Slow battery drain, procedure for checking?

[abracadabra]

Folks-

Well things have been great with the van, as usual, such a good dependable rig, she loves these old Maine roads and I even get to use 4WD sometimes to get out of muddy situations!

Anyway I do have an issue. From time to time we don't get a door shut all the way and the light in the dash drains down the battery. I've had the same battery in the van since I bought it and its been jumped 5-6 times, every time I get a jump AAA tells me I should get a new battery. But I'm broke and I keep going.

Now we haven't had this issue because we have trained ourselves to ALWAYS look at the dash before we let the van sit to make sure the red door light is out.

On Saturday the battery was dead. So dead that the door light on the dash wouldn't even come on. I'm pretty sure the doors were shut but in this case I can't be positive as I parked the van right when we were having a potluck here, I wasn't thinking about that issue.

So we got a jump, AAA once again. The alternator works as the battery charged up and we drove the van on a few errands that day, shut it off, started it up etc.

Next morning my wife has to work early, guess what, the battery is dead. I'm SURE this time the doors were all shut and the dash light was out. Something else drained it.

Anyway it was only drained down to 8V or so and I had my boss come over and jumpstart the rig.

I thought well its time to get a new battery, thinking it was probably crapped out.

We bought an Autozone replacement battery, expensive, smaller than the one that was in there with only 500 CCA, but we're so broke its gotta be the one.

So we're thinking we're good to go. I checked the voltage with the van running to make sure the alternator was up to snuff, the voltage read just under 14V at idle.

I still checked the battery voltage every now and then and it seemed fine, but guess what! Here we go.....this morning my wife has to work EARLY, its still dark out, she comes in and tells me the van won't start! Arghhhhhhh!!!

Anyway I check the voltage on the battery, 8V. What!!?? So the only thing I could do was call my boss in again, he lives down the road, got a jump.

I instructed my wife to disconnect the battery ground strap when she got to work.

So.....what I know is the battery is okay, the alternator works (although I think I probably have been working it really hard with all this charging.....I can only hope it doesn't crap out too!!!)

I'm sure there must be a slow drain/short issue happening. I know its not as simple as us not shutting the doors and having the dash light on. We trained ourselves out of that.

Are there any common scenarios for located this short?

When my wife gets home I'm going to check for amperage draw with the ground disconnected, that way I can see what the draw is (any idea what it should be for normal usage, for the clock etc?)

I'm thinking I can just disconnect the ground strap every time the van is parked in the meantime, to keep the rig in dependable operating condition!!

Any thoughts would be awesome!

thanks,

mark in Maine

[bald josh]

Hey Mark, when theres a current draw on your battery and you pull the ground strap off or put it on you get a little spark, i would try pulling the fuses for radio, clock, dome light...anything that has a hot with the key off and see if the spark goes away, this would give you a starting point to look for the problem. putting the clock fuse back in will give you a small spark, but maybe the radio (memory) will give you a much bigger one and point to something along those wires or the radio itself as being the culprit

[timsrv]

I remember the old "spark test" We used to do that on vehicles that were built in the 70's or before (the ones without electronics). Unfortunately that test went out when electronics came in. Capacitors typically draw a somewhat heavy load initially, but they charge quickly and the load drops to almost nothing. This makes the old "spark test" useless as modern vehicles will almost always spark during initial connection (whether there's a problem or not).

Mark, you will need a multimeter with a "DC Amp" feature. Disconnect one battery cable (pos or neg makes no difference). Set your meter up to read DC amps, then use your meter to bridge the circuit between the battery and the disconnected cable (hook it up in series). You need to be careful about pulling heavy loads while the meter is hooked up & don't try to start it. Most meters can safely carry about 10 amps, some up to 20, but if you exceed these numbers you will likely fry your meter . With the meter hooked up in this fashion, it should display actual loads on the battery. Turn a dome light on / off to verify the the meter is giving you an accurate representation of what's going on. Once you're satisfied with accuracy close the van up (like it's put away) and read the meter. .05A is considered an acceptable level. At this rate it would take about 2 months to drain the battery. For a daily driver, you could get by with about .1A, possibly more, but .05A or less is what a healthy system will show.

