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Old 12-13-2009, 02:13 PM   #1 (permalink)
Oval_Overload
24.27 lbs per gallon Co2
 
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Join Date: Aug 2008
Location: Minneapolis, MN
Posts: 217

Unicorn - '12 Nissan Versa 1.8S hatch
90 day: 31.9 mpg (US)
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its %$*&ing cold up here... (EV winterizing tips needed)

...And I might just kill someone. More on that later.

EV enthusiasts, share with us your winterization strategies. The ideal temperature for lead acid batteries is 78F, and for those of use in a northern clime, winter means we have to get a-thinkin', how do we keep our traction packs happy in sub-zero weather.

The most successful strategy I've seen implemented so far was on the notoriously range deficient Zap Xebra. In stock form, the batteries hang out below for all the voyeurs to see. The solution was to give it a pair of underwear!

The batteries were removed (oh my aching back) and Pink Panther foam was placed underneath. An electric heater was taped to the foam and laminated. Thin, flexible closed cell foam was taped to the sides of the battery box. This is the foam that is used to insulate between a wall and sub-floor in new construction. This solution was enough to keep the batteries warm for several hours while parked but it still wasn't quite enough, so a 150 watt heat blanket was run along one side of the box and fiberglass insulation was stuffed in plastic 'construction waste' bags and stuffed in every crevasse. A wrapped bat of fiberglass was placed along the top of the batteries and topped with Pink Panther foam. The battery box was buttoned up and I parked the car outside. The next morning, it had a full charge at 70 F. The interior of the car was at 32 F and the outdoor temperature was 18F if I remember correctly, which leads me to my current conundrum...

I borrowed the black Wheego Whip from work to go look at an apartment two days ago. The car had been sitting out in the cold for days, so I plugged it in. The internal resistance warms the batteries while they charge. The pack temp climbed about 5 above ambient after a couple hours on the charger. I know that doesn't sound like much, but this car has not been winterized. It has a sealed, but uninsulated battery box. I left work with an 80% charge and an 18F pack. 4 miles of driving netted me 10F and the return trip bumped the pack to 38F, pretty good for an uninsulated car, I'd say. I drove a total of 8.5 miles with probably another mile left in the pack.

Yesterday, I went to this psedo party at the local Perkins (yeah, I know, Perkins >.< ). Partly because I wanted to learn how this car worked in cold weather, but mostly because I am sick of driving my parent's Suburban, I drove the Wheego. I left with a 75% SOC and a 28F traction pack. I arrived 5.5 miles latter with the pack at about 43F and a 20% SOC. What the hell happened??

I parked at the British Petroleum station that shares a parking lot with Perkins and gave the clerk some loose change to let me plug into the socket for the air compressor. After a short while, a troupe of electronics geeks and I checked on the car. Standing in the cold, we drew our calculations on the frost of the back window, trying to figure out how many KwH I needed to get the car back to the shop. One of the geeks was futzing with the CD player and made an off hand comment about the defroster... It was on. It had been on the whole drive over. The fan was on its lowest setting so I never heard it, but the temperature knob was cranked to turkey-roasting mode!

This is where Jimbo goes bizzerk. GOD&*%$ITMOTHER!@#$INGSONOFA&%@#$

Whoever used the car last left the heat cranked up. I burned through 635 wh/m! in a 2400 Lb AC drive car!

3.5 KwH later, I drove back to the shop using about 20% of the charge. The SOC meter barely moved. The pack temp was 58 F

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