Bush Crank Power Bank

[Bishop]

I built this box, using ancient junk from the charity shops of this land. Carved it with the symbols of my people.
The sine of harmonious power and Usb the great connector.
And with a little Geek help, your smiles supplied the reason.



It's a rough prototype for a hand cranked power bank using parts from old dynamo torch, ugly but functional at this stage. Presently capable of charging my old HTC Wildfire smart-phone and Cool-Fire IV vape pipe with minimal effort at a comfortable sixty RPM but It does have limitations. High capacity Lithium cells for instance have special charging requirements so are a problem for it however NiMH, Nicad and old school Lead-Acid rechargeable batteries will trickle charge quite happily. How long of course it will take to charge my phone is anybody’s guess but I will be finding out around Wednesday.


In case anybody is worried that I'm going to blow my phone up rest easy, unlike the cheap Chinese £2 a pop hand-chargers I added a voltage regulator on the output. Superman could spin that crank and not get more than five volts out of it. What is interesting though is that during testing the little 3-phase dynamo can pump out over ten volts with just a bit more RPM effort (22v going at it like a nutter!) and Baofeng walkie-talkies need only 9volts to recharge.

 

[Monikieman]

charging little and often should be possible then or show and tell round the camp fire. everyone will want to have a go

 

[gonzo_the_great]

You may want to add some decoupling capacitors to the input and output of the reg. As those devices can go unstable and oscillate.
I usually solder them directly to the reg pins.

If you are getting far more voltage than you need, how about putting in a little switch-mode step down reg, in place of the linear regulator. You can get them cheaply on ebay, as a made up PCB.
Then you can use everything you generate, rather than just dumping the extra as heat, in a linear reg.

A quick search on ebay... look for something like "MP1584 3A DC-DC Buck Adjustable Voltage Regulator Step Down".

 

[Muddypaws]

You, sir, are a genius! Excellent work.

 

[johntarmac]

Very interesting, how much effort does it take to crank? I'm wondering if a small fan blade would turn it in a breeze.

 

[mousey]

Have you seen that gravity light idea for lighting in Africa? from their website "Combining kinetic and potential energy, GravityLight works by connecting an elevated weight — filled with rocks or sand — to a pulley system that slowly powers a generator as the weight falls to the ground."

maybe combine this gravity assisted powering into your idea then you don't have to sit there and hand crank it?

Awesome idea BTW. - really liking the container.

 

[Bishop]

Have you seen that gravity light

Yes I have and it does have a lot of merit though not sure I could build one. The problem from my DIY perspective is the gearbox, mechanically it's under a lot of strain and small plastic gears have their limits. Then again.. a lighter weight with a longer drop should work with hobby grade gears...

Yeah the box.. killed three birds with that. Made the charger, got some carving practice and discovered I was out of sticking plasters...

how much effort does it take to crank? I'm wondering if a small fan blade would turn it in a breeze.

Effort, surprisingly little. With wind or water as a power source you can also do away with the gearbox and drive the dynamo directly, turning an old greasy skateboard bearing would be a close comparison. Searching Ebay for "Vertical micro wind turbines" may give you some ideas.

You may want to add some decoupling capacitors

I know, it's hideous isn't it
Fitting a Buck converter is definitely the way to go for more efficiency.

 

[TeeDee]

Bishop.

Love this.

Top Marks.

 

[Jaeger]

Aye Up,

Good work Bishop.

I've been down this route previously.

As some have stated it evolves to working on a means of creating the power without the physical effort - or indirect effort.

I've presently got one of those Peltier cells on the sill next to me waiting a means of linking it up to my BRS wood burner..................

 

[Bishop]

Those Peltier devices are mighty tempting, more so since I saw AvE over on Youtube take one apart. My inner MacGyver keeps whispering paraffin lantern, they're cheap, get pretty hot and are controllable. Plus if I use the lemon scented lamp oil Julie will let me work on it indoors.


Phone Update;
99..100 struggling to keep phone charged using the hand-crank but that's with it switched on all the time and the GPS app running in the background constantly. So with normal / minimal usage it looks possible but not entirely long term practical as a solution for the homestead. Unless that is I can train the dog to run inside a big hamster wheel Got a Buck power converter on order and the experiments will continue.

 

[Jaeger]

Aye Up Bish,

If the regulator is anything like this one -



I've been using them for about three years on various pieces of tech which is left outdoors for long periods and they have proven to be excellent pieces of kit.

 

[Bishop]

The box of my people received an upgrade this afternoon and Oh Yeah! feeling that Technomage magic in action now.
Significant improvement in the charging time of my smart-phone, downside however with less electrical energy being wasted it's taking a little more effort to turn the short crank handle. Julie described the change as the difference between stirring a cup of tea and bowl of thick custard. If I do another one then the MkII will need a bigger box to keep the longer handle inand some vent holes. That little 10 watt generator is now working at full power getting warm to the touch now after fifteen minutes of cranking!



Went with a MP1584 Mini DC-DC Buck Converter rather than the LM2596 suggested by Jaeger and kicked myself for not reading the dimensions when the postage stamp size circuit board arrived. Space inside the box was always going to be a issue but it's not that tight a problem. Still, it works though is fiddly to set the desired voltage. Thankfully Usb is tolerant of meddling mortals and permits some wiggle room between 4.40 to 5.25 volts and calls it five. With no oscilloscope to see just how ugly the output from the three phase generator is slugged the input supply rail after the bridge rectifier with a 2200 uf capacitor. That seems to have helped the buck converter during its start up cycle and touch wood nothings gone POP or released smoke... yet.

Not enough current produced to activate the charging circuit for a £land El-cheapo Power Bank, though it is close. I know the Unicom Powerbeam flashlights can do it with similar hardware and a lead acid battery picking up the slack.

Next experiment, set the buck converter to 9-10 volts, cross fingers and plug it into the Baofeng UV5R radio.

 

[Jaeger]

Aye Up,

Looks like you are making progress there Bish.