Power Needs of Battery Management System?

[EKS89]

My Chevy Spark 2015 has been exhibiting the same problem (.7kW continuous draw at full charge). HOWEVER I think I might have caused it myself and I think I know where the issue is. These are simply hunches.

In short I installed a 12" sub-woofer. The install was successful after a few missteps. The worst of which was attempting to plug in the remote wire to the instrument panel fuse box. I had neglected to remove the negative lead to the battery and I sparked the 15A fuse that I was attempting to plug into the fuse box along with the remote wire lead. This ended up blowing the fuse. I'm fairly certain is also hurt the Logic Mode Run Relay in the instrument panel fuse box. Part No. 13500116, A green "Latching" relay. I don't have access to service manuals so I'm not sure what this does. I suspect it has something to do with the TMS.

I went to the dealership and waited and hour and paid $70 to have them tell me the 12V battery is OK. I left very frustrated. I've scheduled an appt at a local vehicle electronics shop during a day their "Auto Computer Specialist" will be checking out my vehicle.

See the imgur album for some details: https://imgur.com/gallery/TyL3ZEo


Some other symptoms possibly related or not:

• 
  My vehicle drawing up to 4kW continuously while stopped. This is typically on a hot day where it was not plugged in prior to driving. It typically destroys the "efficiency" on the history chart only to go back to normal after some amount of driving.
  
  The vehicle is re-adjusting the efficiency calculations as shown in the imgur album with a large spike of some unknown mileage/kW only to quickly go back to much lower. This alters the range calculation. I'm not entirely sure if this has to do with me sparking the instrument panel, or the fact that I put some pretty bulky tires (205s) on the entire vehicle. Yes I recognize that hurts efficiency, but it's the efficiency "swings" that concern me not the approximately 10 miles of range I lost by putting on thicker tires.
  
  I also seem to believe that the music gets significantly louder at during heavy acceleration (80kW+ output for more than 3s)

I welcome anyone to offer any advice you might have. I also have been having a devil of a time trying to locate a replacement relay 13500116 so any help with that would also be appreciated. The only retailer I've located is alibaba and I really don't want to wait 2-3 weeks for the replacement. I'll be monitoring this post to respond to any questions anyone might have. I might also consider creating my own post so as not to hijack this one.

 

[NORTON]

>My Chevy Spark 2015 has been exhibiting the same problem (.7kW continuous draw at full charge). ...

>>I went to the dealership and waited and hour and paid $70 to have them tell me the 12V battery is OK. I left very frustrated. I've scheduled an appt at a local vehicle electronics shop during a day their "Auto Computer Specialist" will be checking out my vehicle.

>>>Some other symptoms possibly related or not: My vehicle drawing up to 4kW continuously while stopped. This is typically on a hot day where it was not plugged in prior to driving. ....The vehicle is re-adjusting the efficiency calculations as shown ....

I welcome anyone to offer any advice you might have. ..

>Daily, I'll see .6-.7kW of TMS and/or BMS (Cell Balancing) for ~15-20 minutes after I get the charge complete txt msg from the car via Onstar.
~20 minutes later I'll get the txt msg from Chargepoint saying that the 'car is drawing little power and probably done charging'.
On my Chargepoint page I see the .6-.7kW rate during the end after the 3.3kW charge rate.
If you don't allow the car to top up and then stay for the TMS/BMS "house cleaning", it will take longer to Balance the Cells when you finally do.

>>Yep, they're dogs. $70 to hang a handheld battery analyser on it for less than a minute. I did an Aviation-style Capacity Check on my 12V that took 90 minutes.
My 4 year old 12V tested like a brand new battery. These batteries don't do much. But if the car sat for say 9 months on a dealer lot and the battery got discharged deeply and sat like that for a long time, it could be damaged and have a shorter life.

What do you expect from an "Auto Computer Specialist"? Has this guy been trained on Spark EV's or any EV for that matter?

>>>Sounds like normal TMS trying to get the battery back to a happy temp range. Not the ideal way to drive an EV. Go easy if the pack is hot and sucking up TMS power. This should all be display in the 'Energy Page' after the drive.

