It was bought in February, 2009 with 6,304 miles on the clock. Prior to the purchase, the car had been sitting unused somewhere for 7 months. I know this because a service was carried out in July, 2008 when the mileage was 6,219.
The Honda refused to start earlier today and, when the RAC came out to take a look, they diagnosed a battery problem - the cells were apparently fucked. My SO, who was in the car at the time, had to buy a new one.
I am curious to know what deleterious impact, if any, does leaving a car unused for 7 months have on the battery.
Most cars have a small drain on their electrical system even when they are turn off. Some things need a tiny bit of power, like the radio so that it doesn’t lose its setting, and the engine computer, also so it doesn’t lose its settings. Most cars can sit somewhere between one and three months before the battery will get too far drained and you run into trouble.
Lead acid batteries don’t like to be fully discharged, or they chemically self destruct. If you aren’t using the car for more than a couple of weeks, it’s a good idea to disconnect the battery so that it doesn’t die, or periodically attach the battery to a trickle charger so that it won’t go dead.
If a battery sits perfectly still for long periods of time, the electrolyte can also stratify. You end up with different density layers through the battery, and this causes small currents to circulate through the battery. This ends up sulfating the battery plates and ruins the battery.
Note that on some cars, disconnecting the battery will trigger the anti-theft device in the car, or may require the engine computer to be reset. If you have one of these types of cars and you are letting it sit for a while, you may need to follow some special procedures or you won’t be able to start the car again when you reconnect the battery.
Also, as the car was serviced on 11 August 2009, and the battery given the all clear at that time, is it likely that the cells have only deteriorated to a state of uselessness between then and now, i.e. should a problem have been picked up during the service?
My 91 Mustang with a Ford Motorcraft Silver battery routinely sits between 1 and 2 months at a time (garage queen.) Not good I know, but my battery is at least 5 or 6 years old and I’m surprised that a new Honda battery would be unchargable after sitting 7 months. Could have just been a marginal battery when it was made.
Exactly what was done? “Serviced” usually means routine maintenance, which seldom goes beyond a quick visual inspection as far as the battery is concerned. Unless specific tests were done on the battery, the “all clear” was nigh meaningless.
The voltage is the rest voltage, which in this case tells us the battery had the correct charge. It would take further tests with specialized equipment – which I really doubt were done – to assess how well the battery could hold a charge. I don’t know what the “B/M” and “O/L” might mean.
It appears what was done was a superficial check that would only reveal certain fairly obvious problems, and did not address the issue with this battery.
And on top of that, lead acid batteries that aren’t shorted out can be reconditioned with electronic chargers. I’ve seen aviation batteries brought back to life this way and they’re basically identical to car batteries in concept (more like the older car battery with the plates spaced farther apart).
Lead acid batteries can last a long time if kept fully charged. They don’t like to be discharged and can be damaged if kept discharged for a long time.
12.53v is a little low imo. I like my batteries to be near 12.7v. They probably have a minimum spec of 12.5 so it just barely passed. If they didnt know the car had been stored for a long time there was probably no reason for them to be suspicious of 12.53v.
Batteries can fail suddenly with no warning. The plates can get “growths” on them and be perfectly fine until one day the two plates touch and then that cell is no good. So good one day and total failure the next.
battery went bad. Cell failure is usually the case when you go from 100% to 0%. A battery that is in the process of dying will usually die slowly (get progressively harder to start, for example.)
Somebody left the headlights on overnight. Very common in new cars where you don’t have good habits yet.