nathan christiansn via EV wrote:
Thanks for all of your suggestions.
I am doing more research as to whether or not I actually need a battery
heater in order to charge the leaf batteries at 20 degrees fahrenheit.
Hi Nathan,
I live in Minnesota, so cold weather is very common. We just came
through a week of sub-zero weather (and that means 0 deg.F, not 0 deg.C)!
Batteries (all types) are "cold blooded". Below some (rather arbitrary)
temperature, manufacturers will suggest that you restrict or refrain
from charging or using them. But it's not a hard-and-fast limit, like
when water freezes. The truth is, the colder they get, the worse they
perform. So it will *always* help to keep them warmer. Your range will
be greater, and you can charge them faster.
The best solution is to add insulation. Even 1" of foam insulation makes
a drastic improvement. With insulation, the waste heat generated by
charging and driving may be all you need. When I drive my EV every day,
1" of styrafoam insulation is enough to keep them warm without any extra
heaters.
The automakers don't seem to have figured this out yet. A steel box with
an air space around the batteries isn't "insulated". It takes a lot of
heat to keep the batteries warm in this situation.
If you have insulation, 1 or 2 of the little 50-100 watt "battery
blankets" that they sell for normal ICE batteries is enough. You can
also use an electric blanket, or soil heating strips, or the heat tape
used to keep pipes from freezing.
Without insulation, you'll need several hundred watts of heat. This is
best done with commercial products that are built to handle the higher
power and heat loads.
Insulation can also cause overheating in hot climates. Batteries work
great at high temperatures; but heat can also considerably shorten their
life. On my EVs, I make the battery boxes so I can remove the insulation
from the lids in the summer. That, and a small fan to circulate outside
air is enough in my climate to keep them cool.
Lee Hart
--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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