Roadster Battery Coolant

I would call the local Tesla service center and see what they recommend.

Hey, Fluke!

I just ran into this, myself. See this thread: http://www.teslamotorsclub.com/showthread.php/23223-The-Mystery-of-the-Vanishing-Coolant

I also had no luck finding Havoline XLC-PG. I ended up asking at the Service Center and was told that they're using Peak/Sierra Propylene Glycol. While I was there, they topped it up, and ran a pressure check, but couldn't find a leak.

The level stayed steady for almost a week, then it was suddenly low again. I went back to the Service Center and scheduled an appointment to leave the Roadster with them a few days (they can't fit me in until late next week), and they gave me a jug of coolant to hold me over.

Here's the surprise - when I got home, I found that the coolant level was full again. Since then, I've found it very low some mornings, but full again in the afternoon. Looks like this is just thermal expansion of the coolant, and not a leak. The weather here in Maryland has been all over the place the past few weeks, with a few days near freezing, then back up in the 70's, and now coming down again.

I'd say we've found something that hasn't been mentioned here before (at least I haven't been able to find it) - if the ambient temperature is near or below freezing, wait until the battery has warmed up a bit before checking the coolant level.

Let me know what you find.

I can't seem to find Peak Sierra anywhere here in the Bay Area. I am a bit low on the coolant - my CPO Roadster had a defective reservoir which they replaced but did not top it off.
Will Prestone PG work just as well?

I found it at a Tractor Supply store near me: http://www.tractorsupply.com/en/store/sierrareg;-automotive-antifreeze-1-gal

asgard said:

I can't seem to find Peak Sierra anywhere here in the Bay Area. I am a bit low on the coolant - my CPO Roadster had a defective reservoir which they replaced but did not top it off.
Will Prestone PG work just as well?

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I'd call Tesla service and arrange for a quickie top-off. Like Curt reported earlier, I've noticed over the years that my Roadster's coolant level varies a lot, so I'd be concerned about over-filling.

Hello,

Does anyone know if this coolant is the same fluid that is used to preheat the car as well, or is the only preheating done by the battery charging?

asgard said:

I can't seem to find Peak Sierra anywhere here in the Bay Area. I am a bit low on the coolant - my CPO Roadster had a defective reservoir which they replaced but did not top it off.
Will Prestone PG work just as well?

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asgard or other interested folks:
Did you ever find out whether Prestone PG is OK? I am unable to get either Peak Sierra or Halvoline XLC-PG anywhere in the Bay Area. The Peak company website says two Tractor Supply stores carry it in the North Bay (farm country!), but both say "haven't seen it for 2 years - they're not shipping to CA anymore." Interesting that such a "green", environmentally sound product would be banned from CA retail stores, though I gather the Tesla Service Centers can still get it.
Bottom line: What's a CA Roadster owner to do for an occasional top-off short of driving by the Service Center?

There is nothing special about the cooling system. The battery cooling tubes are aluminum, as are the heater and A/C heat exchanger. Any propylene glycol antifreeze will work. Ethylene glycol cools better but is toxic and doesn't fit the "green" theme, which is probably why Tesla recommends propylene glycol.

Hopefully not hijacking, but I was about to post on this. I'm in Louisiana so my pump is running 24/7 even with the occasional OVMS cooldown. Battery pack seems to stay between 95 and 110F. Since I purchased the car back in April, I've noticed some small accumulation of coolant by the passenger rear wheel. In the past month or so I've now topped my reservoir off twice, each time with about 6-8oz of distilled water (I was told the Peak coolant needs to be mixed 50/50 with water anyway so this is OK for diagnostics).

My coolant is VERY foamy so I'm trying to determine if the accumulation is a result of foam slowing push through the reservoir overflow or if I have a crack in the reservoir (or something else).

Going to order a gallon of Peak Sierra from the local NAPA today.

Any thoughts?

Good news is that my NAPA can get Peak Sierra. Bad news is that it only comes in a case of 6. Prestone Low Tox is looking good. Might need to drink a cup of each to see if I get equally sick.

Safety data sheet for Prestone Low Tox AF555: http://apkgroup.com/msds/English/Prestone%20%28271%29/70052%2810-23-2013%29.pdf
Safety data sheet for Peak Sierra: http://www.sfm.state.or.us/cr2k_subdb/MSDS/SIERRA_ANTIFREEZE_COOLANT.PDF

You need to have the pump off for around a half hour to let the foam subside and then check the level. If it foams up again there is air in the system. Keep cycling the pump on and off (Inhibit the APS in the service menu to turn it off) until the foam is gone. I don't understand Tesla's reasoning behind letting the pump run continually without the A/C on, as the pump itself creates more heat in the system than is dissipated to the air when temps get over 90. I turn off the APS every night when my garage gets too hot.

MLAUTO said:

You need to have the pump off for around a half hour to let the foam subside and then check the level. If it foams up again there is air in the system. Keep cycling the pump on and off (Inhibit the APS in the service menu to turn it off) until the foam is gone. I don't understand Tesla's reasoning behind letting the pump run continually without the A/C on, as the pump itself creates more heat in the system than is dissipated to the air when temps get over 90. I turn off the APS every night when my garage gets too hot.

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I was under the impression that without circulation, you could have heat build up deep in the battery pack, and was guessing that circulating hot water was better than heat concentrated in pockets in the pack. Again, that's me speculating.

I do appreciate the method to shut the pump off so I can get a decent level reading on the reservoir!

Whoa. Hadn't even seen this thread - but received a pm from another Roadster owner, very concerned about what he was reading:

Bad, very bad idea. He's shutting down the APS / Whole power system of the Roadster when it sits overnight and temps are above 90F. He asked a question of why is Tesla running the pump all the time... Well one thing I can say is that lots of investigation was put in there by Tesla to find the safest, least annoying way to manage that battery pack and one of the reasons was to prevent thermal runaway fires of the battery!!! Now he's shutting down the whole system, coolant can't flow and distribute the heat, heat pockets on bricks now will build up, the HVAC system can't run when it needs to if temps get above 104F, and essentially this is a ticking time bomb!

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I totally agree.

Thanks Bonnie. Do you think it's OK to shut it off for 30 minutes to get a decent reading on my reservoir? I hope to see a Ranger soon and the plan is to flush & pressure check. I also caved and purchased the full case of Peak Sierra. Guess I'll go through it eventually.

So a little more from my behind-the-scenes friend :

There's a huge thread talking about this when Martin was working on the Roadster. It use to run 24/7. But they investigated it further and discovered they can run it when temps are high where you really need it to run, and not when temps are low. I consider 90F to be the upper end. And the HVAC is instructed to kick on at 40C/104F no matter what.
This is the *main* reason why Tesla does not want people mucking around with stuff behind the scenes like Diags.

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Here's the archived thread, with full discussion, about the water pump: That Little Water Pump

And the HVAC is instructed to kick on at 40C/104F no matter what.

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Hmm, I learned something today. I don't think I've ever experienced the HVAC turning on when the car was off. I wish it would turn on at a lower temperature to really cool the pack rather than just running the pump without eliminating the heat.