Roadster 1.5 in Storage Mode-"Backup Power Supply Service Required"

[djf]

My Roadster has been in storage mode for a couple of months, nicely holding to 30 mi range by charging automatically for a few minutes every day. All was well until today when the VDS showed this:

The EVSE used is the Clipper Creek HCS-40 which is a reliable workhorse which shows a green light, no fault. Used with Henry's reliable Can JR. After changing to the Tesla UMC, the message still appears. The message also still appears after changing the charge mode to Standard.
It seems to charge OK despite the message (my buddy who is my Roadster-minder let it charge in Standard mode for a few minutes back up to 32 mi range and then switched it back to Storage mode).
Does anyone know what this message is all about? The only thing I could find on the forum about "Backup Power Supply" referred to the 12V battery - which to the best of my knowledge is not present in the 1.5s (mine is #243). If the message persists I am going to just change the charge mode to Standard and fill 'er up in order to have some SOC buffer in case this develops into a failure to charge. I'll be back home in a month so a Standard charge would last until I'm home to deal with it.
Bottom line: Can any of you pros tell me about the "Backup Power Supply" on a Roadster 1.5 and shed light on the significance of this message?- Many thanks!

 

[wiztecy]

Since the 1.5 does not have a 12v battery as an auxiliary / backup power supply (APS), it uses sheet 1&2 from the ESS as the backup power source for 12V accessories in the car such as lights.

With that said its a simpler system vs. the 2.x versions with the extra battery that needs replacing every 2 years, however if there's an issue the ESS needs to be dropped, opened, and the APS that's internal to the ESS needs to be troubleshooted.

Reason I say this is that I had an APS failure on my 1.5 a few months after the warranty expired. I had 20/25k on the clock. Tesla repaired the issue by giving me an entirely new/refurbished ESS and did it under "goodwill" even though my warranty had passed. Note that its not recommended to drive a 1.5 if you're having APS errors. Reason being is that the entire vehicle can and will shutdown without any warning due to an APS fault which can surely understand to be quite dangerous, especially if pulling out in traffic.

Are you still under warranty?

 

[spaceballs]

All was well until today when the VDS showed this:
View attachment 103149
...

Odd message, get USB logs see what is voltages on each sheet.

 

[dhrivnak]

This is just a wild guess, but with such low mileage (32) and in storage mode a long time could the pack become unbalanced as the 2 sheets have a low current draw for the 12V system? You may need to perform a full charge or even a range charge to balance the sheets. If the message disappears charging to a full standard charge then this would confirm my suspicion.

 

[wiztecy]

^That's highly probable^ Great suggestion, lets hope that's the case since its a simple and inexpensive fix

When I had my issue that was APS related, I didn't receive any APS nor Backup Battery warnings. Below were my errors:

1) HVAC cable fault
2) DMC HW: ESS Cable Interlock fault
3) BSM: Positive contactor / economizer stuck low
4) BSM: Positive contactor / economizer stuck high

 

[djf]

Thanks and let's hope dhrivnak is right on the money. It's an explanation that is both logical and much hoped for as I'm not quite ready for my $29K new 3.0 battery since my CAC is still in the high 150s! My buddy will be checking on the car on Monday and I'll ask him to do a full Standard charge and then let it sit and balance and see if that doesn't resolve it. Fingers crossed. I'm on the Skeleton Coast in Namibia right now so I can't do much myself. As long as the satellite internet continues to work I'll be in touch with follow-up in a few days. Thanks again.

 

[spaceballs]

Thanks and let's hope dhrivnak is right on the money. It's an explanation that is both logical and much hoped for as I'm not quite ready for my $29K new 3.0 battery since my CAC is still in the high 150s! My buddy will be checking on the car on Monday and I'll ask him to do a full Standard charge and then let it sit and balance and see if that doesn't resolve it. Fingers crossed. I'm on the Skeleton Coast in Namibia right now so I can't do much myself. As long as the satellite internet continues to work I'll be in touch with follow-up in a few days. Thanks again.

I would still get logs so you know brick voltages first before you start your charge.

 

[wiztecy]

I agree with spaceballs about getting the logs to establish a baseline. Note if its really out of balance it may take a few std. mode charges to get things back in balance. Refurbished battery packs are way out of balance since they just sit at a lower (don't know the exact SOC but I presume 40-50%) and it can take months to get those back up to be fully balanced.

By the way I like how the error ID is 420 on your VDS screen! You care close to the Emerald Triangle!

 

[djf]

Good "wild guess," dhrivnak! Did a Range charge and let it balance for an hour and the Warning Message is gone. Not surprising that the pack could get a bit unbalanced after 2.5 months in storage mode. It took it up to 204 Estimated range. Don't have the Ideal range reading but it is probably 220-240. The remanufactured battery has been great with a CAC in the high 150s. I can't get logs now (I'm in West Africa) but I will check them when I get home in 3.5 weeks to see if there is any brick disparity. Thanks to dhrivnak, spaceballs and wiztecy for your guidance. I think this is a good point about storage mode that can be useful to others - it is probably a good idea to do one full charge every month or two to keep the pack balanced. Although I'm not sure which is "worse" - an unbalanced pack in storage or a higher SOC while in storage after balancing the pack. In any event, problem solved!

 

[dhrivnak]

Wonderful and thank you so much for the update.