Battery vs Alternator Issue

[sleepycruiser]

So I have been having issues with my 80 dying after a few days. I changed the battery with a newer one and having the same issues.

I checked for parasitic draw and seems there is a constant -.35...which seems pretty low. I pulled each accessory I have on the battery and the draw did not change so it shouldn't be an issue with anything I have connected in the past.

When I get into the LC it is DEAD...no lights or anything. Jumps off no issues. Battery gets up to about 14 volts. When I turn on the headlights on bright and some fog lights etc it will drop to 12.5 volts and remain pretty constant. Turn the vehicle off and the batter is around 11.7 volts. Turn the key to ACC and the battery light is lit up.

I checked the alternator by using a multimeter on the negative post and put the positive on the alternator case...got a -.02 or -.03. When reviving to around 1500 rpms I get about -.04 or so.

Where is my issue?? Connections on the alternator?

Thanks!

 

[mct75]

I have no idea how to help you, but I must applaud your efforts to provide us with as much data as possible and not take a single blurry picture. This thread is sticky-worthy.

 

[JohnVee]

@sleepycruiser Did this start before or after you wired in the new accessories?

 

[sleepycruiser]

@sleepycruiser Did this start before or after you wired in the new accessories?

Way after, but I checked for a parasitic draw after disconnecting the entire fuse box and the draw didn't change.

It actually started happening after I did the window up/down mod that allows you to use the windows when the car is off.....but I checked that parasitic draw by unplugging the entire window unit and no change.

Is it possible that the previous battery was on its way out and then killed the alternator as well? Seems as though both are working fine when tested....but obviously there is an issue.

 

[sleepycruiser]

I have no idea how to help you, but I must applaud your efforts to provide us with as much data as possible and not take a single blurry picture. This thread is sticky-worthy.

I used this video, as this guy seems to know a ton. I always search for his videos when I have an issue:

 

[LandCruiserPhil]

A couple things I would check -
Check for a voltage difference between the alternator, actually battery post, and the battery terminals using the same grounding point.
Check the termination of all grounds from battery to block and body.

 

[george_tlc]

You are trying to measure parasitic current with your meter on the voltage range.... wrong... Though you meter makes it REALLY DIFFICULT to tell which what the rotary selector is pointing at...

I'd start with your meter on the 10A range, then put the red end into the 10A hole on the meter. Use it is SERIES with your battery to measure the current. If not above 200mA (per your meter max), then you can put the meter on say the 200mA range and put the red end back into the V.ohm.mA hole.

Typical parasitic draw for an 80 (without problems) is typically sub 20mA.

Anyhow, your parasitic current measurements are erroneous due to incorrect use of your meter.

No idea how you are measuring the alternator -0.03, not clear what you have connected or how you meter is set up.

It may also be possible that you have blown the meter fuses in the past on the 10A and mA ranges if you don't know how to use them, so you may still get nothing useful displayed even when the meter is set to the correct range with the probes in the correct holes.

cheers,
george.

 

[sleepycruiser]

You are trying to measure parasitic current with your meter on the voltage range.... wrong... Though you meter makes it REALLY DIFFICULT to tell which what the rotary selector is pointing at...

I'd start with your meter on the 10A range, then put the red end into the 10A hole on the meter. Use it is SERIES with your battery to measure the current. If not above 200mA (per your meter max), then you can put the meter on say the 200mA range and put the red end back into the V.ohm.mA hole.

Typical parasitic draw for an 80 (without problems) is typically sub 20mA.

Anyhow, your parasitic current measurements are erroneous due to incorrect use of your meter.

No idea how you are measuring the alternator -0.03, not clear what you have connected or how you meter is set up.

It may also be possible that you have blown the meter fuses in the past on the 10A and mA ranges if you don't know how to use them, so you may still get nothing useful displayed even when the meter is set to the correct range with the probes in the correct holes.

cheers,
george.

The parasitic draw was tested using the 10amp setting (-.36)...it is one of the first pics but you can't see it. The other pic showing the 20 setting (-.03) was when I touched the alternator casing. I touched the negative terminal of the battery with black probe and alt casing with red probe. I did it according to the video.

 

[Cruiserdrew]

If your parasitic draw is 0.350 amps, that's huge. It means your battery is usually less than 12.6 volts which pretty much starts the cycle of sulfation and capacity loss. So it's very likely your battery is already bad. And thus being killed quickly by your parasitic load even after charging.

The very first thing I would do, is figure out where all that current is going. As George says, normal is 20-25 mA (0.020A) so your draw is more than 10 times that. It's very abnormal and should be investigated and killed off before you install a new battery.

Take out the Alternator and have it tested on the bench. That's the only way to really narrow down where to look. Once you know battery and alternator are ok, then it's wiring and loads. Check the circuits one at a time until you find the draw. My guess is if you added anything aftermarket, it's there. Stereo, brake controllers, amplifiers, lights, etc. Especially anything added upstream of the ignition switch (likelyou always on window mod). You have to find it though or you will be replacing a battery every few months.

