Battery Heating message during charge

Neb · Dec 9, 2009

Has anyone seen this? You plug in the charger, and instead of switching into charge mode, it says "Battery Heating n%" and does nothing? (Except, presumably, heating the battery?)

We've had a stretch of sub-zero temperatures for the last 3 or 4 days, and that's what I'm seeing now that I went outside and checked on the car. There's nothing in any of the documentation describing this state.

Ben

ChargeIt! · Dec 9, 2009

Neb said:
Has anyone seen this? .... There's nothing in any of the documentation describing this state.
Ben

Actually it is in the documentation ... and yes that's normal. What is not in the docs is the fact that the blue flashes while heating. (And the VDS temp display shows a YELLOW bar in the left-most temperature position (out of 7) for the battery, instead of a blue one.) Might take an hour to heat enough before normal charging starts (depends on time exposed at overnight ambient low and current ambient temp) -- that's when it switches from blue-flashing to amber-flashing.

From an early version MY2008 owners manual: "Depending on the temperature of the Battery, heating or cooling may be required before it can be charged. This is activated automatically but may result in a significant delay before charging begins."

Neb · Dec 9, 2009

ChargeIt! said:
Actually it is in the documentation ... and yes that's normal. What is not in the docs is the fact that the blue flashes while heating. (And the VDS temp display shows a YELLOW bar in the left-most temperature position (out of 7) for the battery, instead of a blue one.) Might take an hour to heat enough before normal charging starts (depends on time exposed at overnight ambient low and current ambient temp) -- that's when it switches from blue-flashing to amber-flashing.

From an early version MY2008 owners manual: "Depending on the temperature of the Battery, heating or cooling may be required before it can be charged. This is activated automatically but may result in a significant delay before charging begins."

Thanks, I was searching for the verbiage on the VDS and found no hits.

Mine has been flashing blue for a few hours now. When I started, it showed "9% complete," and now it alternates between 0% and 10% approximately once per second. Weird, huh?

The outside temperature is approximately -7F. I have put my 3kW electric heater on in hopes of bringing the garage temp up a little to see if that "helps." I do think I am still within the specified range, however.

Ben

ChargeIt! · Dec 9, 2009

The "one hour" battery heating experience is with overnight low at 22F. -7F is a bit "extreme" (not for you may be but for the battery). You should verify operating specs for the battery and/or contact Tesla Motors. The heater will help, but the slow progress is an indication that there's an issue. I would recommend you do not operate the vehicle until you have verified operating specs ... so as to avoid a possible vehicle warranty dispute in the future.

Addendum 1: Ah ... just found it (new MY2010 Manual, page 10-19): Battery charging spec (ridiculously enough) is 32F to 113F

But more importantly: Battery Driving spec is -1F to 122F.

Addendum 2: If the 32F (for charging) is "exceeded" (lower) as far as ambient, but the heating can get the battery up to 32F ... and the car DOES start charging on its own ... then I would HOPE you are not violating the spec. Same for driving ... if you can start the car ... etc ...

Neb · Dec 9, 2009

ChargeIt! said:
The "one hour" battery heating experience is with overnight low at 22F. -7F is a bit "extreme" (not for you may be but for the battery). You should verify operating specs for the battery and/or contact Tesla Motors. The heater will help, but the slow progress is an indication that there's an issue. I would recommend you do not operate the vehicle until you have verified operating specs ... so as to avoid a possible vehicle warranty dispute in the future.

Addendum 1: Ah ... just found it (new MY2010 Manual, page 10-19): Battery charging spec (ridiculously enough) is 32F to 113F But more importantly: Battery Driving spec is -1F to 122F.

Addendum 2: If the 32F (for charging) is "exceeded" (lower) as far as ambient, but the heating can get the battery up to 32F ... and the car DOES start charging on its own ... then I would HOPE you are not violating the spec. Same for driving ... if you can start the car ... etc ...

Hmm, you're right. For some reason I thought I remembered the lower boundary being -20F.

There will eventually be a lot of cars that could be parked, at least overnight in some cases, in much lower than 32F. To date the sample size may be so small that Tesla simply hasn't had to deal with it. I've lodged my support request and will share whatever I can glean.

Ben

p.s. -7F is plenty extreme for me, too. This is an unusual cold spell for us!

Neb · Dec 10, 2009

I looked around to try to figure out how I got this -20F number in my head as the lower extremum for operating temperature. Turns out some of the old blog entries on the Tesla site reference this -20 number back in 2005 and 2006. They also were using Celsius units, however.

Anyway, -20C is -4F and so that number is still too optimistic vis a vis the actual specs. I've advised one of the service managers to have someone go back and add a note on that stale data so someone else doesn't read it and get confused.

I left 3kW of heat on the car all night, and today it seems back to normal. I am awaiting a follow-up to learn if these exceptional temperatures DAMAGE the battery or simply create a situation where one cannot do anything (charge or drive).

Ben

Palpatine · Dec 10, 2009

I own a company that sells lithium iron phosphate cells. This is a different chemistry than those used by Tesla, but many of the properties are similar.

From our experience, they charge much less efficiently at lower temps. Your wall to battery energy consumption is going to be much higher if you are charging while below freezing.

