Airshield "Ion-Drive" is complete...

There have been a few new Airshield post recently so I thought I would post the success of my installing an "ion-drive" to my own. The NiCd battery pack for the Airshield costs around $40 pluss S&H and tax where applicable. I retrofitted 3.7v Li ion batteries from Battery Junction using a compariable plug from Radio Shack and some connector wire and a bit of solder. I also bought a smart charger for the batteries. Easy task and the cost per battery is around $5 each. Two of these batteries powered my Airshield for 16 hours before I got tired of trying to wait for the juice to run out and I just turned it off. So, clearly these out last the OEM packs by many hours (the best I couold get out of the OEMs was 7 hours run time on two). Pictures below...

Name Code Qty Each Options
-------------------------------------------------------------------
Universal Smart Charger TLP-2000 1 $19.95
for Li-Ion battery Pack
(3.7V - 14.8V, 1-4 cells)
(Shipped)
Lithium-Ion 18650 3.7V 186502200PTC 4 $5.29
2200 mAh rechargeable
battery with TAB with PTC
Subtotal 41.11
Shipping 8.15
Tax 0.00
Total 49.26


My next job is to retrofit a good replacement for the internal filter...

Chris,
That's good to know. If I ever change my mind (what--me? change?) and decide to go with an Airshield I hope I can remember to reference this thread. 16 hours? Gee whiz, I can't do anything for 16 hours!:rolleyes:

I guess that your hope in replacing the filter is to bring it up to NIOSH standards?

Does it use a sock type filter like that used on the 3M Airstream?

If, on the other hand, it is a rectangular filter, you may be able to get the N100 material that is used to make the disposable face masks.

I see that, like me, you are proving that it is possible to make a silk purse without actually using silk. My silk purse makeover project involves a Delta 1440 lathe as the baseline (a.k.a. sow's ear).

Bill

Quote:

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Originally Posted by Bill Boehme

Does it use a sock type filter like that used on the 3M Airstream?

If, on the other hand, it is a rectangular filter, you may be able to get the N100 material that is used to make the disposable face masks.

I see that, like me, you are proving that it is possible to make a silk purse without actually using silk. My silk purse makeover project involves a Delta 1440 lathe as the baseline (a.k.a. sow's ear).

Bill

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Bill,

The internal filter is the plastic and fabric strip affair that is just to the left and above the battery in the first picture. The outter portion of the fliter is just random mat PE but, the inner side appears to be the "N-100" type of embosed filter. A modest plastic frame serves to strech the affair across the intakes and has a foam seal on the insdie edge. It looks like it wouldn't be too much of a chore to make a very low cost replacement. I think an OEM replacement for this filter is around $10/ea.

Quote:

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Originally Posted by Mark Pruitt

Chris,
That's good to know. If I ever change my mind (what--me? change?) and decide to go with an Airshield I hope I can remember to reference this thread. 16 hours? Gee whiz, I can't do anything for 16 hours!:rolleyes:

I guess that your hope in replacing the filter is to bring it up to NIOSH standards?

---

Hi Mark,

For test purposes the Airshield sat on a table while I worked in my office, like you, I doubt I could do anything for 16 hours either. My biggest motivation to reverse engineering a replacement filter has to do with the price. While $10/ea is probably not going to send me out for a second mortage, it is highly overpriced for what it is. I have a hard time paying that much for something that may demonstratively have a cost to build of less than $1 for Trend. My own best guess is that I can duplicate the filter for less than $1/ea in materials (but then there is my time...) and hopefully in a way that make more sense than paying 10 times costs of materials and labor. I probably can't make this mask NIOSH compliant, it was never intended to jump that hurdle.

Having made about a dozen of the battery packs using 3 rechargeables per, I'm still intrigued by your ingenuity, and would like to try it out. I do have some questions: Do those batteries have leads to which you attach the wires? If not, how do you attach them? In the battery packs I made, I bought the holders with wires attached and had an idea of how to attach them to the plugs. In your pack, where does the negative wire go? Lastly, do you think there will be any problem using a 3.7v battery instead of the 3.6 which comes with the airshield? Sorry to ask what for everyone else is probably a dumb series of questions, but I am mechanically dumb!! Hilel

Good tips Chris....

So what's the trick to soldering to a battery? Never done it and need detailed info.
When I flew Radio Controlled airplanes, I used to get all my batteries from SR Batteries. Great batteries and great service. I always got the packs prebuilt and never learned the craft of making my own "packs".

The batteries I bought from Battery Junction came with solder tabs attached at each end of the battery. All I had to do was solder the wire to the tab and in turn, the plug which is a standard size "N" power plug. The inside contact of the plug is positive and outside jacket is negative. My neighbor is an electrical engineer and he looked at the voltages and said it wouldn't make any differences and should be well within tolerances of the Airshield. In fact we measured the voltages of a fully charged OEM cell (= 2.98v) vs the replacement cells (= 3.71v) prior to running them in the unit for the test of run time. I found it interesting that even with a full charge the new OEM batteries didn't even reach the operating voltage for the unit.

Chris,

It might be possible to cut up a sock type HEPA filter from the Airstream and make at least four of the filters of the size on the Trend Airshield. I believe that the cost of the Airstream filter is about $28.The only potential problem that I see by using the P100 filter material is that the airflow may be reduced. If that is the case, folding or pleating the material to get more surface area would help.

Battery voltage is not a problem as your neighbor said. The output voltage of a battery varies considerably from the time that it is freshly charged until it is time to recharge. Since the load is just a DC motor, you could probably operate at 200% of rated voltage with some reduction in motor life and other performance penalties.

Bill

Chris,

This is a great tutorial and excellent solution to improving the usefulness of the Trend Airshiled. I am going to get started putting one together for myself. Thanks for sharing it with us.

I make a motion that his be moved to the Articles and Reviews section for future reference. How about it Mods?

I just bought the Airshield along with an extra battery pack for the additional $30. The two battery packs should for now take care of my needs for power, but I am really interested in less expensive options for the filters if you find a solution. Thanks for sharing your information.

Thanks for the kind works David. I am now getting about 16 -20 hours per charge of two batteries in my Airshield. These replacement batteries appear to be far superior to the OEM batteries.

So joining this forum made me understand how furniture is created, and that makes me be a little more respectful with it.

How are you regulating discharge voltage? If the voltage on those cells drop below 3V per cell they may become unstable. If you have no PCB to protect them please be advised LiIon cells can be just as dangerous if over discharged as they are over charged. They make regulator boards that may be a smart investment.

Jason
Battery Builders/MTO Battery

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