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What voltage to charge min max ?
#11
That's a very good illustration of my point - what are you using to do the /cell charting ?
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#12
Interesting.  I've set mine to be _just_ below the knee on purpose.  Having started with fairly capacity-balanced packs, it allows me to quickly identify packs that have developed some sort of issue.


Eg. in this screenshot, 3 packs clearly need attention.  Had I set the cut off at 3.45V, the differences would not get amplified, and I'd be blissfully unaware of the problem until it became much worse.
Modular PowerShelf using 3D printed packs.  40kWh and growing.
https://secondlifestorage.com/t-AJW22-s-...PowerShelf
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#13
(07-20-2019, 02:36 PM)Sean Wrote: That's a very good illustration of my point - what are you using to do the /cell charting ?

Batrium info saved every 5 minutes to a database.  Then PHP pChart to pull and display in web page.

(07-20-2019, 05:35 PM)ajw22 Wrote: Interesting.  I've set mine to be _just_ below the knee on purpose.  Having started with fairly capacity-balanced packs, it allows me to quickly identify packs that have developed some sort of issue.


Eg. in this screenshot, 3 packs clearly need attention.  Had I set the cut off at 3.45V, the differences would not get amplified, and I'd be blissfully unaware of the problem until it became much worse.

Yes - I understand.   In your case it looks like you have a 200mv (or more) difference in the display.  In my case it was only 130mv.   So in my case - it wasn't enough to be worth it at this point.    Later on, hopefully after a few years!!,  the battery will degrade and I'll have to expand the voltage range / DOD %.   As long as it continues gracefully - e.g. <= 100mv - I'm not going to over-stress about it.  However, as the battery ages and I reach 150-200mv range on a pack, then I plan to focus on it.

So I'm opting to take my current yes (e.g. 30mv->80mv range with no balancing is perfectly healthy for 42 packs) as a yes and save the extra work for the future.
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#14
thanks interesting reading
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 300, untesteded.
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
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#15
Might be the wrong place for this, if so I’ll move it..
Im about to purchase a Chevy volt gen2 pack..,16s2p 3kw 64v 55ah
The array (already installed) that will connect to charge controller (midnite 150sl) atm is 2s3p 66v 30amps, which I have to rewire to 3s2p 99v 20amps for the cc to have enough voltage to charge the 64v pack properly..
What I need to figure out is how many max amps I should set the cc to charge the pack to not hurt batteries from charging pack to quickly..
Then also need to figure out how many amps I should set my GTIL2 to draw from the pack to not drain the pack to quickly..
I’d like for the GTIL2 able to produce 1200w so I was thinking I could set it to draw max of 20amps from the pack.. 1200w wouldn’t be needed often in the evenings due to most of our high loads getting done during peak solar output..only time inverter would use 20amps in the evening would be when aircon or heat would come on for 15min at a time..
Eventually I will get another pack and parallel it with the other to be able to use more of the 2000w inverters capacity..
But for now I need help with the amps coming into and out of the pack to not cause harm to it.. very much appreciate any knowledgeable persons time
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