How to Recondition/Service Your 12V Battery

[dtbaker61]

I agree with Lee - if your modules have not been updated, that should be top priority. I did a test last year and my car was NOT maintaining my LVB when the EVSE was not connected. In February I had the dealer do all the updates and then tested again. I was able to confirm that the car maintained the LVB when not plugged in and off.

Before software updates:

After software updates:

The HVB charging finished at the 1:00 mark. At around the 8:00 mark, I disconnected the charger. You can't really tell when I disconnected the charger because now the car is maintaining the LVB just like it was when connected to the EVSE.

BTW - the LVB was draining so fast because I was monitoring the car with a OBDII scanner and CarScanner. Normally the LVB should never discharge that quickly, unless there is something else draining it.

so, you had the car 'on' with timeout 'off', right ? did you turn off headlights too?
This would mimic LVB maintenance while under normal 'on' background load which is around 200 watts. The ODB reader itself is a tiny load, but the background accessory loads for all the computers, modules, center screen, etc is pretty high.

The trickier maintenance mode for the LVB is when MME is 'sleeping'. background loads *should* be tiny, which means that 'periodic' wakeup checks *should* catch it before it goes too low to wake up. This measurement is hard to catch unless you have an external data logger or leave the hood up and check manually without waking up the MME

...if everything is working properly, it works great.
...if HVBJB is damaged, or modules are stuck way back with bad parameters, maybe not

I had CSP 21p22 updates done while they did my windshield recall, and never had a problem w LVB.

 

[dbsb3233]

OK, that's the first time you mentioned you got a charge fault! That right there will drain the 12V battery if you leave it like that. The charge fault is probably the cause of the 12V going dead.

If you ever get a red ring error, UNPLUG it before it drains the 12V! Red ring errors need to be figured out because they drain 12V batteries. That's going to be an issue with your EVSE or charge port most likely.

I wondered about that because 2 of the 3 times I got the SSN and sub-12.2v readings were after plugging into (different) L2 EVSEs and seeing red lights (for no more than 20 seconds at a time on a few attempts). Both of these were hotel Clipper Creek chargers.

But last Friday we got the SSN just out on a normal drive to the bank, no plug in. And I subsequently L2 charged at home (Grizzl-E) with no problem. And after the car finally restarted at the hotel after the first SSN here (2nd of 3 overall the last week), I then plugged in that same Clipper Creek and it started charging fine.

Maybe my battery has just been teetering on the edge the whole while, and sometimes that would push it over, sometimes not? It's usually been around 12.3-12.4 since I got the car. Maybe it was weakened in transit from the very start?

 

[Mach-Lee]

Maybe my battery has just been teetering on the edge the whole while, and sometimes that would push it over, sometimes not? It's usually been around 12.3-12.4 since I got the car. Maybe it was weakened in transit from the very start?

Yes, that may very well be the case. Let’s replace it and see how things are afterwards.

 

[Shayne]

OK, that's the first time you mentioned you got a charge fault! That right there will drain the 12V battery if you leave it like that. The charge fault is probably the cause of the 12V going dead.

If you ever get a red ring error, UNPLUG it before it drains the 12V! Red ring errors need to be figured out because they drain 12V batteries. That's going to be an issue with your EVSE or charge port most likely.

If it is plugged and the 12V gets too low you always get the red port ring. Messages are not fast enough but this is also a symptom not the cause. His 12V is going down for the count is my guess. Early warning signs. The question is why are 12V going down before there time.

 

[dbsb3233]

Yes, that may very well be the case. Let’s replace it and see how things are afterwards.

So hopefully they get the battery in today and can install it here, and that's good enough to finish the trip and get us home Monday.

But then I'm wondering if I should just trust the car to treat the new battery right, or if I should go ahead and get one of the various battery minders and hook it up every month or something for a day or two? Can those just be hooked right to the car's jump points? If I had to isolate the battery by unhooking the negative cable every time, I don't think I'd bother.

My current car charger at home is an old Sears model I bought in probably 1978.

 

[mkhuffman]

so, you had the car 'on' with timeout 'off', right ? did you turn off headlights too?
This would mimic LVB maintenance while under normal 'on' background load which is around 200 watts. The ODB reader itself is a tiny load, but the background accessory loads for all the computers, modules, center screen, etc is pretty high.

The trickier maintenance mode for the LVB is when MME is 'sleeping'. background loads *should* be tiny, which means that 'periodic' wakeup checks *should* catch it before it goes too low to wake up. This measurement is hard to catch unless you have an external data logger or leave the hood up and check manually without waking up the MME

...if everything is working properly, it works great.
...if HVBJB is damaged, or modules are stuck way back with bad parameters, maybe not

I had CSP 21p22 updates done while they did my windshield recall, and never had a problem w LVB.

The car was off for the testing. The only difference was removing the EVSE and plugging it back in. With the EVSE connected, the LVB was maintained properly. With the EVSE disconnected, it was not until I got the software updates.

As you said, the OBDII scanner creates no significant load unless it is reading things from the car which keeps car systems operating, and draining the LVB. I was using it to monitor the LVB which caused the systems to drain the LVB. Ironic.

 

[mkhuffman]

can't use ODB2 while MME is 'off'.

You can but it drains the LVB. See previous post.

