I got my new Trend Air/Pro a couple of weeks ago. I think its a really great piece of equipment, but has room for improvement. During the purchase process, I was debating on weather to spend the extra funds for the hearing protection. Im glad I did, even if your not concerned about protecting your hearing, or you use ear plugs, or whatever, you will notice the ear muffs are very helpfull in stabilizing the helmet on your head, that was well worth the extra $25-30 I paid, I feel that hearing protection was a secondary benefit.
Secondly, I noticed that the weight of the battery, while not extremely heavy, throws the helmet around a little when you are moving around the shop. This was not only annoying to me but was causing some neck strain (I have some neck issues anyway), so I immediately started thinking of how to build a remote battery system and upgrade the battery in the process. This part of the project I will discuss a little further down the page.
Thirdly, I was getting some intense “compression headaches” after wearing the helmet for only 10-15 minutes. I was constantly having to remove the helmet to take a break, this is not conducive to production. Here is what I did to address the compression headache. I went to The big chain pharmacy and bought some Dr. Scholes memory foam insoles. I then used a straight edge and. Razor knife to cut a 1” x 8.5” strip out of the insole. If you remove the sweatband from the helmet, you can install this by reinstalling the sweatband over the foam strip. Cut a shorter piece to fit the pad that goes over the crown as well. This cost me about $12 and no more headaches!
Ok, so back to the remote battery project. First off, im no electronics genius, but I manage ok, and I got some input from my father-in-law who is. I was surprised, as many of you were, that Trend is using NiMh battery pacs. A little behind the times dont you think? My design uses Li-Ion 18650 batteries. The 18650 is a pretty amazing battery being used mainly in tactical flashlights. A single cell is 3.7 volts and 3400 mAh. Thats about the same output as the entire Trend battery pack, in a cell the size of my pinky finger! Just make sure you use a “protected” battery, they have circuitry built in to every cell to protect from under/over voltage, fire, etc. The panasonic is probably the best rated 18650 battery on the market and less than $8 each. I decided to use 2 cells wired in parallel so I would maintain the 3.7 volts, but double my run time. In the future, i may build some single cell packs.
Here is the list of products I used, everything came from eBay and amazon.
Batteries: 2 ea panasonic NCR18650B LiIon batteries if you get something else make sure they are “protected”.
Project box: dimensions about 4” x 2” x 1”
Belt clip: I use the type used for kydex sheaths, I used Chicago screws to mount it to the project box lid:
Battery holder with leads, 2 singles or one double:
Coil wire to connect battery pack to helmet: I bought a car charger with the proper 5.5 x 2.1 mm barrel which matches the charging port of the helmet, you will cut the car charging end off to use the coil wire and splice in a male pigtail connector of the same size.
Extra connector pigtails, you need 2 male and 1 female 5.5 x 2.1 mm:
As mentioned above, you will have to do some mods to the battery holders and project box to get it all to fit. Note in the first picture the female connector is mounted in the project box and hot glued into place. You will be splicing a male connector onto the cut end of the coil wire resulting in the coil wire having two male connectors, one on each end. You will power the helmet via the charging port installed in the back of the helmet. I mount the battery pack to my apron shoulder strap, its light weight and out of the way.
Charging: I purchased a Tenergy intelligent charger:
You will use one of the male connector with pigtail to charge the batteries, see pic.
Charge them before using them, they only come charged with about 3.5 volts, a full charge is about 4.1 volts.
The first time using this I noticed a vast improvement of weight and balance of the Helmet on the head. Not bad for a (roughly) $40 investment with lots of materials left over for additional projects.
One thing I did notice is the low voltage warning buzzer going off, I originally thought the batteries weren’t charged al the way. It turns out the female connector on the helmet is slightly loose, so if the extension wire is pulled to the side under tension, it will cause a partial disconnection. I will open up the helmet and put some JB Weld around the connector to support it better.
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