Slow battery drain, procedure for checking?

[Speach]

I got this van with low miles and it is in pretty good condition. I have been doing a ton of neglected maintenance. New front end, plugs wires, cap, rotor, master cylinder, brakes etc. I have something draining the battery over night. I thought the problem was the ignition, but since rebuilding that I am still having the problem. Does anyone know of any typical issues like this? Im thinking the regulator is probably fine since its a Toyota and I will be tracking down any grounds that might be the culprit but if anyone has advice, I'm all ears. Im ready to drive this thing regularly but not until I fix this drain.

[timsrv]

An overnight drain would likely be a shorted diode in the alternator. Read through my 1st post in this thread: http://www.toyotavantech.com/forum/s...lternator-woes. As prompted in that post, disconnect your alternator wire from the "+" box and tap it on the post there. If it arcs when the connection is made/lost, then it's a shorted diode. Tim

[Speach]

Tim. You are awesome! Thank you so much for your work o the site. I read the thread that you referred me to. Ill be getting into it this week. I just installed a new master cylinder and rear wheel cylinders last week so I'm taking a few day break.

[Speach]

Well I tool apart my alternator and everything looked great. I still installed a new regulator but after a full charge my battery drained in about a day. GRRR. Its the one single thing I need to fix before I can drive it daily. Today I'm on the ground wire hunt.

[timsrv]

As prompted in that post, disconnect your alternator wire from the "+" box and tap it on the post there. If it arcs when the connection is made/lost, then it's a shorted diode. Tim

Did you do this test?

[Speach]

Yup I did that test. No spark, and my diode has the coating and looks bran new.????

[Speach]

Today I checked out the ground strap. Mine was horrible at every end. Its interesting that from the battery the ground goes from there to the chassis then on to the engine block. Is there a reason why this is necessary? One cable grounded at two locations. Anyway i put a new ground strap on and mounted it the same as the factory. There are usually reasons why things are the way they are. So now I'm gonna wait a day and see.

[timsrv]

Then the next thing to do would be put an amp meter on the battery & record draw. Next have somebody watch the meter while you start pulling fuses. When you pull a fuse that makes the draw go away, take a closer look at that circuit. Acceptable draw is .05A or less. Anything over that should be investigated and repaired. Tim

[Speach]

Thanks. Yea so I checked my van today and found a dead battery. Apparently it wasn't the ground cable. Glad I put a new one on though because it needed it bad. So please help me understand how it works to take the fuses out. Doesn't the fuse keep the circuit working? I have heard this is the way to locate a problem but I just don't fully get it?

[timsrv]

If you have a meter capable of testing DC amps hook it up in series with the battery. To do this disconnect one of the battery cables, then put one lead of the meter to the battery post and the other lead to the cable. Draws on the system will now be displayed by the meter (should be less than .05). If your draw is enough to drain the battery overnight, then I'd expect it to be around 2 amps or more.

In theory, since most of the power drawing circuits come off the fuse box, the draw will most likely be passing through one of your fuses. When you pull a fuse you are essentially turning off the circuit powered by that fuse. If you happen to pull a fuse and see amp draw drop significantly, then you'll at least know what circuit to focus your attention on (use the diagram below to determine what each particular fuse powers).



Just remember that when the doors are open you'll have some draw associated with that (door lights and dome lights), so when you pull the dome fuse you're going to see a drop there. You should start testing by determining how much that draw is so you can disregard it. If you think you found the draw, close the doors and confirm it's below .05 A. If pulling fuses doesn't expose the draw, try pulling the big alternator wire from the + box to see if draw goes away. Tim

PS: Word of warning: Don't try to start the van with your meter hooked up in series. Most meters max out at 20 A or less. Starters pull around 100 A, so if you try to start you will likely smoke your meter. Tim

PPS: One more thing, if you're "newish" to the van world, you might not realize the proper way to shut-off the ignition switch. There is a little black button above where the key goes in. Before pulling the key out, rotate the ignition counter clockwise until it stops. Pushing the black button allows you to rotate the key counter clockwise even further. Pull the key out of the ignition only after you've rotated to the max CCW position (while pushing the button). If you're pulling the key out without pushing button/rotating to max CCW, then you're not actually shutting everything down. Tim

[Speach]

Man your awesome! thank you so much for the time. I will be back in it at some point over the next few days. Now I understand how the pulling the fuses helps locate the problem. The people who owned it before had a aftermarket alarm hooked up at some point because I found remnants of it. I don't know what circuit its run through but it would be my guess my problem might be found there. Thanks for the heads up as far as the ignition. When I first purchased the van and noticed the drain I realized that I had been taking the key out in the accessory position and I thought that was my problem. The previous owner I guess had worn down the key so much to make this possible. I then took my ignition off and had them cut new keys and found out that the ignition needed to be rebuilt as well. So now the key and ignition work great, and I know how to correctly take the key out. I love this van and it's been a lot of fun working on it, and I will be super hyped when I can call it my daily driver.

