repetitive dead battery

[LI Disco]

recently had my mechanic replace the starter and battery.

when the car sits for a day or two without being driven the battery is dead upon start up. The truck takes a jump start and hold the power everyday it is driven, however if I let it sit for a weekend it is dead when I go to start it


I Had the alternator, starter, and battery tested all are good.

my mechanic is clueless to what keeps causing the battery to die, and starting to get frustrated,

any ideas?

 

[ptschram]

my mechanic is clueless to what keeps causing the battery to die, and starting to get frustrated,

any ideas?

Find a new mechanic. This is such a common malady that anyone who gets frustrated by it should find a new line of work. Especially when it's a '95 DI, the simplest Land Rover other than a Series truck.

 

[LI Disco]

Find a new mechanic. This is such a common malady that anyone who gets frustrated by it should find a new line of work. Especially when it's a '95 DI, the simplest Land Rover other than a Series truck.

okay well how about pointing me in the right direction on what this issue is.

thanks

 

[ptschram]

okay well how about pointing me in the right direction on what this issue is.

thanks

The issue is that you have your truck at a shop where they do not know how to fix this problem.

First step is to put your trusty amp meter in line with the battery and begin disconnecting circuits until the current draw goes away. Most likely, it is the alternator as they are known for doing this while still charging the battery once you get it running.

 

[Papillon]

10 to 1 odds that P.T. just solved your problem.

 

[junkyarddisco]

the bulb in the glove box?

never actually figured a way to verify that one..

 

[ratboy]

10 to 1 odds that P.T. just solved your problem.

PWND!

 

[Cozy41EF]

They make a tool just for this purpose, it is a fused ampmeter, that has a plug that looks like a two blade fuse, you just remove each fuse and plug it in, it tells you how much current each circuit draws with the truck off.

 

[CandiMan]

okay well how about pointing me in the right direction on what this issue is.
thanks

What everyone is trying to say is that your truck has a amperage draw. Some folks also calls it parasitic draw. They both are the same. Besides changing the alternator and starter, you didn't mention anything else that your mechanic has done to correct the issue. That is why PT has suggested a different mechanic. A amperage draw is a common fault in cars/trucks. It takes knowlegde and basic diagnostic skills to find the draw. Most parts changers don't have the knowledge to find a amp draw. You have to decide if your mechanic is a parts changer or has the knowledge.

I can't recall any common areas that might be associated to amperage draw.

Good luck.

 

[ptschram]

Mike:
You are a perfect example of my forming a wildly incorrect first impression of someone!

Your first posts did not exhibit the knowledge your later posts have.

The early Discos do not have the complex circuits the later ones have. There are no real computers and few other "Black Boxes" to deal with that could be remaining "awake" and not going to sleep.

The most common single reason for a mysterious parasitic draw is the rectifier in the alternator that will allow for a huge draw, several amps. The second most common is folks who make it a habit to leave the key in the ignition, thus keeping the interlock solenoid hot.

As has been described, the easiest way to find this draw is to insert your amp meter in the ground circuit at the battery (I say ground as it has a single cable whereas the positive has two and one might be our culprit!). While observing the current with all accessories off, AND the key out(!), begin removing fuses one at a time. When the current draw goes away, back up to the last fuse pulled and you have the circuit. To check the alternator, with the meter in place, disconnect the big-ass wire that goes to the alternator from the battery. Otherwise, once you find which circuit it is, you hae to decide if you can live without that circuit, or if further investigation is necessary.

 

[sbsrlewis]

PT could you please expand your instructions on inserting an ampmeter in the ground circuit? I can't figure out how you would do this. I'm having similar problem with my Bronco II.

Steve

 

[Ol'Drippy]

The second most common is folks who make it a habit to leave the key in the ignition, thus keeping the interlock solenoid hot.
.

Hmmmmm.... Glad to learn that PT, I've never thought about that, but it makes sense.

