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Re: [EVDL] Winter & EVs

Hello Nikki,

In Montana, it only got down to -36 C for about 2 hours and than it normally
steady outs at -18 C for about a month and 0 C for the rest of the winter.

At one time I use one of those round heat tapes, that you can get in any
length on a spool. My batteries were in aluminum boxes which were space
about 1.5 CM from the inside edge of the box. The heat tape wrap around the
batteries in this space starting at the bottom of the battery space about
every 6 CM.

One end tap off a 20 amp circuit breaker in the EV that then tap of the
charging input cable circuit. A adjustable thermostat is install that is
design for this cable with a sensor bulb that is place in the battery box.

The outside of the battery box was insulated with soft 3/4 foam that had a
sew on vinyl cover that can be snap together for removable and cleaning.

I could not let this EV set out side more then 8 hours when the temperature
got to -36 C even with this heat, because the battery temperature could drop
to close to 0 C.

I change the aluminum battery boxes with 1 CM thick fiberglass, and allow
enough space around the outside of the box to install a layer of 6 CM (2
ins.) foam board that is glue directly on the box with a 12 CM air space and
another layer of 6 CM foam board. The outside of the foam board was then
cover with a nylon marine carpet.

A 1.5 layer of foam with the carpet is lay on top of a 1 CM think hinge
cover. This battery installation sets inside a insulated pickup bed with a
insulated hatch back that has a solar passive glass that allows sun light to
come in.

I park in a super insulated garage that is always heated to 22 C which
maintains the EV and batteries temperature at about 22 C. If I had to let
the EV set outside, I would use the round heat tape inside this battery box.

When it got down to -36 C. last winter early in the morning, it was a clear
day. About 15 minutes, before I left with the EV, it preheated the
passenger cab to 27 C. and the battery temp was setting at 22 C. I drove
about 8 km at 16 km/h and park the EV with the glass hatch back toward the
sun. After about 2 hours of setting, the temperature below the hatch back
glass and around the battery box, was about 27 C.

So, there is many ways to keep up you battery temperature. The best way is
to insulated a enclose battery box with a heat tap or even one of those
battery heat blankets you can wrap around the batteries.

Make sure you do not wrap this type of round heat tape tight around sharp 90
degree corners of the battery box, this will cause hot spots in these areas.


----- Original Message -----
From: "Nikki Bloomfield" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, September 23, 2007 11:51 PM
Subject: Re: [EVDL] Winter & EVs

> I'm really interested in this thread.
> The City El of course suffers just like any other car in the winter
> but this year I have some Thundersky lithium Ions in her. When I
> installed the pack I used some thermal 'space blanket' style
> insulation on each of the three packs ( see
> aminorjourney/sets/72157600628045492/ for pictures of the upgrade )
> but I didn't install heating pads for the cells. BIG MISTAKE!
> Since the average temperature has dropped from the high 20 degrees C
> down to 15 degrees C my batteries have taken a big hit in performance
> and the internal resistance has rocketed. The first few miles I tend
> to try and get the batteries as hot as possible so that the car
> doesn't get too rough a performance. Of course also recharging from
> cold isn't that possible as the batteries won't accept charge so well.
> So, I'm going to try and install some heating pads this week from RS
> components. It'll mean removing all of the cells fom the car and re-
> packaging them but at least then I'll have heating for the
> batteries. The sort of pads I'm getting are here:
> 3xu3qw . 30 W of heating per four cells should be enough to keep the
> cells from getting too cold.
> I'm also wanting to introduce some form of mains heating for the car
> as we're about to move house and the garage isn't big enough really
> to store the City El (it's not long enough as it's just a mini-garage).
> With those with heating what sort of performance drop do you get in
> the winter even with heating?
> Nikki.
> _______________________________________________
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