ripple4
Posts: 82
Joined: Tue Sep 18, 2018 1:45 pm
Delivery Date: 18 Sep 2018
Location: Toledo, Ohio

Traction pack heaters and insulation install

Fri Mar 01, 2019 7:35 pm

My one way drive to work is 30 miles, sometime 32 miles. L2 at work! With my 10-bar leaf I would have thought that I was future-proofed for a few years, well the polar vortex taught me otherwise. those two really cold days In the morning it was at zero temperature bars, with -10 to -20F in a garage with a L2 charge finishing right at the departure time. When the temps are 20F out I have 2 battery temp bars for the same conditions. And with even a little headwind I was getting LBC ½ mile from work. The lowest I ever got was 3miles on the GOM pulling in. no heat, no defrost. Only a 12v fan defroster and heated blanket.

The solution as I saw it, short of buying a real car and not a darn golf cart with doors, was to reduce the power draw of the battery heaters by preheating the traction pack, and holding that heat in for ½ hour. So I bought 2x 150w silicone pad heaters and one sheet of foil faced EPS foam board, foam safe construction adhesive and waterproof foil tape. Total $65 spent here.

Inspired by this post (viewtopic.php?t=15673) I installed the heaters on the bottom of the clean battery shell and covered them over with the butyl faced foil tape. Then I cut the foam board to 32” width and various lengths to fit close to the battery. Then I put the same waterproof tape around the edges of the foam board so it would not soak up water and get moldy. to install them I used the glue on them making a perimeter all the way around with the caulk to seal out air.

The electrical situation is not fully fleshed out yet, I have a metal LB box to install and will terminate the heaters to a extension cord inside that box and run the plug up to the motor compartment, until then I have the wires zip tied up to the rocker panel.

I know that this will not work for southern cars, and cars the DCQC 3x times a day, but a L2 only car with mild Ohio weather I figure I can leave these on all year round. The foil facing pointing down will reject heat from hot parking lots and could even, perhaps, keep the battery cooler than if no insulation was there in the summer, the tarmac road surface can be 130F, but the air is only briefly over 100F at 2pm in a summer heat wave. And if my guess is wrong and it’s at 8+ temp bars all the time, I’ll pull it off.

I also sprayed marine rust proofer on the rocker panels, anything metal, and the edges of the battery pack, its like cosmoline, goes on runny and turns into a wax coating.

THE RESULTS, with the heaters running for 90 minutes before departure, the temp readout is at 4 bars, when it normally would be 2 bars. The two mornings that have been below 20F this week to try this idea out, suggest that it works, seemingly adding GOM miles compared to what I am used to. Today I rolled in with 15 miles on the GOM, a 5-10 mile GOM improvement. But its hard to say for sure, since the wind was not so bad today, only a 10mph head wind, but I think 5 miles extra is a reasonable conclusion. time will tell.

Heating pads installed
https://ibb.co/R9xHgn2
Image

Insulation cut and dimensions drawn on
https://ibb.co/C2WT5cY
Image

front half ready for the cover to be on
https://ibb.co/VWt6v9b
Image

Rear half ready for the cover to be on:
https://ibb.co/0h0vVCs
Image

ripple4
Posts: 82
Joined: Tue Sep 18, 2018 1:45 pm
Delivery Date: 18 Sep 2018
Location: Toledo, Ohio

Re: Traction pack heaters and insulation install

Tue Mar 05, 2019 7:25 am

If any day was a test of this idea, as a even minimally effective way to extending cold weather range, it was today, single digits F temps and 25mph gusting headwinds. Started the morning with 3 battery temperature bars after a 2.5 hour timed preheat. and had one ring indicator of regen after about 5 miles and made it on my longest morning route without getting LBC.

Titanium48
Posts: 148
Joined: Thu Jan 31, 2019 7:33 am
Delivery Date: 25 Jan 2019
Location: Edmonton, AB

Re: Traction pack heaters and insulation install

Tue Mar 05, 2019 10:26 am

I don't think the issue is the power used by the battery heaters, but the behavior of batteries in the cold. Internal resistance goes up, the maximum safe charging rate goes down considerably, and I suspect that charging is terminated at a lower SOC. The result is a battery pack that stores less energy, delivers energy less efficiently and can't support much regenerative braking. The internal battery heater maintains basic functionality with minimum power consumption by keeping the battery above about -17°C. Heating it further, especially while charging, reduces the cold-related limitations and restores range.

