# Keeping batteries warm in winter



## scott (Feb 15, 2009)

I'm looking for a way to keep my 144v pack warm(70 degrees F min).They are wrapped in 1/2" to 1" insulation, but it is not enough. I was going to use the KATs battery blanket, but it is not recommended for use above 30 degrees F. I live in north east Wisconsin and the temp. from november to march ranges from -20 to mid 30's. All ideas are welcome.


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## gdirwin (Apr 7, 2009)

I am in the middle of an EV build of a RAV4, and am using 50 Thundersky 200AH batteries (160VDC nominal, 190VDC max). I have 2 battery racks (front and back). I am from Winnipeg, where it gets to -40C or colder, and I plan to drive this year-round.

I am also using insulated battery boxes - If you have the head-room then add insulation on the top (heat rises) - not sure if I have the room or not (once BMS is added etc...).

I plan to use soil heating cables (Gro-Quick) - I will snake/router a path into the bottom layer of insulation and insert these cables. They come in 2 types - internal or external thermostats - I have the ones with a thermostat built into the in-line cable (I will try to put this in the middle of each pack). The other type requires an external thermostat controller. They also come in regular and heavy duty versions, and many different lengths. I am using 2 of the 20ft versions from here:
http://www.morelectricheating.com/default.aspx?page=item detail&itemcode=WRAPON52020

The plan is to always have them plugged in to an external AC line in winter - once you are driving they should generate enough internal heat (plus they have thermal inertia and should not get cold too quickly). I may also have a timer so they are not consuming electricity all the time (I will experiment) although they are only 100Watts each...

My feeling is the battery temperature makes a huge difference - keeping them warm will improve performance and will lengthen their lifetime...

Hope this helps!

Garth


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## scott (Feb 15, 2009)

I've looked at that idea and like, but have a question. Can they be draped between boxes without shorting out? My truck "little red" is shown in the garage and has the batteries ,140ah AGM, in four separate boxes. I have a friend who was in the greenhaus industry that can hopefully help with real world use.


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## marissaruehle (Dec 10, 2009)

Hi, 

I am a student at Topsail High School and we are converting a Ranger. We saw your truck in the EV Garage area and have a few questions... 
1. What did you use to hinge your bed sideways?
2. What type of plastic did you use for your battery boxes? Where did you get it? How did you weld it?


http://thsev.blogspot.com


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## scott (Feb 15, 2009)

Hi,
To question 1)the frame pcs are 3" angle iron,the front angle is 1",the rest is 1 and 1/2" flat stock. I drilled holes and bolted to the boxes existing support rails, the hinge is a hardened bolt with an drilled out nut(spacer).
to question 2)the plastic is 1/4" black ABS(ordered from Key Industrial Plastics, Inc. of Sturgeon Bay,Wi) They also supplied the Weld-on #3 solvent for chemical welding


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## marissaruehle (Dec 10, 2009)

Can you send us a picture of your hinge?


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## scott (Feb 15, 2009)

I added 2 pic's to the garage. I'll have to take some pic's from the drivers side and post.


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## marissaruehle (Dec 10, 2009)

Thank you!


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## vpoppv (Jul 27, 2009)

Here's one way:

http://www.youtube.com/user/BenjaminNelson#p/u/37/Y_L1OhD2K0k


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## Gavin (Oct 7, 2008)

I live in Canada so I decided to follow the lead of truckers and yachts. I bought a Webasto AT 2000 Air Heater. Uses a tiny amount of fuel and will keep the entire car toasty. On ebay for less than $500.


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