Honda Pilot - Honda Pilot Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
Hello- I have a 2007 pilot with about 200,000 miles, still a great vehicle. I have a battery drain of 46 milliamps. This shouldn’t be draining the battery, but if we don’t use it for 2 days it won’t start, It is in the 30’s where I live now. I had a test light in series with the battery and pulled all the fuses and relays and the only one that dimmed it was when I pulled the radio fuse 20 amp. It just dimmed a little. 46 should be considered ok but it the battery is draining. The battery is a year old and has been tested at the place I got it and also at oreilly’s and they both say it test very good. The alternator tests good too. Any ideas? I just joined but I have been lurking here for a few years, I promise to help out when I can. Thanks. Al.
 

·
Registered
Nobili spiritus embiggens pequeño sparus tyre.
Joined
·
10,217 Posts
Welcome aboard.:)


You're probably on the right track with the radio. It wouldn't be the first time.


One way to test that is to pull that 20 amp radio fuse for several days and see whether you still have the parasitic draw.

Do you have any aftermarket electrical accessories, like an alarm system, inverter, remote starter, etc.?

If all else fail and you don't feel like chasing down every wire and connection, there are some other palatable stopgap solutions:

 

·
Registered
2008 Honda Pilot EX-L
Joined
·
314 Posts
46mah draw isn't enough to drain a fully charged battery in such a short amount of time. How old is the alternator? If a diode goes bad in them, they never technically shut off, and can easily drain a new/topped up battery in a short period of time.

Per the following link: How to Test an Alternator for Problems.

Usually, a bad alternator diode will cause your headlights or instrument panel lights to flicker or dim and, sometimes, drain battery power overnight, or in minutes.
  • To check for a possible bad alternator diode, switch your voltmeter to a low setting on the AC (alternating current) voltage scale.
  • With the engine running, touch the meter probes to the battery terminals.
  • Your voltmeter should read 0 AC volts.
Any amount of AC voltage would indicate a bad diode, so you'll need to replace the alternator.
 

·
Registered
Joined
·
1,045 Posts
Honda uses a sensor and the engine computer to control the charging circuit. If this is at fault, your battery may be chronically undercharged. Measure DC voltage at the battery terminals at idle with a load--run the fan on high and turn on headlights. Should be about 14.4 volts at full charging rate. If you read about 12.3, the system is undercharging. Possibly due to failure of the ELD, which tells the computer when to up the charge rate.

Of course, you should check the battery and alternator cables and connections. Corroded grounds are common.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #6 ·
I will further explore the alternator. The alternator testing link looks great. I did use a digital multimeter on ma amps setting in series with the battery to perform the test of parasitic drain. some of the fuses are hard to get at, and I didn't have enough time to keep running to the front of the car testing each fuse. I will probably do this if the alternator checks out though. Thanks for all the help, if I figure this out I'll let you know the solution.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #7 ·
Honda uses a sensor and the engine computer to control the charging circuit. If this is at fault, your battery may be chronically undercharged. Measure DC voltage at the battery terminals at idle with a load--run the fan on high and turn on headlights. Should be about 14.4 volts at full charging rate. If you read about 12.3, the system is undercharging. Possibly due to failure of the ELD, which tells the computer when to up the charge rate.

Of course, you should check the battery and alternator cables and connections. Corroded grounds are common.

I didn't check it under load, but when idling it was just over 14 volts, I didn't have lights or fan on.
 

·
Administrator
2016 CRV Touring AWD, 2005 Pilot RIP.
Joined
·
16,315 Posts
We had plenty of these problems. They got worse during wet weather or high humidity. Set off the alarm sometimes.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #9 ·
So I tested the alternator diode and got a reading of .010 volts ac. My Chevy truck had the same reading, so alternator diode check passes?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #10 ·
OK, I did a little more testing. It does have a aftermarket car starter on it. When I did my testing this weekend it I had the fuses pulled. I realized tonight I need to test it in sleep mode with the starter door locks engaged. So I put the fuses back in and ran the test, it now is pulling 104 milliamps with this engaged. Could that be enough to drain the battery in 2 days enough to fail starting assuming that the batter is good? I ordered a fuse buddy to work with my multimeter to make easier testing of each fuse but it won’t be here until Wednesday. Thanks for any insight you can provide.
 

·
Registered
Nobili spiritus embiggens pequeño sparus tyre.
Joined
·
10,217 Posts
remote starter
For everybody out there playing parasitic draw bingo, you can go ahead and mark aftermarket remote starter on your cards for this one, I think it's safe to say. :)

OP, let us know what the results of your Fuse Buddy tests are when you do them. In the meantime, can your remote starter temporarily be disconnected?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #12 ·
Yes I will update after testing. I have the remote starter disconnected and it’s back to 46ma. I’m going to leave it disconnected and leave it outside and see if it drains in a few days time. Probably have had this problem for awhile but didn’t know it, it got driven every day until COVID my wife works from home now, so it can go 2 to 3 days without use. Thanks!
 

·
Registered
Joined
·
47 Posts
Agree, I had an aftermarket, Compustar remote start on my Toyota Tundra and it would kill the battery in 2 days. I had a car audio company do a parasitc drain test and they confirmed the remote start was the issue. They removed the remote start and I no longer had battery drain issues.


For everybody out there playing parasitic draw bingo, you can go ahead and mark aftermarket remote starter on your cards for this one, I think it's safe to say. :)

OP, let us know what the results of your Fuse Buddy tests are when you do them. In the meantime, can your remote starter temporarily be disconnected?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #14 ·
So I did the test with the fuse buddy. Nothing else was really drawing anything, car sat in the cold for 3 days and felt like full battery. Pretty sure it’s the auto start. Thanks everyone.
 

·
Registered
Nobili spiritus embiggens pequeño sparus tyre.
Joined
·
10,217 Posts
Pretty sure it’s the auto start.
It usually is, if it's not the radio.

Glad to hear you're keeping your charge now as we head into winter.
 
1 - 15 of 15 Posts
Top