Top it up and let it sit for TMS/BMS at least once a week. Keep a log of data from the Energy Page.

 

[EKS89]

Could you elaborate on what the "energy page" is and how to navigate to it? Specifically I'm curious how you monitor the battery temperature. I can only see power uses and readouts, not temps.

I plug my vehicle in all the time. My workplace has L2 charging as well as my home, so the battery should be protected from the elements. It's just using far more power than it needs at the moment, and that will add up over time.

As per the auto computer specialist I doubt they have any specialized training in EV vehicles, but people have to start somewhere I guess. The dealership was next to no help and I've got nowhere to turn. I live in central florida and I haven't found any specialized EV shops in my area. What i expect from them is a much more in depth diagnostic than what the dealership performed. Hopefully something comes up that can be fixed.

 

[NORTON]

I'm talking about the Leaf button - Energy usage page. I can't remember the exact title.

To get detailed temps you can get an OBD-II to Bluetooth adapter and the Torque Pro app for an android.
I have not been able to get the two different adapters I have to work with the Spark. They worked with my Volt and other cars,,, so I can't help there.
I decided I can live with the stock car and not display everything there is to display...
But if you are troubleshooting, I can see how you'd want all this data.

You stated this: My vehicle drawing up to 4kW continuously while stopped. This is typically on a hot day where it was not plugged in prior to driving.
This is not proper behavior if the car was actually plugged in because TMS should have had the pack at the proper temp range.
Was the AC trying to cool the Hot Soaked car?
With Climate Control off the car should not be consuming more than 1kW while in D and stopped.

Take pictures. Keep a log.

Contact GM Customer Service. Your Spark EV still has a Powertrain Warranty, correct?
Maybe find a Chevy Dealer in your area that is not afraid to work on Volts, Bolts, and Spark EV's. Some seem to hate them.....

I think you may be throwing money away asking some outside person to look at your car.

Also, I have a 300 watt Fosgate sub mono amp and a matching driver in an enclosure I built. I have not installed it yet. I don't follow you at all on tapping into a power source and a 'latching relay'. My amp auto powers up when there is input on the speaker leads. I'm just going to tap in near the battery with a fused 8ga. wire to the amp.

 

[MrDRMorgan]

My Chevy Spark 2015 has been exhibiting the same problem (.7kW continuous draw at full charge). HOWEVER I think I might have caused it myself and I think I know where the issue is. These are simply hunches.

In short I installed a 12" sub-woofer. The install was successful after a few missteps. The worst of which was attempting to plug in the remote wire to the instrument panel fuse box. I had neglected to remove the negative lead to the battery and I sparked the 15A fuse that I was attempting to plug into the fuse box along with the remote wire lead. This ended up blowing the fuse. I'm fairly certain is also hurt the Logic Mode Run Relay in the instrument panel fuse box. Part No. 13500116, A green "Latching" relay. I don't have access to service manuals so I'm not sure what this does. I suspect it has something to do with the TMS.

I went to the dealership and waited and hour and paid $70 to have them tell me the 12V battery is OK. I left very frustrated. I've scheduled an appt at a local vehicle electronics shop during a day their "Auto Computer Specialist" will be checking out my vehicle.

See the imgur album for some details: https://imgur.com/gallery/TyL3ZEo


Some other symptoms possibly related or not:

• 
  My vehicle drawing up to 4kW continuously while stopped. This is typically on a hot day where it was not plugged in prior to driving. It typically destroys the "efficiency" on the history chart only to go back to normal after some amount of driving.
  
  The vehicle is re-adjusting the efficiency calculations as shown in the imgur album with a large spike of some unknown mileage/kW only to quickly go back to much lower. This alters the range calculation. I'm not entirely sure if this has to do with me sparking the instrument panel, or the fact that I put some pretty bulky tires (205s) on the entire vehicle. Yes I recognize that hurts efficiency, but it's the efficiency "swings" that concern me not the approximately 10 miles of range I lost by putting on thicker tires.
  
