I've noticed my batteries seem to be taking a bit longer to crank my truck lately so I went to Oreilly to have them load tested. The driver side came up at 76% and pass side was 82% Those numbers sound ok to me but I think I should ask those that know better than me first. Am I just being a worry wart or? Thoughts?

 

If you have the original batteries then it is time to replace them before they fail and cause other problems. Replace both at the same time.

 

They are the originals with 83k miles.

 

Walmart has 3 year 700 cca for $89 and Autozone has 3 year 800 cca for $122. Is there a big difference between 700 & 800 cca on our trucks?

 

Mine was cranking a bit slower so I decided to swap mine out.
My thoughts on this are:
1. I know the batteries will die eventually, I got good service from them already, I'm not wasting much changing them now even if they have some life left.
2. I'd rather change them in my shop than in a freezing parking lot at 5am when I need to be on the job at 6am.
3. I'd rather buy them on sale than end up buying whatever is available at 5am in the frozen parking lot.
4. If my wife needs to take my truck for some reason I know it is dependable for her and the kids.
5. These trucks are electronic EVERYTHING, and a failing battery can take out the alternator at minimum, who knows what in a worst case scenario?
6. I found DieHard Platinums for $162 each and jumped on them.

 

The 800 will last longer if needed, just a little more power. The last time I checked, Walmart has gone to a 2 or 3 year free replacement and no prorated for the years after. Autozone Duramax Gold is 3 year free replacement and prorated for the next 4 years.

 

Autozone Duralast Gold top

i just changed out the batteries in my 2005 with 50K miles.

the autozone batteries were $139 ea, but had 100cca more power than the original eq batteries.

the guys did a good job changing them out, not a 5 min job and you need to know what you are doing,

these are big batteries and you have to place them in and over by the hood struts, with there battery wraps in place.

these new batteries are made in the USA by johnson controls

also, if you have problems on weeknights, sat or where ever you are there is an autozone,

you do not notice the batteries getting weaker, as they do it slowly, but the new batteries kick the old cummins over great.

I use the gold top batteries in my van tractor, so far have gotten good servcie with them.

 

They're 76% and 82% when warm, and have just been charged by the alternater. What do you think they are on a cold morning when they havn't been driven for a couple of days?

Replace them both.

800 vs 700 cca will usually not make any differance at all. Except when you really need that battery.

I replaced mine at Autozone last week. Original cost $122, but they gave me a 10% military discount.