I'm really surprised the "balance" is so poor. If the battery has
reasonable insulation, how much power would it take to keep it warm -
e.g. 50F - for, say 8 hours ? Let's say the outside temp is 0F average.
I don't expect anyone to do calculations. But Lee gives an approx metric
of 30-40 miles when cold and 60-70 miles when the battery is 50F, both
with 0F temp outside. It seems fair to surmise that the difference in
range is due to the temp of the battery. For the 2013 model, I think it
has a 30kWh battery. That means that roughly half of the battery's kWh
is not usable when the battery is at 0F, or about 15kWh. Really, for an
insulated battery, it would take that much energy to keep it warm while
you're out doing something ?
Let me give a real life example. Let's say I buy a Bolt and want to use
it to go skiing. It's 160 miles RT. The average temp while at the ski
area parking might be 25F (hopefully not 0 :). I want to be sure I can
get home without stopping to charge somewhere. If I can heat the battery
while skiing, I should have no problem. If not, I'm probably ok in this
scenario, but not with too much margin. (A lot of hand waving calcs
going on, I know.)
For this wave of early adopters, it's not that big a deal. My guess is
that there's virtually no insulation and the manufacturers are skimping
because it won't matter so much to the current buyers. But if the
manufacturers want to sell mainstream, I think this will come back as a
serious red flag for many buyers. Of course, in the mean time, we're
getting better technology...
Peri
------ Original Message ------
From: "Robert Bruninga" <bruni...@usna.edu>
To: "Electric Vehicle Discussion List" <ev@lists.evdl.org>; "Peri
Hartman" <pe...@kotatko.com>
Cc: "Lee Hart" <leeah...@earthlink.net>
Sent: 10-Sep-19 12:05:06 PM
Subject: RE: [EVDL] li ion battery in cold weather
Ok, then why don't battery heaters - which I thought the Bolt & Tesla
have - give a good winter range ?
Because there is a balance temperature point above which you are burning
more kW just warming up the battery than you get in better range for the
same kWh.. In either case range in winter is less because the battery is
cold or you are using up kWh for warming the battery. Either way, reduced
range.
bob
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