It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of.......... Oops! Wrong story.
Based on the logo painted on the nose of my 2008 TXT PDS, I believe it came from a golf course in Arizona, where the climate is rough on batteries.
The date code on the cart is B0808 (Aug? - 2008 ) and the date code on the T-105 batteries is L9 (Dec-2009), so I suspect the first set of batteries only lasted about 18 months and the ones I received with it were the second set, and no more than about 18 months old when the cart found its way to my place in Jun-2011.
Other than tires with tread wear and slow leaks, the cart ran fine, but the the batteries wouldn't take a full charge, so I figured I'd be buying new batteries in the near future. However, having just bought the cart, my fun and games fund was low and I wanted to put off replacing the batteries until the next spring.
I knew better than to try any of the snake oil treatments, but also know from past experience with portable X-Ray machines and automated delivery systems (robotic carts), that repeatedly charging an already charged lead-acid battery will sometimes improve its storage capacity, so I thought I'd give it a try. After all, the batteries were destined to be trade-ins anyway.
Fortunately, while not taking a full charge, all six batteries in the pack were well matched. The spread between highest and lowest At-Rest voltage back then (and still is) <= 0.05V, so I didn't have to charge them separately to get the voltages in sync for series charging.
For the first few months, I used a Powerwise II, then I went to a Pro-Tech 3616 because it had float charging and when after it gave up the ghost, I got a DPI Accusense 36V charger, which is the best of both worlds.
When I started, they would only charge to a Soc of 85%, two months later they would got to 94%.
From that point on it was mostly being on float charge after the regular charge cycle ended rather than repeatedly initiating charges, but I still do it if they have been sitting more than a few days.
Anyway, Eight months after that, they were up to 98%
Yesterday, they were at 100%+, 25 hours after they came off float charging.
After documenting the voltages, I drove the cart 10.2 miles in PDS freedom mode to eliminate any voltage gains from regen braking.
An hour after I got back, they still had an 82% SoC, which is close to the max I could get them to take originally.
Basically, over the past two years, I gained about 10 miles of range just by judiciously charging my batteries.
Here are the Pack Voltages and SoC from my records.
Jun-2011 = 37.6V = 85%
Aug-2011 = 38.0V = 94%
Apr-2012 = 38.11V = 98%
May-2013 = 38.26V = 100%+
BTW - I questioned the last voltage also, but I verified it with three other DVMs.
Both the dash mount battery meter and two inexpensive handheld DVMs read 38.3V.
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Hopefully, in the next week or two, I'll be replacing the PDS controller with the DCX400PDS I already have and collect some data about what a more or less stock PDS cart (2Ga cable and 18.3" tires) will do with just an aftermarket controller/solenoid upgrade. (It currently does 19MPH in Freedom mode)
Then the six T-05 batteries will be replaced with seven Exide GC-145 batteries I already have, and collect data about the speed increase going from 36V to 42V.