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From: Joerg on 3 Feb 2010 14:13 D Yuniskis wrote: > Hi Ed, > > ehsjr wrote: >> D Yuniskis wrote: >>> I want to hack together a *small* "hand powered" genset that >>> I can use to charge a 12V GelCel to power a SW rig when I am >>> in the field. >>> >>> I should be able to use a DC PM motor with a suitable >>> gearbox and crank. Any suggestions as to how to go about >>> spec'ing the motor for such an application? I figure I >>> should be able to easily generate 20-30W "mechanically" >>> without resorting to "pedal power" >> >> Your arms are gonna fall off, real quick, at 20-30W. >> How long do you figure you'll have to crank the thing? > > I don't expect to need to generate 20+W. Rather, I think > *sizing* for that will put the "sweet spot" of the genset in > a more comfortable ergonomic operating point. > > I think the rig uses about 5-6W during Rx. Tx obviously is > the killer :> But, that's what you have a battery for :> > (i.e., store the power you are generating for those times > when you key the rig). > > Even at 20W, I think it is doable for "reasonable" stretches > provided you have enough mechanical advantage. E.g., a short > crank will kill you a lot quicker than a long one. Well, better start doing push-ups. You goal should be 200 in one stretch :-) Or get a kayak and plough it through the lake at full bore, every day, rain or shine. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: D Yuniskis on 3 Feb 2010 15:12 Joerg wrote: > D Yuniskis wrote: >> Hi Ed, >> >> ehsjr wrote: >>> D Yuniskis wrote: >>>> I want to hack together a *small* "hand powered" genset that >>>> I can use to charge a 12V GelCel to power a SW rig when I am >>>> in the field. >>>> >>>> I should be able to use a DC PM motor with a suitable >>>> gearbox and crank. Any suggestions as to how to go about >>>> spec'ing the motor for such an application? I figure I >>>> should be able to easily generate 20-30W "mechanically" >>>> without resorting to "pedal power" >>> >>> Your arms are gonna fall off, real quick, at 20-30W. >>> How long do you figure you'll have to crank the thing? >> >> I don't expect to need to generate 20+W. Rather, I think >> *sizing* for that will put the "sweet spot" of the genset in >> a more comfortable ergonomic operating point. >> >> I think the rig uses about 5-6W during Rx. Tx obviously is >> the killer :> But, that's what you have a battery for :> >> (i.e., store the power you are generating for those times >> when you key the rig). >> >> Even at 20W, I think it is doable for "reasonable" stretches >> provided you have enough mechanical advantage. E.g., a short >> crank will kill you a lot quicker than a long one. > > Well, better start doing push-ups. You goal should be 200 in one stretch > :-) > > Or get a kayak and plough it through the lake at full bore, every day, > rain or shine. No, my upper body exercise of choice is cutting down trees and digging out the root balls. Four 50'+ in the past year. The hole I dug to remove the root ball for the last one took 7 tons of topsoil to fill (*after* removing the stump to a depth of 4 ft... no idea where the damn soil sneaks off to! :< ). Though I suspect this also places demands on lower body (lifting the soil out of the hole) -- hard to figure out just what portion of the work is done where (though your shoulders sure ache after one of these "events"!). Of course, walking 25+ miles every week helps keep the lower body "well oiled"! :> Putting 6W into a battery for 10 minutes will be a piece of cake!
From: Michael A. Terrell on 3 Feb 2010 15:50 D Yuniskis wrote: > > Hi Michael, > > Michael A. Terrell wrote: > > D Yuniskis wrote: > >> I tried running a battery powered hedge trimmer "backwards" > >> and that seemed to work OK. A few amps into a dead short. > >> About 18-20V open circuit. But, since everything is made > >> out of *plastic* nowadays, there would be no way to remove the > >> motor and site it in a different (size/shape) container. > >> (i.e., the motor itself relies on the plastic to keep > >> armature in place -- PoS). > >> > >> But, that's given me ideas as to other battery operated > >> devices that I might try to cannabilize... > > > > A cordless drill with a dead battery comes to mind. > > Yeah, I started looking through my "collection". Unfortunately, > the ones with dead batteries are the "toys" that were ineffective > hence they were unused and batteries left to die. I have a couple junk drills and one motor from a new drill that someone broke the output shaft of the gearbox. It is from a 18 volt drill. I am going to gut the 14.4 volt drill battery packs and add a 20 foot cord with a cigarette lighter plug so I can use them with one of those 12 volt lead acid 'jump packs' made to start a car with a dead battery. I already use one with a portable DVD player to watch old movies. > There is some advantage to a *non-dead* battery as then the > battery storage is implicitly taken care of (though the batteries > on cordless drills tend to be on the small side :< ) > > <shrug> I will have to play some more... Have you ever seen the hand crank generators made for military radios, in W.W. II? AKA: a 'Gibson Girl' radio. http://www.wftw.nl/gibsongirl/gg113.jpg -- Greed is the root of all eBay.
