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[J. Random User]

Wandering around Target the other day, I stumbled across a hand-crank flashlight that can be used to charge the XO.  (Assuming you have a car adapter.)


http://frombob.to/XO/#hand_crank_charger


I don't know if it generates enough current to run the laptop, but it could certainly charge a laptop that is turned off.  I tried it;  the charging light on the laptop glows quite merrily.

It has already joined the XO and the other XO accessories in my Earthquake Kit.

[tdang]

Hey Random-

Can you let us know when/if you give that a test? I'd be curious to know how much cranking it takes to charge up the XO.

[LaPaglia]

I have the Feeplay "Free Charge 12V". It puts out more current that the above device and it takes 1 hour at 120 rpm to change a 50% XO battery to 100%. This is charge only the XO is off. Trust me that is a LOT of cranking  Thats 7200 turns of the handle. Trust me after 5 minutes you want to let someone else have the fun. After 10 minutes you will pay someone to crank it. 4 of us took turns and did the hour. The next day the 2 of us that are wimps couldn't lift our cranking arm.

It works. Its much better if you use it to charge a cell phone. But in an emergency it will charge the battery. I would not want to use one of these daily to keep my XO charged. MasterBrite, the maker of the one above would not say what the output was at full speed, or define full speed. They did say that it would not do 14 watts at 12 volts. This means that it will take longer than the Freeplay. Possibly a lot longer.  Remember the XO charge lite will turn on at 12 volts even if the current is low. This means that it will take longer to charge at a lower current rate.

Just my 2 cents.

[tdang]

Oof! Thanks, LaPaglia. Yeah, that's a lot of cranking.

[J. Random User]

OK, I've done some tests with this gizmo.

In order to measure how quickly it charges the battery, I have to use the battery applet that comes on the laptop.  Don't have any other tools for that.

But because I'm charging while the laptop is off, I have to turn the laptop on to look at the battery measurement.  It takes a couple minutes to turn the laptop on before I can look at that measurement, and it drains the battery a bit while it does that.

First I measured how much battery charge was lost just from booting up and shutting down the laptop.  I booted the laptop, looked at the battery charge, and then shut down quickly by holding down the power button.  I did this five times in a row, and came to the conclusion that the battery lost about 1% of full charge just from booting up and shutting down.

Then I turned the laptop off and turned the crank at the recommended 160 RPM (or thereabouts) for five minutes.  Had to stop at that point because I got tired.

Then I booted, and found that the charge had dropped about 1% since the previous measurement.

In other words, those five minutes of charging had added less charge than it takes just to boot the machine, if any at all.

I would have to crank this thing for way longer than five minutes to even begin to accurately measure how much charge it actually adds.  I have no plans to do such an experiment.  I expect my arms to be sore tomorrow.

We already know that this kind of cranking is not very efficient, ergonomically.  That's why the yoyo device was invented.

I consider this to be an emergency kit item, handy to have around when The Big One comes.  If somebody desperately needs to use a computer, and can't wait until sunrise when solar cells can be used, then people could take turns cranking.

So no, this is not something one would want to use normally.

I'm still curious about what's inside this $18 item.  Thinking about making some voltage and current measurements.

It doesn't have any voltage regulation;  I can get anywhere from 0 to 20 volts out of it, without load, by adjusting the RPMs.  But it can't be just a generator and a few diodes, because it can also charge the flashlight battery, and there's no switch for that, and you can't see the internal battery voltage at the terminals, so there's a bit more electronics for that part.  One wonders if the circuit is just non-optimal for this application, and perhaps more current could be had if it was modified...  Maybe I should just rip it apart...

 

[Gabey8]

I have the Feeplay "Free Charge 12V". It puts out more current that the above device and it takes 1 hour at 120 rpm to change a 50% XO battery to 100%. This is charge only the XO is off. Trust me that is a LOT of cranking  Thats 7200 turns of the handle. Trust me after 5 minutes you want to let someone else have the fun. After 10 minutes you will pay someone to crank it. 4 of us took turns and did the hour. The next day the 2 of us that are wimps couldn't lift our cranking arm.

It works. Its much better if you use it to charge a cell phone. But in an emergency it will charge the battery. I would not want to use one of these daily to keep my XO charged. MasterBrite, the maker of the one above would not say what the output was at full speed, or define full speed. They did say that it would not do 14 watts at 12 volts. This means that it will take longer than the Freeplay. Possibly a lot longer.  Remember the XO charge lite will turn on at 12 volts even if the current is low. This means that it will take longer to charge at a lower current rate.

Just my 2 cents.

Holy mackerel. I just got the FreePlay Free Charge crank a few weeks ago. Apparently, I wasn't turning the handle quickly enough, because I wasn't able to get the charge light to go on.

Whew... an hour to charge 50% of the battery. Doggone, that's a lot of cranking. On the other hand, that'd give me two hours of computing. So in case of a really major power outage, that's nice to know.

Boy, it's time to embark on a strength training program.

[tdang]

Thanks, Random! That was way more thorough than I was expecting, and pretty discouraging.

