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18650 or SPIM08HP cells for backup power case?
#1
Hey guys,

I'm trying to build 2 different charging cases. 1 is for charging lipo batteries in the field for racing drone and the other is for my mother to use when the power goes out during a hurricane etc...

For the lipo charging case it will just need to run a RC charger and charge 4s 1500mah lipos. The RC charger can run off 3s-7s and can pull a max of 15amps. Currently I'm using a 4s6p 18650 pack with 1000mah cells and a bms. but would like to build a new pack that can charge atleast 2x as many lipos then it can currently...

And the case I am building for my mother i want include a 24v to 120v inverter and some usb ports etc... with. Bms for the battery pack and built in charger so it can be as simple as possible for her... and am thinking about getting a 100watt solar panel/kit so she can charge up during the day if need be... I can see her using the inverter to run things like a fan, radio, small flat screen, maybe a Hotpot pot or small hot plate etc...

I recently bought about 200 18650 cells that are about 1000mah that are in pre-built packs that have to be disassembled which is a lot of work and then every cell has to be balanced which is a ton of work which I'm sure most of you know. But the cells only cost me about $0.30 a piece. I also have just bought 5 of the SPIM08HP cells which are 3.7v 9ah @ 200amps per cell for $7 a piece.

So my question is putting the amount of time and effort it takes to extract and balance the 18650 cells to the side, which method would be most beneficial to what I'm trying to accomplish? With the SPIM08HP cells I would never need the 200 amp rating but each cell is 9ah so I could assemble a pretty large pack with not that many cells at 24 volts...

But using the 18650 cells are a whole lot cheaper less than half the cost for the same 9ah... but would it be beneficial to use the other cells over the 18650's? The 18650 are Samsung INR18650-13Q and LG LGDAHA11865 cells that are rated at 15amp output...

Is there a downside or upside to using either one of these or just the fact that it's a whole lot cheaper going one way but a whole lot more work?

And in my mind I feel like the SPIM08HP cells are a lot more dangerous if something was to happen then 18650s . But that might just be because I use lipos in my hobby and they can cause an extreme amount of damage if they get punctured or charged wrong etc...

Thanks for any input you guys may have or any suggestions you can make for what I'm trying to accomplish.
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#2
anyone?
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#3
(12-22-2019, 01:02 PM)bigjoncoop Wrote: anyone?
I made a small backup power case using the SPIM08HP 4p 7s setup for 24v at the time its all I had but having made a powerwall or two since then I would say they SPIM08HP where a lot less work. Couple of pieces of advice use a bms on each 7s pack than you can charge using a 29v power brick. I throttled mine back to 20 amps a pack as this is all I really needed I found using the riveting tech to be a lot faster that a bus bar with bolts. and put it all in a hard case well protected. 

here are some photos of mine for reference 


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