I have ford 6.0 kr and the battries were replaced in 2010 although now its 2018 my truck s battries are in relatiy only 6yrs as truck is laid up for 6 months a yr and for better part of a yr did not run truck ..I charged both battries as they in basement and they read 1250 to 1300 charge will the be all right to use for another yr .I use a battery minder when truck is parked await ur reply

 

 

I wouldn't rush out and get a new pair of batteries right away. If they are functioning properly then it's a matter of personal security. A new set will make you feel more secure. Try and notice the starter speed every time you crank up. I recently replaced the Diehards under warranty they were two years old but were not holding a full charge. When I cranked up with the replacement batteries I was amazed at how fast it was cranking. It's like boiling a frog, failing batteries crank a little slower and a little slower time after time and you think there is nothing wrong because it didn't happen all at once. I fooled myself into thinking that a slow crank was normal.

 

A fully charged battery after the surface charge has disapiated should read 12.6 volts. 2.1 volts per cell. As a battery ages the lead plates clog with sulfate, a natural reaction to lead and the acid in the battery. constant charging causes faster sulfating of the battery, a hydrometer reading each cell is the only way to see the condition of a battery. Now that they are sealed and cant be tested a load test with a carbon-pile machine is required. loading the battery at its rated cold cranking amps for 30 seconds to make sure it doesn't drop below 12 volts. All of which requires special tools and knowledge of the battery. when in doubt buy 2 new batteries as yours are old and sulfated. They will fail at the worst time I bet.

 

A fully charged sealed maintenance free battery is actually 12.80 volts at 77° F, the 12.65 is obsolete numbers from back when batteries were made with pure lead plates and had filler caps to add water when electrolyte levels were low.

12.65 volts on modern batts is only about a 75% charge!

 

Okay, I'll be the guy that says it. Buy yourself two new batteries. Those are 8 years old and bad batteries can cause very expensive issues with our trucks. If you are going to keep running the ones you have, you really should check them both out. Test the batteries with a Hydrometer and a load test. Be sure you start with fully charged batteries. Also, you need to get yourself a decent battery charger. The Battery Tender shouldn't be used for charging the battery.

 

I brought my volt meter in to buy batteries last time and nothing on the shelf was above 12.7. I picked the two with the highest voltage that matched.

 

Good idea! Well that was because they weren't completely charged up, choosing the highest OCV is good. A tenth or two of volt sure doesn't sound like much but on a percentage basis it looms large. The difference between 100% and Dead is less than a single volt.

New batteries are "stiff" and need a dozen or so start cycles before they will reach full capacity as well. While it is possible to overcharge a battery it takes some serious dedication. By far the number 1 killer of batteries before their time is permanent sulfation - mostly due to chronic undercharge.

Note that this sulfation business actually occurs in the summertime and/or high temperatures. You won't ever notice this though until the current demand goes up - like when it gets cold and then the battery simply chokes when the first cold snap arrives. That's why NAPA and OttoZone will have a customer line out the door for batteries the first 0° F morning just like clockwork every fall. So keep up on charging and preventive maintenance in the summer, it will pay dividends come winter! Battery chargers aren't just for January.

Heat, and vibration, are the enemies to battery longetivity. My garage gets miserable hot in the summer, so batteries get brought indoors where it's cool, when practical. Any battery will naturally "self discharge" or run down over time, but like most chemical reactions high temperatures accelerate this.

 

There older then 8years old manufacturer date

what brand were they sounds like they did great

 

Exactly. He said the truck is laid up six months of the year, therefore the batteries are only 6 years old?

Doesn't work like that. Although if they are charged fully and kept on a float charge they will do pretty good and last a long time.

 

Do you even have a 6.0 in your truck?