Battery drain- Parasitic? Short?

S

SamJay

New member
Hello all. I am hoping your expertise can guide me in the right direction with this issue. I am new to this forum, but am a part of other Toyota forums as I own a Prius and used to own a 97 T100. I have read dozens of threads on this forum and on the Internet about parasitic battery drains, but am not sure where to go next.

The issue is, the battery in my wife's 04 4Runner will not start the car after about 3 days of Being parked. If it's driven daily, we wouldn't know there is a problem. I have also driven it 300 miles in one drive without an issue.

I have had the battery tested in the vehicle and taken out and load tested at an auto parts store. It always passes. I have unhooked the battery overnight and there was no voltage drop at all. My overnight measurements with my multimeter when the battery was left hooked up are anywhere between .1v and .25v. My multimeter fluctuates between .03 and .04 amp draw between the negative terminal and negative battery cable. I usually check the current drain a few hours after the vehicle has been turned off. I leave the hood open as well. I measure this on the 10A scale because when I make initial contact between the post and cable the amp draw is about .6 amps for a few seconds and then goes down to .03-.04. I don't have alligator clips for my multimeter to leave it connected to the battery and then switch it to the 200mA scale.

I have had my alternator load tested and it passes. I have also unhooked the alternator from the battery overnight and there is still a large voltage drop. This would lead me to believe it is not a bad diode and the alternator is charging the battery. The vehicle has a professionally installed auto start. I have disconnected the security bypass module on it and the antenna and there is still a large voltage drop. I have also read posts on this site about people having issue with the daytime running lights and the dome relay. I unhooked both of these last night, and tonight the voltage drop was .25v.

Everything I read suggests the amp draw is within a normal range and that amount of amp draw wouldn't cause this large a voltage drop overnight. So now I think it's is a short, possibly a bare wire rubbing against something or a bad ground, that is intermittent. What are your thoughts?
 
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SamJay said:
Hello all. I am hoping your expertise can guide me in the right direction with this issue. I am new to this forum, but am a part of other Toyota forums as I own a Prius and used to own a 97 T100. I have read dozens of threads on this forum and on the Internet about parasitic battery drains, but am not sure where to go next.

The issue is, the battery in my wife's 04 4Runner will not start the car after about 3 days of Being parked. If it's driven daily, we wouldn't know there is a problem. I have also driven it 300 miles in one drive without an issue.

I have had the battery tested in the vehicle and taken out and load tested at an auto parts store. It always passes. I have unhooked the battery overnight and there was no voltage drop at all. My overnight measurements with my multimeter when the battery was left hooked up are anywhere between .1v and .25v. My multimeter fluctuates between .03 and .04 amp draw between the negative terminal and negative battery cable. I usually check the current drain a few hours after the vehicle has been turned off. I leave the hood open as well. I measure this on the 10A scale because when I make initial contact between the post and cable the amp draw is about .6 amps for a few seconds and then goes down to .03-.04. I don't have alligator clips for my multimeter to leave it connected to the battery and then switch it to the 200mA scale.

I have had my alternator load tested and it passes. I have also unhooked the alternator from the battery overnight and there is still a large voltage drop. This would lead me to believe it is not a bad diode and the alternator is charging the battery. The vehicle has a professionally installed auto start. I have disconnected the security bypass module on it and the antenna and there is still a large voltage drop. I have also read posts on this site about people having issue with the daytime running lights and the dome relay. I unhooked both of these last night, and tonight the voltage drop was .25v.

Everything I read suggests the amp draw is within a normal range and that amount of amp draw wouldn't cause this large a voltage drop overnight. So now I think it's is a short, possibly a bare wire rubbing against something or a bad ground, that is intermittent. What are your thoughts?
Click to expand...
How many amps does your starter draw?
 
I'm not sure I understand the point in differentiating between a short and parasitic draw. If there is a short, it is what is causing the parasitic draw. Semantics?

Hook your meter inline with the neg terminal, as you have done, and monitor the amps drawn. Start pulling fuses, 1 by 1 until the meter reads zero. That fuse will tell you which system your having issues with (lights, horn, windows, etc., etc.)

Once you've determined what system you're having problems with, give yourself a sanity check and leave that fuse out overnight. If it starts the next morning, you have narrowed down the problem.

Now comes the hard part: follow all the wires in the system you have identified and find the short that is causing your parasitic drain.

Fix the short, solve the problem.
 
I differentiated between the two because I am starting to believe it is an intermittent issue and not a continual draw on the battery.

30-40mA should not be draining my battery as quickly as it is. That is a normal amp draw in many vehicles. I have pulled about half the fuses in the main fuse box next to the battery. The only one so far that brings the amps down is the Radio #2 fuse. This brings it down to between 10-15mA. That doesn't seem out of the ordinary to me.

