# balancing for dummies please.



## lou-ace (Jul 21, 2009)

I've been monitoring you guys talking, debating, interfacing, whatever the "balancing" thing for years now with passing interest, but it's my time now ( got 44 cells coming) and I really don't have a clue how to do this "balancing" everyone is talking about. Does anyone have a good link to the bare bones balancing proceedure? what equiptment ect. I think I will go with bottom balancing, manual monitoring, and the jdl404 as bms. I will also attempt my own reprograming of my NG3 or send it to the factory for refit. any help?? thanks.


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## Ziggythewiz (May 16, 2010)

There's no one way, so you have to find the method you think is best. Have fun.

http://www.diyelectriccar.com/forums/showthread.php?t=84252


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## skooler (Mar 26, 2011)

I suggest a read through this thread

http://www.diyelectriccar.com/forums/showthread.php/bottom-balancing-85458.html


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## onegreenev (May 18, 2012)

One way!


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## Caps18 (Jun 8, 2008)

https://www.youtube.com/watch?v=-Ojv-r1ws6k

details:
http://myelifenow.blogspot.com/2012...tml?utm_source=twitterfeed&utm_medium=twitter

Voltmeter:
http://www.lightobject.com/Programm...th-dual-control-Good-for-HHO-System-P408.aspx
(They have a blue model too)

Just make sure your neighbors don't see you. They will call the cops because it looks like a bomb.



Here is the 'professional' product along with tips.

https://www.youtube.com/watch?v=bPreFWPnuhE


I am in the same position that you are in. I haven't bottom balanced a pack before, but will be doing that in the next few months.
https://www.youtube.com/watch?v=bPreFWPnuhE


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## onegreenev (May 18, 2012)

The top one listed there is a pretty cool little bottom balance trimmer. I prefer to use my fat motors to discharge the cells fast then trim with my PowerLab 8. It trims to 2.5 volts using CC/CV with the PowerLab 8. 

Pete


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## onegreenev (May 18, 2012)

EVWEST never did get their bottom balance product to market. I asked from the first day they said they were going to do that and then never did produce it. I think they did one for themselves. I guess not enough demand. Bummer. I would have purchased one. But I got the PowerLab 8 instead. I can do more with it than just discharge cells. Price was fine. 

Pete


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## pm_dawn (Sep 14, 2009)

As I know the whole line of iChargers can do bottom balancing.
the cheapest is the 106B at about $80. 
http://www.hobbyking.com/hobbyking/store/__6792__icharger_106b_plus_250w_6s_balance_charger.html
That one does 10A of regenerative discharge back into a loadbank, just as the PowerLab.

Otherwise if the current can be low, under 1 A this could be an option.
http://www.hobbyking.com/hobbyking/store/__10328__Hobby_King_Battery_Medic_System_6S.html

dont know if they can be set to discharge as far as 2,7v.
But it can do 6 at once.....
And I know that people has upgraded them to do over 1A.
Can be found on endless-sphere.

REgards
/Per


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## Zak650 (Sep 20, 2008)

I've tried getting people onboard with this system but here goes again. If you are building a car and are planning on using either of the JLD meters for about $10-20 additional expense you can build a 160 amp fast bottom balancer. 
I bent the rebar using a rack outside home depot so I could fit it into the car.
You probably already have all these parts except the rebar. 
Parts required: JLD404 or JLD5740, 200 amp contactor/relay, battery straps, 12 volt battery power to run the JLD, 
2 pcs of 3/8" rebar from Home Depot 10' long, 4 heavy duty grounding lug or else weld tabs onto the rebar
You don't really need the breaker shown since I've already verified the 160 amp draw, you could use a fuse.

