nerys
Posts: 685
Joined: Tue Sep 09, 2014 10:11 pm
Delivery Date: 09 Sep 2014
Leaf Number: 020441

Re: Battery pack heat pads installation

Tue Mar 31, 2015 1:49 pm

I have found 240v units but they are all very high power (lowest is 125watt) no 50watt units and with the success of his units at 50watt times 6 I don't know if I want to risk using THAT much more.

I could use 4 which would be 500watt total but still 200watt more than he used and more concentrated.

I would wire them in BEFORE the EVSE circuitry ie at INPUT power so they would run whether the car is charging or not and would not effect the EVSE operation at all. I am already wired end to end for 30amp so I have plenty of safe power bandwidth to handle 300 or 400 watts of heaters.

at home I can just plug in another device but at work I only have teh one L630 outlet and don't want to pester them for more work. leaving good enough alone in that regard. plus it would just be more elegant. second socket next to the J1772 receptacle and a short little cord to plug into the extra receptacle I would install at the base of the EVSE.

Ohhhhh I screwed up. Grrrr was not thinking clearly. Derp. I forgot that the actual EVSE box is at the other end of the evse cable NOT near the car. DOLT. ok scratch that. no point in merging the units together.
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

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keydiver
Posts: 1051
Joined: Mon Sep 05, 2011 1:04 pm
Delivery Date: 08 Dec 2011
Leaf Number: 16484
Location: Hobe Sound, Florida
Contact: Website

Re: Battery pack heat pads installation

Tue Mar 31, 2015 2:25 pm

If they are a purely resistive type heater, you may find that two 125 watt 240VAC units wired in series might work OK. With half the voltage, they might make half the heat each.
2012 Glacier Pearl SL - Delivered December 8, 2011
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smkettner
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Location: Orange County, CA

Re: Battery pack heat pads installation

Tue Mar 31, 2015 2:29 pm

If voltage is cut in half so is the current. 1/2 x 1/2 = 1/4 the wattage. So two in series will put out half what a single heater does.
1 bar lost at 21,451 miles, 16 months.
2 bar lost at 35,339 miles, 25 months.
LEAF traded at 45,400 miles for a RAV4-EV

nerys
Posts: 685
Joined: Tue Sep 09, 2014 10:11 pm
Delivery Date: 09 Sep 2014
Leaf Number: 020441

Re: Battery pack heat pads installation

Tue Mar 31, 2015 4:30 pm

which is about perfect. half of 125 watts is 62.5watts. close enough for me.

is this safe? proper way to do it?
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

nedfunnell
Posts: 56
Joined: Wed Sep 10, 2014 9:07 am

Re: Battery pack heat pads installation

Tue Mar 31, 2015 4:59 pm

As long as you are putting things in series, just put two of the 110v/50w units in series. Note that when a 110v charge is going on, the pads will only make 1/4 the heat, or 12.5w each.

Is it right and safe? It'll be as safe as you build it. The concept is sound. Poor execution is the risk.

Yvesm
Posts: 27
Joined: Sun Aug 04, 2013 10:08 am
Delivery Date: 13 Mar 2013
Leaf Number: 005868

Re: Battery pack heat pads installation

Tue Mar 31, 2015 7:06 pm

I bought a kw meter and at -22 C, the thermo cube had never stopped the circuit. 300 watts is low heat on such a large battery. So 300 watts for 12 hours at about 8 cents per kwh was about $0.29 for that night.
It cost less than a heated garage for me.

I bought a bluetooth odbii elm327 last week. I tried the leaf spy: cool. I will know the exact battery temp next winter

Nubo wrote:Makes a lot of sense. Curious as to how much energy this consumes. Have you tried measuring the electrical consumption over the course of a cold night?

magnemann
Posts: 3
Joined: Sat Dec 10, 2016 3:22 am
Delivery Date: 14 Dec 2016

Re: Battery pack heat pads installation

Fri Feb 10, 2017 11:16 am

Interesting. Anyone else tried this and measured the temp with Leaf spy?

Does anyone have info on how the internal resistance in the battery changes with the temp?

