i have a customers car that has been to the dealership twice for battery dies overnight, both time no fix from the dealership owner said i am there last hope,

symptoms: car will have dead battry in the morning sometimes for weeks

and sometimes the car will start up fine for a week

battery has been replaced

i noticed that the rear speaker to the car are not working. with little more investigation i found a factory amp in the trunk, tested and i do have power to it,althou the amp light does not iluminate, i also noticed that the power comes straight from the batt with a fusable link,

i unhooked it and noticed a pretty good arc from the battery (with ignition off) it still apears to be taking juice.

i hooked it up and the battery had not drained overnight,took it for a ride down the bumpiest road i could find left it overnight and once again it started right up

now does anybody have any suggestions as to where to start looking for this mystery current draw overnight ?

thanks

kurt warren

k w auto

I have heard of several instances of the amps failing in 760s and 780s and causing current drain from the battery when "off." The only fix is a new amp, which is not all that expensive.

Kurt --

I helped a friend (one man Volvo-only shop) solve an overnight-dead-battery on a 760. We first checked the glove box light, trunk light, and under hood light. All were off; in fact we unhooked 'em.

Stereo and alarm worked fine. We disconnected them, too.

The courtesy light in the mirror (passenger side visor) sometimes remained on, but was barely visible. It depended either on the angle of the visor or the size of the potholes, for usually the light was off—and the battery was fine.

Don Foster (near Cape Cod, MA)

I just had a problem with my '84 760 battery going dead after sitting for a short period of time. It turned out to be the glove compartment light didn't shut off when the door was closed.

I tested for the current draw by disconnecting the negative battery cable and connecting a small circuit test lamp between the negative battery terminal and the negative battery cable clamp. If the lamp lights up there is a current draw that will drain the battery. I usually check the trunk, dome, map reading, and or glove compartment lights first, to make sure they are off. Then I procede to remove one fuse at a time until the lamp goes out. See what is powered off that circuit and check that device for a power draw by disconnecting its power connection and rechecking the test lamp.

Over the years I have been very fortunate using this method to find a power drain problem. Most of the time it has turned out to be a light that is not turning off.

Good luck with the Volvo!

Did you notice the arc when you disconnected the power to the rear amp, or when you REconnected it? Audio power amps have larger capacitors in them to filter noise. If you left it disconnected for more than a couple of seconds, it would have taken a lot of current to charge them back up and then the current drain would have dropped near zero.

Has somebody actually confirmed that the battery goes dead by checking terminal voltage, or is everyone ASSUMING it's dead by symptoms? A loose cable at the starter or some missing/intermittant grounds will cause similar symptoms. You could be hunting down a non-problem.

For the fun of it, unscrew the voltage regulator from the alternator and see if the brushes are at the end of their life - and double check the charging indicator on the dash (key on, engine stopped = light on).

i noticed the arc while disconnting the wire from the batt, the only time the car did not start for me was when i picked it up it had to be jumped, i have checked the current before starting the car after sitting for a daty is 12.5 volts after starting the car i get 14.somthing the alt is working correctly when i turned it over when the batt was dead the car did turn over but it seemed the batt wes very low (should have tested it there but i didnt know i would not incounter this problem again, i will indeed check the started cable, i have put all the accesories on and the car still charges well witha large load on it.