Saturday, June 18, 2011

Improvements - Part 1

This past winter I chose not to drive the car so that I can make some improvements. Since the car is seldom used during the tough winter months this was the perfect opportunity. I aimed to complete the work by spring but experienced unexpected delays and only got back on the road in June.

The first thing I did was install a decent battery heater. I was originally using a space heater but this was a temporary solution and not very efficient. My decision was to go with a 60 foot length of heating cable (300 watts) that is used for de-icing the roof of a house purchased from Canadian Tire. This meant that I had to remove all the battery monitors, cell balancers, batteries and battery box from the trunk in order to run the heating cable inside the box.

The cable was fastened at the bottom of the box between to sheets of metal like a sandwich.

While the battery box was out of the car, I put back the stock interior trunk panels and added some carpeting to give things a nice neat look.

In order to control the battery heater, I installed a household thermostat. This can always be swapped out later and replaced by a cell module based thermostat and BMS function that can trigger a relay to turn on the battery heater (TBD).

The second thing I did was plan for another BMS that would allow me to easily resize my battery pack. I modified my battery box to accept an additional 5 cells and use straps instead of bars to tie-down the battery cells.

Before putting the battery cells back in the box, I passed an additional flexible conduit underneath the car between the trunk and the motor compartment for future expansion (ex. BMS or other options). I also mounted a smoke detector inside the trunk for added safety. 

Going from 40 to 45 cells required that I upgrade my charger. The original Elcon charger was 128 volts nominal and the new one is now 144 volts. I also had the new charger enabled for CAN bus control which meant I had to purchase a CAN module.

I was also due for tires so I got myself a set of Kumho Ecowing all-season low rolling resistance tires.

More to come soon in "Improvements - Part 2" where I will describe a new BMS that I am evaluating.

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