# Alternate power supply for 3M AirStream respirator



## AlanZ (Oct 9, 2011)

I recently purchased a used 3M AirStream from an IAP member (StudioSO) and am very happy with the deal.

The repirator was sold without a battery, so I was trying to decide what to use for powering it.

I already have two 3M Breathe Easy helmets, one powered by a 3M NiCad battery pack attached to the waist mounted filter/blower unit, and one tethered to a wall mounted HEPA filter by a long hose.

So the first thing I tried, just to make sure the unit was working properly, was plugging the Airstream into my current Breathe Easy's NiCad battery.

This worked fine, as they are both set up for 4.8 volts (or 6 volts if using a Lithium non-rechargeable battery... the kind that first-responders use)

The problem with this setup is that new 3M batteries are pretty expensive, and although NiCads are still available, the newer units use NiMH batteries which require yet another (and pricier) charger than I currently have for the original battery.

So, rather than get another NiCad, I decided to make use of another power supply that I have and rather like: a Tekkeon MP3450 lithium-polymer rechargeable battery.

I use this battery for powering video cameras and computers when I need extended run time. It's variable from 5 volts to 19 volts, and I have several adapter cords for it.

The battery weighs about 1/2 as much as the 3M NiCad, and has a higher watt/hour rating, so I figured it would be a good match. When you turn on the Tekkeon, it defaults to 5 volts, so it's perfect.

The trick was attaching the 3M unit to the Tekkeon.

Rather than attempting to make an adapter that plugs directly into the Tekkeon, I made an adapter that goes to a car plug configuration.

The adapter I created uses a few pieces of brass tubing glued into some corian as a female socket for the male 3M cord. It's wired into a male car plug I got from RadioShack.

This in turn is plugged into an existing Tekkeon car adapter, and then into the battery.

It works beautifully, should give very good runtime, easy recharge and most of all, I already had the Tekkeon.

So, if anyone else has purchased one of the 3M AirStreams, this kind of setup might be viable for a tinkerer with a soldering iron and some creativity.

I'll be happy to answer any questions about this little project.


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## studioso (Oct 10, 2011)

hi Alan,
thanks again for purchasing the unit:
good to know that other batteries will work as well! I'm sure you won't mind if I link to this post in any future ad, right?

so does that that mean that any battery with a ~5v output will do? what about amperage? will that only affect how long it will power the unit or are there limits I should observe?


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## AlanZ (Oct 10, 2011)

Alex,

I don't have an easy way of measuring the amperage draw of the blower, but the regular 3M NiCad battery is 4.8 volts and about 30 watt-hours.

The Tekkeon is running at 5 volts and is a 50 watt-hour battery.
I'm running my first test on it right now.  The unit has been running for 8.5 hours so far and the battery is still indicating about 1/2 capacity.  It will be interesting to see what the total run time is with the Tekkeon.  For the moment, I'm very pleased with the setup, and will likley make a dedicated cord soon (omit the car adapter plugs), to simplify the setup.

Also note that although there are three prongs on the plug, only two are necessary to run the unit.  One prong is negative, and the other two both go to the same positive lead.  I was able to disconnect either of the positive leads and still get full power.  So one could make a three prong socket, but only wire two of the prongs.


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## AlanZ (Oct 11, 2011)

Test results:  the Tekkeon battery ran continuously for about 16 hours... a fine thing for a battery that weighs half of the original 8 hour NiCad.


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## seasaw (Oct 16, 2011)

Great tip Alan, thanks for posting it. Would appreciate it if you could post the model number of the Tekkeon battery & charger.
    Steve


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## AlanZ (Oct 17, 2011)

Steve,

The model was mentioned in my original post.  It's a Tekkeon MP3450 lithium-polymer rechargeable battery  (comes with a charger).

I'm also going to experiment with a Tekkeon 5volt (only) usb power pack that (if it works) should give about 6 hours of runtime. but weigh in at only a few ounces. I'll post results when I get the unit.


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## KenV (Nov 27, 2011)

Alan -- good threads and approach.  While it will not meet OSHA and MSHA standards - for personal use a very cost effective approach.   

Thanks for Sharing


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