Jeep Wrangler 4xe Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
712 Posts
Discussion Starter · #1 ·
Another day another cold start except this one was very cold. (but I haven’t started it yet)

Ambient temperature -17c (1f)

Oil Temperature -16c (3f)

HV Battery Temperature -11c (12f)

Battery Coolant was -16c (3f)

Obviously the ICE is going to start but I wanted to test the L1 ability to charge the battery and/or Condition the battery in cold weather.

*One thing to note is that the HV battery temp rose from -11c to -6c while the vehicle was still off and the battery coolant heater was NOT active, this was because I had the vehicle on logging a bunch of parameters before I plugged the Level 1 charger in *

I’ve included a picture which shows the progression of the battery temperature, coolant temp and charging current available to the HV battery. In this case a negative value indicates charge, positive indicates a draw on the battery.



The vehicle sat outside all night. When I parked the vehicle, the HV battery was at 74%. When I went out to run these tests it was still at 74%, meaning the battery conditioning system was not active at all simply using the HV battery and nothing else.

I took a log of all the temperatures and then plugged in the L1 charger, this is where things get really interesting.

As soon as I connected the L1 Charger the battery coolant heater came to life and drew nearly maximum power, It took 18.75 amps from the battery, and I’ve logged at high as 22 amps running in electric mode. The Level 1 charger isn’t capable of delivering that much power, so the Level 1 charger when plugging a 4xe in during very cold weather is simply the trigger to start the battery coolant heater up. During this time the battery coolant heater ran at 18.75 amps until the coolant heater got in the mid 60s Celsius (149f) and then it dropped it’s current down.

During the time the battery coolant heater was drawing lots of power the HV battery DROPPED in SOC it was at 73% and when I was done logging these tests it was at 69%. However after about 12 minutes when the battery coolant reached the mid 60s temperature the coolant heater dropped it’s output and the L1 charger began to charge the HV battery.

As soon as I turned the vehicle off the battery coolant heater turned itself off (I can only log about 20 seconds after the vehicle ignition is turned off)

I then left the vehicle for about 40 minutes and went back out to log everything again.

Ambient temp showed -14c (6F)

Oil temperature -15c (5f)

HV battery was back to 74%

HV battery temp was now 7c (44f)

Battey coolant was 39c (102f)



As soon as I put the vehicle to run (without starting the vehicle)

Exact same behavior, coolant heater drew 18amps got the coolant up to the mid 60s Celsius once it reached mid 60’s the battery coolant heater dropped its output and the L1 charger was able to keep charging the battery.

Thoughts & Discussion

  • I haven’t reached the point where the battery tried to condition itself, and that might never happen. I need to get the vehicle parked long enough when the temperatures allow the HV battery to drop below -30c, I suspect that might actually be quite difficult to do.
  • The level 1 charger triggers the battery coolant heater to heat the battery coolant to mid 60’s Celsius when the vehicle is in the “run” position.
  • The Level 1 charger is not actively warming the battery during charging, my guess is it won't start until it needs to keep the battery above -30c
  • If the HV battery assists the battery coolant heater in quickly warming up the coolant, what happens if, you park the vehicle with the HV battery at <1% it, the battery gets colder than -30c and the vehicle is plugged in to a L1 charger, the L1 charger would then be the only source to warm the battery and that would take FOREVER to heat up. Since the manual states the vehicle won’t start with the battery below -30c the ICE wouldn’t start either, which obviously would heat the battery coolant. In this extreme example I could see a 4xe needing to be towed to a warm area to get warmed up before being able to be started. Easy solution don’t let that situation happen and always keep a HV battery charge. I think I’ll test this out but without the extreme temperature. I’ll drain the HV battery completely leave it outside in the cold and then plug In the vehicle to a L1 charger and see what happens.


Other than a few interesting situations that I’m going to test, once it gets into the extreme cold temperatures in a few months I think I’ve thoroughly figured out how the 4xe system works in the cold temps, next is to pray for FORM and work on those parameters.
 

·
Registered
Joined
·
712 Posts
Discussion Starter · #3 ·
I'm fairly certain it will, I haven't got to the -30c temps yet. Having said that, the battery is located inside the vehicle and most times when parked it will be somewhat warmed up. It would take a lot more than say 12 hours for the battery to get below the -30c threshold where it in theory doesn't allow the vehicle to start.
 

·
Registered
Joined
·
83 Posts
This is strange for me. Most lithium batteries that I know state they should not be charged if the temp is below +5 C. I would think it would warm them up more when you are running the vehicle, either via ICE or plug.
 

·
Registered
Joined
·
2 Posts
So do you think it is good to remote start car about 30 minutes before you want to go for a drive while it is plugged in and then let it charge for 15 minutes after the remote start is over? I am thinking the battery will be warmer and give better range when it is very cold.
 

·
Registered
Joined
·
712 Posts
Discussion Starter · #6 ·
Remote start and letting it run for 30 mins is excessive, the battery coolant heater heats the coolant up extremely quickly, at most maybe 10 minutes is all that is needed. The battery isn't losing range because of the cold, it's losing range because it's running the battery coolant heater and the HVAC system when it's colder out
 

·
Registered
Joined
·
3,062 Posts
So do you think it is good to remote start car about 30 minutes before you want to go for a drive while it is plugged in and then let it charge for 15 minutes after the remote start is over? I am thinking the battery will be warmer and give better range when it is very cold.
If you usually leave at the same time every day, you might try adjusting your charging schedule so it finishes charging right before you leave.
 
1 - 7 of 7 Posts
Top