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| Murphy’s Law with my OBD2 reader |
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| tom66:
Yesterday my hybrid Golf GTE flagged an error. This car is a bastion of reliability, mostly due to the Germans -- sorry that was sarcastic. It is throwing up a warning about the 12V battery needing service. I checked the battery with my diagnostics dongle and it reports 12Ah usable capacity out of 44Ah total. And the voltage drops to 11.67V without any load. About 14.5V while charging. (So perhaps I shouldn't be so quick to blame the Germans. The battery is made in Spain.) It seems to be an ordinary flooded lead acid battery so, I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur? Car still runs and drives fine and no other obvious errors are present but I did get one occasion at a roundabout where I pushed the 'go' pedal and the car took about 2 seconds to select the gear. I know the dual clutch gearboxes in these cars do depend on the 12V at significant current to actuate properly so I wonder if that was a sign. I wonder if EV batteries wear a bit quicker because they don't get starter cycles like a regular car. Certainly Tesla had a lot of problems with their earlier 12V systems. It might just be a limitation of lead acid batteries used here and a reason more manufacturers are using LiFePO4 or Li-Ion for the 12V system. |
| sokoloff:
If it's over 4 years old and measuring that low, I'd replace it without any further diagnostics. When a gasoline car is "running" (which is ambiguous/complicated for a hybrid), the battery shouldn't have much effect on current supply for low voltage systems. With a hybrid, I can't draw as firm a conclusion, other than "well, I guess you'll find out when you replace the battery". |
| PlainName:
--- Quote --- I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur? --- End quote --- Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather. |
| AVGresponding:
--- Quote from: PlainName on February 09, 2023, 08:17:31 pm --- --- Quote --- I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur? --- End quote --- Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather. --- End quote --- Presumably because it's an EV... |
| tom66:
--- Quote from: PlainName on February 09, 2023, 08:17:31 pm --- --- Quote --- I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur? --- End quote --- Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather. --- End quote --- I think I'm agreed, it needs to be replaced. That said, all the 12V on these cars has to do is get the contactors to actuate in the main battery pack, then the DC-DC runs everything from that for normal use. In that sense, you can probably 'start' the car on as little as 10V across the battery... it only needs to supply about 10A (computer power, contactors, etc.) for a few seconds. |
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