14 (80 cell) packs built 9.4 kWh?

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May 24, 2017
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Ive attempted to do my first ever spread sheet. As i am a Newbie at thisPowerwall stuff withamps watts etcand figuring out Wh,mAh. let me know if something doesn't look right.

You can see thelist of all my packs and cells mAh listed, I've put 5 of the samemAh cellcapacity in each. My packs are the same design as Petes(Hb Powerwall)80 ineach pack

Does the math look right? If so, what are your thoughts in mixing a big range of cells from 1800-2900 in one pack.

Im building a 48v system, no inverter yet ( looking at the PIP 4048GE), 7x230 panels to start with
Ill start soldering this weekend if i get some time.
Thanks Guys/ Girls
I'm enjoying looking at so many builds and ideas.

Cheers Ty.



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Looks fine.

If thats the cells you have then why not. As long as you do not push the packs it should work pretty good. The cells that can deliver will deliver and as long as you have the same mix in every pack in terms of low cap vs high cap the load should be even among all packs in the string.
 
LOOKING GOOD.
you must have so much beeping going on with all those 4S chargers :D

From what I know mixing the cells will work well, they balance each other out. As long as the mix is similar in each pack it should be all good and according do your spreadsheet they are.
One other thing you might want to consider (if you haven't) is the capacity of the cell you measured compared to what the original used to be. If you have a cell measuring in at 2000mAh but originally it was 3000, then it has lost 33% of its capacity and has therfore likely been cycled over 500 times. Manufactures always list how many cycles theircells are good for before they reach 80%, after which they are considered to be at the end of their life. How long these cells will continue to work is unknown. These cells would have less cycles left in them, so it could be beneficial to group the cells according to this as well. You wouldn't want to have to strip down every pack because you have cells failing in each pack. Keep these cells bunched together to minimise future maintenance work.
At least thats what ill be doing with my laptop cells.
I write the original capacity onto each cell when I take the packs apart, this saves me the work from having to find the specsheets
Right now im taking apart all packs with 2200mAh cells.
 
Got to love the 4s'. I have 6. I got glued the speaker to shut them up.
 
The-J-Man said:
LOOKING GOOD.
you must have so much beeping going on with all those 4S chargers :D

From what I know mixing the cells will work well, they balance each other out. As long as the mix is similar in each pack it should be all good and according do your spreadsheet they are.
One other thing you might want to consider (if you haven't) is the capacity of the cell you measured compared to what the original used to be. If you have a cell measuring in at 2000mAh but originally it was 3000, then it has lost 33% of its capacity and has therfore likely been cycled over 500 times. Manufactures always list how many cycles theircells are good for before they reach 80%, after which they are considered to be at the end of their life. How long these cells will continue to work is unknown. These cells would have less cycles left in them, so it could be beneficial to group the cells according to this as well. You wouldn't want to have to strip down every pack because you have cells failing in each pack. Keep these cells bunched together to minimise future maintenance work.
At least thats what ill be doing with my laptop cells.
I write the original capacity onto each cell when I take the packs apart, this saves me the work from having to find the specsheets
Right now im taking apart all packs with 2200mAh cells.
This is a very good point I hadn't considered.

What's the best way you recommend to finding out the original celll capacity?
 
silverse2m6 said:
This is a very good point I hadn't considered.

What's the best way you recommend to finding out the original celll capacity?

Best to do it from the start, look at the writing on the pack. It will always say the voltage and mAh /Ah (or just Wh). You can calculate the original capacity from that.
If you have all ready extracted them then you would need to google the model number of the cell. The Sanyos have the model number under the wrapper but you can usually read it. Once you have the number type it into google and it should be there straight away.
Its easiest with Samsung Cells as the capacity is in the model number. Example: ICR18650-26C. This is a 2600mAh cell. The two numbers before the last letter are the capacity. ICR18650-24B = 2400mAh etc.
 
Thanks for all the tips and encouragement:)
Oh yeah the beeping drove me crazy even for one day. I put them so far away from the house as possible. Thanks for tip on hot glueing the beeper !!
I've stuck with the same chargers the whole time to try and keep consistency.
 
FiremanDIYPowerwall said:
Got to love the 4s'. I have 6. I got glued the speaker to shut them up.

I tried that, didnt work for me, just as loud, couldn't get the glue to flow into the speaker...
 
Tychipowerwall said:
Thanks for all the tips and encouragement:)
Oh yeah the beeping drove me crazy even for one day. I put them so far away from the house as possible. Thanks for tip on hot glueing the beeper !!
I've stuck with the same chargers the whole time to try and keep consistency.

I have the same chargers I just opened the back and unsoldered the speaker.
 
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