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Electrical issue, possible battery drain

metalneverdies

metalneverdies

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Hey guys, the k5 broke down and I ended up having to let it sit for a bit over a year due to life interrupting. Put a fresh battery in as the other failed before the 3 year warranty ended. Now this battery appears to be draining semi quickly according to my battery tender. Not sure if it's a crappy battery or if I have a parasitic draw on the system.

What is an allowable amount of current draw for these trucks? My truck is LS swapped and has been for a few years. Seemed fine prior to the last year or two. No wiring changes since then.

Also, key off, key out of ignition, the clock stays light up on the factory digital time radio. Is this normal? Having a hard time verifying online.

IMAG1743.jpg
 
metalneverdies said:
Hey guys, the k5 broke down and I ended up having to let it sit for a bit over a year due to life interrupting. Put a fresh battery in as the other failed before the 3 year warranty ended. Now this battery appears to be draining semi quickly according to my battery tender. Not sure if it's a crappy battery or if I have a parasitic draw on the system.

What is an allowable amount of current draw for these trucks? My truck is LS swapped and has been for a few years. Seemed fine prior to the last year or two. No wiring changes since then.

Also, key off, key out of ignition, the clock stays light up on the factory digital time radio. Is this normal? Having a hard time verifying online.

View attachment 265461
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Begin by doing a voltage drop test at the battery.
Go out, loosen negative but dont remove.
Measure voltage at batt posts while carefully lifting neg terminal clear.
Voltage may drop but should be no more than .05 volt.
Assuming nothing obvious is drawing power besides the radio clock.
Now.
If it failed that test, measure voltage drop while someone pulls fuses.
If you see batt voltage dropping like .1 through .5 volts or more, you got a patasitic draw.
There is a great video on youtube.
Guy was a VW mechanic with beard.. Ahh!
Yes, the Humble Mechanic.
Go find his technique for voltage drop analysis.
Great stuff.
 
Thanks for the tips, I have only done the tests by the current draw method.

Neg cable from truck to DMM, DMM to battery. Check for miliamps. Start pulling fuses.
 
Not sure why you'd measure across the fuses like that, vs. the way I've always heard it done, from the battery, measuring milliamps: https://www.popularmechanics.com/cars/car-technology/a5859/how-to-stop-car-battery-drains/

And no, the digital display on the radio should not be on. It should come on with key off IF you push one of the knobs in, but it should shut off again on it's own pretty quickly. See if the knob is stuck. These radios have problems over time, I wouldn't be surprised if that is your issue.
 
dyeager535 said:
Not sure why you'd measure across the fuses like that, vs. the way I've always heard it done, from the battery, measuring milliamps: https://www.popularmechanics.com/cars/car-technology/a5859/how-to-stop-car-battery-drains/

And no, the digital display on the radio should not be on. It should come on with key off IF you push one of the knobs in, but it should shut off again on it's own pretty quickly. See if the knob is stuck. These radios have problems over time, I wouldn't be surprised if that is your issue.
Click to expand...
It is done that way to not disrupt the system.
Even latches the door to make the computer go to sleep.
Testing across the fuse is done after a voltage drop test at the battery confirms a draw.
Because the fuse is acts like a resistor, millivolt drops can be measured across it if current is flowing.
Particularly if the draw is from an electronic item such as an engine management computer or stereo, pulling the fuse might disrupt whatever fail state it was in.
Measuring across the fuse let's you "sneak up" on the problem.
 
But pulling the fuse while watching mA does the same thing, no? Other than having to pull the fuses, albeit worrying about touching the fuses tiny contacts, hoping the connection is clean. I can see new cars where you are worried about resetting some things that are a pain to fix, but on our trucks, I say yank the fuse. lol
 
dyeager535 said:
But pulling the fuse while watching mA does the same thing, no? Other than having to pull the fuses, albeit worrying about touching the fuses tiny contacts, hoping the connection is clean. I can see new cars where you are worried about resetting some things that are a pain to fix, but on our trucks, I say yank the fuse. lol
Click to expand...

