Mechanical battery charger - pedal power!

Say you could produce a kilowatt of power. That would be a kilowatt hour every hour - worth about 12 cents from the power company. This is only worthwhile in a country with extremely low wages or no power grid. Certainly better than no electricity but not for anyone who can afford an RV.

Yes that's true but as an experienced engineer I don't forget about the potential newbie electricians and the excessive wiring run lengths they may do. Nor do I disregard potential overloads, brown outs, and LRA (locked rotor amps) at startup. (just to mention a few things) Anyone can read a spec sheet through a tube. To make things work reliably in the real world you need a wide angle view. For that you add SAFETY FACTORS.

Chum lee

Chum lee wrote:
I agree with Matt Colie and Canadian Rainbirds. I was thinking of the same comparison. As an avid road bicycle rider for 30 years, I know that even the best world class riders/athletes can generate about 1/3 hp continuously using their legs with short bursts slightly higher.

Remember that although 1 horsepower is numerically equal to 746 watts, if you measure the wattage to run a 1 hp (120 volt) single phase motor, even the most efficient motors require about 1550 watts at full load due to mechanical/electrical conversion losses. Three phase motors are slightly more efficient.

Solar panels are looking better and better.


Chum lee

I don't disagree with your conclusions or basic argument at all; however, electric motors are not quite as inefficient as you're suggesting. 80% or 85% efficiency is a not unreasonable estimate for a good quality 1HP single phase motor. The apparent power consumption, and hence current requirements, will be higher due to the relatively poor power factor. NEMA specifies a 78.8% minimum efficiency at full load for standard "design B" 1-4 HP motors.

I agree with Matt Colie and Canadian Rainbirds. I was thinking of the same comparison. As an avid road bicycle rider for 30 years, I know that even the best world class riders/athletes can generate about 1/3 hp continuously using their legs with short bursts slightly higher.

Remember that although 1 horsepower is numerically equal to 746 watts, if you measure the wattage to run a 1 hp (120 volt) single phase motor, even the most efficient motors require about 1550 watts at full load due to mechanical/electrical conversion losses. Three phase motors are slightly more efficient.

Solar panels are looking better and better.


Chum lee

Matt_Colie wrote:
Bryan Allen was the power plant for the Gossamer Condor when it crossed the English Channel. He was a young athlete and in much better share than most of us. He was reported to be about 1/2 HP for about 1 hour.

1HP - 746 Watts
1/2HP - 373 Watts ~ 30 Amps @ 12VDC (Not L/A charging voltage)

All I can say is Good Luck Guys.

Matt

You beat me to it Matt! A top athlete can supposedly produce 5/8 HP (745 watts or so) for a short time. I think most of us are far from being in that sort of physical condition!

Bryan Allen was the power plant for the Gossamer Condor when it crossed the English Channel. He was a young athlete and in much better share than most of us. He was reported to be about 1/2 HP for about 1 hour.

1HP - 746 Watts
1/2HP - 373 Watts ~ 30 Amps @ 12VDC (Not L/A charging voltage)

All I can say is Good Luck Guys.

Matt

15A for an hour of riding?
How much pasta/beer does that translate to?
You gotta maintain your body!

ewarnerusa wrote:
Remember, I'm a bike junkie. I would probably enjoy it.

But I get it, 15 amps for an hour of riding is 15 Ah back into the battery. And that's practically nothing.

15 AH is not too bad, and can make a difference, if you can do this without much suffering. I would imagine a week long bad weather spell, with snow and rain all day, when few hundred Watt solar collects only 7 or 8 AH and you don't want your battery sliding progressively lower and lower for that long. In energy conservation mode - not really "survival" - you can live on 20-25 AH a day. 8+15=23 AH, here you go. 23 AH a day is plenty, if you replace furnace with propane heater, turn microwave into another cupboard and use a propane range for all kitchen duties.

But... if you add a few more hundred Watts of solar, it will do the job for you. Meanwhile you can go skiing, or sleeping, and then ride a real bike outside when sun shines again, rather than pedaling for an hour facing your coach.

15-20 amps into the battery exceeds what my solar panels can do. Now I certainly wouldn't want to be riding a stationary bike for several hours to do a full recharge of a battery at low SOC. I won't even ride a stationary bike for more than an hour when I'm training for a bike race. Too boring, it's like torture. But for up to an hour? Sure. It would add to my training load as well as putting amp hours into the battery. Remember, I'm a bike junkie. I would probably enjoy it.

But I get it, 15 amps for an hour of riding is 15 Ah back into the battery. And that's practically nothing.

I still think it's cool.

In a survival situation - unless it's a hospital - one doesn't need electricity. What he needs, is fresh water, food, fuel for cooking and - if this is an emergency - a communication device. The only item that needs a power is an emergency communication device, and it is (usually) loaded with batteries that have nearly indefinite shelf life. Or it needs very little power to recharge.