 

[rmuller]

To check the alternator, with the meter in place, disconnect the big-ass wire that goes to the alternator from the battery. Otherwise, once you find which circuit it is, you hae to decide if you can live without that circuit, or if further investigation is necessary.

pt -- If it is determined that the alternator is drawing when the truck is off, what is the recommended fix? replacing alt? or is it a wiring issue?

 

[ptschram]

pt -- If it is determined that the alternator is drawing when the truck is off, what is the recommended fix? replacing alt? or is it a wiring issue?

It is usually due to one of the diodes not being a diode anymore requiring replacement of the rectifier. It's easier to replace the whole damn thing.

 

[MUSKYMAN]

the biggest problem searching these is that the alternator does not ground all the time.

they are pretty weird in how they do it.

The diodes are the cause and they dont just ground the second the key is tuned off. The way I first discovered this was I had tracked the drain (about 4amps) to the main lead on the alternator but as I was standing over it it stopped drawing!

I took this alternator in to my rebuilder and told him about it. he went ahead and tested it and said it was fine. I decided to have him replace the voltage regulator anyways. He left the unit sitting bolted into his test bench I said I would see him in a couple hours and left. about 15 min later he called me saying that while just sitting on the bench the diodes all the sudden shorted to ground and just like I said there was a short.

I am betting that this is the problem with this truck as it is one I have since seen a number of times.

 

[ptschram]

PT could you please expand your instructions on inserting an ampmeter in the ground circuit? I can't figure out how you would do this. I'm having similar problem with my Bronco II.

Steve

Disconnect ground lead. Turn meter to highest amp setting, move probes to amp connections. Attach black lead to battery, red battery to battery cable, read current. In this configuration, all of the current flows through the meter, thus you want to be n the highest scale to void blowing up the meter.

Most measurements are made in parallel, this one is done in series.

 

[ptschram]

the biggest problem searching these is that the alternator does not ground all the time.

they are pretty weird in how they do it.

The diodes are the cause and they dont just ground the second the key is tuned off. The way I first discovered this was I had tracked the drain (about 4amps) to the main lead on the alternator but as I was standing over it it stopped drawing!

I took this alternator in to my rebuilder and told him about it. he went ahead and tested it and said it was fine. I decided to have him replace the voltage regulator anyways. He left the unit sitting bolted into his test bench I said I would see him in a couple hours and left. about 15 min later he called me saying that while just sitting on the bench the diodes all the sudden shorted to ground and just like I said there was a short.

I am betting that this is the problem with this truck as it is one I have since seen a number of times.

It's not weird at all, it's most likely a thermal function that as they heat up, they open, cool down, short to ground.

C'mawn Thom, you know your chemistry/physics better than that!

 

[chuck c]

I had this problem. That odd 4 amp draw it the tip-off, see if you have it. Another simple test is let the truck sit on a cool day, then put your hand on the alternator. If it's warm, bingo. The one of the diodes has turned into a resistor. It puts out current fine when running, but when stopped it's heating the engine compartment. The LR is the only vehicle I've ever seen do this, usually when a diode burns out there's no current output. You need a new alternator. Replace the belt while you're at it and save the old one as a spare.

Look at it this way: it's a more survivable failure than in any other vehicle. Even with a burned-out diode you can still drive it if you feel like disconnecting the battery every time you stop!

 

[LI Disco]

I did the amperage draw test over the weekend pulled all the circuits and everything was okay. next I did the rectifier in the alternator test.. and bingo that was the draw.. replaced the alternator and all is back in perfect working order..

Thanks to everyone who helped me through it

 

[Lake_Bueller]

Gotta love Dweb! This 4 year old post helped me solve my battery drain problem. I recently replace a "squeeling" alternator with a high output that I had in the garage. Immediately started having parasitic drain problems after 1-2 days. Alternator was charging the battery fine. But a diode test revealed the problem.