View Single Post
Old 03-21-2018, 12:46 PM   #5 (permalink)
redpoint5
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,456

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - CBR600 - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - Dodge/Cummins - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.68 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)

Model Y - '24 Tesla Y LR AWD
Thanks: 4,211
Thanked 4,390 Times in 3,364 Posts
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:

__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
The Following 2 Users Say Thank You to redpoint5 For This Useful Post:
California98Civic (03-21-2018), MetroMPG (04-02-2018)