Ill specifically get the wires in the altanator checked tho...thanks *S*

 

I had a vehicle years ago that kept draining the battery. After several checks, It was found that the fuse box was loose. How did this drain the battery, I don't know, but it fixed the problem.

 

The easiest way to find a draw is to connect a test light between the negative battery post and the cable. If the light comes on, you have a draw or, in technical terms, a closed circuit. Make sure you close the doors so the cab lights aren't on, this will cause a false reading since the door switches are closed. Also, unplug the underhood light if you have one.(this could also be the cause of your problem if it doesn't go out when the hood is closed). Start pulling fuses out until the test light goes out. This will tell you the circuit that is suspect. Concentrate on this area first. Amps are one thing, but it takes voltage to make those amps work. I used to work on semis and I was very busy with electrical problems. Electricity isn't easily understood by most technicians, let alone most people.

 

BTW, I've seen more alternators be the cause of amp draw than not, especially if it they have some age on them. Start by removing the positive lead from the alternator when using the above test light method. I'd be willing to bet that it is the cause.

 

WOW!!,Rob,

Those were some great posts. I'm not hoving that problem now, but I have in the past. Now I'll know how to trouble-shoot it.
THANKYOU! Keep up the good work.

wmcnally

 

[font size="1" color="#FF0000"]LAST EDITED ON 04-Aug-01 AT 04:18 AM (EST)[/font][p]thanks so much rob.....
I am going to do exactly what you suggested...thats a sure fire way to nail the problem...and your right...most people dont know anything about electrical stuff...especially me
thanks again *s

 

A test light will work (more or less), if you don't have an ammeter. A bulb that lights up with 1 watt would tell you that there is a .083A current flow, at 12V. (watts = volts x amps) But, while the bulb is added in series like this, it changes the circuit you are testing. The 12V drop has been divided between the test light and the circuit(s) that are drawing current. It becomes a little complicated to determine what the current draw would be when the light is removed from the circuit.

Make sure you aren't using a bulb that is too small or you will be pulling your hair out trying to find which circuit is drawing the current. Many circuits are drawing some current all the time (radio memory, PCM, keyless entry, remote starter). Too large of a bulb, and it won't be seeing a small draw that may be the culprit.

But, if you have an ammeter, I can't see any advantage to using a test light instead. Using a test light in this way would be kind of a poor man's ammeter. It works OK, when you're dealing with large current draws, not so good for small draws.

If his measurement of .03A is accurate, it should take several months to drain a good battery. So, assuming his battery is good, the drain must be higher than his measurement, at least intermittently.

If it were me, I would seriously consider one of those solar battery chargers. Well, I would attempt to fix it properly. But, at some point you have to call it quits and sell the truck, or go for the easy fix. These electrical bugs can drive you nuts if you let them. I have heard many stories, about seemingly simple problems, that should have been easy to fix. But, after spending way too much time, very good electronic techs still had no answer.

In electronics class, we had a multimeter that would record amps on a paper wheel. You could set it up to run for a few days at least, and record current thru a circuit while you were away from it. It was cool, but it probably wasn't cheap. It would prove the draw is intermittent, but still may not help you in the end (still wouldn't know what is causing the problem).

Also, batteries can have an internal short that would be draining it down (even new ones). You won't be able to measure it (from outside the battery). But, if leaving the battery disconnected while your away cures the problem, then that's not it.

Hope you figure it out.

 

jerry, You've made some good points regarding my test light test, however, any draw that is able to illuminate a test light to the point where it is clearly visible in daylight is far too much. The test light is an easily visible instrument that can be remotely positioned while pulling fuses from the block. Heck, I have even used a buzzer in situations when I couldn't see a test light. I have yet to fail with this method. My opinion about ammeters is, they are good when dealing with individual circuits and for people that understand them. The general public would have no use for such sophistication. The test light is easier to use since it's either "on" or "off". There's no confusion. Granted, test lights should never be used when diagnosing electronics since the amp draw of the light has the potential of damaging components.

The likely hood of having 2 "bad" batteries in a row is possible but rare. I'm placing my bet on the alternator.

 

a quick easy way to check your alternator:

start the truck
pull the ground lead off your battery.

if the alternator is bad your truck will die. Replace it and your should be good to go.

there is a chance the alterator may be "going" bad, giving weak voltages, in this case the vehicle may stay running, to see if it can keep up, turn on a bunch of electrical components, lights, stereo,.fog lights,..if the alternator is going bad, it will not be able to handle this kind of load.

