Battery's dead !!

[Jgill508]

Ok guys here is the deal, I travel for a living and my 2007 F-250 sits for a week at a time. Went out to start it up, dead as a door nail won't hit a lick! I jumped it off went on with my day. Then let it sit for another week dead again, when I drive it I drive it all weekend so plenty of time to charge the battery's. I put a brand new alternator on it let it sit and dead again. Now I put two brand new battery's in it and now it won't even start. I did a draw test nothing was pulling. I took thr program out went back to stock. Now that I put two brand new battery's in it it piped up a code saying that the FCIM had low voltage I took it out bc it did not have the voltage range it neede. What my question is do think that was thr prob thr whole time???

[dannyboy950]

Is this a no cank or a no run situation? You have to have some kind of a draw somewhere to totally kill 2 new batteries. Did you run the draw test off of hot batteries or were they allready dead?

[Jgill508]

Both battery's were good to my knowledge

[southend]

[quote=Jgill508;3326046]Both battery's were good to my knowledge.

Check your cables.

Sent from my phone that somebody didn't help me get.

[Tuscany]

First of all the purpose of your alternators isn't to charge dead batteries to full capacity. The purpose of an alternator is to replace the charge that was drawn off of the batteries from the engine starting and to power any other accessories while the truck is running. Take the batteries out and get them completely charged up and load test them individually as well and replace if need be after testing them as well.

[Jgill508]

There is two brand new battery's in it now. Tell me how you test for a draw?

[dannyboy950]

To test for a draw disconnect your negative cable, connect a voltmeter inline with the cable and the bat neg post. With no key on you should only show a couple of volts for keep alive circuits, anything more and you have a draw. Just remember when testing you have always on circuits; fused and unfused circuits so just pulling fuses doesn't tell the whole story. It is a process of elimination.