The Stovebolt Site Forums The Shop Area The Electrical Bay Can my truck be killing batteries?

The battery in my 53 AD (converted to 12V, with alternator) runs down consistently. Of course, that can be due to any number of leaks/shorts
that I need to debug. However, as part of this
issue, I have had several batteries tested at parts stores. The guys declare them "bad", and replace them, sometimes for free (so not a sales ploy, I don't think). The question is, are there leading candidates for problems in the truck that might be leading to battery failures? I went through a charging check some time ago, and all seemed right - maybe I should repeat that.

If there is a trickle leak running down the battery, and then the battery is recharged
repeatedly, can that lead to eventual failure
of the battery cell(s)?

Pat

I have never realy understood batteries. To me they should never fail and yet they do. They seem to fail during cilmatic weather changes (hot to cold,cold to hot,wet to dry, dry to wet.)
But why do they fail? It is a chemical reaction between zinc,lead and acid. I suppose if you let the darn thing draw down far enough it would no take a charge. But I have never killed one for that reason. What I mean is that I have allways been able to recharge them on a trickle charger left on for 24 hours if it was only discharged.

Pat,,,,I have wasted two almost new battery's on my 52 because of a power drain,, never could find the problem so I have a quick disconnect switch on mine. so yes you can drain a good battery dry....it may also show 12 volts and still be bad.........

you get a disconnect switch cheap. better then ruining your batter till you can find your problem..

PM53,

Not being a battery guru, these are just thoughts! I think the prime killer of a battery would be overcharging. If your rig still has the ammeter, you would see a constant charge.

Sometimes the battery compartment becomes coated with a crust from the off gassing battery, and the battery would run out of water. This would be a clue to a overcharging battery.

A bad bridge rectifier (trio) in the alternator will allow the unit to charge, but will also allow the battery to discharge through the shorted diode when sitting.

Discharging, then charging shouldn't be life threatening for the battery, within reason.

I think the tests available at the parts stores for battery health are probably mediocre at best.

A battery that sits for an extended length of time in a discharged state will usually fail prematurely.

I would check for a overcharging situation first.

It wouldn't be a bad idea to have a real automotive electrical shop check the alternator for a shorted diode (?) that might cause a drain.

Stuart

shorted diode.......................wonder if that might be my old problem........can it be tested while on the truck? would the shorted diode still allow the alt to charge as usual.....

The same shop that tested your battery, or a FLAPS like autozone, does free alternator tests either on or off the truck. Just take the truck, or the alternator, to them and tell them you think its bad, they'll hook it up and tell you.

I just replaced three batteries... all at 6 years of life... one was 35 months, one was 48 months and the other was a Wards Lifetime (champion)... the key is keeping them clean and full of distilled water...

recharge them at the slow rate (2 amps)....

A quality battery will typically last the advertised life span... an elcheapo battery will cause you to exercise the warrantee.

Put a tester on your alternator to ensure you are putting out a little over 14 amps. If you are then your alternator is working right. Do you get any kind of squealing from your alternator that you can hear? If you are you may have it wired wrong and it will backfeed causing problems as well.

A battery can,t be tested unless it is charged up. A quick test to see if there is a drain from the alt. take the main wire off the term. & touch it to the term. Watch real carefully & see if there is a small spark. If there is you have a shorted diode. Do the same with a bat cable to check for drains in other parts of the system. These alts. are fun to work on if you like to fix things yourself. Get a book & follow the instructions.

see ya in Kansas City

To test for a draw on a vehicle without computers, with all circuits OPEN (off) and all doors closed. remove the neg. battery terminal and install a test lamp between the negative terminal on the battery and the loose end of the neg. cable. If the lamp lights there is to much draw. To locate the sourse of the draw start unpluging fuses untill the lamp go's out. Note; if you have the door open the interrior lamp will cause the test light to stay on so you may have to close the door each time or disconnect the open door switch. Note also that the alternator is not fused so remove the positive cable from the back of the alternator to test it.

In California, a circuit that is OFF is an open circuit...maybe it's different the further east you go!


Stuart

UPPS I WAS WR-WRO-WRON- MISTAKEN!

not many fuses on my 52 I think I will let one of the Kansas city guys check mine out real quick with my handy-dandy volt meter... the only thing I find out of whack is that when I turn on the dome light,,I have to play with the switch to get it to come on. If I take off the switch cover, the switch seems to turn on better...........but....