On newer cars definitely. The method in the video looks just as effective and the mA version. 6 of one half a dozen of another difference.

I didn't think to push the knob in... I did everything but that and it didn't respond like it was powered up. Pushed the left knob in and now the time stays off when the key is off. Poke the knob and the time briefly displays. Now that that issue is fixed (eventually need to just upgrade the poor tired radio) I am going to do the voltage / mA test. Really wish there was a spec in one of the manuals.
 
Most cars, with a computer, and a radio, with a memory, have a parasitic draw of .01 to .02 amps.
 
I had one truck that would be fine for months at a time, then a dead battery (no start) out of the blue. It might do that 3 times in a month, then no problems at all for 6 months. I searched for current draws and a newer vehicle has an annoyingly high number of them, turning down at varying times after key off. However, even 100mA should take weeks to drain the battery (It's not this simple, but 100mA out of 50A-h battery is over 20 days. A typical 10mA should start the car after months). Turns out it was the battery. There must have been a loose piece of plate or something that would make contact occasionally. So if you have another compatible battery, you might swap vehicles for a while to see if the problem follows. At least if you can't find a current draw.
 
It is possible the alternator is drawing the battery down though a failed diode.
 
blazer74 said:
It is possible the alternator is drawing the battery down though a failed diode.
Click to expand...
The alternator, almost never drains the battery. Unless it's a FORD. LOL.
A shorted diode, will drain the battery, for a short time, overheat, burn up, and therefore, open the circuit, no more drain. The best test, is to buy a cheap Harbor Freight digital volt meter. They have a 10 amp circuit for the amp gauge. Disconnect the battery cable, and put the meter between the cable, and the battery post. The meter should be on the 10 amp scale, with the red meter wire, in the upper position. The meter will tell you, down to the 100th of an amp, whether you have a drain. The meter, will support up to 10 amps through the leads, so you can cycle the ignition switch, turn on the park lights, etc up to 10 amps, without hurting the meter. This way, you can see if there is a drain, pull fuses, disconnect the alt, etc., and see if the drain goes away. Normal would be .01 to .02 amps, or less.
 
My friend had a vehicle come in his shop with a battery drain issue ,park it several days and the brand new battery was dead as a doornail..
It was a older Dodge van..

He did the usual "amp draw" test using a light bulb between the positive battery cable and the battery post,but nothing showed a large drain,but the test bulb would barely glow a dim orange at first--then go off,and sometimes it would glow again after a few minutes..like it had only a few volts instead of 12 trying to light the bulb..

He began pulling fuses,no change--then removed the alternator main charge wire,and some under the hood things that evidently had been added by someone--still no change..

He then thought about the brake switch might be staying on at night,so he put it up on the lift so he could check it--it was adjusted properly and not sticking "on"...then he decided to look under the vehicle for any non original wiring..

He found someone added a trailer hitch and the plug they spliced into the tail light harness felt HOT !..the rubber was all gooey like gum,and evidently wires inside it had corroded or shorted out,and one of them must be "live" even with the key off--he cut the wires off the plug,the test lamp went off and stayed off..

The battery was still fully charged and whipped it right over every morning he tried starting it for several days (and it was winter and very cold),so he figured that was the "drain"and that cured it..

..the owner said he never tows anything,so do not to bother replacing the trailer plug..also said he had taken it to three other shops and paid a lot of money and they never found the problem!..
 
Many atrocities are committed "installing" trailer wiring.

I remember somebody's story of chasing a drain for months and finally found where mice had chewed some wires and used foil gum wrappers in their nesting material. I would build evil varmints like that their own cozy house if they wouldn't destroy my stuff.
 
It seems like getting the display to turn off fixed it so far. I think there was other parts of the radio that must have been powered up when the system was not functioning correctly. Battery voltage has been higher than before and maintained 12.55 over a few days.
 
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