Battery Betrayal

In preparation for our upcoming grotto cave trip I was attempting to repair my electric headlamp. I cleaned up the contacts and reassembled the lamp and plugged it in to charge. After 2 days of charging this 4V battery is still only registering 2V. I checked with the local BatteriesPlus store but the didn't have any of these particular batteries in stock. Well I should've bought a car battery while I was there as after dinner my car wouldn't start. It turns out my car battery is dead and no longer holding a sufficient charge. So I got myself to Wal-Mart (Batteries Plus is closed by now) and bought a new battery. Well this being Wal-Mart I was not surprised when I returned home to find that the battery from the 48-3N shelf was actually a 24-3N. So what does this mean? I haven't a clue, but I do know that the battery tie downs in my Jeep are too short to secure this new and bigger battery. I ended up just tieing the battery in place with some string. Hopefully this will secure it until I can find some new tie downs. For this trip I gave up trying to repair my old headlamp and bought a new Petzl Myo 5 from REI. So far I'm impressed by the headlamp. It has a powerful main beam as well as and array of 5 LED lights which can be used to conserve battery power. I'll try to offer a review after a day of caving with it this weekend.