Duracell Commercial Battery, Group Size 31PA

These are great batteries I use them in my tractors my dozsers motorhome plow truck I have bought dozens of thsee Duracell batteries and they never have let me down. And they are a bargain. You can,t go wttong

I bought a pair of these Panasonic 31A batteries for a 2006 Dodge RAM 4x4 truck in February of 2017. That is 6 years, 10 months. I recently discovered the battery voltage dropped to 2.4 volts. That's right 2.4, not 12.4 volts. I thought what the heck and put a constant current charger on them and set it for 10amps. The electrolyte started at 1.0, same as water. It took a little over 24 hours at 10 amps into both batteries in parallel, but the electrolyte was brought back up to 1.85. I know that's a little high, but figured if I were to save these batteries, I'd have to get them above 1.277, the set-point for a 100% charged wet cell battery. I then disconnected them from the truck and let set for a week, but still conncected in parallel. After a week, one battery measured 1.22 on the specific gravity on all cells and the other battery measured 1.85 except for one cell in the middle, which was 1.1. Looks like one battery has a bad cell, which somehow pulled down the other battery. Rather than mess with it, I replaced them with new ones from SAM's Club. However, when I got to SAM's, there were only two batteries left and they were of different dates. One is dated 11/23 and the other is dated 06/23. I wasn't happy, but I also didn't want to start having to drive around town looking for other SAM's Clubs to find a matched set by age. I brought them home and proceeded to measure the electrolyte in both. The one dated 11/23 had a reading of 1.8 or better in all cells. The older one dated 06/23 had readings of 1.20 to 1.25. That's way too low, so I put it on my power supply at 10 amps and let it charge for 8 hours. The electrolyte came up to 1.85 or better on all cells. I let the battery cool off back down to room temperature of 72 degrees as it did get warm, about 88 degrees. The voltage measured 13.08 volts after setting overnight as well. I then put a 100 amp test load on this battery. It's voltage dropped to 12.08 volts while connected to 100 amp load for 60 seconds. When the load was removed and the battery was able to sit for 15 minutes, the voltage stabilized at 13.0 volts. The battery with the date of 11/23 measures 12.77 volts at rest and drops to 11.75 volts at 100 amp load after 60 seconds. It comes back up to 12.77 volts after resting for 15 minutes. I put the 10 amp constant current charge on it for 2 hours to bring it up to where the older battery is at and will run them in parallel in the truck like that. I am happy with the original battery performance and life span of almost 7 years, which is why I replaced them with the same brand and capacity. I am not pleased that the two batteries have different manufacture dates and I will be closely watching their performance when I get close to the one-year warranty expiration date.