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Balancing Leaf Packs
#1
Hi DIYers,

Just turned my system on yesterday. Everything seems to work fine, but I have unbalance between Leaf module packs. Wondering if I should re-arrange the modules. Modules purchased from 2 different vendors. Do you think Batrium can achieve balance? Or should I mix the modules in between various packs?
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#2
Batrium can balance.  Enable bypass and/or auto-balance and be patient.  Doesn't look like you have an emergency as long as you aren't trying to charge so high that the higher ones go above the 4.15-4.20v range  Smile

P.S. I typically parallel my cells or use iCharger X8 (discharge -> fixed storage v) to bring cells to a similar voltage before putting them online as a battery - which makes a touch up balance even faster.
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#3
(06-29-2020, 03:05 PM)OffGridInTheCity Wrote: Batrium can balance.  Enable bypass and/or auto-balance and be patient.  Doesn't look like you have an emergency as long as you aren't trying to charge so high that the higher ones go above the 4.15-4.20v range  Smile

P.S. I typically parallel my cells or use iCharger X8 (discharge -> fixed storage v) to bring cells to a similar voltage before putting them online as a battery - which makes a touch up balance even faster.
Thanks Offgrid. On the first charge cycle the 3 higher modules began to bypass at 4.10 volts and they started to get pretty hot. So I shut charging down and lowered the overall bulk charge voltage to 57 volts which I think will give Batrium the opportunity to balance out without getting so hot.
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#4
(06-29-2020, 04:51 PM)ZimInSeattle Wrote: ... the 3 higher modules began to bypass at 4.10 volts and they started to get pretty hot. ....
Do you mean the leafmons are getting hot?   If so - that's to be expected.  They can reach 65C (149F).
You can control how hot they get in a few ways....
1) You can set the Bypass Temp Limit and/or Bypass Current Limit on the Hardware -> Cellmon page (lower left corner).  I restrict mine to 1a and 55C - mainly to extend their life.  Others on this forum have their own ideas on this and may chime in. Smile



2) and/or use fans to keep them cool if your setup would allow this.   I use WM4 + Expansion and it has 'fan' control - to turn fans on/off based on temp to keep the batteries (and mons) cool.   I don't use it - but its a nifty advanced feature. 

You should set things up so you're not worried about running balancing...  and of course be aware that they will get hot - its what they do as they burn excess power off from a cell Smile

FYI  - Here's a auto-level balance youtube using Batrium by @Daromer - https://youtu.be/qNNffhusbXQ   Auto-level is different than bypass in that you can run it all day as you use the system - doesn't depend on the cells being 'at the top'.  This is what I use mostly when I want to do a touch-up so the system can continue to operate. 

FYI  #2 - here's the PDF on mons from Batrium website - https://s3.amazonaws.com/helpscout.net/d...er-2.0.pdf
On page 5 - Operations section - its says the that mons will auto-shutdown if temp exceeds 75C (so they can get to 70s..  which is quite hot!).    I read somewhere else that for long life, the temp should stay more in the 50'ish C range as a max - which is why I have mine set to 55C - but can't find it right now.
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#5
Did you capacity test each module ? I have leaf modules from three (possibly 4) different sources and the capacity varies from 250wh to 350wh per module. Big difference. When I assemble into the final battery I will try to spread out the modules into 7 packs in a way that will make them as close as practical to each other as far as capacity goes.
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#6
Maybe boost charge the lower pack/cells to bring them up to the others?
Keeping the series strings of cells matched in cell capacity is a good idea, otherwise you'll be chasing unbalancing forever.
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#7
(06-29-2020, 05:04 PM)OffGridInTheCity Wrote:
(06-29-2020, 04:51 PM)ZimInSeattle Wrote: ... the 3 higher modules began to bypass at 4.10 volts and they started to get pretty hot. ....
Do you mean the leafmons are getting hot?   If so - that's to be expected.  They can reach 65C (149F).
You can control how hot they get in a few ways....
1) You can set the Bypass Temp Limit and/or Bypass Current Limit on the Hardware -> Cellmon page (lower left corner).  I restrict mine to 1a and 55C - mainly to extend their life.  Others on this forum have their own ideas on this and may chime in. Smile



2) and/or use fans to keep them cool if your setup would allow this.   I use WM4 + Expansion and it has 'fan' control - to turn fans on/off based on temp to keep the batteries (and mons) cool.   I don't use it - but its a nifty advanced feature. 

