if .....?.....

If somone offered you a hand charger that could
1) Power your cell phone or
2) Power your PDA or
3) Power your MP3 player..till you get home , or back to your car..

a) how big would be too big , what if there was something you could in your briefcase , that , if your cell is running out of power , kind of like those military crank generators but smaller..i used that as an example because i think everyone has seen them in movies , but with todays technology they can be a lot smaller..
EDIT :: i didnt mean run up your cell phone LOL..
i meant power your cell phone

Ok what if it was the size of a standard hard drive ?

Are you talking about a "charger" or a battery pack & charger?

There are a few very nicely packaged 7 Amp Hour and 11 Amp Hour gell cell battery packs out there in very nice cordura carry cases... Charger included...

Regards, Mike

I am talking about a hand crank charger, with super capacitors to hold the charge, like a battery..

There are a few very nicely packaged 7 Amp Hour and 11 Amp Hour gell cell battery packs out there

Click to expand...

they must weigh a ton.,... well alot..

You'd find a hand crank will be rather difficult to charge with. It has limited power.

Supercaps still have very limited capacity in the "power" sense; they have had limited success in replacing batteries only in very specific low current scenarios like low power LED flashlights, and even then not for long. Charging an MP3 player takes like 100x times that.

I took apart my hi-tech 3-LED hand crank flashlight. It's powered by a miniature rechargeable lithium battery, really tiny capacity. Now I checked the battery capacity vs the hand crank current. It turns out the advertising was off by like 10x, that crank could put out only a limited number of mA and it would take that long to charge the battery capacity. And the capacity wasn't that great either. It was still useful though, just not as miraculous as claimed.

Students at the Automobile Technology Department at Hochschule für Technik und Architektur (HTA) Biel have demonstrated that it is possible to start an internal combustion engine with BOOSTCAP ultracapacitors instead of a lead acid battery. These tests have been performed at a test bench and with a real car.


**broken link removed**

Anyway,williB.What are you trying to do?Asked about this charger just out of curiosity?Or you might want to try developing one?

I think it's not difficult to calculate the wattage an average person generates with a hand crank.Then we can compare it with the wattage a normal charger consumes to find out if it's practical.

I'd prefer combining a battery pack with such hand crank.So you don't have to keep rotating the crank when you are charging something.Instead,do it when you have time and let the battery pack hold the energy.

Alex_rcpilot said:

Anyway,williB.What are you trying to do?Asked about this charger just out of curiosity?Or you might want to try developing one?

I think it's not difficult to calculate the wattage an average person generates with a hand crank.Then we can compare it with the wattage a normal charger consumes to find out if it's practical.

I'd prefer combining a battery pack with such hand crank.So you don't have to keep rotating the crank when you are charging something.Instead,do it when you have time and let the battery pack hold the energy.

Click to expand...

i allready have a working model.. but the coils were wound for a different size magnet , thus less efficient.
i have an idea for a portable generator (hand crank) that can be 5.125" by 4.625" minus the crank, that could put out an awesome amount of power..for its size..

Sounds cool! Then it's really awesome.I'd appreciate it if there is such a device.It will help a lot for people with lots of portable devices.You might need to work on some connecting mechanism to suit connectors on most portable devices.

Expecting your good news!

williB said:

Students at the Automobile Technology Department at Hochschule für Technik und Architektur (HTA) Biel have demonstrated that it is possible to start an internal combustion engine with BOOSTCAP ultracapacitors instead of a lead acid battery. These tests have been performed at a test bench and with a real car.

**broken link removed**

Click to expand...

800F, but only 1.9V... wow. Those are some awesome caps! 1.4kJ @ 1.9v, that's enough to be quite dangerous if damaged, even at that voltage! The ESR is incredibly low. I'm trying to picture just what would happen if you jammed a screwdriver into the side of one, it's not high voltage so probably something like an arc welder.

Be realistic about what you actually have available though. If you had a humongous 1F stiffening cap like they use in car stereos, you'd only get 1 amp-sec over a 1v drop. The far smaller PCB "supercaps" with a rating of only 3v or 5v may have large capacity but often very poor ESR ratings. This lowers the rate of charge and discharge plus the efficiency. The ESR lowers of course as you put more caps in parallel which gives you more current capacity, though the efficiency issue remains unchanged since the resistive losses incurred in moving a particular charge in and out of each cap does not change. Surplus catalogs carry supercaps cheap but try to look up the ESR or get a sample first and test it.

