Modding an old frame to electric

I recently got the chance to purchase a Scout carbon with a moster 185 from a friend for a very reasonable price. Since I wanted a frame I could do more XC on, it was a perfect fit.

Now I’m stuck with my old frame, a Kangook phoenix k2, which has a moster as well, just sitting in the garage. Since I work for a motor controls company now, I’m planning on selling the moster on the kangook and building the frame out to be electric.

At work we have literally hundreds of 48v-650A motor controllers meant for applications like e-motorcycles and golf carts, so I’ll probably use one of those. I’m still on the fence between using 2x 6S packs for 12S2P or using two 12S 44.4v Ag sprayer drone packs that come pre-packaged. I have access to a full machine shop, so building a mount to fit the Moster bolt pattern shouldn’t be an issue. This is the motor I plan on using for the build. Anyone flown on Ag drone 12S packs before?

hi, if you weigh less than 55 kilograms and use a very large, slow wing, the setup you describe will work. not particularly efficient but you can fly with it. if you want to build a real eppg use the setup like sp140 or setup like in europe. geiger, hacker, rotex / mgm.

why do you say that? 600A @ 44.4v is still a top-end of 22kw, or like 30HP.

I’ve done the math already on thrust, and with a 70KV motor at 44v, I should swing a 125cm prop about the same RPM topped-out as a Moster at 8600rpm does with a 2.68:1 gear ratio.

The battery packs are rated at least 25C, so if I get 22,000mAh packs at 25C, that’s 550A top-end for a single series, and I’d be running two in parallel for the overhead.

Other than just calling it crap and saying to scrap it and build a standard SP140, what is actually wrong with this parts selection?

Nobody said that your parts are crap. I said that the possible performance is only sufficient for very light pilots and that it cannot have a particularly good degree of efficiency.

Nobody asks you to take other people’s experiences seriously. You can of course also collect the experiences yourself.

Listen to Bratwurst, he knows what he is talking about and last I heard he still holds the world record for foot launch E-ppg endurance.

I believe the biggest issue is the voltage you are trying to run. It is simply too low to run a large motor efficiently. Many of the European paramotors are limited to about 54 volts nominal and they are already seeing many performance limitations from it. 44.4 volts will only make things much worse.

The motor controller you are on the fence about could be another issue. Applications like golf carts and E-motorcycles require an entirely different software for the ESC to allow the motor to run properly. This software may not work well with a motor that’s driving a propeller.

I’m aware that on standard motors used in the SP140 this is an issue, but that’s because the motor used on the SP140 is only 40kv. Winding the motor for a higher KV (70 in my case) ups the RPM output at a lower voltage. You match the motor to the voltage/rpm you want to target and you should be fine.

yes, however I work for the company that makes the controllers, and have extensive programming knowledge within VCL to edit them as needed. They’re not ESC’s so much as pure sine-wave controllers. Much more advanced than traditional ESC’s adapted from drones. That’s also the reason I went with a hall-sensored motor, as our controllers rely on positional feedback for even higher efficiency up to 10k RPM, not that it’ll ever hit that high since the motor is 70kv. The controller I plan to use is a new one we only sell to specific clients, so it’s not listed on the company site. I have like 5 examples of it sitting on my desk now though in various states of disassembly.

Worse comes to worse, I have several models of this controller that are rated up to 144v, so if needed I can just up the pack voltage without issue.

A 70kv motor running at 45 volts producing 20kW output power will never come close to matching the efficiency of an equivalent quality 35kv motor at 90 volts producing the same 20kW output power. Additionally the higher kv motors will always produce more heat greatly limiting their usable continuous power output.

I wish you the best luck on your project.

Motor efficiency is based on slot-fill percentage and not kv. There’s also a lot to be said about matching load.

that also depends very much on the design. with a geiger hpd motor there are several millimeters of space between the windings and nevertheless it often has more degree of efficiency than other which are filled with press coils. there is a large interplay of kv - number of poles - windings - slots spacing accuracy of the spaces between the magnets and of course the control in general. and yes if the load does not fit to the motor, everything is in vain. this is where most of the mistakes are made in the hobby area.

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