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Old 03-21-2018, 01:46 PM   #5 (permalink)
redpoint5
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Quote:
Originally Posted by cr45 View Post
What size of LifePo and Capacitors would you suggest?

The weight reduction would be nice as this car is already quite light at 845 kg.
As oil pan says, this is likely more hassle than it's worth considering the temperature sensitivity.

If I were to tackle this project I'd start by measuring typical electrical draw while the engine is off. This would determine what size battery to run, but I wouldn't go less than 20 Ah. I always recommend this 20 Ah pack:

LiFePO4 Prismatic Battery: 12.8V 20Ah (256Wh, 10C rate) (24.0) - UN38.3 Passed (DGR)

As far as capacitors go, you can probably start the vehicle using 6 series connected Maxwell 350 F caps.

https://www.ebay.com/i/302040184049?chn=ps&dispItem=1

You would connect the cabin located LiFePO4 in parallel to the caps that live in the engine bay, possibly with a very low ohm current limiting resistor. The resistor would force the caps to do the majority of the heavy lifting to prevent the wires and LiFePO4 from overcurrent.

Basic concept of the idea is in my video here:

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