Hand Crank Generator / Battery Charger





Introduction: Hand Crank Generator / Battery Charger

About: museum visit pic

Years ago I had converted an old cordless drill into a hand crank generator, I got the idea from an article in Everyday Practical Electronics magazine the September 2009 issue. While the generator worked I could only get 3 or 4 volts max. out of it. I just couldn't turn it fast enough to get a usable (to me) voltage out of it. Then I remembered that I had a Hand Crank Grinding stone that could be mounted on a work bench or board.

The video can be seen in step Three.

Step 1: The Parts Used

A Hand Crank Grinding Stone

The completed cordless drill converted into a Hand Crank generator,

-The drill was a 19.2 volt Craftsman drill that I had picked up at a yard sale. ( I actually got 4 of them without batteries) The drills didn't work, I have the same drill that I had bought years before. The reason mine still works is that the power transistor that is part of the speed control circuit was fastened to a substantial copper heat sink. The failed drills same model but later manufacture had an inferior aluminum heat sink that just couldn't dissipate heat fast enough under normal to medium use and so the power transistor failed. I imagine that there were a lot of returns.

Some plywood, 2 x 6 board, 4 x 4 post, assorted screws and bolts.

I also used a high current bridge rectifier with spade connectors on the output of the drill.

The reason for the bridge rectifier is that no mater if the crank is turned clock-wise or counter-clock-wise the out put polarity is always the same. I hooked the o/p of the drill to the AC terminals of the Bridge Rectifier the o/p from the Bridge Rectifier comes from the + and - or the positive and negative terminals.

A 1/2 inch by 3 inch spring, a 3 inch piece of 7/16" threaded rod, a 3" long extension nut.

Step 2: Assembly

The drill was previously mounted to a board, I then mounted it to a larger piece of plywood. It was also elevated at the back side of the drill so that the chuck of the drill would be level with the mounting of the Hand Crank Grinding Wheel.

On the grinding wheel I attached the extension nut in place of the original nut ( I also used tread locker) then I screwed in the 3" piece of threaded rod with tread locker as well, then I screwed on the spring ( this turned out to be harder than it sounds).

Next I attached this completed assembly to the chuck of the drill. Then I measured and cut some boards to get the right elevation. Then those boards were fastened to the plywood that the drill is attached to. I used 3" wood screws.

Step 3: Demonstration, Proof of Concept.

Demonstration Items:

Two Fluke digital meters, a 10 watt 12 volt halogen deck light, my camera on a tripod for the video.

One of the meters was set to the d.c. amps setting, the other to the volts d.c setting.

The volt meter was attached to the + and - terminals of the bridge rectifier.

The current meter was hooked up in series with the 10 watt lamp load.

During operation I was able to get .8 amps at 13.45 volts out of the Hand Crank Generator to light the lamp.

If you notice some flickering of the meter displays this is from the leaves of the trees moving in the wind as I videoed it outside.

To see video click on show all items on the pictures, the video is at the bottom.

Step 4: The End

I made this to see if I could get enough voltage out it to charge a battery, it should, but your arm would get tired. I'm glad it worked so well!

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    Great instructable - nice to see a dead cordless drill brought back to life.
    A lot off topic, but I was wondering if anyone has tried a military radio hand-crank generator to charge batteries (or built a similar device)? Old technology, but portable, often used a two-handled crank with longer arms.

    12 replies

    Suggest you check prices on surplused military generators . . .


    1. They tend not to be cheap. In your browser of choice query: "military" hand crank generator

    2. The outputs are not common. I.e. Output: 162vdc @ 60ma & 3.1v @ 300ma. The infamous "Gibson Girl" kite antenna radio generator produced 24v and 330v for the tube radio.

    Shiseiji - more of a suggestion/query than anything else. The hand crank looked to be ideal for what John wants to do, but, I haven't bought any
    military surplus for at least 40 years (no need or interest), so not up on current prices.
    One more option: long ago, non-functioning military/government equipment could be purchased for a bit more than scrap value. If that is still possible where you live, and if the crank mechanism is good, should be possible to cobble up some brackets and replace a non-functioning military generator with one from a car.

    John, my primary point is that 19v volts will damage a 12v battery. Desperate times can call for desperate methods, one time probably won't kill it, but the cost has to be weighed.

    I grew up outside what's now the Marine Corps Logistics Base Barstow, and knew several people involved in military sales, including my brother. Yes, times change. Sometimes good deals can still be had, I have a couple of first editions courtesy of being being willing to buy a "pallet box" (47-1/2" x 39-1/2" x 28") of books in the hope something good might be in there.

    Auctions . . . yes "but" (Behold the Underlying truth), since the late 80's most of the decent lots are purchased by deep pocked folks who can afford to out bid the smaller bidders till they give up and quit coming to the auctions . . .

    Regardless, I've never seen a military hand generator voltage that could be used for charging anything. The idea to use a military hand crank generator has several assumptions that aren't valid. Since some people aren't given to doing much research, I decided to speak up rather than let invalid assumptions stand. If someone knows of a military hand-crank generator that produces a usable voltage, I'm very interested. There are Chinese ones hitting the market ~ $300 USD as of this date, that produce high (430V, 130 mA) and low voltage (6.3V, 2 A). Not real useful for charging a battery or other common use electronics. Use what you can and forget the rest.

    Just my $.02


    Hi Shiseiji, I can see your point now about the 19 volts, As I was testing it I found that I couldn't get the drill to put out more then 13.85 volts. I had it clamped down to the workbench and was turning it as fast as I could. The drill has two speeds Hi and Low, I used the High setting all the time since I could not get it to turn when it was set to Low, The gearing in drills on the the Low setting is for more torque and less speed ( from my own experience using cordless drill). One could probably get the 19 volts out the drill if it was hooked up to a larger flywheel or some kind of bicycle arrangements as some other commenters have suggested, both valid ideas by the way, but then I would lose the portability and that's what I was aiming for. Thank you for your comments though, it's always good to have another set of eyes look at something and give some ideas.

    Ah, a perfect voltage! If you mentioned it earlier, I apologize for overlooking it. I saw one picture, on the web?? Here?? there the author had used bundle ties to put one on a bicycle chain (lower) stay. Just mentioning in case someone stumbles across this as an "not-quite-so-portable" option.

    I have several things that detractors pointed out the flaws from their point of view. While completely disregarding what I had as my criteria. Some was good, but most was irrelevant. You obviously experienced some of that, but took what you could use and said politely No thanks." to the rest. Hope to see more of your work.


    Thank you Shiseiji for the nice comment.

    I think a lot of us tend to have a bad reading day sometimes.

    Thank you again for the feedback.

    DUH, you had it in plain sight at the bottom. Chalk it up to a really bad reading day.

    Thanks tmspro, when I told a friend what I was doing, he also suggested the military radio hand-crank generator idea as well.

    Put the grinding wheel against a bicycle tire.

    A larger flywheel would make it easier to spinning with less effort -- just slower on the start up.

    3 replies

    some minor modifications to make spinning it more easily / less effort. But then again compromise on portability and weight.

    A good idea, but it is limited by the grinder's mounting bracket. Thank you though.

    I love this. Not because it's overly useful, but because it could be. The spring coupling is a golden idea as well, eliminating the need for precision alignment as well as providing some shock absorption for a potential rapidly varied load.

    And I have an old drill . . .

    1 reply

    Thank you KipA2, I'm glad you realized why I had done that, It's not original on my part though, I'm sure I saw it somewhere else. Good luck with your old drill project.