From: D Yuniskis on 3 Feb 2010 17:03 Hi Michael, Michael A. Terrell wrote: > D Yuniskis wrote: >> Yeah, I started looking through my "collection". Unfortunately, >> the ones with dead batteries are the "toys" that were ineffective >> hence they were unused and batteries left to die. > > I have a couple junk drills and one motor from a new drill that > someone broke the output shaft of the gearbox. It is from a 18 volt > drill. I am going to gut the 14.4 volt drill battery packs and add a 20 > foot cord with a cigarette lighter plug so I can use them with one of > those 12 volt lead acid 'jump packs' made to start a car with a dead > battery. I already use one with a portable DVD player to watch old > movies. You might find this "won't work" :> (I can't say for sure) I tried doing this many years ago with a battery pack from a cordless Gardner Denver WW gun. I was only using a *short* length of wire and the IR drops in the cable were unreasonable. (of course, I think the battery was a much lower voltage... I'm not sure of the details). Point is: test this before you invest lots of time and effort so you don't find yourself disappointed. (also test under load) >> There is some advantage to a *non-dead* battery as then the >> battery storage is implicitly taken care of (though the batteries >> on cordless drills tend to be on the small side :< ) >> >> <shrug> I will have to play some more... > > Have you ever seen the hand crank generators made for military > radios, in W.W. II? AKA: a 'Gibson Girl' radio. > http://www.wftw.nl/gibsongirl/gg113.jpg Yes, this was what I had in mind for packaging. I think the genset for that radio was pretty puny, though. Akin to these hand cranked "emergency radio/flashlight/foot massagers" they sell nowadays (how many t's in "toy"?) Hmmm... even if I don't *gut* the "good" drills, maybe I can still use them to empirically derive some information regarding power (and V and I) available for a given "rated" motor...
From: Joerg on 3 Feb 2010 16:58
D Yuniskis wrote: > Joerg wrote: >> D Yuniskis wrote: >>> Hi Ed, >>> >>> ehsjr wrote: >>>> D Yuniskis wrote: >>>>> I want to hack together a *small* "hand powered" genset that >>>>> I can use to charge a 12V GelCel to power a SW rig when I am >>>>> in the field. >>>>> >>>>> I should be able to use a DC PM motor with a suitable >>>>> gearbox and crank. Any suggestions as to how to go about >>>>> spec'ing the motor for such an application? I figure I >>>>> should be able to easily generate 20-30W "mechanically" >>>>> without resorting to "pedal power" >>>> >>>> Your arms are gonna fall off, real quick, at 20-30W. >>>> How long do you figure you'll have to crank the thing? >>> >>> I don't expect to need to generate 20+W. Rather, I think >>> *sizing* for that will put the "sweet spot" of the genset in >>> a more comfortable ergonomic operating point. >>> >>> I think the rig uses about 5-6W during Rx. Tx obviously is >>> the killer :> But, that's what you have a battery for :> >>> (i.e., store the power you are generating for those times >>> when you key the rig). >>> >>> Even at 20W, I think it is doable for "reasonable" stretches >>> provided you have enough mechanical advantage. E.g., a short >>> crank will kill you a lot quicker than a long one. >> >> Well, better start doing push-ups. You goal should be 200 in one >> stretch :-) >> >> Or get a kayak and plough it through the lake at full bore, every day, >> rain or shine. > > No, my upper body exercise of choice is cutting down trees and > digging out the root balls. Four 50'+ in the past year. The hole > I dug to remove the root ball for the last one took 7 tons of > topsoil to fill (*after* removing the stump to a depth of 4 ft... > no idea where the damn soil sneaks off to! :< ). > Wow! Ok, I take everything back, you must be in top shape. I did split a lot of firewood but it's been a while and I probably won't be able to compete. When I was younger I could have competed. Torqued off a 16mm-thread crane hook at a company ... screeeee ... *POCK* ... thoroughly impressed the guys that an electronics jockey could do this. > Though I suspect this also places demands on lower body (lifting > the soil out of the hole) -- hard to figure out just what portion > of the work is done where (though your shoulders sure ache after > one of these "events"!). Of course, walking 25+ miles every > week helps keep the lower body "well oiled"! :> > Same here, I spend a lot more on sports shoes than on car tires. But 25 miles/week ain't that much. > Putting 6W into a battery for 10 minutes will be a piece of cake! Yes, now I believe it. Maybe put a li'l solar panel on top to cheat a bit :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |