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Re: [EVDL] Winter & EVs

Hello Hunter,

You will still have to insulated them, because the minimum temperature they
can withstand is -4 F. I use to work on NiCad's and they not worth the
trouble in preventive maintenance that should be done about once a month.

In running a aircraft battery shop, I broke down these batteries done every
30 days, discharge them to 0 volts, added new KOH electrolyte, charge them
to 1.21 volt (cannot overcharge them at all, tested them and install them
into silicon insulated cases, connected all the links and put back in
service.

These were only 10 ah cells at the time and good for about 500 cycles. I
have calculated that to replace my 300 ah lead cobalt cells, that I would
need 170 of these cells per string and 30 strings which would be a total of
5100 cells which would be as bad as the Tesla batteries.

With the 300 AH at 204 cells, I could go up a 7 percent grade hill at 60 mph
for about 2 miles which will draw about 400 battery amps and 600 motor amps.
I could make four runs or run four days for about 25 miles before the
batteries would get to 50% DOD.

The advanced life cycle of the cobalt cell is about 800 cycles so this is
about a average of 800 weeks or 15 years. I replace them in 10 years with a
Exide X220 6 volt battery which also got me 10 years, but did not have to
drive up that long hill any more.

Roland


----- Original Message -----
From: "Hunter Cook" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, September 24, 2007 9:53 AM
Subject: Re: [EVDL] Winter & EVs


> Hi everybody-
>
> Not to take anything away from the various battery heating/insulating
> projects, but why not just use a NiCd pack? Just seems like less
> trouble, and as a bonus they'd last way longer than lead acid and be a
> lot cheaper than Li-ion.
>
> Just a thought...
>
> Hunter.
>
>
Roland Wiench wrote:
> > 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.
> >
> > Roland
> >
> >
> > ----- 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 http://flickr.com/photos/
> > > 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: http://tinyurl.com/
> > > 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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> > >
> >
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>
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