Specifics about the TMS system?

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tkdbrusco

Member
Joined
Nov 20, 2017
Messages
19
Can anyone shed some light on the specifics of the TMS system on the FFE? I just got a 2017 FFE and am a long time Leaf owner, so I know a bit about EVs, but wanted to know some more detail about the TMS system. Some specific questions are listed below.

1. I know the FFE has one, but I'm not sure the parameters of it. At what point will it kick in to cool down the pack? And does the car need to be plugged in for this to occur? If I am in a parking lot on a hot day, will it start pumping coolant to cool the battery down? Furthermore, with this train the 12v or the high voltage pack?

2. Regarding the TMS heating the pack for more efficient use in the winter, I'm assuming this only occurs when plugged in? The pack doesn't draw from itself in order to warm itself up?

Thanks,
Jonathan
 
Here are some details, although I don't think it mentions temperature points.

https://www.dropbox.com/s/6vpsdoelmahhrof/Lesson-3-Cooling-System.pdf?dl=0
 
Anecdote, when perusing FORScan Lite, I have rarely seen battery coolant temps higher than 77F or so... think that might be a regulation point of sorts.
 
It's been years ago (2014) and I don't remember where I got the data from but on the early FFE's and I would think it is still applicable to the new FFE's the TMS regulated the battery temp when the battery temp dropped below 50F or rose above 95F.

1) TMS kicks in to cool the battery when the battery temp exceeds 95F. Yes if the car is off it needs to be plugged in for the TMS to function. I'm not sure about the TMS but for preconditioning (GO times) it needs to be plugged into L2 (240V). At least in theory the TMS heater 900W can be supplied by L1 which can supply up to 1440W. The TMS will also function when the car is "on." It does not function when the car is off and unplugged so if your car is in a parking lot on a hot day it will not cool the battery. I don't know if I believe it but I have read the battery is pretty well insulated and it's temperature lags high ambient temperatures by many many hours.

2)A cold lithium battery has severely reduced capacity. To the point it could in theory impact driveability if the battery is cold soaked to a very low temperature. I emphasize "in theory" as I've never heard anyone complain about this and my FFE lives in a warm garage so I wouldn't know from experience. Anyway that "lost" capacity comes back once the battery is warmed. I cannot say with 100% certainty that the heaters do come on when the battery is below 50F but I believe they do based on high winter Wh/mi numbers (when not using any cabin heat). If I am remembering correctly the battery heater is pretty small at only 900W (3x 300W heating elements). I don't know whether or not it does but I would assume it would also use the waste heat from the inverter/motor to also heat the battery once you are rolling. At least with the 23kWh battery FFEs winter weather can reduce your range by about 40%! Not sure how this will translate to the '17s with the larger batteries.

As a side note I did let my FFE sit outside for about a month and a half in the cold (mid Nov-end of Dec.). When I started it up the HV battery was at the same SOC as when I had shut it off. Since the manual says to unhook the battery if parked for > 30 days I was pleasantly surprised my 12V was not dead.
 
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