battery question

catchthespirit · Post by **catchthespirit** » 19 Aug 2006, 11:01

I have a '91 740. Everything has been working great. This week, I went on vacation in a different car, so as a result, the 740 sat in the driveway for about five days.

Today when I tried to start it up, it didn't, and it seems to be a battery failure. Is this caused just from the car sitting for a few days, without being driven? I haven't left lights or the radio on, so I have no idea what else would cause this. If I ever have to leave the car again for a few days, does this put the battery at risk again? Thanks.

Post by **billofdurham** » 19 Aug 2006, 11:55

How old is the battery and what was its state of charge when you left it? Do you do mostly short start/stop runs or does it get a good run to recharge it regularly?

Over a period of 5 days a well charged battery should be OK. One of the main causes of this type of problem is a light left on that is not easily seen eg interior, engine bay and trunk. Are they all switching off when the doors etc are closed?

Bill.

catchthespirit · Post by **catchthespirit** » 19 Aug 2006, 15:39

Hi, thanks for replying. I'm not really sure about the state of the battery. I bought the car last October and it's been fine until now...I'm not sure how old this battery is and how much juice is left. Someone told me I could go to Napa and have them do a load test on it...?

cosmiclobster · Post by **cosmiclobster** » 19 Aug 2006, 15:42

A car battery should easily last 2 or 3 weeks with no problems.
Over the years I have had 2 or 3 batteries die with no apparent reason.

If you have a voltmeter, measure the battery voltage. If it is any less then 12.6 volts, then it is toast (beyond repair).

Get a jump and measure the voltage while your engine is running. If it goes up to between 13.2 and 14.3 volts, then the charging system is O.K. and you just need to replace the battery.

CarVolvo · Post by **CarVolvo** » 07 Sep 2006, 22:32

Taking the battery in to do a load and capacity test should be your first step.. lots of time they will do this free.. also ask them to charge it for you.

Then connect the battery and see if it works, if it continues not to work after this then obviously something is draining it. Perhaps as the previous poster suggested try checking the glove compartment light or the trunk or hood (bonnet) lights are on if so equiped.

Are all the electrical parts of the car working? lights, radio etc? or is something grounding and causing the battery discharge?

My 240 sat around for more than a month in cold winter temperatures and always had enough juice to start from the battery, so something or the battery needs inspection and fixing.