A few years ago I bought a Black & Decker "jump start" battery
, one of those portable batteries that you plug into a small included wall charger and has built-in jumper-cables so you can jump-start a car with a dead battery
They also work as a short-term way to keep the lights
on if your trailer battery
goes dead. Problem is, like all batteries the battery inside the jumper can go dead, too, and it doesn't help that they use really cheap batteries when they make them.
So mine went dead. During my LED demonstration at the Oregon Gathering my jumper battery couldn't even run my sample display for an hour. It should have kept going for four hours. So I am left with the choice of spending $55+tax for a new jumper battery with the same cheap battery inside, or disassembling the unit and replacing the battery inside with a better one. What do you think I did?
This is what the charger's innards look like with the old battery, and a reference picture of how the battery wiring works. (I love digital cameras: Instant documentation so I can keep which wire goes where straight!)
I bought a replacement AGM battery from a local store called Batteries Plus for $36+tax. It wasn't an exact replacement; I had to drill holes in the new battery's leads so they would allow me to bolt the cables to them. (Actually I drilled and tapped threads into the leads, but used the original nuts that were used with the old battery.) Here's the new battery installed before I closed the case up.
It works just fine, and saved me $25.