Thread: [WIP] Extended Akku Other Half
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dirkvl is offline dirkvl
2014-01-14 , 16:15
Posts: 1,104 | Thanked: 5,652 times | Joined on Feb 2010 @ Holland
#27
Originally Posted by shadowjk View Post
Li-Ion and Li-Poly in parallell are just fine. The important thing is that they are both same voltage when you connect them together, after that they will stay balanced.
This is an extremely bad idea. Connecting batteries in parallel can only be done with exactly the same type and size. Lipo's are extremely vulnerable.

Originally Posted by shadowjk View Post
Why? Because in lithiun-ion (including lipo) chemistry, the voltage has direct relationship with state of charge, so if you draw 1A from a small battery, its voltage drops faster than the big battery. When the voltage gets even slightly out of balance, the bigger battery with the higher voltage supplies more power. The end result is that both batteries will have become full at the same time when charging, and empty at the same time when.discharging.
This is simply untrue. No two batteries are exactly the same, especially if your mixing types. It will catch fire. Lipo's require a very specific charger that monitors the battery while it charges. You can't even connect two exactly the same Lipo's and charge them parallel.

Originally Posted by shadowjk View Post
Some smartphones and tablets these days use "stacked" batteries, several batteries with different shape and size to fill up as much empty space as possible.
Yes, stacked batteries.. And in the case of Lipo's, they are connected individually to a power management chip. My Lipo laptop-battery as a consequence has 10 (instead of 2) wires coming out.

Originally Posted by egnat69 View Post
so basically frankensteining a second jolla battery onto the existing and covering it with a custom other half should be possible, right?
The comparison with Frankenstein is very accurate. (spoiler alert: everybody dies in the end)
 

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