in2pro

The battery hooked up with correct polarity?

73shark

For a battery to die completely in 30 seconds, something has to be heating up significantly. Did you check the battery to see if its hot and any other components for temperature rises?

eikonaws

The starter is not staying on. The battery is not hot nor is the Alt or an wires that I can touch with my hands. The battery has correct polarity and hooked up correctly. I had a friend if mine come by and he is a mechanic with his own shop and he checked everything for about an hour and a half and he couldn't find anything. We used his truck to jump it and left it hooked up and running for about 30 minutes and then took the cables loose and within 30 seconds it was dead. That's with a new battery and Alt installed in the last 24 hours.

a55bruce

Get a clamp on amp meter that will measure DC amps. Use it to trace the power draw is killing the battery. It can tell you if your battery is being charged or discharged. With the engine off, clamp the meter on the battery cable and turn on the headlights. If the meter shows +amps turn the meter over, so that it shows -amps for discharge. Start the engine, a normal reading would show +amps from the alt charging the battery. In your case you'll probably see a huge -amp reading that is killing the battery. Move the meter to other wires looking for where that large amp reading is going to.

eikonaws

Thanks a55bruce I will go and get me a clamp meter and test it and see what's up and post the results. At this point I should just stop working on it with all the time and money I've put into it but I'm just curious as to what's going on now.

eikonaws

I just got back from autozone again. Hey charged my battery for me for free. I tested it as soon as they finished and it was showing 12V. I put it in the Tahoe and it started up. It ran for about 10 minutes and then died. The battery is dead again. I got a clamp tester and I am going to test it when there is more light outside tomorrow.

in2pro

That is just plain crazy
Will the truck stay running once you have it started and then disconnect the battery? A properly working charging system should keep the vehicle running with minimal loads i.e. no lights on, no ac or heater blower on....
If it dies the second you disconnect the battery while running , there is something wrong with the charging system...

eikonaws

If I jump it off and then undo the cables it will run about 30 seconds and then shut off. From what I read from other people having the same symptoms they have put in an alarm bypass and that fixed it. The passlock(alarm) makes the truck think its being stolen and shuts it down so they bypass it and it works just fine. Yeah well that didn't work for me. I also spoke to the dealership today and they told me that it's either the battery or Alt but autozone says they are fine. I don't know if it matters at all but my AC is bypassed and it had an AC bypass pulley installed but that has been on there for a very long time. I am going to check the voltage tomorrow and then I'm going to take the Tahoe to autozone and have them check the charging system one more time. I'm probably just going to run another cable and have both battery's hooked up at the same time just so I can make it to autozone.

in2pro

With the truck running the alternator should be putting out about 14volts, and that is what you should be able to measure at the battery post while running... it could be a bit less but it should definitely be more then 12 volts...
recheck the cable from the alternator to the battery, make sure its not shorting to the support braket(s) and is not melted or pinched anywhere between...

eikonaws

So put in the new battery that has been recharged and I stuck it in the truck. It read 12V. So I started the truck and tested the battery and it had about 14V. I took the battery loose with it still running and it ran for another minute maybe and then croaked out. I attached the battery back up and it wouldn't start so I jumped it and let it run while attached to both batteries as I drove to autozone and they said that it is charging, now I am not sure I believe them and with that being said I went to another autozone and they told me the same thing. I replaced the wire from the battery to the Alt even though it looked just fine and nothing changed. Now all 3 wires to the + post are new(starter,Alt,fuse box) and the negative is new as well. I am honestly dum founded by what's going on here and have no ideas what to do next.