NiMH rechargeable batteries and overheating

Greetings, everyone!

I've been experimenting some things regarding saber-building, and I've gotten stuck with a little problem.

I usually use four 1.5 V AAA alkaline batteries (1000 mAh) to power my sabers. The circuit only heats up when the batteries are new, and not enough to cause problems.

When I decided to cut my expenses and power my sabers with rechargeable NiMH batteries (1,2 v, 900 mAh), the circuit overheated and the heat insulation, as well as the soldering, melted down.

I used pistol glue as heat insulation and did all the soldering with tin (melting point: 230 º Celsius).

Any ideas on how to create an environment-friendly saber (i.e. NiMH-compatible, heat-tolerant)?

Thanks in advance.

What is your setup? Are you running direct to the LED or do you have a driver/soundboard? Give us some more details please. : )

Sounds like you have a short some where. I use NiMH batteries all the time and have not had any problems with them. I have accidentally shorted them out for a few seconds before and they did get very HOT, but once I fixed the short they were fine.

Hot melty Ni-Mh batteries = a short somewhere. Just like Rhyen says. Re do your wiring.

@ Dagin: I'm not using drivers or boards, just a 2.2 Ohm 5W resistor (w/ a red Lux III). No heatsink either, the LED's encased in PVC. I know, it insulates the heat rather than dissipating it, but it never overheated with alkaline batteries.
It was a low cost project intended to be sold (no luck with that).

@ the other guys: I'm going to do better: I'm going to replace the Lux III circuit with a P4 circuit, with an appropriate resistor, copper heatsink, heatshrinks around the soldering points and insulating the resistor with some kind of tape used inside pipes.

Do you guys reckon it might help?

You could try 2 li ions with a 5 volt regulator. 18500s would be plenty of power. To keep heat down use aluminum body non inductive type resistors secured to the chassis & don't run batteries to the current limit.