Now also keep in mind that a cap stores energy by varying its voltage, unlike a battery. Thus if you only look at how much energy you can store from 5.1v to 4.9v you'll not get much output. If you employ a buck and/or boost converter that can output a particular voltage over a wide range of input voltages, you can get many times the energy out of a particular cap while not troubling the load with inconsistent voltage and/or current.

In WWII many radios utilized a hand crank, it was pretty cool. I'm not sure how much power they put out.

Remember the guy who was selling handheld, D-cell green laser pointers with a 1/2 watt output that burned through plastic cups and such? I had a goofy idea to use a small but high current battery with a hand crank there to power it. Something about the idea of a extremely dangerous hand crank device sounded pretty damn cool. Too expensive though, and he's stopped selling those things after the FBI started asking questions.

You seem to be ignoring the inventions of Trevor Bayliss?, using energy stored in a mechanical spring is simple and efficient, and radios and torches have been in production for years.

Seems a far better idea than hand cranking to charge a capacitor?, and has the added advantage that it could just as easily generate AC as DC (with no converters required).

while googleing bcap0007 i found this..

https://www.electro-tech-online.com/custompdfs/2005/06/AABC_2002.pdf

their BCAP0010 has a capacitance of 2600 F @ rated voltage of 2.5 V
with an ESR of 0.7 mΩ
oznog thats 8.125 kJ !!
maximum current is only 600 Amps , pffft , throw it out ...LOL

just an update on my generator , i wound one bad a*s coil the other day
i used 18 gague wire , lol
The resistance measured was a fanominal 0.3 Ohms so six would be about 1.8 ohms..

another update .. the other day i got over an amp DC from just three coils ..

You wod need to crank a LOT to fill that cap.

Cod you imagine shorting that 2600F cap! It wod explode.

Hmm 43 minutes providing 1 Amp until the voltage wod drop 1V.That is a LOT.

Cod be nice to use whith an solar cell.

yeah that cap is pretty cool..
i am going to wind another coil soon , that will give me four so far..
i am going to need a zero crossing detector so i can use power Mosfets to get the most current from this when i'm done..maybe a PIC could provide this..?

----------------Results of Four coils Test -------------------------
**AC test:**
Voc =20Vp-p

(Loaded) is with a 1 ohm resistor
VLoaded =12Vp-p
average power:
(VmIm/2)= 6*6/2= 36/2 = 18W

**DC Test..:**
(a bridge rectifier setup) was used ,and a 3000uF cap across the output to smooth the wave..
VLoaded = 4V
I = 1300 mA (measured)
power 5.2W

I did the walkman test
when my 2-AA rechargeables run down to around 2.29-2.32 V the walkman switches off..
the walkman uses 50mA of current whether it is full blast or the volume is turned down :roll: dont ask me why this is so...

after 6 min of cranking they lasted 2H 20 min before switching off again..

A diode replaced with MOSFETs and a zero crossing detector is sometimes referred to as a "synchronous rectifier". A PIC will not do this very well, a comparator will. Op amps can sometimes be used in this capacity too but it depends on some specific details of the device.

Your device needs to be hooked up to a switching mode regulator, it might be a buck, boost, or buck-boost depending on your needs. It is possible for a PIC to do this but an off-the-shelf converter is probably better. This will allow you to put out a constant voltage as the capacitor voltage drops, and can do so quite efficiently especially if you substitute MOSFETs for the schottky diodes. This is considerably more tricky but results can be nice. BTW, the PICs with "Enhanced PWM" like the 18F1320 have special outputs for driving the synchronous rectifier. Since the PIC sources the PWM signal it does not need to sense the current direction with a comparator. But the freq needs to be high and the PWM needs a decent resolution at high freq. The PIC may be a bit problematic with its resolution at high freq, and they use substantial idle current to keep going at 40MHz.

If a boost or buck/boost converter is used, you would be able to continue to produce 12v for example while the cap voltage is only 1v. This greatly increases the effective size of your caps while eliminating the voltage regulation issues. You can potentially replace the series array of caps with a parallel one too, which may or may not be helpful.

The bootstrapping issue with the boost converter here is that the regulator's logic requires more than 1v source to run. You could source it off of the output (12v), but then it has no way to start itself when the output cap is uncharged. Adding a lithium coin cell or two used only to get it started will solve the issue beautifully and will last basically forever.

ya think this would work?
assuming i could get the zero crossing detector to drive the fets at the right time and with the correct voltages
there are four pairs of Hexfets , each pair would have their gates tied together..
when the top line comming in from the coils is more positive than the bottom , A&B would be on & C&D would be off and visa versa...
with todays low Hexfet ON resistances i think i could expect LESS than 40 milli Ohms per " on " leg...