Hey, i often read about electric paramotors having a flight duration of 20-40 minutes… what does that mean? Is that on full power or just a guesstimate based on a couple of peoples flying style?
Depends on the amount and type of batteries used. Most of us choose to use a relatively conservative flight style. I haven’t heard of anyone on here use this machine for lots of slalom type flying. Casual flying can get 40 mins with 6 batteries. I’ve done tests where I use max power (Watching voltage sag) until the battery is empty and it takes at least 20 mins. If I were to do this in the air I’d probably be at 4,000 ft.
It means “your mileage will vary”.
I run 4 6s Bonkas in batch 4 machine. I charge to 4.15 volts/ cell. After a 10 minute flight (launch, climb, cruise, glide to land) my chargers will put about 10-12 amp hours back into the batteries which is just about half the rated capacity.
Theoretically I could fly for 20 minutes. However I want to have some left over when I make my landing and I want to baby my batteries 'cuz the cost me $1300CDN.
Going to six batteries and maintaining the same 10 minute cushion for safety and battery life I could fly for 20 minutes easy.
Thanks for the reply. I’d never be satisfied with that kind of flying time though.
Yeah it’s pretty short. I’m thinking hard about more or bigger batteries. Or an Atom 80. 
I think Tesla will soon show us some major breakthroughs in batteries at their battery day event. May not be able to get them for paramotors for a while but will show us where battery tech is headed. If anyone can produce and manufacture a superior battery it’ll be tesla.
We just need Tesla to develop battery with a C rating we can use.
Or high enough energy density that we can carry 6-8kwhs. Current draw of 250amps would not require really high “C” rating of the capacity is really high.
I’m thinking their upcoming breakthroughs will be in durability, robustness, and cost, not density.
If you want that technology, it’s sort of available.
https://oxisenergy.com/products/
These batteries are currently in production (very small scale) and they have 400w/kg which is twice what the open ppg batteries hold.
These cells are rated at a constant 1c which would give you about 130a also where at about 1/3 throttle you are pushing the battery to the limit. At that power level (1/3 throttle) they will likely have less than 275w/kg usable power and possibly down lower than 200w/kg.
At this point you might as well just go with a standard li-ion or lipo battery which at the cell level can hold in excess of 200-250w/kg and with the proper set up you can hold full throttle the entire flight.
I’m just trying to show that it may sound great to just go with a higher capacity battery pack, but with those super high capacities the batteries they typically have an exponentially worse C-rating as the capacity goes up.
Short circuiting the math a bit. A 1C battery means it’ll maintain constant amperage high enough to drain rated capacity in 1 hour. If its also light enough that we can lift substantially more than and hour of battery capacity (say 90 mins) then 1C continuous is enough. For PPG flying this would be about 8-10 Kilowatt hours.
Of course they still have to be capable of perhaps 3C for a burst long enough to take off and climb. Two or three minutes might be enough.
Checking the spec sheet on the Oxis site I see that 400wh/kg was obtained with a 0.1C drain not a 1C drain. - sigh…