Charging a cold battery - problem?

[jkirkebo]

I just tried to charge my TMS wil a cold soaked battery. It had sat at 15-20F temps for a couple of days with a 64% full battery. I needed a 90% charge.
My TMS is European, I connected the UMC with a 13A 230V adapter on it (3kW max).

It did however not start to charge. Just a current spike to 5-6A, then it always (I tried many times, restarting car etc.) fell down to 1-2A.

I did not expect it to start charging at once, but I did expect it to start heating the battery. 1-2A is however not enough for that, and I also left it drawing that for 30 minutes with no change. VisibleTesla showed 0.0A battery current the whole time.

So I decided to heat the battery manually. I disconnected the charge cable and started pre-heating in VisibleTesla. After 20 minutes I turned it off, then connected the charge cable.

Now it charged happily away at 13A, VisibleTesla showing 7.2A battery current and the range display increasing.

But shouldn't battery heating start automatically when I want to charge? Surely it should draw the whole 13A/3kW for heating until the battery can take a charge?

 

[Doug_G]

Yes the pack heater should switch on, and when the packs reaches a certain temperature it will start charging.

I do this all the time in the winter.

 

[andrewket]

You should leave the car plugged in when preheating. It will use shore power to heat instead of the battery.

 

[jkirkebo]

You should leave the car plugged in when preheating. It will use shore power to heat instead of the battery.

Yeah, I know. I just unplugged it this time to test if there was a mains power problem.

But I do not want to heat the cabin to be able to charge

- - - Updated - - -

Yes the pack heater should switch on, and when the packs reaches a certain temperature it will start charging.

I do this all the time in the winter.

And the pack heater draws more than 300-500W I guess?
If so, I wonder why I could not get it to draw more.
Will have to do some more testing.

 

[AmpedRealtor]

Keep the car plugged in at all times. Per Tesla, the car maintains the battery temperature while plugged in. If you do that, your car should charge without issue and you shouldn't have to jump through any hoops.

 

[Doug_G]

No, the car doesn't maintain the battery temperature when plugged in, unless you are actually charging.

 

[mknox]

Keep the car plugged in at all times. Per Tesla, the car maintains the battery temperature while plugged in. If you do that, your car should charge without issue and you shouldn't have to jump through any hoops.

I think it has to get really cold before the car starts heating the battery even if plugged in and just sitting. Last winter, I would have almost no regen in temps just below freezing even though the car was plugged in. Power use would go through the roof for the first few miles as the pack heater worked away. This winter, I'll use the mobile app to condition the car on shore power before heading out in the morning.

I wonder if the OP's issue was a bad connection? I've had lots of problems with my UMC not connecting to the car properly in the past. My 3rd UMC seems to be working a lot better.

 

[Doug_G]

I think it has to get really cold before the car starts heating the battery even if plugged in and just sitting. Last winter, I would have almost no regen in temps just below freezing even though the car was plugged in. Power use would go through the roof for the first few miles as the pack heater worked away. This winter, I'll use the mobile app to condition the car on shore power before heading out in the morning.

Right... I think it does start applying a little heat to the pack somewhere between -25C and -30C, but I haven't totally sussed that out yet. Last winter only had a few hard-core cold days. But I don't think it matters whether the car is plugged in or not. In fact at -30C it appears to apply some pack heat continuously when you're driving on the highway.

 

[jkirkebo]

I wonder if the OP's issue was a bad connection? I've had lots of problems with my UMC not connecting to the car properly in the past. My 3rd UMC seems to be working a lot better.

No, I don't think so. I've used the UMC to charge in dozens of places, all without incident. This was the first time I tried to charge a cold battery though. After I warmed it up it worked flawless as usual.

I suspect maybe a bug in the EU 5.6 firmware. I will have to do further testing.

 

[Cottonwood]

I suspect maybe a bug in the EU 5.6 firmware. I will have to do further testing.

That could well be.

I have 4.5 and a 14-50, 40A/240V, 9.6 kW UMC that I use at RV parks, etc, and at my home. Before going on trips, when the car is cold soaked, I use the trick to leave an hour or two of charge required. Then I either set the start time on the charging or start the charging with the iPhone App so that the charging is finished 1/2 to 1 hour before departure. This warms the battery on shore power and saves many miles consumed on the road to warm the battery. This has always worked for me; the car uses shore power to warm the battery as it ramps up the current into the warming battery.

 

[montgom626]

That could well be.

I have 4.5 and a 14-50, 40A/240V, 9.6 kW UMC that I use at RV parks, etc, and at my home. Before going on trips, when the car is cold soaked, I use the trick to leave an hour or two of charge required. Then I either set the start time on the charging or start the charging with the iPhone App so that the charging is finished 1/2 to 1 hour before departure. This warms the battery on shore power and saves many miles consumed on the road to warm the battery. This has always worked for me; the car uses shore power to warm the battery as it ramps up the current into the warming battery.

I am doing the same thing. I can actually feel the bootm of the battery getting warm to the touch!!

 

[AmpedRealtor]

No, the car doesn't maintain the battery temperature when plugged in, unless you are actually charging.

Your statement contradicts printed material directly from Tesla:

Note the following sentence: When plugged in, the battery can be charged, cooled, or heated as appropriate, while remaining systems work towards optimization.

 

[strider]

Your statement contradicts printed material directly from Tesla:
Note the following sentence: When plugged in, the battery can be charged, cooled, or heated as appropriate, while remaining systems work towards optimization.

You're both right. What Doug meant is that it will only heat or cool if it gets VERY warm or cold to protect the batteries from damage and it will do that whether the car is plugged in or not as long as it has the energy. If it's not plugged in and it runs out of power it will go into hibernation mode.