54larry

I have a 96 CTD. The truck has been sort of groaning and turning over slow when I first start it in the morning, and I suspect my battery is starting to go. It only does this on initial startup in the am.

A couple of questions. First, the truck has two batteries. It is apparent to me which one is conected to the starter, but is it possible that a failure of the other one could be causing my slow turnover problem?

Second, before I go replacing anything, I want to disconnect both batteries and give all the connections a good cleaning. Will this cause any problems with the electronics in the truck that I need to understand before I start? My history of mechanical work is all back in the 60s and 70s when you could just pull things apart and put them back together without all this worry about electronic assemblies being affected. Sorry if this is a dumb question.

infidel

The batteries are connected in parallel, both are used at all times to run everything on the truck. The only problem with disconnecting the batteries for cleaning is that you'll lose your clock setting and any radio station pre-sets.
If you have one bad battery it can pull down the other one.
Best to always replace both batteries at the same time if you want them to last longer.

54larry

Since I just went through the pain of setting the clock on my aftermarket radio/CD player, and I still remember how to do it , I think I will start by giving everything a good cleaning this weekend.

Timmay2

If you only disconnect one at a time you dont lose your battery powered memory settings They are in parallel, so with one disconnected the truck is still powered.

mjgcamper

I would do another test to see if the charging is strong enough to keep the batteries from going bad.

The best way is to run down the batteries a little like say turning on the headlites for two minutes. Then start the truck having a volt meter across the battery terminals. It should read for a good charge of at least 14.3 volts to 14.7 volts. If it does not, then I'd suspect the Alternator, but, just don't buy a new alt., you should first disconnect all the batteries, and then clean all the terminals connected to the back of the alt. and any other connectors to the bats.

Here I go on an on, and it's probably just the batteries anyhow! You really need to replace both because an older bat. will run down the new one if paralelled. It causes the regulator to either overcharge the new bat or, undercharge the old one

On a side note; if you see the voltage dropping fairly rapidly while you have the headlites on, engine off, chances are it's batteries.

rbuchana

If it's a newer aftermarket radio you'll only lose your clock, not anything else. Just disconnect both batteries for cleaning. Minimizes your chances of shorting something out.

infidel

My local Les Schwab tire dealer who replaces a lot of batteries uses a device with a 9 volt radio type battery that plugs into the cig lighter, provides enough juice to keep the clock and presets current while the vehicle battery is removed.
I've seen these devices sold at various places for less than $10 or a guy could make one easily himself.

jrs_dodge_diesel

I just went through this recently with my batteries. I had found that my drivers side battery had been dead for quite some time and the truck was running on the passenger side battery. Eventually the passenger side battery started to fade away, starting was getting slower and slower so I bit the bullet and bought a pair of Optima batteries. If you can get them I highly reccomend them. These thing have impressed me on how well they perform and my battery terminals have not corroded at all since they went in.

fschiola

If you have an Auto Zone close by, they will load test the batteries for you for free. That will tell you if you have a weak one. I had mine done that way and all I did was isolate each battery to test and didn't loose any radio settings.