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5/13/2026
I made a human powered generator out of an ACT II elliptical exercise machine and want to transfer all of the power to a battery bank real time without significant loss. If you can afford me any assistance, please advise & we will get this done.
The battery in the circuit is represented by a lamp. Where are all of the battery type symbols? Where are all of the generator type symbols?
Two ea. 14.4v, 6.5 amp nimh batteries in series receive the energy generated by three each 24 volt 350W DC scooter motors used as generators, all driven the same way by the same belt off of a single heavy flywheel, with their 3 ea. DC outputs connected in parallel.
With no load, the output of the 3 parallel generator array is 16 - 30 volts. Actual power generation of the three generators is limited by human cadence when load is attached. Tough to get to over 20 volts with full load attached. Schottky diodes protect each of the 3 generators from being back-fed by the nimh battery bank.
These 3 generators are simultaneously spun up to approx. 2400 rpm from the approx. 60 rpm cadence of the elliptical, through mechanical pulley stages.
This approx. 30 volt generator output is dumped directly into the 28.8v nimh battery which can handle up to 33 volts - I am not using the full volt ceiling of the batteries.
Also connected in parallel with the 30v battery, is the input end of a buck converter or buck converters in parallel each with Shottky diode isolation, taking the varied voltage and amperage output of the generators, down to about 13.8 volts. Or whatever the Buck converter is set to. I could directly feed a lifepo4 storage battery here, but that would seem very sketchy so instead...
The 13.8 volt output end of this Buck converter, connects in parallel to both a 12 volt AGM buffer battery, and to a 120 volt power inverter with a load on it such as a lifepo4 charger that is in turn connected to a lifepo4 storage battery. You can see that I have the storage battery somewhat isolated from the original DC output voltage of the generators. This might not be necessary.
The concept is to charge a LIFEPO4 battery bank with this device as an adjunct to the solar energy charging of the LIFEPO4 battery bank. The idea being to run it for an hour or two daily, accumulating about 1200 Wh over a week of use. With several people each contributing to scheduled daily accumulation of energy over the course of a week, the device obviously could generate and store significant electrical energy for later use.
I estimate that this device when coupled with fit humans, can potentially generate 200 watts of stored output indefinitely as long as it is operated at full capacity by fit humans.
I am hopeful that the 'energy flood' into the nickel metal hydride batteries from the 3 generators, will be super-efficient - though the schottky diodes must waste some.
With 24 people each working the machine for one hour a day, it could potentially generate 4,800 watts of STORED HUMAN POWER. IN JUST ONE DAY. 33.6Kw/week.
Are we going for the record?
...where otherwise there would be zero electrical energy available. It would be a village energy core, its power used for well pump, communications, lighting, entertainment, security, irrigation, automation - & health/exercise.
The hypothesis works now. I can directly drive an old 12 volt trolling motor in a barrel of water, by pedaling the elliptical, with the 30 volt output of the generators alone, with or the battery bank, or using both and it is obvious in all cases that there's a tremendous amount of energy being transferred from the elliptical. I can watch the voltage tick up while simultaneously pulling work from the other end. Seemingly more energy than can be adequately explained, but also as anyone who has operated this machine will testify, definitely NOT FREE ENERGY!
I just need to figure out how to extract maximum current from the system. That is the bottleneck right now - cheap buck converters are not supporting enough wattage, and they also act weird when used in parallel. I just need one, very capable and sophisticated buck converter - then I could go generator --> nimh --> buck coverter --> lifepo4 storage.
The nimh batteries are aftermarket Gen 2 Prius battery modules. They like charging and discharging very fast, maybe around 10C, their tradeoff being that they are bulky and heavy and very expensive. Built to last. I am using 2 in series, but could use 14 ea. in 7 series-pairs if I thought it would help - I think they serve best as generator output buffers, they are about the best way I've come up with to gather the generator output without significant losses. Can you think of a better way? Let me know!
There is an extra Schottky diode in the circuit as redundancy against back-feeding the motor/generators should a primary Schottky diode fail and let voltage back-feed. I am sure that all of these huge diodes are wasting energy but I've not quantified how much.
Any suggestions? Feel free! 5/13/2026 Jonzo
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