It really looks to me like the biggest barrier for OLPC isn't Windows / Linux / Sugar, but power. I'm a big doofus when it comes to actual electricity, and I took at face value the idea that a kid would be able to charge their own laptop. That's starting to sound like a fantasy.

[davewa]

With my XO off, it takes the AC adapter 90 minutes to re-charge a battery which is discharged to the "red light" condition.  I haven't measured the power (voltage and current) delivered by the AC adapter while charging, but let's assume it's 10W (12V at 0.8A).  That says the charge cycle delivers 15 Watt-hours.  (I think I read somewhere on the wiki that the capacity of the LiFePO4 battery was 20 wH, so this approximation sounds reasonable.)

15 watt-hours is about 13 kilogram-calories.  Burning 13 calories will definitely make your arm tired!

[sambot]

So the DIY inventer guy at our house is thinking of how to use pedal power from an old tredal sewing machine to power up a charging device.

Personally, I'm not holding my breath.

[tdang]

So the DIY inventer guy at our house is thinking of how to use pedal power from an old tredal sewing machine to power up a charging device.

I've so wanted to do the same thing! Got an old treadle sewing machine, and it just looks like I should be able to sit there waggling my feet while typing on my laptop. Probably just steampunk romanticism, though. I expect a stationary bike would be much more efficient.

[davewa]

In terms of deliverable power, a stationary bike would be the best mechanism.  Delivering 10W for 90 minutes on a bike wouldn't even get you breathing hard.

[BeckyJ]

In terms of deliverable power, a stationary bike would be the best mechanism.  Delivering 10W for 90 minutes on a bike wouldn't even get you breathing hard.

Imagine all the daily wasted motion in the gyms around the planet (apart from the cardio, etc. benefits to the participants)!

Shouldn't all the bikes, treadmills, etc. be plugged-in?

[tdang]

Imagine all the daily wasted motion in the gyms around the planet (apart from the cardio, etc. benefits to the participants)!

Shouldn't all the bikes, treadmills, etc. be plugged-in?

But they are plugged in, so that they can show you the blinky lights and an LCD animation of the hill you would be climbing if you were really doing something!

Sorry, that comment brought out the bitter in me.

[LaPaglia]

I have the Feeplay "Free Charge 12V". It puts out more current that the above device and it takes 1 hour at 120 rpm to change a 50% XO battery to 100%. This is charge only the XO is off. Trust me that is a LOT of cranking  Thats 7200 turns of the handle. Trust me after 5 minutes you want to let someone else have the fun. After 10 minutes you will pay someone to crank it. 4 of us took turns and did the hour. The next day the 2 of us that are wimps couldn't lift our cranking arm.

It works. Its much better if you use it to charge a cell phone. But in an emergency it will charge the battery. I would not want to use one of these daily to keep my XO charged. MasterBrite, the maker of the one above would not say what the output was at full speed, or define full speed. They did say that it would not do 14 watts at 12 volts. This means that it will take longer than the Freeplay. Possibly a lot longer.  Remember the XO charge lite will turn on at 12 volts even if the current is low. This means that it will take longer to charge at a lower current rate.

Just my 2 cents.

Holy mackerel. I just got the FreePlay Free Charge crank a few weeks ago. Apparently, I wasn't turning the handle quickly enough, because I wasn't able to get the charge light to go on.

Whew... an hour to charge 50% of the battery. Doggone, that's a lot of cranking. On the other hand, that'd give me two hours of computing. So in case of a really major power outage, that's nice to know.

Boy, it's time to embark on a strength training program.

I had posted this in the thread where you had said you had one and it didn't work for you. You probably just missed it.

"Good news everyone". I just got a Freeplay Freecharge 12V and it does charge the XO. If I put it in and started cranking it would not charge but if I got it up to speed and had someone else plug it in while i was cranking it started to charge the battery. With the battery removed it would run the XO. At least through the boot sequence. I got tired after that 

Interestingly enough after it started to charge the first time I could stop for a few secs and then start to crank again and it would start charging again.

So it does work you just need to have it at speed the first time in the charge cycle before you plug it in.
Next, when my arm heals  will be to remove the battery and see if I can supply enough power to boot it up. Wish me luck.

[Gabey8]

You were right. I wasn't turning the crank fast enough. I tried it again a little while ago.

Oh. My. GOSH. That exercise program is a definite must for anyone who wants to go off-grid with a crank charger. LOL. Even if you alternate arms (hold charger steady/turn crank alternated with hold crank steady/turn charger) that's a lot of exertion.

Maybe I'll build my endurance by cranking the charger itself. I have the Targus charger that I posted about in a separate thread, from one of those Woot.com sales. Conveniently, it beeps and its LED light turns green when it's getting enough power. It also beeps and the LED turns yellow when there's NOT enough power, so that's good feedback.

Time to start turning the crank for a set number of minutes per day, then gradually increasing the minutes. Hey, if the St. joe's Hawk (college basketball mascot) can flap his wings nonstop for the entire length of a basketball game and not keel over, I can learn to crank a charger for extended periods of time.

I hope your arm makes a speedy recovery. You took one for the team there, for sure.

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