ALL CELLS WIRED IN PARALLEL using battery straps 

Parallel bottom balance 4 to 6 batteries using 20 feet of 3/8" rebar as a resistor @3 volts = 160 amps
(160 amps through 20 feet of 3/8" rebar heats the rebar to a temperature of 160 degrees F)

DON'T SHORT THE PLUS AND MINUS ENDS OF THE REBAR TOGETHER(obviously, no breaker or fuse no protection)

See this thread: 
http://www.diyelectriccar.com/forums/showthread.php?t=84591


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## pm_dawn (Sep 14, 2009)

You can also use the Cellog8 or Powerlog6 to do a discharger.

here is one:
http://www.helifreak.com/showthread.php?t=407109

another thread:
http://www.rcgroups.com/forums/showthread.php?t=1131817&highlight=powerlog+6+discharg

I use the iCharger 4010 duo.
I can do two batteries at the same time. 
That is nice. 

But the rebarb kit seems Heavy Metal !!!!

Regards
/Per


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## lnpurnell (Sep 27, 2012)

Zak650 said:


> I've tried getting people onboard with this system but here goes again. If you are building a car and are planning on using either of the JLD meters for about $10-20 additional expense you can build a 160 amp fast bottom balancer.
> I bent the rebar using a rack outside home depot so I could fit it into the car.
> You probably already have all these parts except the rebar.
> Parts required: JLD404 or JLD5740, 200 amp contactor/relay, battery straps, 12 volt battery power to run the JLD,
> ...


Hi Zak,

Your process looks good! Do you have a video with a close up on how you have set it up? 

I can only see the set up from one angle.

i have 15 60AH cells that I need to bottom balance, Trying to reduce the time it takes and also trying to automate the process slightly.

It is a shame though that the energy cannot be fed into a separate central battery pack as I need to bottom balance several packs.

Leigh


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## pm_dawn (Sep 14, 2009)

The iCharger 4010duo can probably do that for you.
It can do regen discharge to a battery source of max 50v.
So that could work with the 15s lifepo4 pack. 

Just saying......

Regards
/Per


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## Zak650 (Sep 20, 2008)

lnpurnell said:


> Hi Zak,
> 
> Your process looks good! Do you have a video with a close up on how you have set it up?
> 
> ...


The process is completely automatic the wiring I did in the video was just to see if the draw on all the cells tended to be even. Once that was determined the individual positive leads to each cell was unnecessary and all the cells are simply wired parallel with the standard battery straps. You can do one group of 7 cells and one of 8 cells. The contactor will cycle rapidly when it first reaches the target voltage but quickly settles down and eventually stops engaging altogether. If left connected overnight you will be done with that group, repeat for the second group, you're done. separate the cells and check their individual voltages. Use the settings in the 160 amp balancer thread, report your results, and if you thought it was easy and worked. The 12 volt power that drives the JLD and contactor has to be maintained overnight as well. The rebar and contactor connections to the pack should be as close to the middle of the parallel cells as possible


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## lou-ace (Jul 21, 2009)

great reply's guys and thanks for all the help. But the answer for me now came from the guy that I bought the cells from he introduced me to the the little cell balancers from ev-power in Australia.

http://www.ev-power.com.au/-EV-Power-BMS-Cell-Modules-.html

These snappy little guys regulate the individual cells in the pack making sure that they don't overcharge or over-discharge by operating a shunt that operates between 2.5v and 3.6 volts. Now I think that you will have to do a coarse balancing if the cells are really out of whack but these little cell regulators seem to be " the bomb" elegant, economical, efficient. and easy, the also look really cool when installed.I put them on my pack ( not done yet soon to be a 140v #44 cell) 96v, 60ah ca60 calb cells and used my non-adjusted zivan charger ( still set and lead acid 120 volt setting, 165 volt finishing WAY TO HIGH)to "play" with and each of the modules shunted at 3.6 volts and turned red. this protected all of the pack and " top balanced" the pack. I ran the rig down the road and back and all of the modules turned to green. It will be interesting to see how the shunt works and discharge. Now this is something that I don't want to repeat again ( I seriously will adjust the charger to the proper setting and voltage for my final pack), but it demonstrated very well the properties of these balancing modules. This with the jdl 404, hopefulle this should provide me with all of the monitoring that I should need. I Will post with more DATA later. thanks again.


