Hello, I've got an issue with a battery drain on my '05 Accord. At first it was draining really fast, from fully charged to discharged in about 24 hours. After reading about a lot of people having battery issues with the small batteries in this car, I tried replacing that (about 2 weeks ago, now it will last a few days, but the drain remained. I've measured a power draw that ranges between 90-240 milliamps (tends to settle at about 90, with spikes every few seconds up to higher numbers). Currently I'm just disconnecting the battery when I'm not using it to preserve it as best as possible, I know that constantly draining it like that is not good for it.

Here's where I am stuck. After doing research on this website and others, I found suggestions to pull fuse 15 in the under-hood fuse box. Doing this does successfully lower the current draw to about 10-30 milliamps (an acceptable amount based on everything I have read/watched). So then I started looking at the fuses in the interior fuse box that were connected to that circuit. I tried to measure for voltage drops across all the fuses in that box and found none, I also pulled all the fuses related to under-hood fuse 15 (interior fuses 5-9 according to another forum post I found). Unfortunately, with fuse 15 installed, pulling interior fuses changed nothing and the full 90 milliamp+ draw remained. Then I was curious if perhaps the fuse was bad under the hood so I removed fuse 20 (says "option" in the cover but everything I've found says it's for heated seats/power seats) which is also a 40A cartridge fuse, and put it into slot 15. The power draw was gone, so I went the next morning to buy a new fuse to replace fuse 15. I installed it, and the drain was still there... Upon further investigation, I found that when fuse 15 OR fuse 20 (both under the hood) is pulled, the drain goes down to the acceptable 10-30 range. If both are installed, it's 90+ milliamps. I checked any interior fuses that might correspond with fuse 20 as well with no luck, I don't have heated seats so that fuse is empty on the interior. I've tried swapping relay switches that could be related to those fuses since they both deal with interior accessories, but had no luck (recommended by an electrical engineering friend of a family member who has some experience with Hondas).

I'm basically ready to take it to a dedicated electrician at this point, my usual car shop wasn't able to find anything. I was just wondering if anyone had any ideas/suggestions on things to try before I do that?? Thanks for any help.

 

Post # 7 in this other thread has info. from a Honda service news bulletin regarding excessive parasitic draw: https://www.hondaaccordforum.com/for...y-drain-57492/

For example, something like a faulty power door switch can be the cause. If all the doors, etc. aren't detected as locked/closed, this may cause the issue.

You can unplug the hood switch to simulate a closed hood.

 

The 40 amp fuse is upstream of a bunch of fuses. Since you can read the current draw, just setup your amp meter. Then pull the normal sized fuses one by one in the underhood fuse box to see what fuse reduces the draw. Plug them back in and do the same thing for every fuse in the under dash fuse box. Let us know what you find.

Also, try unplugging the alternator connections to see if a faulty alternator is draining the battery.

 

I had seen some other things about faulty door switches, do you know a way to check this? I checked the Driver's door switches specifically, removing the panel and disconnecting the switch box, and found no changes to the amount of drain. I also don't know that it's showing the doors being open, for example when I've tested the current draw with the driver door open, it shows upwards of 490 milliamps. When I close the door and test again, it quickly drops down and settles around 90. Also, do you happen to know where the hood switch plug would be? I have searched and cannot find one anywhere.

Alright, I checked all the regular fuses in the underhood box, no changes to the drain. Same with unplugging the alternator. I also forgot to mention in my original post that I did have the alternator and starter tested when I first noticed the issue, and they both were good.

 

What is your setup for measuring amps?

Did you disconnect the large wire to the alternator? An alternator can test good for amp output, but still could have a weak/bad diode and slowly drain the battery.

 

I'm using a multimeter across the negative terminal of the battery and the negative cable. I don't have any clamps to keep the meter in place while testing so I have to sit the meter down and then re-connect the leads each time, which isn't ideal but it works.

Yes, I did disconnect that large wire as well but saw no change.

 

Here are some photos of some of the switch connectors. The door lock **** switches are part of each respective door lock actuator assembly. You don't have to close the door/trunk/hood when you disconnect the respective switch to test; unless, something else stays on in that door or trunk.

The security system monitors the following signals:

• Battery voltage
• Door lock **** switches
• Door switches
• Ignition key switch
• Radio connection
• Security hood switch
• Trunk key cylinder switch (sedan)
• Trunk latch switch

 

Unfortunately taking apart the doors to disconnect the switches is beyond my level of comfort/ability, though based on the videos I used for reference on how to test the current initially (and what I see if I leave a door open), a door open switch draws a considerably higher current than what I am reading. My next course of action is going to be pulling each interior fuse one by one just in case one them changes something (though I read no voltage drops across any of them and already tried unplugging the ones directly connected to under-hood fuses 15 and 20). Pending any other recommendations I think the next step beyond that is to take it to an electrician.

 

I have spent 5 days trying to figure out this battery drain and changed the alternator and battery. Alternator tested bad and finally after days to clear the light on the dash and now there is no power drain on the system