Took my desperately dirty 2007 through the car wash today. Chose the wash with the undercarriage rinse (don't recall requesting this previously), put the car in neutral to roll through the wash. About 1.5 minutes into the wash - just after the undercarriage spray - the red triangle lit up on the dash and the main battery icon on the display lit up. It told me to put the car in park to charge the battery immediately. Needless to say I was freaked out at the thought of getting stuck in the car wash and was out of there as soon as I could get free from the track. I was running the A/C on low and radio while going through the wash. Once free, I drove the car for several miles pulsing and lightly braking and it brought the battery back to down from 2 bars and all green. By the end of the day it was all but 2 bars and blue. Did I get water in there somewhere that was causing problems, or is my 12V going out or is the "main" battery the traction battery on the display?
This, plus a 12V battery on its last legs, may be your problem. At any rate it should be investigated before considering HV issues. The A/C runs off the HV battery. And if you were in neutral, even with the ICE running, it wouldn't recharge the HV battery for the A/C use. The 12 V battery has a typical service life of ~4 years. Sustained high or low air temps shorten the life somewhat. There's a good chance that your 12V (nominal) battery has reduced capacity and couldn't be recharged from the HV battery which was being discharged. Do you have a way to measure the 12V battery voltage?
I checked it over the summer using the system check. I had let the car sit over night and tried it first thing in the morning. Since I had forgotten to turn off the A/C when I parked, it dropped pretty quickly and would have been considered as needing replaced based on the voltage reading. However, I discounted it at the time because I had left the A/C running and figured I was getting an invalid reading. I have not rechecked it since that time. I have used this car wash two other times with both A/C and radio on while going through the wash with no issue. On this trip, however, I did have to wait idling for about 5 minutes while they rinsed off the truck in front of me. I did not have to do this in the past and wonder if it has any bearing on my experience today. If I need to replace the 12v battery, I would rather do that now than get stranded later this winter. If it's the traction battery (again I don't know for sure what the "main Battery" icon on the display refers to), I need to get it dealt with while the car has less than 70K miles on it.
As Rokeby points out, the AC runs off of the HV battery. The HV battery also supplies 12V for the radio, dash lights and other electronics and also recharges the 12V battery. When you are in neutral, the HV battery is electrically isolated for safety purposes. So, it cannot be charged by the ICE and it cannot supply 12V for the radio, etc. or recharge the 12V battery. With the AC runnning and not able to be recharged by the ICE, it will discharge rapidly. This would be the reason for the warning lights. Next time, turn your AC off while in the car wash. The radio should be fine for this short period, assuming you have a decent 12V battery.
Good, you're familiar with that procedure. I would recommend that you do it again tomorrow morning. Readings 12-12.3 should be considered marginal. Readings below 12V would indicate a new battery is in order, soonest. Please post-up in the morning so we know what's up. I don't think that the HV/Hybrid system is faulty. I think that the HV battery had gotten so low that it was approaching the HV System Auto-Shutdown, Tow-Me-to-the-Dealer state, but didn't get there... Lucky you!
"I think that the HV battery had gotten so low that it was approaching the HV System Auto-Shutdown, Tow-Me-to-the-Dealer state, but didn't get there... " Yes, lucky me. I did have the presence of mind to shut it all down when I got the warning, but still worried I would not make it out of the wash. Couldn't imagine how they'd get a tow truck in there... I'll recheck tomorrow, but may not get to post until later in the evening due to work.
Your 12V battery is marginal. If you have access to a battery charger, you may wish to charge the battery overnight, then see whether the voltage measurements improve several hours after the charging has ended. (You don't want to measure the voltage immediately after the battery has charged. Instead, wait a few hours for "surface charge" to dissipate.) Regarding being in the carwash with the need to run the air conditioner compressor, perhaps you would be better off leaving the gear selector in D so that the traction battery can be charged by MG1 as needed. Of course you would not want to depress the accelerator pedal while the car is being transported by the carwash machinery. If that strikes you as an unsafe practice, then an alternative would be to find a carwash where the car can be stationary and in P, while the machinery moves back & forth around the car to wash it.
I tend to agree with you. However - this is the first time I have had to wait forever to get into the was and I was idling in D while waiting AND this is the first time I've had the undercarriage wash (which was pretty high pressure). It was just at the end of that wash that the car started buzzing at me. I did notice today that sitting at a light the bars on my battery went from 1 from the top and green to 3 from the top and blue and that was a short light of less that 45 seconds. That alone concerns me, as it doesn't seem like it should be discharging so quickly. Please clarify for me, is the battery on the display (the one with the bars) the traction battery or the 12v?
The state-of-charge display is showing the traction battery status. Sometimes the SOC display will move up and down pretty fast. If you don't have warning lights on, don't worry.