How would I check how much my starter is drawing?
 
ok. not trying to be picky, just making sure I wasn't missing something in your question.

If you have the JBL audio system, and your problem is intermittent, I would start there. Those amps have been known to be an issue.

If you don't have JBL, I'm out of ideas. Good luck.
 
SamJay said:
How would I check how much my starter is drawing?
Click to expand...

Go to Advance Auto or Autozone and have them check you battery and starter. I had mine checked this weekend and my battery is weak, and the person who tested it said the starter was drawing 215 amps. They said that was high and should be closer to 100. Here is were the confusion begins for me. I don't know what "normal" is, I have read that our ignition/starters will draw that much or more even if it's just for a half a second, but I have yet to find anybody that actually knows. No offense to the kid at Advance, she was very helpful.
 
Thank you for the starting suggestions. I do have the JBL system and will unhook that over night to see if it continues.

I will also stop by Orielly's to have the check the draw on the starter. I had them test the battery in the vehicle while it was running and load tested in their machine in the store, both times it passed.
 
A short would burn something up and do so fairly quickly. Sounds more like an old battery. How old it is?
 
SamJay said:
I differentiated between the two because I am starting to believe it is an intermittent issue and not a continual draw on the battery.

30-40mA should not be draining my battery as quickly as it is. That is a normal amp draw in many vehicles. I have pulled about half the fuses in the main fuse box next to the battery. The only one so far that brings the amps down is the Radio #2 fuse. This brings it down to between 10-15mA. That doesn't seem out of the ordinary to me.

How would I check how much my starter is drawing?
Click to expand...

40mA is pretty normal considering all the things in a vehicle requiring constant power.
To measure the amount of current the starter draws you'd need a clamp - on ammeter, but I don't see why you need to.
 
Well it isn't the JBL system. I took out the radio #2 fuse overnight, which I read is the one for the JBL, and the voltage drop was .5v in 24 hours. This is what is making me to think its a short. The voltage drop ranges from .1 to .5v in 24 hours. It is never the same.

The battery is only a year old. It is an Oreilly's Super Start. It has been bench tested, continues to test good and has zero drop in voltage in 24 hours when unhooked overnight.
 
No aftermarket alarm system. She has an auto start, but I've all ready unhooked it without luck.

Chaz- both of those are looking like pretty good options at this point, thanks for pointing them out.
 
SamJay said:
Well it isn't the JBL system. I took out the radio #2 fuse overnight, which I read is the one for the JBL, and the voltage drop was .5v in 24 hours. This is what is making me to think its a short. The voltage drop ranges from .1 to .5v in 24 hours. It is never the same.

The battery is only a year old. It is an Oreilly's Super Start. It has been bench tested, continues to test good and has zero drop in voltage in 24 hours when unhooked overnight.
Click to expand...

Take a wire connect it to the positive side of your battery then attach the other end to the frame. That is a short. See how long it last before it goes up in smoke. I would suggest you have a fire extinguisher on hand. You clearly don't have a short.
 
Yep, I trusted those fuses as well.... until I physically disconnect the amp and the draw went away. Sure it take a few minutes to get to it but better than being stranded with a dead battery.

CEH
turned 205,000 miles this week
04 Limited
 
[MENTION=123624]SamJay[/MENTION]

Something to point out; if you're pulling fuses to try and isolate a parasitic drain on a CAN vehicle you might be shooting yourself in the foot. Keep in mind that some vehicles may have modules that stay away for up to 30minutes or more and/or have modules that turn on after the vehicle is turned off (i.e. EVAP monitor running 4hrs after shut off.) By removing the fuses you've reset the module(s) on that line and now they will be "awake" and thus give you a false positive on your parasitic draw readings.

One of the better ways for testing for a parasitic drain involves a DVOM and checking the milivolts going through a fuse, then using a chart to convert the measurement into a usable "live" miliamp reading. This is safer and more useful than pulling the fuses because you are passively testing the circuit instead of actively interrupting it/waking modules up by pulling the fuses.

I posted this in a thread a while ago with one of those said charts including instructions on how to go about some parasitic drain testing. (I do need to get off my lazy ass and update the Toolbox Sticky with some new information one off these days :hiding: )

http://www.toyota-4runner.org/4th-gen-t4rs/188322-parasitic-drain.html#post1917929

Post Note-

I would not classify a Parasitic Drain as a "Short," one possible cause may be a short; but that does not mean all parasitic drains are shorts. In fact many are simply high resistance or a logic circuit that is staying awake for some reason causing too much draw.
 
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