Love from cold Norway with no garage. :)

hwfailure
Posts: 1
Joined: Tue May 09, 2017 7:33 pm
Delivery Date: 10 May 2017
Leaf Number: 009365

Re: Battery pack heat pads installation

Tue May 09, 2017 8:46 pm

First, thanks Yves (if you get back here). You gave me all I needed to start the project of heating the US 2011 SL Leaf I bought during the very cold winter nights near Montreal (Quebec, Canada).

I installed 2 battery warmers (120V, 80W each) and 4 thermal pads (12V, 90W each) and 5 thermistors protected by aluminum tape and fiberglass insulation. Then I put foil-faced bubble wrap under the plastic protective plates under the car.

Here are 2 images of it.

Image


Image


I know, some water and humidity can stay between the foil-faced bubble wrap and the metal plate holding the battery cover during the summer. Well, I bought the car, it is now 6 years old and it won't have 10 supplemental years to run. We will see what happen. Anyway. only some salt was present on the grey paint of the plate under the battery cover when I removed the protective plastic plates.
I don't have a lot of autonomy on this old electric car and I don't plan to drive and charge on a quick charge station then drive again, then charge again so I expect that the battery temperature will not rise too much during the hot summer days (30 Celsius degree). It is a choice I have made.

I plan to use a small micro-controller to enable or disable the 2 battery warmers through the use of solid state relays. All the thermistors will be used to stop heating if it is not required anymore.
I also plan to help maintain a bit the battery warm when the car cannot be plugged (like at work) and the car is exposed to temperature like -25 Celsius degree for about 10 to 12 hours by using a big deep discharge 12V battery that could drive the 12V thermal pads. I know it won't be for hours but I don't plan to drive each thermal pad to 90W. I will use pulse width modulation (PWM) to drive them to an equivalent of a quarter or less than 90W and one at a time. Anyway, this has to be tested and scaled.

Now, here is some info about the tests I have done with Leaf Spy Pro. I did only 1 test during a cold evening last winter (for now the 2 battery warmers are permanently powered when the 120V plug I put in the recharge lid is connected.

At 9:16PM, the exterior temperature reported by the car (in the dash) was -12C.
Battery temperature was 1 bar.
Leaf Spy Pro reported the warmest of the 4 temperature sensors in the battery was at -5C.
I plugged the 2 battery warmers (160W of heating, minimal heat going outside due to the foil faced bubble-wrap).
I took also the resistances of the 5 thermistors using a multimeter and I froze my fingers while doing that with a flashlight and writing it down while the wind was blowing.

At 10:20PM, the exterior temperature reported by the car (in the dash) was -13C.
Battery temperature was 1 bar.
Leaf Spy Pro reported the warmest of the 4 temperature sensors in the battery was at -1.3C.
Took the resistance of the 5 thermistor again.

At 11:25PM, the exterior temperature reported by the car (in the dash) was -15C.
Battery temperature was still 1 bar.
Leaf Spy Pro reported the warmest of the 4 temperature sensors in the battery was at 0.6C.
Took the resistance of the 5 thermistor again.

It was late enough and I had data for my next experiments. Battery warmers have been able to get the interior of the battery from -5C to 0.6c in 2 hours. I would expect using less energy to only maintain a temperature than to try to increase it. Not bad for a first test.

Love to Norway people from a Canadian that visited Norway 2 years ago (beginning of june 2015) during the spring. Enjoyed a lot your beautiful and peaceful country.
Hope this help others too like Yves helped me with his original work. Thanks Yves.

Yvesm
Posts: 27
Joined: Sun Aug 04, 2013 10:08 am
Delivery Date: 13 Mar 2013
Leaf Number: 005868

Re: Battery pack heat pads installation

Thu Sep 14, 2017 4:57 pm

Hi hwfailure,

i just saw your post, and found my password to reply

I am glad to see what you did. I had not thought about the foil. nice. it must be better than my install in the winter temps
does it increase the battery temperature in the summer ? on the years that there could be a summer (none this year)

for my part, all is well. still running , good mileage, love the car!

Yves

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