Where’s my electrical guys

[Craigerz]

For the past 6 months I’ve had a drain on my battery. If I let it sit for more than a week it’s dead. I’ve taken the battery and had it tested and they said it was good. Firgured I might have a alt issue since I’ve replaced it. So I did the “short” test. Put a test light in between the neg terminal and neg cable and it lit up. Doors closed and all that stuff. Hook up the meter and it goes from 9.1, there’s a click under the dash, and quickly goes to 3.0. Took out the alt to make sure it was a diode or Voltage regulator and did the same thing, so I hope that means that’s ruled out.

So before you ask what 9.1 to 3.0 means...... that’s what I’m here to ask y’all. And no besides reading volts I don’t know what any of that other stuff means.

 

[sehaare]

First things first, I'm assuming that you have the ammeter hooked up between the negative terminal and the negative battery cable with the engine and all accessories/light etc off. you are on teh 200mAmp scale reading 3.0. that woun't be that accurate switch it to the 20mAmp scale and see what you get. Unfortunately once cars started using computers that go into and out of sleep modes finding a parasitic load isn't as easy as it used to be. Do a search here and on Youtube for parasitic drains. There was a long discussion either here or my VW group a while back about how to find what is causing the drain. You used to be able to just start pulling fuses until it went away, now you have to worry about waking up a computer but just opening a door to get in to pull a fuse. You will find a good video that shows how to take that into account. You basically have something that is draining the battery and you have to isolate it and get rid of it.

Good Luck

 

[Craigerz]

When I change the meter it just changes decimal points. My next step was pulling fuses

 

[J_C]

One thing I see wrong is you may have already blown the fuse in your meter. Do not set it to 200mA yet, the initial current draw when the battery saver circuit is active (disconnecting and reconnecting battery, even just opening a door less than 40 minutes earlier can cause this) EXCEEDS 200mA so assuming the meter has a 200mA fuse in it, that should have blown the fuse.

If a 2nd gen vehicle has the correct current draw you might get away with using a meter with a 400mA mid-low current range but otherwise will need to use the 10A range on that meter.... is one of the reasons those cheap meters aren't the greatest for some uses... not even sure if it has fuses on both the 10A and 200mA ranges!

So, you'd have to test the meter in a different way to verify it but you are probably off by a decimal point if the fuse isn't blown, which I suppose it isn't if I understand your post correctly that when completing the circuit you hear the battery saver relay under the dash click on which is normal.

The way to test this is do not operate anything electrical for ~45+ minutes, including opening and closing doors. When you disconnect the battery terminal, have your meter leads already on the battery terminal and the battery cable so you are never breaking the circuit. This will give you your reading for completely off, without the battery saver relay activated at which point you should read a few tens of mA. Unfortunately the HF meter you have many not be able to indicate that in the 10A range, may round down to 0 unless the excessive current drain is high enough to round up to 0.1A.

Regardless, if in the 10A range it is rounding down to under 0.2A, then if your 200mA range fuse isn't blow you should be able to repeat the test in 200mA range as long as you do as described above, leaving the vehicle undisturbed so the battery saver circuit isn't live, THEN you can pull fuse and note the change after you devise some way to keep the meter probes in constant contact with the battery and cable so it doesn't reset the battery saver time-out period.

The battery saver relay itself is one component that can fail. You could try pulling that out to see if it makes a difference in the current reading, swap a different relay into its position, and if that makes a difference the relay is bad. If that doesn't make a difference and the current is still excessive above a few tens of mA, look at what is on the battery saver circuit and test each of those for excessive current with the respective fuse out.

Another thing to try is disconnecting the cable between the battery and alternator, measure that in 10A range then if under 0.2A reading, try it again in the 200mA range. You should have 0mA between the cable and alternator lug when the engine is off. If there is any current there it is probably a sign your alternator has failed/leaky diodes.

