Ran my 03 about 300 miles saturday hauling my stock trailer. Parked the truck for the night, then went to crank sunday morning, DEAD. jumped her off, all was fine, but looking at the sight glass on the original batteries, one was green, one had nothing.

go to the local walmart to get a new battery, trying to be cheap, i was only going to replace the bad battery... i think i might have pulled a stupid though. as i was carrying the battery back into walmart to turn in the core, i saw the green light, i thought, wow, it must have been marginally bad, and now the green light is on. i turned the battery in, and went on my merry way.

Monday morning, everything was fine.
Tuesday morning, everything was fine.
tuesday afternoon had to haul the stock trailer again.


Wednesday morning the stock trailer is still on, and the battery is DEAD.
so i think it is the stock trailer draining the battery. jump her off, all is good.
i run around all day yesterday and the truck cranks fine. i figure i will deal with the stock trailer wiring this weekend.

Thursday (today) i go out to crank the truck, and she is totally dead, barely unlocks the doors, fan motor barely blows. The trailer was NOT hooked up last night. i put my cables on, and it took about 5 minutes before the truck would fire over. during that time i was looking at the battery sight glass on the one original battery, and it was dead....also the positive terminal had some play in it. i tightened the terminal. once the truck was running, i hit the fluke meter and i am reading 13-14 volts.

i realaize at this point that i may have either tossed the good battery, and left the old battery in there, or maybe the old battery that was good, has gone bad in the past few days.

My biggest concern is what could be draining the batteries overnight, but letting them crank for short runs throught the day?

am i missing something really basic here?

thanks in advance for any suggestions you might have.
chris

 

You really need to look at the electrical system as "one battery" not two separate ones. If one goes dead, more times than not the other is on the ragged edge. Most importantly, both batteries need to be tested. If they test ok, an amperage draw test needs to be performed.

 

I will test the batteries in a few minutes, but how do i do an amperage draw test? what tools will i need?

this may sound like a stupis question, but do i need to disconnect the battery cable on each battery to test them? i am assuming the answer is yes, but i am not certain.


thanks again, chris


also, if one of the batteries tests bad, do i still need to do an amperage draw test?

 

new battery tested fine.
old battery read weak, but not bad.


any idea what the next step is?


thanks, chris

 

I had always thought that like any battery powered device that all batteries needed to be replaced at the same time. Two unequal batteries will run each other down trying to keep them equal. If it was me I guess i would also replace the second battery and see if that corrected the problem. Also have Wal Mart of whoever replaces the battery do a draw down test on the newer of the two existing battery to see if you may have harmed it and if ti is questionalbe have it replaced under warranty also.

 

Amperage draw requires a DVOM and a jumper wire for a shunt. Got that stuff handy?

 

Pull the fuses one at a time and if you have a current function in the meter ( most have fused to 10 amps) check the current draw and see if it is what it should be.