rear fog lights = battery dead?

so our volvo S70 had a dead rear light.
to compensate for it for safety and legal reasons, until we had time
to replace it, we used our rear fog lights. car was just used 4-5
times.
2 weeks later, can't start the engine, the mechanic claims it was the
rear fog light draining the battery.
wtf?
anytime we turned off the engine, the rear fog light turned off when
ignition was off, although the switch was probably left on.
is it still possible to drain the battery even though the light is not
actually on?

 

Your mechanic is full of it, if the rear fog lamp drained the battery, then
something is wrong with the electrical system. If the fog lamp was not on
with the car off, your problem is unrelated.

Personally I would look for a more competent mechanic.

 

No !! it is time to find a new mechanic who knows what he or her is doing
Glenn K
Volvo Certified Technician
ASE Certified Technician

 

I used my fog bulb to do the same and no issues, the only way it could
drain power is a short on the circuit, so ask him how he detected the
short and how bad it is, or the sign says heesamoron.

 

Thanks everyone for your feedback,looks like it's time to find a new
mechanic

 

snort, the guy at the local firestone told me the battery he sold me
died within 11 months because i had a cb radio plugged in to the
cigarette lighter. (which was off when the key was off, in case
there's any doubt) After i got the new battery on warranty i didn't go
back there again, obviously.

 

i'm ceertain it's not the case here, but, technically, in a stupidly
designed vehicle, that is possible; if the fog light switch were
connected to a relay which is always hot but the lights themselves are
connected via the ignition switch (and the relay).

for example: i got the idea for this possibility from the local
newspaper car advice column; somebody's pickup truck (detroit, don't
remember the make) had intermittent battery dying overnight; turned
out to be that he had bought the snowplow package, but not sprung for
the auxiliary lights that were optional with the package. well, even
if you didn't buy the lights, the package's standard wiring harness
came with the relay which was connected to the dash switch which was
always hot; so if the switch was on and the ignition was off, the
battery was draining through the relay and you had no way to know it.

 

Your mechanic may have thought the fog lights were a home-wiring job
that are on all the time. You need another mechanic. I would have
the battery and connections checked. Next concentrate on the charging
system.

 

i copy NASCAR and just paint the headlights on the front of the car.
no chance of them burning out the battery that way.