Convert Your 7.2v Power Tools to Use RC Batteries
I have several cordless power tools. They all use proprietary 7.2 volt batteries. The photo below shows two of my cordless power tools: a Black & Decker saw and a Skil drill. Each of these power tools comes with two 3.6v batteries (installs in series to make 7.2 volts). Although the batteries are exactly the same, they are built into physically different packages. The Black & Decker's batteries are called VersaPak, while the Skil's batteries are called Flexi-Charge. Over the years, these batteries dies due to age, or due to lack of use. You can still find replacements online (see "Related Links" below), but they are extremely difficult to find in local stores.
One of the reason for their extinction is that the power tool manufacturers want you to not only buy more batteries, but also want you to upgrade your tools. So they keep coming up with new battery form factors, rather than selling you the same old stuff. For example, at this writing, rather than producing more VersaPak tools and batteries, Black & Decker is marketing a new line of tools and batteries called the VPX system. There is nothing new in the VPX system, except that the batteries are Lithium Ion, rather than NiCd or NiMh. The VPX battery is still 7.2 volts.
Tired of dying proprietary batteries with their own charger to take up my workstation, the overnight charging just so that I have to finish the work a day later, and the inability to interchange the same batteries between all my power tools, I decided to convert them all to use the standard 7.2v R/C battery. You see, the 7.2v has long been standardized in the Radio Control (R/C or RC) hobby industry. They are used in RC cars, RC planes, and other RC toys. You can buy the 7.2v battery packs at any RC hobby store, or you can build your own. Most of them uses the standard 7.2v Tamiya battery connector. And, best of all, there are lot of inexpensive 15-minutes quick chargers for these batteries. That's right, you can charge up one of these battery packs in 15 minutes! That means you can finish your work the same day even if you run out of battery. Having a few battery packs to charge in parallel means you never have to stop and wait for the battery to charge.
Luckily for me, I've been a RC car addict in the past and still have a Panda quick charger and several batteries laying around. But I have no problem picking up a few new 7.2v battery packs. The standard Tamiya battery connector is available at local RC stores or online (see "Related Links" below).
After picking up several Tamiya battery connectors and battery packs (they are now available in both NiCd and NiMh types), I took my power tools apart. Once they are apart, I soldered the Tamiya battery connectors onto the existing proprietary battery connectors. Next, I shaved off parts of the inside so that the standard 7.2v RC battery can slide in, but not loose enough to slide out by itself. Now, all my power tools uses the standard 7.2v RC batteries (see photo below).
I recently converted a old Dirt Devil portable vacuum to use the 7.2v RC battery pack as shown in the photo below. This Dirt Devil portable vacuum used a 3.6v battery that has long died. After taking the vacuum apart, I saw that there is only a simple circuitry from the battery to the motor inside the casing. The motor was a basic analog magnetic motor, so I suspected that with more battery voltage, the motor will just spin faster; a more powerful vacuum. So I wired up the RC battery connector to it. The vacuum worked beautifully after that!
Thanks for the suggestion! I used a pair of small RC 7.2vDC NiMH batteries in parallel for a total of 2800mAh and they've been a vast improvement over the original Versapaks. They also fit inside the drill necessitating only the removal of the original Versapak battery holder (no cutting required). Thanks again!
I also recently found the smaller airsoft batteries could fit nicely in electric tools. Check out the size differences below.
Dear Mr. Cheng:
I have a variety of RC battery packs that I use with the drill. It ranges from 1100 mAh to 2300 mAh. I have both NiCD and NiMh batteries. I've been using 7.2v battery packs, 8.4v battery packs, and 9.6v battery packs. They all seem to work with my Skil cordless drill very well. Probably because it only has an analog motor without sophisticated electronics.
I have been following the airsoft articles on this web site. The tactical Picatinny weaver rails is the solution to mounting hobby batteries (NiCd, NiMH, LiPo, LiFe) to power tools. See these articles:
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