I leave Monday Morning at 9 AM, and typically return home either Thursday morning or Friday morning for the weekend.

About a month ago, my 19 month old batteries were too weak to start my truck, so I jump started to get going. I was fine the rest of the week, and since then.

Last Monday morning, same thing; batteries were too weak to start truck. I jump started, got going, and was fine the rest of the week.

I got home Friday morning, and Saturday morning I felt the batteries. I found that three of the batteries were cold, and one was WARM! Aha! I found the culprit. So I put batteries on the charger @ 10 amps Saturday, and hopefully I will get started tomorrow morning. When I get get home next weekend, I will replace the bad battery, and hopefully everything will be copacetic after that.

I would change them all, the bad one often causes damage to the good ones

They are all coneected together, so when you charge one, you charge them all.

CHANGE. He said change them all.

agree 100%

Chances are the cold ones are bad, the warm one was doing all the work, need to load test them all, and they MUST be done seperately. How long they have been in doesn't tell you how old they are, they sit in the warehouse for months sometimes.

The only way to accurately test them is with a volt meter or battery tester. You could take them to a parts store, such as Autozone. In fact, you could just drive your truck to one of their locations and they can test them while they are still in the truck. You could also go to Harbor Freight or some other tool store and buy a battery testor and check the batteries yourself. One bad battery can pull down the others and eventually ruin the good batteries.

Years ago I started out on a trip, truck started fine, everything was good. Only got out of the yard and got low voltage warning. Same as first post, 3 batteries were cool to touch, one was hot. I isolated (disconnected) the hot one, volt meter was back to 14, everything was good for the rest of the trip. Replaced all batteries when I got back home, they were about due for it.

Update!!! It has been a few months since I changed the one (1) bad battery. Everything has been fine & dandy since then, proving that there is no need to change all your batteries when only one out of four is bad. My highly successful philosophy: "If it ain't broke, don't fix it!!!"