I believe that I solved the wiper coming on when I first start the truck,, I tighten up the bezel nut on the switch and thus far it seems to be ok??

joker,

A loose bezel nut has been a problem since the dawn of time! I see your pushing 10k...


Stuart

agree, a lot of miles on this old body

Sparks can be hard to see. Invest in a cheap volt meter and learn how to use it to find shorts, charging conditions, and voltage drops on starters and such. Lots of fun.

It's hard to check an alternator for a shorted diode, unless you take the alternator apart and use an ohm meter. You can't check for a shorted diode by taking the alt to a FLAPS. An alternator with a shorted diode will still charge the battery at 14 volts (volts, not amps). I have yet to see a flaps tester that you could rely on, to fail an alt with a shorted diode. You could have a shorted diode with a low battery drain in a car that you drove everyday and you would never know you had a bad alternator.

My first sentence is technically wrong. You can check an alternator with an oscilloscope.
[img]http://home.earthlink.net/~roadruner/diode.jpg[/img]

Check for a drain in the car/truck wiring as Toyvo suggested.
Check for a drain in the alt as wrenchbender suggested or just disconnect the alt and let the truck sit the same time period as before.

If you are running a one wire alternator and the vehicle is stored for extended periods of time with the battery hooked up it will run down your battery thru the field in the alt. Solution: disconnect your battery.

Turn off your engine. Pull the bat wire from the alt. Put your volt meter in series with the negitive to the alternator terminal and positive to the wire end. Read with the voltmeter set to The 50 volt scale and if no reading set to the 10 volt scale to be sure. any drain through the alternator will be a reading.
(if you have pos ground reverse the meter conections). You can buy a multi-meter for less than $20.

see inliners tech section page
:::

Find That Short the Easy Way!
-6NHeat


Nothing can be more frustrating or confusing than trying to find a short in you car's electrical system. Especially when it's not enough to blow a fuse but still drains your battery! Obviously, if you find a blown fuse, replace it, turn the key on, and the fuse blows immediately you've found the circuit within your car's electrical system that the short is in. However, if the draw does not create enough current to blow a fuse, than we have to find out which circuit it's in to fix it. Before I get started, my intention in this Tech Tip is not to teach Electrical Systems and Electronics. Instead, I just hope that this article will give anybody a systematic approach to finding a short. So lets get started... First, lets make sure that you have a short! Electrical systems have a specific route for electricity to travel along and any change from this route causes problems. If electricity can find an easier route it will always take it. So lets find out if the electricity in your car is finding a ground sooner than it's suppose to... What we're going to do is take a test light and attach the clip end to the negative battery cable and put the tip on the negative battery post. Then we're going to remove the

negative battery cable making sure we don't touch the test light. Now we haven't broken the electrical connection here. All we're doing is letting the current, if any, flow out of the negative battery post, through our test light to see if it illuminates, and continue on along the negative battery cable to the short. Word of caution, If you're attempting this on a computer controlled car it is very important not to break the connection of the test light to the negative battery post.

By not breaking the connection, the computer will maintain its learned driving strategy in the Keep Alive Memory (KAM). It will also ensure your computer will not have to go to factory baseline and relearn controlling your car's engine for maximum fuel economy and performance. While we're on the subjects of computer control, module equipped cars have a small parasitic drain caused by the modules' KAM. This is normal and module or modules can draw 10-21 milliamps (mA) with the key off. However...

If you have a parasitic draw that is in the milliamp range and is beyond normal specs, you will have to use an Amp Probe for a Digital Volt Ohm Meter (DVOM) to diagnose this and the method below may not work due to the very low current draw. But let's get back to those major shorts that give us all those headaches...

Oh! by the way, a DVOM can be used in place of a test light. Just ensure your leads are in the proper connections to measure Amps. Using this tool will not only tell you if you have a current draw when you're not suppose to, but will also tell you how many Amps are being drawn.

Okay, you've confirmed you have a short, now how do you find it? The first and easiest test is disconnect the alternator and see if the test light goes out or the DVOM display changes. Often old or worn out alternators ground themselves internally causing a short. If it does you've found your short and repair or replace the the alternator or appropiate components. If the test light remains lit or the amperage on the DVOM does not change, you have to try and start isolating which circuit within your car's wiring has the short. This can be done by pulling fuses one at a time. A fuse is nothing more than system protection. All the current that flows through a circuit must go through the fuse. By pulling a fuse we've created an open and current can no longer flow. Continue doing this until the light goes out or the DVOM display changes showing no current draw. Once you've found the circuit that has the short you must find where in that circuit the short is located. It's always best to take the least intrusive method to diagnose. Besides, who wants to tear out the dash or remove the interior just to trace a wire. So this is where a simple tool you can make comes in very handy...

