.ebay.com/itm/US-Plug-AC-100-240V-to-DC-12V-2A-Switching-Switch-Power-Supply-Adapter-Converter-/141756734500?hash=item21015c1c24

Then a DC step down converter of 24watts size to feed it 4.2 or 4.1volts etc
http://www.ebay.com/itm/5A-Adjustable-Power-DC-DC-Step-down-Charge-Module-LED-Driver-With-Voltmeter-/131163180152?hash=item1e89ef4c78

Then build it into a suit case like this guy...
https://endless-sphere.com/forums/viewtopic.php?f=3&t=69244&sid=2afc4d02562ef11d3428a020210681dd#p1045777

Then operate it with a muslim headscarf in your garrage witth the door open, then get raided by swatt then sue for a million dollars like this guy.
http://mobile.abc.net.au/news/2010-12-21/haneef-wins-substantial-compensation-settlement/2382174

TheBeastie · Sep 17, 2015

TheBeastie said:
Then build it into a suit case like this guy...
https://endless-sphere.com/forums/viewtopic.php?f=3&t=69244&sid=2afc4d02562ef11d3428a020210681dd#p1045777

Then operate it with a muslim headscarf in your garrage witth the door open, then get raided by swatt then sue for a million dollars like this guy.
http://mobile.abc.net.au/news/2010-12-21/haneef-wins-substantial-compensation-settlement/2382174

I think my weird ending of this post is now quite vindicated..

http://www.washingtonpost.com/news/morning-mix/wp/2015/09/16/they-thought-it-was-a-bomb-ahmed-mohamed-texas-9th-grader-arrested-after-bringing-a-home-built-clock-to-school/

I guess the only thing that's left to do is get left wing political folks to find and fund this boy with the best lawyers possible to sue the government, well that's what I think would happen in Australia these days.

So anyone going to build one of these with a headscarf on or what? :mrgreen:

You got to imagine it with x 12 LED step downs flickering away etc, would look pretty badass/dubious.

Charging/ Balancing through the balance leads only

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