4 ms·

At first I thought that you could charge the batteries through the hand crank. Does anyone know if it would be throetically possible to fit something like that

At first I thought that you could charge the batteries through the hand crank. Does anyone know if it would be throetically possible to fit something like that into such a small enclosure? I actually have an electronic game toy from when I was a teen that has a hand crank. If anyone wants to see a pic of it let me know.

jbay808 4y ago
Yes, it's possible. The components needed are very small. However I think it would risk people damaging their device (or their fingers) by trying to crank-charge the batteries too zealously.
- MBCook 4y ago
  I think that was one of their original ideas. On top of your reason I think the problem was when they looked into it it was incredibly impractical to actually charge the device that way. You just couldn’t generate enough electricity with such a small crank. I mean if you had the crank for 10 minutes and it would only charge the little battery in that thing 1%, would it be worth it? That’s the impression I got.
twobitshifter 4y ago
This is what I thought it would be for, I have a small radio with a similar crank and it should be possible to power it that way. The designers probably considered it and I wonder why they didn’t do it.
- deleted 4y ago
  [deleted]
- philistine 4y ago
  A radio compared to an ARM chip with a display for gaming are not in the same hemisphere of power needs. You simply cannot power a system like that through a crank.
  - twobitshifter 4y ago
    It clocks in at 2.74 Wh (740 mAh @ 3.7V). https://www.ifixit.com/Teardown/Playdate+Teardown/143811 https://www.ifixit.com/Teardown/Playdate+Teardown/143811 Assume 75% usable charge that’s about 2Wh. Ads say 8 hour active time so you’d need to make 0.25 W to power it. Say the crank is about 0.1m and you turn it at once per second, 6 radians per second, your force needs to be roughly half a newton when accounting for losses. Half a Newton is about the weight of two AA batteries. So it’s perfectly achievable to keep it running, but we’d have to really think about how much you can output with a hand crank. You wouldn’t want to crank it and try to play at the same time, so you’d be cranking to charge and then play. I found here many crank chargers useful for charging phones and some with as high as 20W output. The ones that are small and cheap can do 1A, 4W, but that would be plenty. 15 minutes of cranking would give 4 hours of play time. https://housegrail.com/best-hand-crank-generators/ https://housegrail.com/best-hand-crank-generators/
    - danachow 4y ago
      > 15 minutes of cranking would give 4 hours of play time. Ok that doesn't sound fun at all. But here are the bigger problems: > https://housegrail.com/best-hand-crank-generators/ https://housegrail.com/best-hand-crank-generators/ Those things are fucking huge -- you are comparing some junk ass Ali Express device to proposing actually integrating in the product. Could you find a cheaply and readily available mass produced motor/dynamo that would fit in this 9mm thick form factor and still produce enough power? And at the end of the day the only reason that a device like this is possible for them is they can basically build around easily sourceable, highly integrated parts - The only thing really custom on this is the shell/mechanicals - and that probably blew the majority of their design budget. Spending 10s of thousands for a custom micro dynamo for a dumb feature doesn't seem like well placed priorities. Also, you would have to integrate this without interfering or degrading the primary function of the crank.
- nsb1 4y ago
  Pretty sure the gearing and/or flywheel spinning required to actually reasonably charge a device like this would make using it as a gaming input mostly useless. If you've tried any of those hand crank devices, they take quite a bit of force to get going.

jbay808 4y ago

Yes, it's possible. The components needed are very small. However I think it would risk people damaging their device (or their fingers) by trying to crank-charge the batteries too zealously.

MBCook 4y ago
I think that was one of their original ideas. On top of your reason I think the problem was when they looked into it it was incredibly impractical to actually charge the device that way. You just couldn’t generate enough electricity with such a small crank. I mean if you had the crank for 10 minutes and it would only charge the little battery in that thing 1%, would it be worth it? That’s the impression I got.

twobitshifter 4y ago

This is what I thought it would be for, I have a small radio with a similar crank and it should be possible to power it that way. The designers probably considered it and I wonder why they didn’t do it.

deleted 4y ago
[deleted]
philistine 4y ago
A radio compared to an ARM chip with a display for gaming are not in the same hemisphere of power needs. You simply cannot power a system like that through a crank.
- twobitshifter 4y ago
  It clocks in at 2.74 Wh (740 mAh @ 3.7V). https://www.ifixit.com/Teardown/Playdate+Teardown/143811 https://www.ifixit.com/Teardown/Playdate+Teardown/143811 Assume 75% usable charge that’s about 2Wh. Ads say 8 hour active time so you’d need to make 0.25 W to power it. Say the crank is about 0.1m and you turn it at once per second, 6 radians per second, your force needs to be roughly half a newton when accounting for losses. Half a Newton is about the weight of two AA batteries. So it’s perfectly achievable to keep it running, but we’d have to really think about how much you can output with a hand crank. You wouldn’t want to crank it and try to play at the same time, so you’d be cranking to charge and then play. I found here many crank chargers useful for charging phones and some with as high as 20W output. The ones that are small and cheap can do 1A, 4W, but that would be plenty. 15 minutes of cranking would give 4 hours of play time. https://housegrail.com/best-hand-crank-generators/ https://housegrail.com/best-hand-crank-generators/
  - danachow 4y ago
    > 15 minutes of cranking would give 4 hours of play time. Ok that doesn't sound fun at all. But here are the bigger problems: > https://housegrail.com/best-hand-crank-generators/ https://housegrail.com/best-hand-crank-generators/ Those things are fucking huge -- you are comparing some junk ass Ali Express device to proposing actually integrating in the product. Could you find a cheaply and readily available mass produced motor/dynamo that would fit in this 9mm thick form factor and still produce enough power? And at the end of the day the only reason that a device like this is possible for them is they can basically build around easily sourceable, highly integrated parts - The only thing really custom on this is the shell/mechanicals - and that probably blew the majority of their design budget. Spending 10s of thousands for a custom micro dynamo for a dumb feature doesn't seem like well placed priorities. Also, you would have to integrate this without interfering or degrading the primary function of the crank.
nsb1 4y ago
Pretty sure the gearing and/or flywheel spinning required to actually reasonably charge a device like this would make using it as a gaming input mostly useless. If you've tried any of those hand crank devices, they take quite a bit of force to get going.