When electricity flows through a wire it creates magnetism. We're going to use this magnetism to find our short! Many tool vendors and auto parts stores sell short detectors. The one in my tool box is from MAC. It's convenient for me because it also has an audible alarm which I can hear in a noisy shop environment. I'm pretty sure NAPA sells one also. The tool to the right consists of a 10 Amp circuit breaker with buzzer, wire leads, clips, and a compass. But for our purposes we're going to make our own which I believe is better than the ones you can buy outright.

To make our short detector, we'll need the following items:

1 x 20 Amp circuit breaker
2 x alligator clips
2 x spade connectors
2 x 2 foot pieces of 18ga wire
4 x 1 foot pieces of 18ga wire
1 x magnetic compass of any type
*modify length of wires to meet your needs*

MAC's ET251 SHORT CIRCUIT FINDER. Quickly locates short circuits in all 12v automotive electrical systems. Eliminates the need to remove upholstery and floor coverings. Operates through metal posts, panels, and other obstructions. Simple hooking to affected fuse posts; induction-type needle indicator pinpoints shorts. Packaged in high impact plastic box; schematic included


(Not To Scale)
Connect the pieces together as shown. This should allow you to hook your tool up in place of a fuse no matter what type of fuses your car uses. The reason I recommend a 20 Amp circuit breaker instead of a 10 Amp one is it allows current to flow longer and thus building more magnetism. This is important especially if the wire that the short is in is buried under items like the carpet, rocker cover, door panel, pillars, etc. The more magnetism we can build the easier it will be to pick it up with our compass.

At this point it helps to know how the wiring loom or wires run for the circuit that has the short. A schematic is very helpful here especially if it has component locations. If you cannot find one or your vehicle is older you will have to trace the wire(s) from the fuse on...but this is not that hard and you'll see why. The reason we want to know which way the wire is going from the fuse box is because we're going to use the magnetism that is built buy the electricity along that wire to locate the short. Place your tool into your fuse box or where you pulled the burnt fuse from instead of the fuse and turn the key on to the RUN position. Now what's going to happen is electricity is going to flow to the short. Because we have a circuit breaker in there instead of a fuse we're allowing magnetism to build along the wire. As the current flows through the circuit breaker it starts to heat up (careful the tool may get very hot). The bi-metal strip inside the circuit breaker will eventually bend away from the contact breaking the circuit and creating and open before any damage can be done. This is always associated with an audible "CLICK" from the circuit breaker. With an open, no current can flow through the circuit breaker and the shorted circuit. With no current flowing, the bi-metal strips cools very quickly and reforms itself back to it's original shape and touches the contact allowing current to flow and once again creating magnetism.

We're going to use this magnetism and our compass to locate the short. Here is how the this works... A wire (conductor) will build magnetism. A short will not. So we put our compass along the wire or wire loom and the current flowing through the wire is building magnetism. This magnetism will draw the north seeking arrow on the compass towards it (one way or another). We leave our compass in place until we hear the "CLICK" from the circuit breaker. When the circuit breaker opens the magnetism will be lost and the north seeking arrow of the compass will deflect back towards the magnetic pole of the earth momentarily. This deflection is important! Because once we get to our short there will be very little or no deflection at all. So after each click and deflection we move the compass about 6-12 inches along the wire, wait, and watch for the needle to deflect as the circuit breaker opens and closes. We continue doing this until we come to a portion of the wire where the needle is not being drawn towards the wire (weak or no magnetism) and there's no deflection of the compass needle when the circuit breaker opens. Congratulations! you've found the area where the short is located. However, you still have not found the short, but at least you know where to dig in. Expose that portion of the wire and locate the short in the wire. Here's a hint - if there's a bunch of wires there, shorts create heat. So look for the hot wire, hot metal, or hot component. Then look for any wire or component that may be broken, cracked, smashed, exposed, or punctured.

Now that you've found the short, repair it by splicing in a new piece of wire, fixing, or replacing the shorted component. You can cut & solder, use a butt contector, or electrical tape if you have nothing else. At one time automobile manufactures only recommend solder, however, the quality of butt connectors are so good today that many allow this type of repair. Now that you have the short out of your system verify your repair, replace the fuse if necessary, and pat yourself on the back for a job well done.

That's all there's to it folks. Go for it!

Thanks CT, good info...