I apparently need to post once before I can attach a file. So I'll try on my reply.
Ive been reading up on building a solar/lithium system for my RV. We plan to tour the country totally without shore power. This forum has been a great help. Ive salvaged around 700 cells right now with access to many more if I need them. I built a few practice packs with my battery spot welder from Malectrics (works great). Id like to check in and see what some of you think about my plan. Heres what I have so far:
I have a 90 Watt 120VAC mini fridge. So at ~30% duty it should use ~720 Wh/day. Our microwave is around 900 W continuous for a few minutes per day and I heard they can startup above 1500 W. My wifes hair dryer is 1500 Watts for a few minutes per day. All-in-all I see us needing no more than 1500 Wh/day and a max occasional draw of about 1500 Watts. Ill most likely buy a 2500 Watt inverter.
My pack
The capacity of my pack will range from 2400Wh - 2800Wh depending on the test. From what Ive read here I should limit myself to a max current of 2A on each cell. I would like to build these cells into a 7s34p pack. My chart shows the distribution for 240 cells which is about how many I need to keep it under 2A max draw. So with 238 cells, 2000 Watts is 2.0A/cell. Should this be enough headroom for my occasional 1500W draws? My main concern though is the distribution of the cell capacity. Is it too spread out? As you can see the bulk of them have a range around 300 - 400 mAh (on the 800 mA test). Will the outliers at the low or high end cause a problem? Do I need to start salvaging more cells to get a smaller range? Im selling my lower capacity cells on eBay to offset the cost of buying used packs.
Thanks for any help
Ive been reading up on building a solar/lithium system for my RV. We plan to tour the country totally without shore power. This forum has been a great help. Ive salvaged around 700 cells right now with access to many more if I need them. I built a few practice packs with my battery spot welder from Malectrics (works great). Id like to check in and see what some of you think about my plan. Heres what I have so far:
I have a 90 Watt 120VAC mini fridge. So at ~30% duty it should use ~720 Wh/day. Our microwave is around 900 W continuous for a few minutes per day and I heard they can startup above 1500 W. My wifes hair dryer is 1500 Watts for a few minutes per day. All-in-all I see us needing no more than 1500 Wh/day and a max occasional draw of about 1500 Watts. Ill most likely buy a 2500 Watt inverter.
My pack
The capacity of my pack will range from 2400Wh - 2800Wh depending on the test. From what Ive read here I should limit myself to a max current of 2A on each cell. I would like to build these cells into a 7s34p pack. My chart shows the distribution for 240 cells which is about how many I need to keep it under 2A max draw. So with 238 cells, 2000 Watts is 2.0A/cell. Should this be enough headroom for my occasional 1500W draws? My main concern though is the distribution of the cell capacity. Is it too spread out? As you can see the bulk of them have a range around 300 - 400 mAh (on the 800 mA test). Will the outliers at the low or high end cause a problem? Do I need to start salvaging more cells to get a smaller range? Im selling my lower capacity cells on eBay to offset the cost of buying used packs.
Thanks for any help