I am very interested in how this setup behaves when you drive 100 km a day in the summer. If summer battery temperatures don't increase significantly, this looks like an excellent idea for anyone driving a Leaf in a cold winter climate. If they do, then we need to figure out an easy way of removing the insulation in the spring and replacing it in the fall.
2016 SL

ripple4
Posts: 82
Joined: Tue Sep 18, 2018 1:45 pm
Delivery Date: 18 Sep 2018
Location: Toledo, Ohio

Re: Traction pack heaters and insulation install

Tue Mar 05, 2019 10:53 am

Thank you for the correction, I misunderstood something I had read in the past, and thought the traction battery heaters operated 1) at a higher power level than 300w and 2) at temperatures above 0F. but the reasons you list seem reasonable and I can go with that. if you're right i should have the battery heater running for longer than 90 minutes or even longer than 2.5 hours proir to departure, to maximize the temp when the battery get close to 100% charged, so it goes to the higher SOC.

https://www.cars.com/articles/2011/06/2 ... e-details/

Where I live, we don’t get a heat wave until late July or August, but if I remember I’ll post an update here. What are the criteria for a battery that is too hot? 8 temperature bars, the red zone? The top of the red zone? XXX oF or XX oF? I have a greenlots DCQC close to me that now works so I can see how many bars it goes up doing that right now.

Titanium48
Posts: 148
Joined: Thu Jan 31, 2019 7:33 am
Delivery Date: 25 Jan 2019
Location: Edmonton, AB

Re: Traction pack heaters and insulation install

Tue Mar 05, 2019 2:41 pm

With battery degradation being strongly temperature dependent, I'd suggest that any significant increase in summer battery temperatures would be something best avoided. Battery heating quickly transitions from a good thing to a bad thing past about 20°C. It will be interesting to see which effect is more significant - the insulation of the battery from radiant heat from hot pavement or the reduction in the ability to transfer heat out at night or while driving.
2016 SL

Oilpan4
Gold Member
Posts: 961
Joined: Wed Jan 09, 2019 10:51 pm
Delivery Date: 10 May 2018
Leaf Number: 004270

Re: Traction pack heaters and insulation install

Sun Mar 10, 2019 11:08 am

The difference between 8 and 12 temperature bars is only the difference between around 120F to 140F.
Once I hit 8 bars I don't drive or charge.
2011 white SL leaf with 2014 batt.
Chargers: Panasonic brick moded for 240v, duosida 16a 240v and a 10kw setec portable CHAdeMO
Location: 88103

estomax
Posts: 228
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Leaf Number: 424033
Location: Seattle

Re: Traction pack heaters and insulation install

Thu Mar 14, 2019 7:13 am

do you know if these pads are installed near the temperature sensors? I would be concerned about the heating effects right near the pad on the cells local to the pad and the battery pack temperature sensors not picking up on that appropriately. there are only 3 temperature sensors in the pack that i know of.

Marko
2013 Leaf SL Premium
27k, 93% SoH 2/17 32k, 96% SoH 6/17
46k, 94% SoH 2/18 52k, 88% SoH 6/18
62k, 87% SoH 2/19 68k, 84% SoH 6/19

ripple4
Posts: 82
Joined: Tue Sep 18, 2018 1:45 pm
Delivery Date: 18 Sep 2018
Location: Toledo, Ohio

Re: Traction pack heaters and insulation install

Mon May 06, 2019 5:11 pm

update with a warm weather day, there was a question if the insulation would contribute to warm weather problems. I level 2 charged all afternoon 4+hours in full sunlight with 76F air temps, but the temp meter read 85F even with the windows cracked open. The car had 5 bars of temperature and after a 40 minute 55MPH drive it clicked up to 6 temp bars just as i pulled in the garage. today was far from an august heat wave day with 95F+ temps, will update then.

Return to “Accessories / Mods”