Battery drain, what should i do?

[pgengman]

Once the truck is up and running the alternator keeps the truck running, but as as soon as i shut of the truck and tries to start up the engine the battery is below cranking power. And if i let the truck sit for a few days the battery is completely dead.

What can be draining my batteries? The truck is stock so nothing should drain the batteries once turned off.

Any advice is welcomed.

 

[Optikalillushun]

How old are the batteries? I would either have them charge or charge them and then load test em. Could be a bad cell(s). I would also check to see if the alternator is properly charging. If that checks out OK, i would perform a parasitic draw test.

 

[icanfixall]

Battery age and contition is what you need to find out. Cables are another place to look too. The connections needs to be clean. What are the cranking amps to the batteries. An alternater has a disconnect in it that cuts off the power from the batteries when the engine is shut down. If thats not opening you will draw down the batteries overnite but not like you posted here. What you posted sounds like battery connections or batterys shot...

 

[lotzagoodstuff]

+1 on the parasitic draw test, basically using a voltmeter to see if something is causing a small ground somewhere, I've seen lots of dirt accross a battery top turn into a conductor and drain a battery.

If you need a quick short term solution, you could also just unhook one negative post on your batteries, or put in one of those nifty terminal disconnects if you want it to be really easy, although I don't know how much current you can put through one of those.

Good luck.

 

[OLDBULL8]

With your dead batteries, once you get it started, check the alternator output. It should be 14.3 to 15 VDC, any lower than that you prolly have a shorted diode(s) in the alternator which will drain the batteries in short time. Fully charged batteries should check 12.3 + VDC, disconnect the POS + terminal drivers side battery and check each one individually, if one is lower than the other then that one could possibly have a shorted cell which will drain both batteries.

 

[Agnem]

If the alternator is suspect, the first thing to do is put your hand on the alternator when the engine is cold. If the alternator is warm, then yup.. bad diodes, and the answer is easy. Get a new alternator. After that, it gets a little harder. The next thing to try is to see if the batteries are fighting each other. Disconnect both negative cables, and then run a wire from one negative post to the other. Monitor the voltage with your volt meter. Should not drop below 11.9. Once you confirm they are good, it's time to go hunting for parasites. The common positive bolt on your fender solenoid will have all kinds of wires attached to it. Disconnect them all and attach one at a time, while monitoring the voltage. When you find one that gives you grief, find out what doesn't work when that wire is disconnected and then start disconnecting those things by pulling fuses or disconnecting wires. As you can see, this is all a pain in the butt because it may take several days to figure out if your batts are dying or not.

 

[gunz]

Glove box light swtich got me on this same thing once. When the truck is off place a meter on the terminals. See what the voltage is. Check it agian later . Do this once with the batteries connected, once disconnected, then you will know if the drain is from the system or the batteries arent holding a charge.

 

[Optikalillushun]

How to perform a parastic draw test:

http://www.ehow.com/how_2249402_find-parasitic-battery-drain.html

First thing i would do is charge each battery and load test. While they are charging inspect the battery cables and clean/repair/replace as nesseccary. If both batterys are testing OK, then move on to the charging system. If that checks out OK perform the parasitic draw test. If that is OK, bring a 5 gallon container of gasoline and a pack of matches and set the truck on fire. Bring a lawnchains, beer and marshmellows to enjoy the show.

 

[typ4]

Once the truck is up and running the alternator keeps the truck running, but as as soon as i shut of the truck and tries to start up the engine the battery is below crankin

Any advice is welcomed.

If this is an immeidiate restart attempt the batteries are junk or the starter

 

[franklin2]

Another way to check for a drain. Take the driver's side battery positive cable off and put it in a safe place where it won't touch anything(cover it with something if you have to).

Go over to the pass side battery and take the negative cable off. Take a testlight and clip to the negative cable end you just took off(don't let it touch any metal) and then put the probe of the testlight on the negative of the battery. If the testlight glows bright, then you do have a drain that needs to be found. If it does not glow bright, then you do not have a drain and you need new batteries if the alternator is charging correctly.

 

[finitetime]

Type 4, it could also be a single bad battery pulling the other one down.

 

[Shadetreemechanic]

that vintage also seems to have a problem with ignition switches that don't turn all the accessories off all the time. If you find you have a parasitic draw try wiggling the ignition switch and see if it goes away.

 

[MIDNIGHT RIDER]

If I read the initial posting correctly, you have dead junk batteries.

You may have a host of other problems, but my bet is that the batteries are done for and new ones will cure the problem.

Easiest way to tell is to immediately dis-connect the cables after driving for a spell; engine OFF, of course.

Then, the next morning, re-connect the cables and see if she will crank strongly.

One bad battery will pull down the other, but usually not so quick as you describe.

You really need a voltage meter to make an intelligent diagnosis, checking voltage of each individual DIS-CONNECTED battery (engine OFF), the pair connected together (engine OFF), and also voltage at the batteries with engine running (alternator output -- which should be 14.5-volts, give or take).

Take these readings immediately after engine shut-down and again after sitting over-night with all cables dis-connected.


You must have at least 11.5-volts to crank.

Multiple batteries will have the AVERAGE of the voltage of all batteries.

For instance, if one battery has 12.6-volts and the other only 9-volts, the pair will only have 10.8-volts.

Each cell of a healthy battery will have 2.1-volts; six cells = 12.6-volts.

 

[Agnem]

Another way to check for a drain. Take the driver's side battery positive cable off and put it in a safe place where it won't touch anything(cover it with something if you have to).

Go over to the pass side battery and take the negative cable off. Take a testlight and clip to the negative cable end you just took off(don't let it touch any metal) and then put the probe of the testlight on the negative of the battery. If the testlight glows bright, then you do have a drain that needs to be found. If it does not glow bright, then you do not have a drain and you need new batteries if the alternator is charging correctly.

This works on a totally stock truck, but depending on your stereo system or other options, many devices these days have "soft power off" which means that some circuitry remains on to "see" you push the power switch. It is not like the power switch is actually a circuit interupter like in the old days. A good example of this is some of those self contained sub woofers. They actually turn on and off based on the presence of audio, but when you connect one to a battery, it will come on full power long enough to decide if there is audio or not. Such a device will make the test light glow quite brightly.

 

[plywood]

I had a similiar problem on a truck recently and ended up noticing if I put the battery charger on, it would pull 8 amps forever.

I pulled the cables and put the charger on one battery and it went right down to 0 amps right away indicating a charged battery. When I hooked the charger to the other battery, it would take an 8 amp charge continuously with no cables hooked to it. Basically, it was an 8 amp engine bay heater in theory.