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## GerhardRP (Nov 17, 2009)

lou-ace said:


> I've been monitoring you guys talking, debating, interfacing, whatever the "balancing" thing for years now with passing interest, but it's my time now ( got 44 cells coming) and I really don't have a clue how to do this "balancing" everyone is talking about. Does anyone have a good link to the bare bones balancing proceedure? what equiptment ect. I think I will go with bottom balancing, manual monitoring, and the jdl404 as bms. I will also attempt my own reprograming of my NG3 or send it to the factory for refit. any help?? thanks.


I never understand why people are in such a hurry to balance cells or why they make it complicated.
OK, so I only had four cells, but here is my approach: I connect the positive terminals to a common bus through 0.1 ohm resistors. The negative terminals are bused directly together. The two buses are connected with 3.5 ohms giving a total current of a little less than one amp or C/240, about 10 days. This is a completely equilibrium discharge as shown in the graph. Note that there is virtually no rebound in the half day after the inter-bus resistor is removed.


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## onegreenev (May 18, 2012)

> I never understand why people are in such a hurry............


Don't ya know, People always put off until the last minute, then need it yesterday.


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## lou-ace (Jul 21, 2009)

Hey guys thanks for all the great responses. I've decide on the great balancers that I found about through the guy that I ought the cells from ( watch out B baker) these guys are GREAT and they take all of the guessing out of the equation. now you will still have to do some GROSS balancing but once you have the cells close just put them together in the pack and forget it. they will balance high and low ends WAY cool 

http://www.ev-power.com.au/-EV-Power-BMS-Cell-Modules-.html


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## pm_dawn (Sep 14, 2009)

How does these cell modules balance LOW ends ?

I can see no reference in the documentation about balancing at low end.

REgards
/Per


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## EVfun (Mar 14, 2010)

The ev-power cell modules balance the pack at the top, not at the bottom.


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## tomofreno (Mar 3, 2009)

EVfun said:


> The ev-power cell modules balance the pack at the top, not at the bottom.


They may have told him they CAN be used for bottom balancing, similar to what Dimitri did with his minibms modules which are similar in design concept to the evpower ones ( I think early open discussions of the evpower design were his starting point):
http://www.diyelectriccar.com/forums/showthread.php?t=39025&highlight=dimitri+bottom+balancer


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## lnpurnell (Sep 27, 2012)

Zak650 said:


> The process is completely automatic the wiring I did in the video was just to see if the draw on all the cells tended to be even. Once that was determined the individual positive leads to each cell was unnecessary and all the cells are simply wired parallel with the standard battery straps. You can do one group of 7 cells and one of 8 cells. The contactor will cycle rapidly when it first reaches the target voltage but quickly settles down and eventually stops engaging altogether. If left connected overnight you will be done with that group, repeat for the second group, you're done. separate the cells and check their individual voltages. Use the settings in the 160 amp balancer thread, report your results, and if you thought it was easy and worked. The 12 volt power that drives the JLD and contactor has to be maintained overnight as well. The rebar and contactor connections to the pack should be as close to the middle of the parallel cells as possible


Thanks for this Zak,

One question, Why would I need to do a group of 7 and a group of 8? Is the current draw too much for the rebar?

Thanks,

Leigh


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## Zak650 (Sep 20, 2008)

lnpurnell said:


> Thanks for this Zak,
> 
> One question, Why would I need to do a group of 7 and a group of 8? Is the current draw too much for the rebar?
> 
> ...


The current draw on 20' feet of 3/8" re-bar is in the neighborhood of 150 amps @ 3 volts. It's irregardless as to the number of parallel cells. The 7 or 8 cells was based on a per cell amperage target of around 20-40% of the cells ah rating. 
Here are some examples:
180ah cells = 2-4 cells in parallel
100ah cells = 4-8 cells in parallel
60ah cells = 6-10 cells in parallel
The re-bar heats up to 160 degrees F @ 3 volts over time and the current diminishes slightly as the bar heats up and as the voltage of the parallel cells decreases.


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