 

[Craigerz]

Thanks for the help. The meter is some 10 dollar job my grandpa got on sale somewhere and bought 10 of for all of us lol. I don’t know the first thing about electricity unless I can read instructions and that’s about it. I have a Limited but I have disconnected just about every electrical thing on it (with instructions from people on here).

That being said I understood about half of what you guys said. I did disconnect the battery and let it sit for 20 minutes or so Incase the battery saver was still on. The alternator is completely disconnected and it still does the same thing.

Might just bite the bullet and call my dad.....

 

[Rick]

If the top of the battery is very dirty the battery can self discharge from current flowing across the top of the battery between the posts. Just a thought.

 

[EB4X]

70% of the time a parasitic draw is from radio / stereo (especially if aftermarket).... get / log reading from battery tonight when done driving...pull radio fuse out.... re-test battery in morning - if same reading as night > bingo!

 

[J_C]

Something else I just noticed is you have the meter set for 200mA (which you shouldn't do yet as mentioned previously) but have the positive meter probe in the 10A socket which can only be used with the 10A dial setting. If you later attempt to measure in 200mA mode (are certain it won't blow a fuse because the 10A measurement is below 0.2A) the probe needs to be in the lower mA socket.

That would also account for the strange/inaccurate current readings.

 

[Mbrooks420]

I’d leave it in the 10 amp socket, and use it on the 10 amp setting. If you are experiencing a real draw it’s likely it’s going to exceed an amp. Accuracy isn’t really important here, it’s just a significant change you are looking for.

 

[J_C]

^ Maybe it will exceed an amp but might not considering he wrote the time period of a week. A week at half an amp or less could be enough to drain a battery, especially if the battery is prematurely aging from being drained so deep over and over.

 

[masospaghetti]

Try the 10A setting but don't go too crazy with it, usually the 200mA plug is fused (which might be blown by now), but the 10A plug is not -- if you go above 10A you'll probably fry the meter.

Best advice is to pull fuses until the amperage draw goes to zero but the radio is a good place to start. Could also be silly things like your power seat motors/inflators shorted out, cigarette lighters, etc but pulling fuses will show you.

 

[Mbrooks420]

If the fuse was blown I’m pretty sure it wouldn’t read any amperage. The fusing will be higher than the range of the meter.

 

[imp]

If the top of the battery is very dirty the battery can self discharge from current flowing across the top of the battery between the posts. Just a thought.

@Rick
This post I really like! Because that crud which collects on top of batteries contains a significant amount of acid, which conducts electric current quite well. But an amp or two would mean 12 to 24 watts being wasted, quite a bit of heat generated (not enough to feel, proly, given the big area of the battery top.

It is an interesting thought, though. The batteries which lasted longest for me, always had a bit of baking soda water poured over them every 6 months or so.........

imp

 

[sehaare]

This is not how I used to look for parasitic drains, BUT after I watched this video I was converted. As the You Tube Video says. this is the BEST way to look for your drain.

 

[J_C]

^ Good way if it finds the drain, not all drains go to a circuit with a fuse there.

The video does make a great point that is seldom mentioned, to latch the door latch so you leave it open, aren't opening it and waking the vehicle up to increase parasitic drain. Then again you shouldn't need to do it to "all" the doors as the video instructed, just the driver's.

Latching it will not work on very old vehicles with the pin-plunger style door switch rather than one on the latch mechanism that ours have, but most vehicles that old won't have the wake-up current draw because they don't have any battery saver type circuit, and yet you'll still have to account for that because with the door open the interior light is on.

 

[J_C]

If the fuse was blown I’m pretty sure it wouldn’t read any amperage. The fusing will be higher than the range of the meter.

The way he had it hooked up in the 10A socket, wouldn't be putting the current through the 200mA range fuse if present.

Indeed the fuse rating should be a bit higher than the 200mA itself, and ironically on dirt cheap generic meters you may have another problem that make the fuse less likely to blow or at least an unknown variable and safety hazard (at least to the meter itself in this case), that generic fuses often vary wildly from their designated current rating, often need significantly higher than the rated current to blow.

