Question About Batteries, Starters, and other Tron Robbing Devices

[TLBREWER]

Here's some background. Carla had mentioned that the WTS light had been staying on longer and longer on her truck lately. Finally Saturday morning, the light took forever and the truck wouldn't start. I attribute some of this to the overnight temp and not plugging it in. It wouldn't even jump start.

Here's my dilema. I metered the batteries before hooking up the charger. Passenger side was good at ~12.1V. Driver's side was at ~10.4V . Next I charge the batteries. Driver's side doesn't seem to draw. Passenger side takes a draw and charges up to ~12.3V. Driver's side still the same.

Hook up the batteries and WTS is more normal and it starts right up. Metered both batteries while GPC warmed up and not much draw. During starter cycle, both batteries drop to ~9.3V. Book says that's normal. While running, charging system seems to be working fine. Both batteries are at ~13.4V. A few minutes after shutdown, both batteries are still at 13+V. Don't know if that's normal. Seems odd to me.

I still need to check cold voltage on both batteries after it sits all night. So my question is where's my weak link? At first I thought one battery may be bad. Then I thought the starter may be pulling too much amperage, but according to the book that's fine. Could be voltage reg, but charging seems fine. Not sure about the residual V after shutdown though. I'm stumped. Could just replace it all, but that seems like wasted $.

I may just be looking in the wrong direction altogether. Ideas?

Tom

 

[LCAM-01XA]

Your alternator or VR or both ain't working right, you should be at like 14.2V or so with the engine running. With the engine off 13.2-13.4V sound about right, that's what I usually read on each battery in my diesel, and also in my Lincoln, my old '78 F150, and my old '79 Chevy C10.

 

[towcat]

tom-
start simple.
clean terminals on both batteries and check the grounds. individually load test each battery. I suspect your 10.4v battery is done. I would replace both at once though. if one is done. the other is soon to follow. My Interstate guy loved me when I was actively running my towtrucks. Visually, the trucks weren't anything to look at, but maintencewise, they were kept at EMS standards. Batteries were replaced once a year for PM purposes. They were put through hell all winter long and was suspect when temps got warmer.

 

[geonc]

Tom, I'd be looking real close at the drivers battery.

I know you guys live a bit out ... is there a place to load test the batteries?...a 15 second load test the batteries should hold 50 percent of their rated cranking amps.

When you said you charged them...were they disconnected from each other ? 10.4 volts is on the low side as the low limit is 9.6 volts or so.

Possible damaged internal plate or loose post internally......

.....

 

[sassyrel]

as tow and geroge said--batt bad---but--ive put just one new batt in--and have never had a problem-----case in point--ever replace a batt on one car more than the other--who knows why?? but you can have just one batt flunk out---

 

[rubberfish]

My opinion is as follows.
Replace both. At the same time.
When you change out the batteries in your flashlight,
do you switch them one at a time?

 

[sassyrel]

My opinion is as follows.
Replace both. At the same time.
When you change out the batteries in your flashlight,
do you switch them one at a time?

in the case of the batts i have ---yes---nickel metal hydrite----rechargeable---sometimes one goes bad--not allll of them---next analogy----

 

[rubberfish]

OK. How about like this then.

There is a florescent light fixture on the ceiling......
It contains two tubes, one of which is burnt out....

 

[Mike]

Changing batts on a diesel??? Both batts atta time....

 

[riotwarrior]

If one battery is fried.....then the other has had to muscle up to get you by. ERGO it's not really in good shape or long for this world so


Change Both Batteries!

 

[reklund]

Tom-

I've got a load tester if you need to borrow it. I suspect that drivers side battery as one or more dead cells. That's what my problem was when my batteries went a few months back...

Ryan

 

[sassyrel]

OK. How about like this then.

There is a florescent light fixture on the ceiling......
It contains two tubes, one of which is burnt out....

yup--the damn ballast is bad--and the electrician i asked couldnt explain it--i got one that keeps burning out the same one!!!!!!!!!!!!! on a twin tube 8 footer!!!!