I bought 4 separate 6 volt golf cart batteries from Batteries Plus in Tucson (Wilmot Location). I have them tied in series in a 24 volt configuration for a special solar application. I regularly check the status of my batteries and make sure they are always charged and maintained properly. One of the four batteries began to have a diminished capacity. When the other batteries where at 6.2 volts this one battery was at 5.8 volts. There is no reason for a battery in series with other batteries to be unbalanced unless it is bad.
I took the 1 year old defective battery back to the store where I purchased it and they said they would have to fully charge it before they could test it and I would have to leave the battery overnight. I called the next day and they said the battery was fine and I could pick it up. They had charged it for over 10 hours with a 40 amp charger. When I picked it up I asked them what the battery voltage was and they said "6.5 Volts". I thought that was pretty good and I was pleasantly surprised they were able to get it charged. A fully charged 6 volt deep cycle battery should read about 6.35 volts fully charged and almost 7 volts if it just came off the charger. After I put the battery in my car, I tested it with my own volt meter and it was only at 6.1 volts. I went back inside and told them that it was only 6.1 Volts.. They said "well it passed the load test so its fine". The problem is that a load test is not the same as a capacity test. Also they refused to do a hydrometer test because they said it would be inaccurate because I added distilled water to the battery, which may be true, but that doesn't mean that the hygrometer test should read dead.
I attempted to prove my point and explain that the load test is not the same as a capacity test, and they refuse to understand what I am saying. In fact, they kept saying things like
"whatever.. I guess you know something about batteries that we don't".
"here you go, you battery is charged and ready, you can come pick it up any time".
"I've been here for 10 years and I think I know what I'm talking about"
"Your volt meter must be bad".. Note: My volt meter is $400 certified calibrated fluke meter... EXTREMELY ACCURATE
"its over 6 volts so its charged"
and my favorite:
"Whats the difference between a load test and a capacity test!? There is no difference".
The entire experience was dreadful. All they did was talk to me like I was stupid and treat me like I didn't know what I was talking about, but in fact, they didn't know what they were talking about... Either that, or they didn't want to warranty the battery. Now, I've made several trips to the store (40 miles round trip each time) and walked away angry each time. They are rude, a-holes and scammers. I still have yet to know if they will warranty my battery, but even if they do I will never buy from them again... not because of the defective battery (that is expected to happen occasionally with batteries), but because of their lack of knowledge and rudeness towards me.
I know all of this might be a little too technical for a lot of people to grasp the profoundness of their errors, but please believe me... Me and my fellow engineers just laugh and cringe when we talk about this. Batteries plus Tucson location on Wilmot is STUPID.