100% charging below -15F should prevent battery damage?

[TonyWilliams]

I have installed 6 x 50 watts pads and 1 thermostatic switch tc1. I have no picture because the time and difficulties working at about 32 degrees was not easy. I finished and the sun was down , I was frozen.

The pads: http://www.amazon.com/Kats-24050-Watt-Universal-Heater/dp/B000I8YPQ4
And the switch : http://www.amazon.com/Farm-Innovators-TC-1-Thermostatically-Controlled/dp/B001ADUKRO

The pads really heat up not installed but do not get really hot once installed. The heat was going up to the sheet metal of the battery casing.

I added fiberglass insulation on the pads holding with aluminum tape to prevent heat transfer to the plastic covers

I will use the picture above to show where they where installed. For the moment, the thermal switch is set in front of the battery where the power output connector is

Good work. 300 watts might keep a well insulated pack warm. Be sure and get the "LEAF Spy" app for Android and the $20 ELM327 Bluetooth plug so that you can see that ACTUAL temperature in the battery.

Be careful with any insulation that can hold water and cause corrosion. I would probably only recommend styrofoam that was glued/bonded directly to the metal battery case and over the heating pads.

That thermal switch is NOT satisfactory, as it can't measure the temperature of the metal battery case. You need a thermostat that can bond directly to the battery case, is NC (normally closed) and can handle at least the 2.5 amps at 120 volts. I recommend not letting the metal case get hotter than about 30C. Here's a good place to look:

http://www.digikey.com/product-search/en?pv130=14&pv735=3&FV=fff4001e%2Cfff8011b&k=thermal+switch&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25" onclick="window.open(this.href);return false;

http://www.digikey.com/catalog/en/partgroup/r53-series/6417?mpart=CS703025Y&vendor=317&WT.z_ref_page_type=PS&WT.z_ref_page_sub_type=PD&WT.z_ref_page_id=PD&WT.z_ref_page_event=DC_Link_Table" onclick="window.open(this.href);return false;

The Cantherm R53-CS-7S can handle 10 amps, is set at 30C degrees, is Normally Closed (NC), and has automatic function with 100,000 switch lifespan.

If you have questions about this, or other choices, I'd write or call Digikey:

techs@digikey daught com
800-344-4539

 

[pkarza]

Yves -

Looking forward to seeing where and how you put in the pads!

Thanks!

 

[rmay635703]

On the other hand, if the electrolyte were to freeze, mightn't that be likely to burst the cells even without powering up?

Ray

Generally most all Lithium batteries are designed to be capable of freezing (whether the leaf can or can't I have no idea but would venture YES or they would be a hazard)

Next ALL lithium batteries will work (discharge) down to about -80 degrees, where the problem comes in is that you can't charge a frozen battery because of the BURST or more likely separator damage that would happen.

A car isn't of much use if you can't charge it. I have read however that again you can charge frozen lithium but at a very glacial rate, sadly few publish any of the facts and figures for either situation above. But I doubt either is very flattering, probably C/100 but this would also warm the cell increasing the rate, odd situation having lithium in cold.

Cheers
Ryan

 

[TimLee]

On the other hand, if the electrolyte were to freeze, mightn't that be likely to burst the cells even without powering up?

Ray

Generally most all Lithium batteries are designed to be capable of freezing (whether the leaf can or can't I have no idea but would venture YES or they would be a hazard)

Next ALL lithium batteries will work (discharge) down to about -80 degrees, where the problem comes in is that you can't charge a frozen battery because of the BURST or more likely separator damage that would happen.

A car isn't of much use if you can't charge it. I have read however that again you can charge frozen lithium but at a very glacial rate, sadly few publish any of the facts and figures for either situation above. But I doubt either is very flattering, probably C/100 but this would also warm the cell increasing the rate, odd situation having lithium in cold.

Cheers
Ryan

Interesting response. Are you basing this on personal experience in the use of lithium batteries (non-automotive) :?:
Can you provide any sources of the information?
Any information on the temperature at which the LEAF battery will freeze?
Is the -80 degrees you quote for being able to discharge degrees C?
Will the ability to discharge still continue after the battery has frozen?

 

[Yvesm]

I thought that at cold temps, the pads would only rise the battery temp but not be able to reach 30. It is good advice to add a thermal cutoff at 30 ish. I will check to add this to the metal enclosure. Thanks

The corrosion is also a good thought. I need to check next spring and react accordingly. Foam might be watertight but would need to support a defective shorted pad without caching fire. Now, it is silicon (pad envelop), fiberglass and aluminum so it can withstand high temps

I have a spare pad (bought 7 ) so I can Photoshop a resulting installation. As soon as I find time, I will do this. I will install the pad on sheet metal

Addition. I will also check out the ELM327, that would be cool for monitoring

 

[Yvesm]

Results:

The pads and thermal switch are perfect. I had a timer for a few days but it looses time if ac fails for a second so I removed it. One morning at -27C, timer resetting and not triggering the heat pads, I almost did not make it home from work.

We have current night temps at -26C , and day temps at -19C
Just the thermal switch/pads keeps the battery at around 0C (4 bars). The thermal capacity of the battery keeps it at 2 bars during working hours. Then driving home, brings the battery back to 3 bars. Night heating brings the battery to 4 bars again.

In this cold weather, i charge at 100% . So the range is similar to mild temps, 80 km (my mild temps). Without heating at -27 C, I got around 30 km. Summer, I get about 130 km (proof that winter tires kills the range)

I will post an installation message under the "Mods" section

 

[LeftieBiker]

The battery does have a lot of thermal mass, so it isn't going to hit ambient quickly, but after multiple hours exposure it will begin to approach ambient.

Yes, but those "multiple hours" can actually be days. I've only had my 2013 battery pack heater come on once, and that was more than a day after frigid temps hit. I think it takes it about 12 hours just to fully cool down from driving temps.

I'd like to take this opportunity to complain about people swapping Fahrenheit and Centigrade readings. I've read here that the battery is disabled at -20F and -20C, and that the heat pump stops working at -5F and -5C. Big difference, there! Lots of other sources also claimed, pre-release, that the heat pump worked down to -5F, when I believe the correct number is -5C. It makes a difference, dammit!