  I also seem to believe that the music gets significantly louder at during heavy acceleration (80kW+ output for more than 3s)

I welcome anyone to offer any advice you might have. I also have been having a devil of a time trying to locate a replacement relay 13500116 so any help with that would also be appreciated. The only retailer I've located is alibaba and I really don't want to wait 2-3 weeks for the replacement. I'll be monitoring this post to respond to any questions anyone might have. I might also consider creating my own post so as not to hijack this one.

Just a guess but 4 kWh sounds like the AC is in operation. When I first turn on my AC, I see about 4 kWh is being drawn while the car is not in gear or in motion.

 

[EKS89]

So I've become a little obsessive over this vehicle. The "what I'm about to make into a very long story" short is that much like the original person who posted this thread my vehicle has largely returned to normal.

The only thing it is doing still is not shutting down the battery cooling functions during a charge. This is likely due to the JuiceBox forcing the vehicle to draw power in some way. The most likely time for this to occur is when I plug in the car immediately after driving it home, while having the charge profile immediate and the JuiceBox app unrestricted in how much energy it's allowed to feed the vehicle. When I restrict the power allowed to go to the vehicle through the JuiceBox application the car is perfectly happy and functions as expected. When I set the charge to occur in the middle of the night I get good charge profiles (i.e. 20-40min of battery cooling post charge and then full shutdown) even if the JuiceBox app is unrestricted. Throughout this adjustment period the car has never once alerted me to it needing to turn on the battery conditioning functions while parked in the sun. I've checked the battery temps with and OBDII reader and they all seem nominal. The hottest I've seen is 32C after doing 25 miles highway driving, and the coolant temperature was 27C during that time so I know it wasn't getting too warm.

MrDrMorgan was spot on with the 4kW at idle being a heat soaked heater core from sitting in the sun. 10 min of remote start while plugged in drastically reduces the vehicles power needs during the first 5 mins of driving and in effect extends it's range because of the increased efficiency.

The final verdict on the cause of my problems in my opinion is that the tire was rubbing on the metal plate underneath the shock spring. This was causing increased resistance in a very odd profile for the car so the vehicle was swinging the efficiency from very low to very high. Since the 1000 miles I've driven the swings are gone and when driving carefully I can get a 5.1 mi/kWh efficiency which is as good if not better than what I was getting with stock tires.

I've harped at Chevy's customer service line a few times during all of this. I wanted to get my battery capacity bench-marked by the dealership in my area but I've decided it's not worth it. The OBDII says I have 14.33 kWhs of capacity. The LEAF button calculation I did after using 80% of the battery gives 15 kWhs. I found a pic of the LEAF button page before I put the new tires on and I was seeing 15.2 kWhs capacity, but that had only been used at 44%. All in all I'm not really worried about the .2kWh dip in capacity and it seems that the dealership will do a capacity test of it's own over 24hrs to determine whether battery should be replaced under warranty at a cost of $150 a test. I will not be paying that more than once after I feel confident from readings of the OBDII and dashboard calculations that the capacity is far lower than the 35% trigger for the warranty replacement. My net cost on this vehicle used was so low I doubt I'll even care about doing a warranty replacement when it comes time to need it. I would hope there might be some aftermarket options for higher capacity batteries by then, but I recognize that's probably a pipe dream and I'll just need to purchase a new vehicle once the Spark isn't fit to use for my commute anymore. The car ate about 400 kWhs during this period for about $50 of cost for energy. That was for a 15 mile commute as I was charging at work after my leg there was complete. I expect this cost to drop significantly now that I know how best to restrict the vehicle's energy usage without it complaining.

Final note: if you make a change to the vehicle or your commute I would strongly suggest resetting the "trip odometer." It seems like the vehicle stores and uses all of the data the trip odometer has seen in order to calculate the approx range of the vehicle. My average mi/kWh went from 4.0 to 4.4 just by deleting the data from the adjustment period of the new tires.

 

[NORTON]

So I've become a little obsessive over this vehicle...... My average mi/kWh went from 4.0 to 4.4 just by deleting the data from the adjustment period of the new tires.

Ya'think?
I just drive it for free most of the year and plug in at home during the dead of winter. Cheap to operate car !!

Also, that 4.4mi/kWh is a default reading when it is reset. All of them do this.