[Speach]

Well. I just spent some time testing. Just after getting done my meter went crazy bringing up a ton of random numbers. So when you do this you do it with the van in the off position correct. I assumed so because the drain is happening when it is off.

These are the numbers I got:
Battery-12.83

All fuses in - 10.65
Tail - 10.63-65
All others - 10.66-69

From this it seems that the tail is the odd man out. This Van was one of those between Factory and dealer conversions. It had auto locks etc, rear defog, and washer bottle in back.Since getting the van I replaced the rear door with another that does not have these options so the auto lock etc connectors are wrapped up in tape but I did have the drain before installing the new rear door so I'm not sure what to do. I took off the rear lights and didn't see anything out of the ordinary. The only thing I know to do at this point is to leave out the tail fuse and see if it still drains hoping iv'e isolated the problem. It looks like the tail fuse is connected to many lights which could lead to the alarm that was installed. Any suggestions?

[Speach]

This is some wiring that seems a bit out of place. Although it looks to be above the quality of a do it yourselfer. I think this wiring has to do with the alarm. Does anyone know if your van has these extra fuse links and the wire placed in the engine fuse spot to power something? The brown wire that is plugged in the fuse box goes to the blue connector and so does the grey wire that was just capped with a delete plug at the end. The upper two plugs go together but the way I found my van wired is the far left blue plug was plugged into the blue plug that has the fuse links on it. I have tried to plug in the left two plugs because that seems to be the way the factory would have originally had it. I don't know but if someone can let me know what or how these blue connectors look on other vans that would be helpful. Oh and everything seems to work fine either way I plug the blue plugs in.

[timsrv]

The numbers you posted don't make any sense. I think you need to read the instructions I gave more carefully. I'd give more detailed instructions regarding your meter, but there are lots of different meters out there. If you post a picture of it I'll tell you how to hook it up. I hate wire hacks (which is what you have). I especially dislike fuse taps (last picture) as they damage the conductors in the fuse box.

Oh, and one more thing. When you did the + box wire tap test, was the battery charged? Testing things with dead batteries doesn't work and is a waste of time. Tim

[Speach]

I tested it on the 12 volt setting. Aren't these numbers consistent to a 12volt battery charged. I took the power wire off and put one prong to the positive on the battery and the other to the hot battery cable to be in series. Oh and yes every bit of testing I have done has been with a fully charged battery including the plus box diode test.

[timsrv]

1st off you need to have a meter capable of measuring DC amps (not all do). If yours does you'll need to set it in the DC amp mode (not volts). On most meters you will also need to insert your red lead into another port specific for amp testing. Never put your meter between the positive & negative terminals of a battery while it's in this mode (smoke will likely come out of it) . If you post a picture of your meter or give me a make & model I'll tell you if it's capable of doing the amp draw test. Tim

[Speach]

Yea I smoked my tester. Ha Ha. I just got a new one and see where it has the volt settings. What did you mean by putting one lead one the battery post and the other on the battery cable. I must have misinterpreted what you were saying.

[ninz30]

Google "how to do a parasitic draw test." I'm sure you'll find more info, so you can better understand how to perform the test.

[timsrv]

Sounds like you were trying to find out how many amps were in your battery . Most average automotive batteries will put out around 500A when shorted across the terminals. Unfortunately most automotive amp meters max out at around 20A. When you exceed this amount, smoke usually ensues. When the meter is set in the amp mode, the meter becomes a conductor. Putting the leads between the positive and negative of a power source (like you'd do for checking voltage) is the same as shorting out with a hunk of wire..........except meters are more expensive than wire. If you do this downstream of a fused circuit you will usually blow the fuse & spare your meter. If you put the leads directly across battery terminals, exciting things will usually happen . Sorry for not explaining this clearer. Hope it wasn't an expensive meter. I think every tech out there has learned this lesson the hard way . After using your meter in the amp mode, always put the leads back to the volt position or remove them completely. Since volt tests are the most common, it's easy to grab a meter to check voltage on something without realizing the leads are still in the amp test positions (don't ask me how I know this) .

When I gave instructions I was being literal. You disconnect a battery cable (+ or - doesn't matter), then you complete the circuit between the battery and the disconnected cable using your meter as the conductor (put one lead on the battery terminal, and the other on the disconnected cable). This routes all the power being consumed through your meter and is the most accurate way to determine current draw. Just don't try to start the van or anything else that would cause it to pull more current than your meter is capable of carrying.

Once your meter is hooked up (as described above), turn something on (like a dome light) to verify it "sees" it. Dome lights pull around .5 amps (give or take). Tim

[SamPrevia]

Most multimeters can only handle 10 Amp max, and only for a short period of time. 30 to 60 seconds. Here's clear video showing how to measure current using a typical multimeter.

https://www.youtube.com/watch?v=7lwZkl0yBqA