If you detect a drain, like Josh said, start pulling fuses and check the meter each time. If you find one that causes the draw to go away, then that's the circuit you need to focus on. Based on your description, I think you likely have a shorted diode in your alternator. An alternator with a shorted diode will still charge, but it will allow current to flow both ways. This means it will suck the power back out after the van is shut off. If the previously outlined checks are inconclusive, then go to the little black + box (drivers side engine compartment near the Air Flow Meter) and disconnect the big wire going into it (that's your alternator output cable). If the load goes away with that disconnected then your problem is in the alternator. Here's the + box:





A shorted diode will pull about 5 - 10A, so if you're detecting that kind of draw I'd bypass the other checks and go right to the alternator test. Be careful not to ground out any wires when messing with the + box. Be aware that there is 12V battery power here & steel tools conduct electricity . Tim

[bald josh]

Tim, i ask only to understand, i thought capacitors held a charge, at least for a time, wouldnt they charge up, hold that charge and then the spark test would work?? or are there different types of capacitors that dont hold a charge once disconnected?
In any case the multi meter seems a whole lot more accurate than looking at sparks....i wonder how much time ive wasted looking at battery posts over the years

[bald josh]

just thinking out loud here, doesnt the key isolate the electronics from the battery when in the off position? so a draw with the key off would have to come from something hot in off...or am i missing something.unless the ignition switch played into it.
granted the spark test has always seemed primitive and i like the ohm meter much better!

[timsrv]

Too many variables to say for sure. I'm not saying it can't work......or perhaps give you an idea, but it could also create a big waste of time. Sometimes the smallest variables can make a big difference while trying to find a problem. As a general rule it's always best to eliminate or reduce variables when troubleshooting. Multimeters are cheap and readily available. IMO anybody who repairs their own vehicle(s) should have one (just saying). Keep in mind not all multimeters are created equal. Make sure it's got a DC amp function if you're buying one for doing this test.

That being said, if the draw is in the alternator I suppose you could use the spark test at the + box. A spark here during connection/disconnection would indicate a shorted diode. Tim

[fuquan]

Hi, I am seeing a draw of 0.36A. I pulled every fuse I know of and the number didn't drop. Are there some hidden fuses that I don't know about? I tested the fuse box below the glove box, and the little 2-fuse-box next to that. Also tested the big fuses near the power steering fluid reservoir. Well, the only one I did not pull is the one that is held in with a screw. I also disconnected the connection in the + box as advised above in this thread. Draw is still there. Any ideas?

[timsrv]

So let me get this straight, you are still showing .36A draw with all the fuses pulled & the big alternator wire disconnected from the + box? What happens when you also pull the negative battery cable? If it stays at .36A then your meter is messed up. Assuming it finally drops to 0 with the negative cable removed, then it's got to be something that's not fused. I'd pull the big wire to the starter next and see what happens. Starter draws are rare, but anything is possible. Tim

[fuquan]

So let me get this straight, you are still showing .36A draw with all the fuses pulled & the big alternator wire disconnected from the + box? What happens when you also pull the negative battery cable? If it stays at .36A then your meter is messed up. Assuming it finally drops to 0 with the negative cable removed, then it's got to be something that's not fused. I'd pull the big wire to the starter next and see what happens. Starter draws are rare, but anything is possible. Tim

I used a 2nd meter to confirm that mine was reading properly. Looks like the problem is the starter. After disconnecting the starter the reading dropped to 0.000. Then I put the dome light fuse in and turned the light to on, that gave me ~0.3ish, turned that off and the reading dropped back to 0.000. I proceeded to reinstall all fuses and the connection in the +box, checking amperage along the way. No draw with the starter disconnected.
Yay!! Thanks Tim! I can finally stop pulling my hair out. But, what now ? The positive connection/bolt at the starter looks clean. Do I have a problem inside of my starter? The previous owner had a kill-button bypass at the starter, which I had removed because it was flakey and prevented me from starting the van a few times. Could that switch bypass wiring have damaged the starter?

[timsrv]

Next I'd drop the starter then hook it up to a battery via a set of jumper cables (ground to housing and + to the battery terminal). Use your meter to determine if there's any draw present. If there is then you know for sure it's the starter. Pull the solenoid cover off and inspect the contacts (see picture below). About the only thing that could cause continuous draw would be having the solenoid spring missing or perhaps having foreign conductive material inside the housing there. Tim

[fuquan]

When I reconnected my starter in the morning, so that I could move the van to a more suitable work location for removal of the starter, the draw was gone. Yesterday I double and triple checked that the draw was actually coming from the starter. Now I observe a ~0.01 - 0.02A draw with my stereo completely disconnected.

I drove around for a couple of hours, checked along the way. Everything is normal. Perhaps there is something ajar in the starter or solenoid. For now I am glad the problem is resolved, but I would like to know what the problem was. I'll continue to test for parasitic draw regularly, and will take a peek inside my starter the next chance I get.

