6.0 2006 battery drain/no start

[spike352]

need help again guys.....
when truck is parked at airport when I travel it does not have enough juice when I get back to start
need jumped....first trip 4 days, last trip 7 days, mid 30's temp both times
have the truck on a block heater at home and it starts no prob, but that's running it every day so batteries don't go down too far
batteries not all the way dead just not enough to start, needs cables and a jumppack to start

one battery is redtop optima, other is redtop, not sure what brand

I am on my second alternator replacement.....not even a month on this new one

got lost in all the posts on here

anyone have a test pattern I can use to diagnose the problem?

batteries tested good, unhooked, when the last alternator went out

any and all help appreciated
thanks in advance guys
Spike

[Scoutin]

The simplest thing to do is pull the batteries and have them tested at an auto parts store. The batteries could simply be old and need replacing. Second thing to do is wait 5 to 10 min for all of the accessories to power down and put an amp meter on and see how much draw you have. There should be less than .5 amps, and more likely down into the milli amp draw range. If one battery tests bad both need to be replaced at the same time. This is just some of the simple things to check first. Hope this helps.

[PowerstrokeTech82787]

yea volt meter - post of battery to + post of alternator at idle, See what its putting out. IF its less than 13v even after you rev it to 2000rpm, the alternator is bad. Replace it with OEM remanned only. napa car quest advance auto they dont last.

If you have a current/amperage draw on the batteries you will have to find what is staying powered that shouldnt be. basically put.

[spike352]

thanks guys, gonna check that out today

[Scoutin]

Make sure the glow plugs aren't on when you check the voltage. That will skew the test.