Hi All
Firstly thank you to all the information posted on this forum I've been reading, researching and learning a lot from what is contained in the forums nice to have these communities that help each other out.
So to give a bit of background, I'm in the process of installing a diy off grid solar project with roughly 3kw of panels on my summer house roof and 4kw of panels on my garage roof, i have an 8kw hybrid inverter that has two inputs of 4 kw so one array on each is my plan.
i am also planning to build an 18650 powerwall from recycled batteries ( mainly salvaged from dyson vacuum cleaner batteries) I have been ripping these out and testing them over the last 6 months or so and I have just over 1200 all around 1750 - 2000mAh ive filtered out low capacity batteries and self discharging ones. i also have a 250amp daly bms and planning to build a 14s100p pack for around 10kwh of storage.
i have a few questions in relation to the putting together of the pack that i would like some advice on my maths with cable sizes and thing too please
1) Mixing cells : i have found conflicting information on this, my cells are mainly sony and LG but i am around 200 batteries short so was planning on buying those new (3600 mah) is this much of a difference in single cell capacities and potentiall differnt chemistries an issue or is sorting them using repacker ok? i see many people puting them together from various laptops/ powertools etc.
2) my inverter can put out a max of 8000w of power ( i dont think ill ever draw this much) , im building a 48v system so 8000/ 48 = 166.66 so the max amp draw is 166 and a bit amps this divided by 14 packs is 11.9 and that divided by 100 is 0.119 so does that mean even a max draw its only pulling 11.9 amps per pack and only 0.119 amps per cell? or have i got my maths wrong?
3) Wire sizing: i was planning on planning on individually fusing each cell with 5 amp fuse wire, but if my above maths is correct is 3 amp or even 1 amp if there is such a thing not better? also i have some 4mm2 (12 awg i think) i was planning on using for the busbars is this ok or does it need to be thicker?
4) pack testing : i have litokala lii 500 testers for individual cell testers, but i don't really understand how to test ( charge and discharge ) for capacity and heat anomalies etc the 100p packs or potentially the whole thing put together even. please can i ask for some advice as to what i need and how to do this so i can get things ordered
i think that covers everything
Many thanks in advance for your help.
Firstly thank you to all the information posted on this forum I've been reading, researching and learning a lot from what is contained in the forums nice to have these communities that help each other out.
So to give a bit of background, I'm in the process of installing a diy off grid solar project with roughly 3kw of panels on my summer house roof and 4kw of panels on my garage roof, i have an 8kw hybrid inverter that has two inputs of 4 kw so one array on each is my plan.
i am also planning to build an 18650 powerwall from recycled batteries ( mainly salvaged from dyson vacuum cleaner batteries) I have been ripping these out and testing them over the last 6 months or so and I have just over 1200 all around 1750 - 2000mAh ive filtered out low capacity batteries and self discharging ones. i also have a 250amp daly bms and planning to build a 14s100p pack for around 10kwh of storage.
i have a few questions in relation to the putting together of the pack that i would like some advice on my maths with cable sizes and thing too please
1) Mixing cells : i have found conflicting information on this, my cells are mainly sony and LG but i am around 200 batteries short so was planning on buying those new (3600 mah) is this much of a difference in single cell capacities and potentiall differnt chemistries an issue or is sorting them using repacker ok? i see many people puting them together from various laptops/ powertools etc.
2) my inverter can put out a max of 8000w of power ( i dont think ill ever draw this much) , im building a 48v system so 8000/ 48 = 166.66 so the max amp draw is 166 and a bit amps this divided by 14 packs is 11.9 and that divided by 100 is 0.119 so does that mean even a max draw its only pulling 11.9 amps per pack and only 0.119 amps per cell? or have i got my maths wrong?
3) Wire sizing: i was planning on planning on individually fusing each cell with 5 amp fuse wire, but if my above maths is correct is 3 amp or even 1 amp if there is such a thing not better? also i have some 4mm2 (12 awg i think) i was planning on using for the busbars is this ok or does it need to be thicker?
4) pack testing : i have litokala lii 500 testers for individual cell testers, but i don't really understand how to test ( charge and discharge ) for capacity and heat anomalies etc the 100p packs or potentially the whole thing put together even. please can i ask for some advice as to what i need and how to do this so i can get things ordered
i think that covers everything
Many thanks in advance for your help.