Are You Wired In?
He was happy to take a few D31M BlueTops off my hands for his father's trolling motor and indicated the police department could also use a few batteries for their portable radar speed display station. After I confirmed that this station didn't actually cause anyone to get citations, I agree to give them two D31M BlueTops, to replace the original batteries, which were in their fifth year of operation.
The officers had explained that even though the unit had a solar panel for recharging, they could only get about 36 hours worth of use out of it now, before the batteries needed recharging- even in sunny weather. That was far less than they could get out of it when they first bought the unit. When we opened the unit up, I noticed a sign underneath the lid, which read, "LEAVE LID OPEN WHILE CHARGING BATTERY. " That is excellent advice, as these batteries appear to be somewhat sealed inside a weather-proof case and if the batteries did happen to get overcharged, they could vent gas that is both flammable and toxic and it's not a good idea to keep those gasses sealed up in a box.
When we went to disconnect the batteries (which were wired in parallel), I noticed that one of the negative cables was loose and not solidly-connected to the second battery. When we pulled the batteries, the resting voltage was 12.6 volts for both batteries, which is probably pretty close to a full charge for those batteries. However, with the wiring the way it was, it was possible that while riding over bumps in the road to whatever destination the unit was going to, that it lost it's connection to the second battery and the reserve capacity was decreased significantly.
Did they need new batteries or better wiring? I didn't have a load tester with me, but both of the original batteries seemed to be holding a charge and from what they described of their maintenance habits, the original batteries seemed to be holding up very well. I don't know that they needed new batteries or better wiring and suggested that they have their original batteries load-tested, as they could have significant life left in them. Likewise, the wiring should be reviewed as well, to make sure all the connections are solid after six years of use, especially the grounds.
Batteries are often the easiest thing to replace when faced with electrical issues, although that doesn't always solve the problem and may only mask the real issue for a period of time. If you think your battery needs to be replaced, check out this video first, before pulling the trigger on a new purchase. Your battery could end up being just fine and all that may be necessary is the tightening of a few wires to resolve your issues. Lastly, here's a few fun facts about this portable radar speed display station-
The unit can keep track of the speed of every vehicle that passes it in both direction
The unit can keep track of the exact time of day each vehicle passes by
The unit can have a pre-set speed limit, so people can't drive past it at a ridiculously high rate of speed, just to see how fast they are going on the screen