[timsrv]

If it's a missing solenoid spring or foreign conductive material inside the solenoid housing then the draw would be intermittent. I think a broken or missing spring is the most likely as it would at times allow the "plunger" to rest on the contacts. I've never actually seen this before, but this is my best guess. Tim

[wirewrkr]

I know that the budget is tight, but it's a really easy job to pull the starter and replace those contacts and do an inspection in there. The contacts are cheap as hell on Ebay. Well worth the time and trouble.

[fuquan]

I know that the budget is tight, but it's a really easy job to pull the starter and replace those contacts and do an inspection in there. The contacts are cheap as hell on Ebay. Well worth the time and trouble.

With encouragement like that I will not delay in pulling the starter.

[timsrv]

Here's an article that gets more in depth with starter issues: http://www.toyotavantech.com/forum/c...witch-question. There is also a link to the eBay contacts in the article as well. Tim

[fuquan]

If it's a missing solenoid spring or foreign conductive material inside the solenoid housing then the draw would be intermittent. I think a broken or missing spring is the most likely as it would at times allow the "plunger" to rest on the contacts. I've never actually seen this before, but this is my best guess. Tim

Update on my disappearing short: A couple days ago my van broke down due to lack of fuel. Unfortunate that it was in Canada and had to be towed to the USA (pita). Glad I have unlimited towing (better world club) as I've already used it three times this year, but that's not the point of this post. This breakdown was due to lack of fuel. I checked the wires going to the fuel pump and fuel gauge sender. The wires to the pump were bare / severed, both in approximately the same place. This must have been the source of my intermittent 0.36A battery drain. Sound plausible? I bet that plug became jostled and un-shorted when I disconnected my starter, and that is why I thought the starter was the drain. Here is a pic.

[timsrv]

Plausible I guess except this is a fused circuit & powered off when the ignition switch is turned off. The draw should have disappeared when you pulled all the fuses. One other thing I previously forgot to mention is the position of the ignition tumbler assy. If you look close at the tumbler (place where you put the key in) you will see it's labeled "Lock", "Acc", "On", & "Start". The key is only supposed to come out when in the "Lock" position, but these are cheesy tumblers & when they get worn the key can be removed from any position. Sometimes "van newbies" don't realize this and will pull the key out while the tumbler is in the "Acc" position, thus leaving some circuits powered up. I'm sure this isn't the case, but wanted to make sure you were aware of this possibility. For the record, (this is for the future benefit of newbies), in order to get the key to the "Off" position, the little black button above the key slot must be pushed while you're rotating the key. Tim

[fuquan]

Plausible I guess except this is a fused circuit & powered off when the ignition switch is turned off.

What if the two wires were not shorting with one another, but the + cable shorting with ground on the chassis? I am rather new to thinking about electricity, so maybe I am way off base. I finally reinstalled my stereo (just a deck) and am only drawing <=0.05A. The drain has not reappeared.

One other thing I previously forgot to mention is the position of the ignition tumbler assy.

Good point. I did check the tumbler several times... thinking that I must have made a silly mistake the key turned or the door ajar. The tumbler was always in the 'off' position. Depending on which key I use, I can pull it out in most any position. So I was wondering if the tumbler could be causing the drain even though it was set to 'off'.

Now that everything is back together I can't stop blowing dome fuses. Every time I put one in it will instantly blow if the engine is running and I open a door or flip on a dome light. If the engine is off (not sure if this is with key out or in) then the fuse doesn't blow.

[timsrv]

What if the two wires were not shorting with one another, but the + cable shorting with ground on the chassis? I am rather new to thinking about electricity, so maybe I am way off base. I finally reinstalled my stereo (just a deck) and am only drawing <=0.05A. The drain has not reappeared.

There can be different degrees of shorts, but typically a short of a large battery cable to ground would be quite spectacular. Typically when that happens sparks fly and "unintentional welding" occurs.

Now that everything is back together I can't stop blowing dome fuses. Every time I put one in it will instantly blow if the engine is running and I open a door or flip on a dome light. If the engine is off (not sure if this is with key out or in) then the fuse doesn't blow.

Here's a link to a previous thread on that subject: http://www.toyotavantech.com/forum/s...ight=dome+fuse Hint: For organization reasons, please use the search feature. If you find a similar thread & still have questions, then please make your post there. If you can't find anything on the subject then start a new thread . Thanks. Tim

[fuquan]

Final solution found. The real short was at the wiring to the driver door light fixture . The door panel is not properly attached to the door and closing the door caused the light fixture wires to chafe on the door... at first this caused the 0.36A draw, later my DOME fuse would simply blow as soon as I put it in.