The same is true for automotive fuses, so it's not a good idea to get cheap Chinese vehicle fuses as the wiring may fry before the fuse trips if there's a fault. Sometimes they even melt themselves into the fuse holder which isn't much fun to fix. They can also throw off the voltage readings in the video sehaare linked to.

 

[Craigerz]

Well it’s time to start digging into this problem again.

So assuming I have the meter hooked up correctly on the negative battery terminal this is the reading after letting the vehicle sit for an hour and a half. Yes the meter was hooked up the entire time.

Pulled fuse 6 under the hood (alt/reg) and no change at all. Pulled fuse 25 from reading other people’s post and it dropped from .29 to .01


So I’m assuming that’s a safe place to start looking? I do t have an aftermarket radio or amp either.

 

[J_C]

0.29A (290mA) is within an acceptable range for current draw while the battery saver circuit ticks down to zero, around 40 minutes.

If one of the triggers to it, for example a door latch switch, is broken, it may stay in this current draw state. With everything working properly, it should drop down to less than 50mA.

Since pulling that fuse resulted in only 0.1 (10mA), it is not only disconnecting something that is a problem, but also disconnecting something that is a normal source of power draw when everything is working properly.

Yes you should look at everything going through fuse 25. On my '98 that is shown as GEN, instrument cluster, and securi-lock. Is that the case on yours? The more common circuit where people see the excessive drain is through the battery saver circuit which on mine is fuse 26.

Had you tried the other fuses? I might try the others to see if you can narrow it down any further, BUT those relating to the GEM, pulling power and restoring it by pulling the fuse, may reset the battery saver count down timer and put you back at 290mA, fouling the test.

If it is your gem, I don't know all the triggers that could make it stay in a higher power state, but one thing you could try is keeping the fuse in and unplugging the gem. However if the problem is tied into the battery saver circuit, pulling a perfectly good gem could turn the battery saver circuit off so it isn't so clear the gem is bad.

It is a bit hard to speculate more than that. Much of this needs looking at a wiring diagram (some of which are linked in my 'sig, not sure if "all" are 100% accurate for a '97 5.0L) while you are using a multimeter to probe for power or ground in wires where there shouldn't be any with the vehicle off.

 

[Craigerz]

Well the .29 is the reading after sitting for an hour and half so that should be when everything went to sleep.

If .29 is 290mA and it dropped to .01 shouldn’t that be a drop of over .280 mA? Sorry electrics isn’t my thing just trying to follow instructions.

without being technical I guess I can pull fuse 25 leave it out and if it starts after 3 days that’s the source?

i haven’t tried any other fuses, it gets dark 20 minutes after I get home.

My owners manual doesn’t have a fuse for the power saver relay on any of the fuses listed.

 

[J_C]

Yes the 0.29A after an hour and a half should be when everything went to sleep, but something not going to sleep could be the issue, then it is whether it is a control module or something it senses that is the problem and if something it senses, if the thing is bad or the wire to it.

Yes. 290mA dropping to 10mA is 280mA difference, except your meter may not be able to reliably measure only 10mA on the amp scale setting, but still it is relatively close enough to know there's a big change.

If you measure only 10mA with fuse 25 out, it is already safe to assume it will start after 3 days unless you have a bad battery or alternator failing to charge it, but that would be a separate problem if your 1.5 hour drain rate is still too high at 290mA.

Are you sure your manual doesn't have fuses for those things? The following diagrams below are out of my '98 manual, except color coded in light fruity colors for visibility from a color laser printer, lol.

The main thing I am thinking is that your 290mA reading looks like what would happen if the power saver circuit never shuts off, like something it senses is still triggering it.

Maybe I should back up and ask, what is the current reading BEFORE much time has elapsed, with all doors shut and lights off, what does it read right way with the engine off? Is it the same 290mA or is it nearer twice that? If nearly twice that, you have an independent drain. If nearly the same then it's probably a power saver circuit trigger.