Weird Startup - Jumping Speedo and Tach

[02SilverStroke]

In the last few days my PSD has been a little bit slower in starting on the first startup of the day, especially if it sits more than 24 hours. I'm sure the problem is either or both batteries (still have factory originals at 129,000 miles). Yesterday I cleaned the battery posts (also did the 500 while I was "in the mood"). This morning when I started it (30 degrees outside), the speedometer jumped from 0 to 100 and back to 0 a couple of times. At the same time, the tachometer was doing the same. The truck started, but it was a bit slow. As I noted above, I'm sure the batteries are on the last legs. I was checking out the possibility of replacing the batteries, and noticed the "snap-on" parts on top of the left battery. Is that a cover that is on top of the battery? This is my first experience with one like this, so I don't want to screw up anything if I try to save some money by going to Wal-Mart and getting new batteries, and doing my own work. Of course, Ford had a "better idea" when removing the ammeter in lieu of a tranny temp gauge with the auto trannies. Any thoughts are welcome.
Before anyone asks, yes I have replaced many batteries in the past on smaller (than F250's) vehicles.

 

[fordtrucker4life!]

I would deffinately replace the batteries. On average a battery is expected to last 3 years. The snap on parts you are talking about they probably are serviceable batteries. The caps will pop off allowing you access to each cell. The acid eventually loses it's ability to transfer charge. There is a tester that tests the acid's capability, but I would just replace them 5 years into it.

 

[JRJ04]

I think what he was referring to was the cover on top of the battery next to the air intake. and yes, that is a cover that just snaps on. If i recall correctly, you have to remove the posts before you can take the cover off. I would not buy batteries from wal mart to cut corners. youll end up paying for it later. go to orileys or anywhere that sells motorcraft and get them. they have the best warranty. im pretty sure its a 3 year free replacement and 5 year pro-rate. they'll set you back about 100 each, but well worth it.

 

[02SilverStroke]

I think what he was referring to was the cover on top of the battery next to the air intake. and yes, that is a cover that just snaps on. If i recall correctly, you have to remove the posts before you can take the cover off. I would not buy batteries from wal mart to cut corners. youll end up paying for it later. go to orileys or anywhere that sells motorcraft and get them. they have the best warranty. im pretty sure its a 3 year free replacement and 5 year pro-rate. they'll set you back about 100 each, but well worth it.

Yes, I was referring to the cover on top of the battery. In the past, I've good luck with Wal-Mart batteries, but have never bought any this large. This may be a stupid question, but do they both need to be replaced at the same time since one is an "auxilliary battery", or can just the main one be replaced. Again, I'm new at this. Only previous diesel ownership was a 1980 Chevy Caprice, but that was a "horse of a different color" that I didn't have very long.

 

[F350DRW1]

There really is no "Main battery" in the system. Its still only 12 volts but you have enough amps to crank over the engine. Replace em both.

 

[WD40]

Just spend the money you old tight wad. Go and get two new motorcrafts battery and you will be happy again, and
your truck will love you again. LOL

 

[JRJ04]

yes you definately need to replace both of them. a diesel requires a lot of power to turn it over because of glowplugs etc. they are totally co-dependent on one another and there really isnt 1 that is more important than the other.

 

[DaveBen]

We go through this every year about this time of year. REPLACE BATTERIES IN PAIRS. Don't go cheap and do one, as the bad battery will kill the good battery in a few weeks. Do them both.

Dave

 

[02SilverStroke]

We go through this every year about this time of year. REPLACE BATTERIES IN PAIRS. Don't go cheap and do one, as the bad battery will kill the good battery in a few weeks. Do them both.

Dave

Thanks for the info everyone. I know what you mean about replacing them all. I've had problems in the past when I thought it was the battery when the alternator was going too.

 

[Dogman]

I had to do the battery thing too. I had One new motorcraft battery 875 CC amp battery at the shop and had to order the other should have it friday. If you can do it get the 875 CC amp battery. Turns the motor over like it's nothing..