 

[george_tlc]

As Drew mentions, 0.35A is way too high for parasitic. That's 0.35A x 24 = 8.4AH consumed each 24 hour period. A few days and you will have a discharged battery and that will kill the battery in short order. After that you'll be chasing issues due to a defective battery.

You need to isolate and track down the high current draw source, that is job #1.

Pull fuses, pull fusible links to isolate the problem. You can disconnect the alternator + to ensure you don't have dead diode(s) in the rectifier stack causing high parasitic current draw. Do all these measurements with engine OFF.

cheers,
george.

 

[sleepycruiser]

Thanks @Cruiserdrew and @george_tlc

First thing I am going to do is pull the jumper for the window up/down when the car is off. I have a feeling that is a part of it. I don't recall having these issues before doing that, but didn't think the draw would be that large.

I pulled all of the major stuff and tested when I pulled everything and there was never a change.

I will say that once I pulled the window jumper and put the large fuse back in the battery volts are actually going up when the vehicle is OFF.....but not much. 11.83 volts when off and sitting for a few minutes.

@LandCruiserPhil Did you experience any draw AFTER you took the window LED out?

 

[Dave 2000]

Diode failure in the alternator?

Regards

Dave

 

[LandCruiserPhil]

Thanks @Cruiserdrew and @george_tlc

First thing I am going to do is pull the jumper for the window up/down when the car is off. I have a feeling that is a part of it. I don't recall having these issues before doing that, but didn't think the draw would be that large.

I pulled all of the major stuff and tested when I pulled everything and there was never a change.

I will say that once I pulled the window jumper and put the large fuse back in the battery volts are actually going up when the vehicle is OFF.....but not much. 11.83 volts when off and sitting for a few minutes.

@LandCruiserPhil Did you experience any draw AFTER you took the window LED out?

IIRC the window switch light load is ~1watt. My parasitic load is higher than most due to electronics that never power down.

 

[Cruiserdrew]

Thanks

I will say that once I pulled the window jumper and put the large fuse back in the battery volts are actually going up when the vehicle is OFF.....but not much. 11.83 volts when off and sitting for a few minutes.

[COLOR=#ffffff]So that means nothing. You probably know this but a "12 volt" battery is kind of a misnomer. The resting voltage of a fully charged lead acid battery is 12.6-12.7 volts. When your truck is on and running, the voltage regulator will hold the voltage somewhere near 14 volts or a bit higher. That provides the "push" to charge a battery. An electrically dead "12 volt" battery will have a resting voltage around 11.6 volts. It's fully discharged at that point.

A fully dead battery, charged for just a few minutes, will still be a dead battery. Even if the battery is good, and will take a charge, it takes HOURS to fully charge it. I'd take the battery out of the truck and charge it with a decent regulated charger overnight. Then see what it's resting voltage is. If it's 12.6 or so, it may charge up even if it's capacity is low. If it won't hold 12.6 volts without a load, your battery is already bad.

But find the circuit with the parasitic draw. At least narrow it down to that and eliminate the problem. Otherwise all the troubleshooting in the world will still leave you with a discharged battery, and a discharged battery is damaged just by sitting at less than full charge, even for a short time.

You need to eliminate variables here. Charge your battery and then get it tested. Get your alternator bench tested. Find and fix your parasitic draw. Then you will fully grasp the extent of repairs needed. I'm going to go out on a limb and *guess* that you need a new battery and you need to fix your excess draw. It's likely your alternator is OK. But while it's out of the truck is a good time to replace the brushes. And then replace the bad parts and drive on.[/COLOR]

 

[sleepycruiser]

Thanks....so if I am testing the draw and remove each connection to the battery one at a time (one is a Blue Sea fuse box, one an amp wire, etc) and the draw doesn't change then it should mean the parasitic draw is NOT coming from that part of the equation, correct?

 

[Malleus]

Maybe. To simplify troubleshooting, although not mandatory if you can keep the revised circuit diagram in your head (or if you're really high speed, have marked up an OEM EWD), keep all the disconnected "accessories" disconnected until you find the problem. It's possible there's a compounded problem, if there is more than one additional tap in the OEM circuit.

Don't forget to look at the connections when you break them while troubleshooting. A closed loop needs to be closed in order to work.

 

[sleepycruiser]

So I reversed the auto window up/down last week and put the fuse back in. Tested the battery every day but didn't crank it. Tested ok. Went out today and it cranked right up....so it was the window mod that was creating the issue in my case. Weird for such a small draw, but before it would be dead after 1-2 days....now it has been 6 since the reversal....and it cranked no problem.

 

[Cruiserdrew]

So when you start your truck, what does the voltage rise to at the battery terminals? If it's less than 14 volts, you still have a problem.

Glad you have a likely solution though.

 

[sleepycruiser]

Studdered a second and then when cranked is around 14.5.