Make a Battery Pack for POTMC Suit

POTMC hazmat suits are awesome but most of them are around 40 years old, and battery chemistry 40 years ago isn’t what it is today! Even so, any rechargeable battery likely won’t last for 40 years even if it was made with futuristic battery guts, and that’s to say you have the original batteries for your suit!

For those who are don’t know, the suit took two 6V 7Ah nickel cadmium batteries wired in series, but we will be using sealed lead acid batteries for this project.

Before I get started, I wanted to say that while this isn’t a very advanced project, it does require some prior knowledge on electrical things that requires soldering. If you are not super familiar with these sorts of things, I would suggest finding someone who is. I cannot be held responsible for anything going wrong with your suit if you choose to take on this project!

Each battery was hooked into one end of the air pack individually and wired together inside the air pack.

Power connectors on each side of air pack

The connectors used by the original batteries are made by a company called Bendix. Very high quality connectors but they are hard to find and very expensive. There is another company, Amphenol that makes the connectors too at a much cheaper price so it doesn’t hurt to look around if you simply must have these connectors. Alternatively, the plugs are held in by nuts and they can be undone and replaced with a much more common plug, like a barrel plug.

Like I said, this isn’t a very advanced project and the only supplies I needed other than the Bendix connectors were two 6V 4.5Ah batteries, slide connectors, some male and female barrel connectors, and some cable.

If you have the Bendix connectors and after cutting the outer wire back, you’ll see two wires: black and white. The black wire is ground and the white wire is positive, and I soldered them to a female barrel connector.

Next, take your cable (which should have a positive and negative wire) and solder one side to a male barrel connector.

Next, add some slide connectors on the end of the other side of the cable. Remember, this process needs to be done twice since there are two batteries.

At the end, it should look like this:

Make sure you tug on each wire after you are done soldering or crimping it to make sure that no wire will come undone while you are suited up! That wouldn’t be good, I mean unless that is something that you like.

To charge the batteries, simply unplug the batteries from the slide connectors and attach the batteries to a 6 volt battery charger which can easily be found online, or you can go the extra mile and make a female barrel connector attachment for your charger and plug your batteries directly into that!

I suppose that’s it, I hope this has helped! If you found this tutorial useful, don’t hesitate to drop me a line letting me know that this worked for you!