Tesla likely has some software code in their battery management system that is just protecting the overall system health.

The space heater in the garage is a good idea if you are seeing that type of message on the VDS. That is not from Tesla. That is just my opinion based on experience with our own lithium cells.

ChargeIt! · Dec 10, 2009

Neb said:
I am awaiting a follow-up to learn if these exceptional temperatures DAMAGE the battery or simply create a situation where one cannot do anything (charge or drive).

Yes! ... it would be important to know if the car (firmware) is intelligent enough to prevent any damage and possibly related future warranty dispute in-spite-of an uneducated user

From all other accounts the firmware does seem to be programmed conservatively to protect the car from user mistakes or inexperience ... let's see if that's also the case with temperature extremes at the low end (the high end temps idiot-proofing was "tested" successfully by several owners this past summer).

Neb · Dec 10, 2009

James said:
From our experience, they charge much less efficiently at lower temps. Your wall to battery energy consumption is going to be much higher if you are charging while below freezing.

Yeah, the VDS showed 64kWH consumption to "charge" a battery that was already showing full before I plugged it in.

bolosky · Dec 10, 2009

Cold =? No Regen

It's well below freezing here, and has been for several days. This morning when I started to drive, the Roadster had the no regen yellow light on, just like you get with a full range mode charge, but I was in standard mode.

Every time the car would have been doing regen breaking, the yellow TC (traction control) light also came on and there was no regen. Turning off traction control had no effect, the light still came on.

After driving for 15 minutes or so the car returned to normal.

I'm assuming that what happened was that the battery was too cold to charge, so the firmware turned off regen. Once it warmed up from driving (and blasting the heat, because I was cold, too) it turned it back to normal.

Has anyone else seen this?

I also noticed much larger than normal energy consumption on my drive to work. The little graph showed > 400 Wh/mile while I was around 250 Wh/mile in the summer. Presumably some of this was not running regen, and certainly a big chunk was the cabin heater, but I wonder if they were also running the battery heater.

Luckily, even with this kind of energy draw the battery is way bigger than I need to commute.

Neb · Dec 10, 2009

bolosky said:
Has anyone else seen this?

Yes, I have seen this in the past few weeks, and I think your theory is correct.

In my case, it happens only at the start of my drive, which consists of a steep downhill grade for about 800 vertical feet and two miles. By the time I get to the paved road, regen is usually working. The coldest I have driven it at is about 15F. I have not seen it do this in balmy 30F conditions.

Ben

johnr · Dec 10, 2009

Wouldn't it make sense to keep the car plugged in all the time when it's setting in the garage? That way you're guaranteed the batteries will always be at a safe temperature - and the charger won't use any more energy than it needs in order to achieve that.

Neb · Dec 10, 2009

johnr said:
Wouldn't it make sense to keep the car plugged in all the time when it's setting in the garage? That way you're guaranteed the batteries will always be at a safe temperature - and the charger won't use any more energy than it needs in order to achieve that.

You'd think so! I left that detail out.

Most of the time, whenever I leave it plugged in for days, it is in an error state when I get out to the garage. Usually the GFI trips (I only have the 110V charging cable with the integrated one). Also, once the car is fully charged, it just stops and acts like it's not plugged in. (In this particular case, though, I think it got too cold for the heater regardless -- and there was a different error message on the VDS.)

If there's something I'm doing wrong, I'd love to hear from the experts. I've thought about chopping off that dumb, trippy GFI, but I'm still expecting to get my 220V charger soon.

Ben

DaveD · Dec 10, 2009

Neb said:
I've thought about chopping off that dumb, trippy GFI, but I'm still expecting to get my 220V charger soon.

Unless they've changed the MC120 design since I got mine, the GFI can be removed from the cable without damaging the cable or the GFI. there's a cover plate on it that unscrews and exposes the screw terminals for the cable wires. You can do what I and several other owners have done, by removing the GFI and replacing it with a standard plug ($3.00 or so at your local Home Depot). The tradeoff for no more GFI trips is that you need to be a bit more careful when using the connector. When charging, always attach the Tesla connector to the Roadster first, then plug in the 120V plug, and you'll be safe. After charging, unplug the 120v plug before detaching the Tesla connector from the Roadster.

TEG · Dec 10, 2009

Also, don't stand in a puddle in bare feet and jiggle the roadster end of the charge cable while someone turns on other equipment on the same circuit as the charge cable. It is unlikely anyone will ever get hurt even without GFCI, but minimizing the risks involves not touching the Roadster while it is charging.

Neb · Dec 10, 2009

Yeah, I already have a GFI on the circuit. I only wish there were some puddles I could stand in around here...

bolosky · Dec 10, 2009

johnr said:
Wouldn't it make sense to keep the car plugged in all the time when it's setting in the garage? That way you're guaranteed the batteries will always be at a safe temperature - and the charger won't use any more energy than it needs in order to achieve that.

My car was plugged in and it still went into the no regen mode this morning. It was probably about 20F outside, maybe a little warmer in the garage. I hadn't driven in for a day and a half, so it had plenty of time to cool down after charging up all the way.

I have an RFMC, I've never had a GFCI trip or any other problems like that.

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