Battery pack for Triton respirator

[Mike Nathal]

I bought an older Triton powered respirator at our club's auction, and believe the batteries are kind of weak, they give maybe 2 hours of fan operation but only 30 minutes of that seems to be at a good speed. The pack has 2 NiCad rechargeable batteries, each are 1.2 V 5000 mAh. They look like "D" cells. I was looking for replacement batteries and saw both NiCad and NiMH available with matching specs. But if I was going to the trouble of removing the old batteries (they are soldered to the wires) I was wondering if I could replace them with a Li battery (or 2). Can anyone tell me the advantages of NiMH over NiCad? And if there was a suitable Li candidate that would also work?

[Dane Riley]

NiCad contains Cadmium, which is toxic. Lower leakage NiMH are available (longer shelf life). NiMH have larger capacity.

Li cells have more than double the voltage. They require a different charger.

Can you use something like this? http://www.digikey.com/product-detail/en/BH2DL/BH2DL-ND/56225
Even if you have Velcro it to the outside. With an external D cell charger you will never run out of juice.