You should set things up so you're not worried about running balancing...  and of course be aware that they will get hot - its what they do as they burn excess power off from a cell Smile

FYI  - Here's a auto-level balance youtube using Batrium by @Daromer - https://youtu.be/qNNffhusbXQ   Auto-level is different than bypass in that you can run it all day as you use the system - doesn't depend on the cells being 'at the top'.  This is what I use mostly when I want to do a touch-up so the system can continue to operate. 

FYI  #2 - here's the PDF on mons from Batrium website - https://s3.amazonaws.com/helpscout.net/d...er-2.0.pdf
On page 5 - Operations section - its says the that mons will auto-shutdown if temp exceeds 75C (so they can get to 70s..  which is quite hot!).    I read somewhere else that for long life, the temp should stay more in the 50'ish C range as a max - which is why I have mine set to 55C - but can't find it right now.
Thanks @OffGridInTheCity. Yes, I'm aware that the mons will get hot in bypass. Think I will set the temp limit like yours and check into Daromers auto-level balance. I reduced my overall charge voltage to 56.5 volts as at 57 volts one cell was getting over 4.20 volts during bypass. At 56.5 volts the highest that cell got was 4.17 volts. I want to avoid using a fan as well. Thanks again for the help. Smile

(06-29-2020, 09:34 PM)slimf Wrote: Did you capacity test each module ? I have leaf modules from three (possibly 4) different sources and the capacity varies from 250wh to 350wh per module. Big difference. When I assemble into the final battery I will try to spread out the modules into 7 packs in a way that will make them as close as practical to each other as far as capacity goes.
No, @slimf. I did not capacity test the modules before building. Probably should have mixed the modules, but I'm too impulsive and just built up my packs and went at it. The 28 modules I bought from GreenTec Auto were advertised at 326wh while the 21 I got from TechDirect were advertised at 350wh. We'll see how the Batrium deals with balancing them out.

(06-30-2020, 01:20 AM)Redpacket Wrote: Maybe boost charge the lower pack/cells to bring them up to the others?
Keeping the series strings of cells matched in cell capacity is a good idea, otherwise you'll be chasing unbalancing forever.
Thanks @Redpacket. I may give that a try if Batrium doesn't get the balancing done.
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#8
Depending on the size of your pack, the Batrium doesn’t stand a chance of keeping them balanced if the series packs vary in capacity by a decent amount. I’m afraid I’ll run into this problem myself, and with 91 modules the WM5 balance current is virtually negligible.
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#9
(Yesterday, 10:28 PM)slimf Wrote: Depending on the size of your pack, the Batrium doesn’t stand a chance of keeping them balanced if the series packs vary in capacity by a decent amount. I’m afraid I’ll run into this problem myself, and with 91 modules the WM5 balance current is virtually negligible.  Batrium can balance 91 modules 

>packs vary in capacity by a decent amount
If packs/cells have different AH to a significant degree - they should not be put in series as a battery in the 1st place as its not a health battery situation.  Its not about balancing.    You should test and mix/match (maybe parallel groups of cells) till each one has similar AH to be put in series for the desired voltage.   Then you'll have a good battery and balance will be fine.

Similarly if you have self discharging packs to a significant degree - they should be replaced as you cannot have a healthy battery with this situation - and it indicates near-term-failure. 

Once you have healthy cells - Batrium can easily balance 91 leaf modules - they're only 66ah    I have 84 packs of 100p (260ah) with Batrium WM4 restricted to 1a and 55C and there's no problem balancing them.   WM5 might take a little longer (6ah vs 28ah /day OR  0.3a vs 1.2a - https://www.batrium.com/pages/watchmon-comparison) but that's plenty to balance healthy cells.  
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#10
Trouble is, OP probably hasnt capacity tested, and even if he does, it’s not easy making matched packs with leaf modules as they have other considerations - such as the position of positive and negative terminals and small number of cells vs say 18650.
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