Their power density is off the charts something like 1600wh/kg have already been developed. With the theoretical upper limit on energy density as high as 6000wh/kg.
The catch is they are not rechargeable.
But lets entertain a future where they reach the theoretically accepted maximum energy density, and start getting mass produced and efficiently mass recycled to the point it’s feasible to buy a new / refurbished battery for your paramotor.
At 6000wh/kg, the 20kg SP140 pack would hold an insane 120kwh.
Resulting in an insane 30 hours of flight time!
Even considering the 1600wh/kg figure that has already been produced. Such a battery for the SP140 would yield 8 hours flight time and put the ICE guys to shame.
Wont happen IMHO::
Have to make sure you get to site running on fumes(last 20k electrons) to get your value exchange.
For PPG you will want to have 2, on for flying and one for exchange once spent.
Cost will not be there, high , too many factors due to the frequent exchanges from one of cycle life.
I just dont see it.
One of the main reason I love my Chevy Bolt – I dont have to go to the gas station on cold winter day/night, charge from home.
Cheers
This can be mitigated by trip planning. Buy a few one hour batteries. A couple twos maybe, and a six hour perhaps. Run what you want for the flight. Exchange as needed for fresh ones.
One other problem with the Al/air batteries is the electrolytes are pretty dangerous I think.
Yeah, The cost would probably be more than using a rechargable. But if you wanted an 8 hour flight time for some crazy XC or competition flying, you are probably willing to pay up.
I find this curious.
In the beginning of the electric car design, one of the suggestions for the battery power concern, was to have batteries on racks at fuel stations. a electric car would expend the power from the battery, pull in a station, have the low power battery removed from his car and have a freshly charged battery put in its place, then they would go on their way.
But, I think the one big thing that killed that was warrentee. You would never know what condition battery you were getting, if it had full power potential or if it were on it’s last charge, which of course would effect the amount of range you would have left in that battery.
Car owners prefer to own their car, and that includes the battery. That way they know that their battery is new and fresh where if you were just gettting abattery from a charge station, there was no way to tell what you were actually getting…
Cars are not aircraft. They don’t tend to kill you if you let them run out of gas or don’t pay attention to their maintenance or drive them into really bad weather. Because of this ownership experience and operational expectations of a car is very different than for an aircraft.
Also current electric cars have adequate range with a LiFe battery that recharges overnight. For electric aircraft to be reasonably viable the energy density needs to be three to four times more. If we can get that with a really cheap but non rechargeable battery then exchanging batteries will be one potential solution. I think if we see Al/air batteries cheap enough, then electric cars might start doing that as well.
for sure. I stand corrected on that one. Still, running out of fuel in the air normally creates a much more serious and inconvenient situation than typically does on the road.
what would be handy to have would be a light weight battery pack that would serve as a backup, supply 10-15 minutes that can be switched in when the main battery goes dead, by accident or otherwise.
something that can try to get you home.
How would that differ from having the main pack 15-20 worth larger? We already have to use the lightest batteries available anyway.
Ah you mean have an al/air non rechargeable emergency pack? Could be an interim solution until al/air gets cheap enough to just use it. Let’s do some quick and dirty math on that…
SP140 battery is about 4kwh and it works for almost an hour. For a nice average say we “burn” about 5kwh/hour.
Two stroke paramotors burn anywhere from 2-4 liters per hour. Gasoline is currently almost $2usd/litre here in the great white north. That’s up to $8.00 an hour fuel alone. Add oil, maintenance etc.
If an al/air battery can be exchanged for $1-2 per kwh that’s $5 - $10 / hour. If that happens no one will run two-strokes in anything. Even double that would make many paramotor pilots happy to go to electric I think.
The difference is you would not be able to use up all your battery because it would be a smaller second pack. It would be easy to install a battery switch from the marine world, batt 1, batt 2 both, off.
the main battery batt1 would be used on the flight and generally would be enough to fly back. If for whatever reason, your battery shut down from low voltage, you can switch to batt 2 and bee line home, probably gliding most the way but it is a life boat for power.
You can’t base anything on the cost of gasoline. that market fluctuates too much.
I have my reasons to believe the fuel prices will yet soar but that’s me.
However, California has just created a law stating fossil fueled motors, vehicles etc, cannot be purchased after a certain date. This should really give a jab to the electric vehicle industry and the battery tech we will see should be really helpful to electric Paramotors.
An easier way to do this would be to just set a “reserve” threshold where the controller automatically cuts or limits power when the battery voltage gets to a certain point. Then you could re-arm or whatever to “activate” your emergency last portion of the battery pack. No extra hardware required or other battery to maintain
Does the throttle stop working at a preset charge or does the motor get weaker as the battery approaches full discharge? I’ve been landing my SP140 when the power displayed drops to 10% while applying throttle. Once on the ground, the power display recovers to 20% at rest. I might fly longer if I knew what to expect as the display approaches 0%.
If you’re on the latest update it does a bit better job of recording kWh used so you can leverage that as well. If you’ve consumed 3kWh and have a 4kWh battery (standard size) then you have about 25% remaining.
The voltage does sag as you mentioned under load. Like all batteries, you’ll get more life out of it if you keep it between 20% and 80% charge most of the time. The controller wont cut power ever but the BMS will when it gets to a critical voltage.
I try to always give myself at least 15% left when landing.
Where/How well is this documented? Based on my experience with cell phones, I assume that the last 20% might really mean 2%, and that the capacity (and accuracy of the monitor) will decrease if I just keep topping it off (as recommended for these batteries!) rather than occasionally doing a full drain/recharge. If these batteries and monitors are better than that, or need different treatment, that should be in BOLD somewhere.
I am more knowledgeable with automotive Lithium but it seems they all carry a similar trait.
They develop a chemical memory over time.
The best example I can give is one owner stopped using his vehicle and stored it for about a year. Charge was somewhere around 60%.
When they started driving it again, it has lost about 20% range on the battery.
The only way they could recover that range was to do long purposeful discharges, from a full battery to near discharge.
The recovery is slow and in small increments but everytime they did this discharge, the battery recovered a bit of that lost charge.
Lithiums do not like being fully charged and they do not like being discharged. something to do with the chemistry.
So in the automotive world, a full battery is most likely 5-10% under full charge and full discharge is something like 10 to 15 % discharge.
You can force the car to run below that limit but it could cost on battery lifetime.
for sure. I stand corrected on that one. Still, running out of fuel in the air normally creates a much more serious and inconvenient situation than typically does on the road.