I have a brand new battery and alternator and my car still can't keep a charge for more than 1 night. Once I jump start it, it will run and restart all day.

I need to check to see what is pulling the juice from the battery. I can only assume my alarm/accessories, my window rollup module or some other short is discharging my battery overnight.

I'm sure this is pretty simple, I have a decent multimeter. How do I go about narrowing down the cause of the draning battery?

 

I'd start @ the car audio equipment. Make sure your deck is hooked up to accessory power(not on when key is removed.) There's two wires on decks- constant 12v and ACC(key on). Then check any amps (blue wire on aftermarket decks tells amps to power up- aka remote wire)

 

https://honda-tech.com/forums/showth...parasitic+draw .94

 

I would say it could most likely be the aftermarket alarm, but like what was said about, it's could be the radio.

 

Getting past all the arguments in that link, I did find the info I was looking for: 25-30ma is normal, anything over that and there is some sort of drain. I should be able to narrow this down by testing all the various fuses.
Thx FCM!

 

Results were unexpected:
unarmed 25ma
Armed 30-35ma
This should be well below spec and should not drain my battery in only a few hours (did not start after 4 hours today). Did I get another weak battery from Kragen? I wish we used full size batteries like the civics. Getting sick of push starting my car in this heat

 

Your drain sounds like several amps, in order to drain even a lower rated 25A/hr battery overnight. Might actually feel some heat at the source of the drain, if it was something like a power window motor or antenna motor causing the drain. Given your battery is in decent shape, you can pretty much do the math from the A/hr rating, and determine the drain current. Without an ammeter, you could try pulling fuses to disable accessories like power windows and locks to narrow down the problem, granted nothing critical needs to operate on that circuit. If you can get your hands on a clamp-on ammeter, that can really help. A while back I diagnosed leaky alternator diode/s with a .25A drain, that was taking several days to drain the battery. I had an idea that it was the problem, but at that low of a current, it couldn't be tested by disconnecting the wire and tapping to ground while looking for light sparks. Your drain is probably large enough that you should see sparks just from lightly touching the fuse legs into the contacts, if the drain is downline from a fuse. Of course anything with a cap filter such as a radio will always spark, on initial plug in. I've heard of trunk and hood lights staying on also, which would be in the neighborhood of a several amp drain.

Looking at non-factory installations for drains/shorts is always a good starting point. I had an intermittent short on my car, that I tracked down to a stereo installer before I owned the car who left an unused wire dangling without taping or capping off. Somehow the darn cut end found it's way directly against a small metal area under the dash. I hear you on full size batteries. I tried to fit a full size one in my car, and wasn't thrilled with the fit, although I could have made it work. These smaller ones don't have the greatest reserve, especially when they get older.

 

I appreciate the response, but that it's in mA. So .0025 A. Should not be draining my battery.

 

If you know the amp/hr capacity of your battery (assuming it is anywhere close to rated) then you can simply do the math, and get a ball park idea of the drain, given the amount of time it takes to drain. In your case, 2.5mA is going to take many days, not just hours, to drain the battery.

 

I figured it out. It was hard to track down since it was a short only with ignition on. My DEI window rollers have shorted out somewhere internally and probably pulled just enough amps not to pop the 20A fuse. The power wire was really hot and melting.
Since this is the 2nd failed DEI window module, I'll probably just take it out.

 

Aah non-factory window motors. Aftermarket stuff just isn't the same quality unfortunately.

 

There is no such thing a parasitic draw when ign. is on, by definition parasitic draw is a load over acceptable limits when ign. switch is off, there will always be a load over the limit when ign. is on.

The problem may well have been the DEI window module, but power to it is constant, ign. does not need to be on, I suspect it is a wiring problem because you have gone through two of them, I have installed 100s of them without any problem, in fact I think they are one of the best window modules out there.

Question, where are you getting them, is it from an authorized DEI dealer or some unauthorized online dealer? 94

 

OK, so it wasn't parasitic load, it was a full on short.

Check my diagram for the 530T in this thread:
https://honda-tech.com/forums/showth...highlight=530T
Let me know if you see anything obviously wrong. I'm not even sure how it was sensing ignition ON either, maybe a signal from the alarm.

The wiring was pretty simple. They did last for about a year each, I doubt they were knockoffs. I think the problem might have been installing them inside the door panel and they get wet in the winter months.

Have these been discontinued? Is there a replacement unit?

 

If they got wet, that is your problem, they are not waterproof. 94