I read earlier of other people who were having a problem with their cargo lights and interior lights coming on for no reason at all, ( a problem most have found to be a door switch), are you sure your lights are not coming on?


other than this, i agree with the amp meter test above, you may need a hand reading the meter while you pull fuse by fuse, but it will definitely give you a quantifiable current draw per fuse. Otherwise, you will only be able to say,.."well, the light was lit, off, or "kinda lit", it is much better to say, .2 amps, .09, and so forth.

keep us posted.

 

Alright, I found a good [link:www.repairfaq.org/ELE/F_Car_Battery.html#CARBATTERY_022|Car Battery FAQ]

Here's what that FAQ says about checking alternator by disconnecting the battery:

15.6) Test the alternator by disconnecting the battery with the engine running.
A battery as like a voltage stabilizer or filter to the pulsating DC produced by the alternator. Disconnecting a battery while the engine is running can destroy the electronic components, e.g., computers, radio, stereo, alarm system, etc., or the charging system. [font color=red]Just say NO![/font] if anyone suggests this.

I have tested an alternator by disconnecting the battery. But, I have since learned that it's a bad idea. I know several people that have done it, and I've never heard of any damage as a result. But, I say, "better safe than sorry". The way I check an alternator now, is to simply check the voltage at the battery terminals while the engine is running. Should be around 14V (differs from car to car). Read that FAQ for more info on it. Also, read about parasitic drain (although we've covered about everything in this thread already).

 

[font size="1" color="#FF0000"]LAST EDITED ON 08-Aug-01 AT 11:02 AM (EST)[/font][p]so if I should not test my alternator that way how should I test it? I think it may be the culprit....I dont know.
should I just bring it to a local company here that secializes in electrical systems and alternators and stuff, and have them check it out? I really dont relish the thought of forking out that much money for them to be able to tell me nothing (its really expensive there) Is there a safe and sure fire way to test my alternator, without resorting to that?
I dont know much about electronics, jerry....what if it isnt at 14 vlts, what does that tell me? and what if it is higher or lower?

 

Hey 007, take this advice from a former truck technician. Try the test light test I described. It sounds obvious you have some sort of parasitic loss somewhere. Disregard anything said about ammeters for the moment. This is only going to confuse you. If the test light is lit, unhook the positive lead from the alternator. If the light goes out, there is an internal short in the alternator. It's your choice to reman of rebuild. If it doesn't go out, try pulling fuses until it does. If the light is dim, this could be normal due to on-board electronics that need voltage to keep memory alive ie. engine ECU, radio, etc. Be concerned only with a bright test light. Alternators produce amperage as well as voltage. The only way to accurately test an alternator is to apply a load to it and measure its output. This is usually done on vehicle with a carbon pile tester or on a bench rig with similar setup. Something else you may want to look at are your ground connections. If there is too much voltage drop due to a poor ground, a brand new battery won't start your truck. It takes a minimum of 9.8 volts to start most engines. This includes the drop caused by the starter motor.

I know some people will say I'm full of it, but this has been very successful for me during the 15 years I was twisting wrenches. I NEVER had a come back.

 

Thanks Rob...as a trucker myself, I will take your advice
one question though, where would I find this test light, and how do I hook it up exactly? I need specifics, I havent done anything like this before...what kind of light, and how do I connect it?

 

[font size="1" color="#FF0000"]LAST EDITED ON 09-Aug-01 AT 09:27 AM (EST)[/font][p]You can use most any 12 volt light. I would suggest a marker light from a trailer, or you can buy a test light at most auto parts stores. To hook it up, remove the negative cable from the battery and connect one wire from the light to this cable. Connect the other wire to the battery post. The light is serving to complete the circuit. If there is a closed circuit anywhere in your truck, the light will illuminate. Remember, if it glows dim, this could be caused by your engine ECU or radio. If it's bright, then you have a definite problem. You can see how bright the light will get by opening one of your doors. If you have an underhood light, I would suggest removing the bulb or else it will give you a false reading since the circuit is closed with the hood open.

Always disconnect the negative side of the battery first when removing cables. The reason for this is simple, if you should make contact with any metal surface with your tools while loosening the cable, you won't be showered with sparks. This is why I suggest using the negative side of the battery during this test.

Good luck and I hope you have find the problem.

 

me too....thanks again Rob, for all your help I will post a message indicating the results, providing I dont get hauled out of town before then. If I do, I will post next weekend, indicating the results.