- This topic has 3 replies, 3 voices, and was last updated 7 years, 2 months ago by
.
-
Topic
-
Hey guys,
So I’ve had this issue since I bought the car, sadly this particular problem is something you can’t really preemptively avoid when buying a car. It starts and runs fine, but when it sits for a while is when it completely drains the battery and needs a boost/charge. Exactly when it dies I’m not sure, but it seems to be after the 24 hour period, possibly anywhere from 24-48 hrs.
The odd thing is I have waited a full 24 hrs before, and it starts fine, no hesitation or slow cranking like the battery has been drained. It is very much like a timer, just after that 24 hrs something shorts out or whatever and absolutely kills the battery, and dead. I get a few dim lights but no crank whatsoever, not like a very low battery, just dead.Stats and troubleshooting:
2009 Honda Accord Ex-L
130,000 kms
Was hit in the rear by prev owner.
Noticed the entire passengers side of engine bay has rusted or partially rusted fasteners, as if that side was parked near salt water etc.
Everything works on the car, electrical or otherwise.
New battery doesn’t change anything, a high capacity battery still suffers the same fate at most likely the same time frame.
I say everything works fine above BUT I have noticed that while running, very randomly the lights will dim for a moment. It’s not the fans as it rarely happens, basically comes and goes.
I have put a tester on all wiring in the engine bay, one wire does test a drain while off, possibly the key fob system. When I do pull the key fob/stereo fuse/trunk release fuse, the drain DOES drop.Short of pulling fuses and letting my car die over and over, OR taking it to a shop for an expensive troubleshooting session, anyone ever heard of this or is there anything else I have missed or can try?
I’ve asked a few mechanics and no one has heard of this odd issue. A power drain yes but not a complete kill or short of the battery…
-
Replies
-
The term you’re looking for is “parasitic load.” Basically, when you turn the car off, there are things that are still drawing power from the battery. Normally, this draw is minimal (rule of thumb is 0.5 Amps max) and you can restart a car even after months of sitting. Sometimes things like stuck-on glove box lights or shorted computers will draw the battery down faster. You will need to know how to use a multimeter to troubleshoot this problem. But basically, with the car completely off, you need to get in between the negative battery cable and negative battery terminal with your meter set to read amperage. Start pulling fuses until you find the one that drops your draw roughly below 0.5 Amps. Whatever that fuse goes to is the trouble area that needs to be further investigated. Eric has made a video describing this process BTW. I’d recommend checking it out.
Thanks for the reply’s guys.
Sorry if I wasn’t completely clear with my troubleshooting.
I did in fact do testing in the engine bay with the fuses.
I pulled each and every fuse and the one with the draw was the one that controls the fob system, radio and back truck release. Again, the fob system should shut off after a while as it does, but nothing is jumping out as a parasitic load, and why I came here.
I guess the question would be if it is the fob system, what would be the next step?
What would be replaced (part) at that point?
How would I test that?
Why doesn’t installing a high capacity AGM battery make the draw take much longer to drain the battery, and let me start the car past the 24-48 hour time period?
Why can’t I crank the car over at all, and why is the battery completely killed off rather than a drain past the crank rating?This seems like a weird short or computer system that is faulty and triggers something to short out for some reason. I took pictures last spring when I did the testing, so i’ll have to look to see exactly what the draw was and what fuse etc etc and I’ll post back.
If pulling all the fuses doesn’t stop the parasitic draw, then you may have a bad alternator diode draining the battery.
Disconnect the cables to the alternator and see if the car starts right up the next morning after reconnecting the alternator.If it is indeed the fob/radio/trunk release, you would disconnect each component on the circuit until the draw stops.
If that fails to solve the trouble, then your issue could be a faulty module.
You’ll need to get hold of a wiring diagram to see which module controls these components.Sometimes door switches cause issues–reawakening modules because the sensor says a door has been “opened”.
Basically, it’s detective work.
- You must be logged in to reply to this topic.