batteries draining.. please help!!

[crashyyz]

84 6.2L diesel .. when I got the truck a couple of months ago .. right off the bat I was told by the previous owner it needed two new batteries. he thought it was an alternator issue (not charging the batteries)... then concluded it was the batteries. I installed two new Interstate MTP78DT rated at 800CCA and 1000CA

it's been pretty good, mind you I haven't driven it a whole bunch due to it being in the shop getting some work done (body wise).

i have had it back around 3 days and noticed that my voltage gauge has been sitting around 12 - 13 volts at best, when running. sometimes lower.

yesterday leaving work, it wouldn't start. I was able to boost it with our shop truck and get home. I hooked up a charger to it at around 7pm... voltage at 12.26v. I left it on for the night and went out around 8am this morning and it's at 12.10v (both batteries). either yesterday during the day nor over night was anything left on like an interior light or whatever...

waited for the glow plug light .. cranked it... a couple of turns and that was it. not enough uummpphh to get it running.

I hooked up a spare exide orbital that I have .. still wouldn't go. tried boosting with my astro van running.. still no go.

I have no clue how I'm going to get this thing started... I ordered a new alternator in.. but based on the drop while I was charging the batteries overnight.... doesn't that sound like something is drawing off them when off?

any advice would be appreciated.

 

[dyeager535]

I've been watching my new battery in the truck, it's lost about .1 volt over a week of sitting without being driven.

In my experience, once a battery has gone dead, it's pretty much no good, even though it may still last a long time if the rest of the charging system is in order, and the truck is driven fairly regularly. Maybe deep cycles are different, but I don't run those so I don't know. But the voltage drop even with a tiny bit of load becomes excessive it seems on batteries that have been excessively drained, and even if voltage is "decent", they won't crank the motor for squat. That really becomes an issue if it takes a motor a bit to start, I suspect like on a 6.2 diesel.

Since you can't boost it though, that part sounds odd. My little Hyundai can jump my EFI 350 no problem. I'd make sure the battery cables and what not are in good shape.

Based on the other thread where a dead battery was killing alternators, sounds like you may be in the same boat now. Make sure once you get everything "new" and working correctly, check how much draw there actually is on the system when the truck is off.

 

[crashyyz]

problem resolved! i happened to stop in at my house and checked again.. turns out my positve terminals were loose... on both batteries
on of those loose things like when it's turned one way it's tight and moved just a fraction and it's loose. ah well.. i have a new alternator sitting in it now just incase (good thing i work at an auto parts store)

I'm going to keep an eye on everything and see if it's taking a proper charge...

 

[crashyyz]

well.. I wasn't as 'duh' as I thought after finding the partially loose terminals.

leaving work yesterday I had to boost it again. I got home and installed the new alternator.. the voltmeter is now back up and charging the batteries while running. I took it for a drive for around 30min last night and this morning it fired right up ... awesome!

Thanks again for your help ...