 

[dtbaker61]

You can but it drains the LVB. See previous post.

aha, I guess it depends on your ODB2 unit and what you are using to read it. I use the CarScanner App on phone, connecting via BT, so the MME has to be 'on' for the ODB2 to connect to phone

 

[mkhuffman]

aha, I guess it depends on your ODB2 unit and what you are using to read it. I use the CarScanner App on phone, connecting via BT, so the MME has to be 'on' for the ODB2 to connect to phone

I have a Veepak OBDII Bluetooth reader with CarScanner on an old Android phone, and it works with the car off. I think you have to start the monitoring when the car is on, then turn off the car, and it keeps monitoring even though the car is off.

 

[dtbaker61]

I have a Veepak OBDII Bluetooth reader with CarScanner on an old Android phone, and it works with the car off. I think you have to start the monitoring when the car is on, then turn off the car, and it keeps monitoring even though the car is off.

......ooooooohhhhhhhh, I never tried that!

 

[dbsb3233]

So I picked the car up at the dealer here after had them replace the 12v battery. They said the diagnostics show it as the HVBJB needing replaced, but they said months to get those parts. That sounds like an exaggeration but doesn't matter anyway since we're 1000 miles from home. I just want to try to get the car home and have my dealer there so the HVBJB. And I think a new battery may help improve those odds. Maybe the old one was OK but lots of clues suggest is was getting weak. They also found a TSB available that updated the battery and powertrain modules.

Anyway, I go to start the car to leave the dealership and SSN again, showing 11.5v in my cigarette lighter meter. Aargh. It went into Accessory Mode as usual, but here's what's new... while in Accessory Mode, it kicked in DCDC at 14.8v like normal. My 3 previous SSN starts didn't do that (I don't think). Hopefully that's a result of the TSB, because it meant I could leave it sitting there for a few minutes and let it give the LVB a boost. Which it seemed to do, and started ok.

I'm hoping the 11.5 was just because it was a brand new battery that wasn't fully charged. This was an emergency repair of sorts and I just picked up the battery in the Parts Dept when it came in, so the dealer didn't have time to put it on a charger.

There was a Harbor Freight next door so I ran in and grabbed a 2/8/15A Viking charger (didn't have time to be picky on brands) and leaving the car on AGM Auto charge all night. Hoping that fills it up.

 

[Mach-Lee]

FYI dbsb3233 has an intermittent failure of the precharge circuit/contactor in the HVBJB (P0C78). That's why the car won't always turn on and the 12V battery dies since precharge fails. Main contactors are still okay. Car should drive fine once it is able to get past precharge and power on. It may not power on again after being off. This is a different type of failure than the usual main contactor welding.

The code does make him eligible for HVBJB replacement per TSB 22-2178 since the precharge circuit is also inside the HVBJB.

 

[mkhuffman]

So I picked the car up at the dealer here after had them replace the 12v battery. They said the diagnostics show it as the HVBJB needing replaced, but they said months to get those parts. That sounds like an exaggeration but doesn't matter anyway since we're 1000 miles from home. I just want to try to get the car home and have my dealer there so the HVBJB. And I think a new battery may help improve those odds. Maybe the old one was OK but lots of clues suggest is was getting weak. They also found a TSB available that updated the battery and powertrain modules.

Anyway, I go to start the car to leave the dealership and SSN again, showing 11.5v in my cigarette lighter meter. Aargh. It went into Accessory Mode as usual, but here's what's new... while in Accessory Mode, it kicked in DCDC at 14.8v like normal. My 3 previous SSN starts didn't do that (I don't think). Hopefully that's a result of the TSB, because it meant I could leave it sitting there for a few minutes and let it give the LVB a boost. Which it seemed to do, and started ok.

I'm hoping the 11.5 was just because it was a brand new battery that wasn't fully charged. This was an emergency repair of sorts and I just picked up the battery in the Parts Dept when it came in, so the dealer didn't have time to put it on a charger.

There was a Harbor Freight next door so I ran in and grabbed a 2/8/15A Viking charger (didn't have time to be picky on brands) and leaving the car on AGM Auto charge all night. Hoping that fills it up.

I hope you make it home safely Tim! Sound like you are going to get a new HVBJB, which while painful, I think is good news. I am trying to get mine to fail so I can get a new one. I think the WOT trick is not going to work, however.

 

[dtbaker61]

I hope you make it home safely Tim! Sound like you are going to get a new HVBJB, which while painful, I think is good news. I am trying to get mine to fail so I can get a new one. I think the WOT trick is not going to work, however.

i'd bet that if you:
- drive your battery down to 5% SOC
- find a 150kW DCFC, and charge from 5% to 80%, don't cool down....
- head for the highway and do 'wind sprints' with 5 second accellerations, and full regen cycles
... your HVBJB enclosure internal temp will spike and likely throw SVS and appropriate DTC

If you have a way to watch you ODB2 while driving, display the ChgACtemp and ChgDC temp sensor values, and I'll bet you see 150F or more

 

[mkhuffman]

i'd bet that if you:
- drive your battery down to 5% SOC
- find a 150kW DCFC, and charge from 5% to 80%, don't cool down....
- head for the highway and do 'wind sprints' with 5 second accellerations, and full regen cycles
... your HVBJB enclosure internal temp will spike and likely throw SVS and appropriate DTC

If you have a way to watch you ODB2 while driving, display the ChgACtemp and ChgDC temp sensor values, and I'll bet you see 150F or more

It is much more fun just doing WOTs from zero to 60.

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