Hi all,

I'm fairly new to electrics, but I'm convinced that e-flight is the wave of the future. In that spirit I tried to convert my Showtime to electirc power. To that end, I mounted an Actro 32-3 in the nose with a 17X12 APC electric prop and connected a Jeti 77opto plus ESC to my two TP 5S4P 5300 mah packs in series (10cell lipo). The esc is rated for "up to 10 cell lipo". Well on the first flight, it took off like greased lightening and flew beautifully for about 30 seconds, Then there was a puff of white smoke and no power- an immediate landing was mandatory<G>....

The ESC had completely fried itself!- the capacitors and connection wires were completely burned off and the guts of the ESC completely charred. The wood surrounding the ESC was obviously burned so the thing was actually on fire for a brief period. What have I done wrong? Is this just a bad esc or is there something obviously wrong here that I've missed!

Thanks,

George

post deleted....

The prop is in the range recommended by Hobby Lobby and the ESC is sold as a "package deal" with the motor on their web-site. Other than that I don't know how "thirsty" the combo is, but thought it should be within the tolerance of the "package"...unfortunately, I can't get anyone at Hobby Lobby to answer the phone or respond to an email.

George

Perhaps there is something I have missed. You state you have two (2) packs, each apparently a TP 5S4P 5300 mAh pack. As I figure it, one of those two packs would have have 20 cells in it: 5 cells connected in series, and 4 of these series connected to each other in parallel, for a total of 20 cells. Possibly this is a typo and you meant you had two packs, each being a 5S1P 5300 mAh pack. When tied together in parallel, these two packs would provide a total of 10 cells, in a configuration of 5S2P. Asuming that to be the case, then each 5S1P pack is capable of 42 amps delivery if indeed the pack is rated at 8C as mentioned in Timepilot's post. When two of these packs are wired in parallel, you double the amperge delivery, resulting in 84 amps, and this would exceed your ESC rating of 77. If you are working with TP's Pro-Lite cells, you will most definitely get MORE than 8C capability. In point of fact, under burst load, you could see a 12C output resulting in 64 amps per 5S1P pack or 128A on the 5S2P configuration. Definately more than what the Jeti 77 could handle.

Contact Hobby Lobby, 615-373-1444, enter 210 when prompted for extension, and speak with or leave a voice mail for Don McNett. He should be able to help you. If I had to bet a dinner on it, I would say your TP Lipoly packs delivered too much amperge for your chosen ESC. To me, the numbers just don't add up properly for the equipment at hand. Then again, perhaps I am missing something here. My stongest LiPoly packs are TP 2100 3S1P Pro-Lites, with which I am very satisfied.

RD

Doug,

In fact each of those packs has 20 cells but only 5 (stacks of four each) are in series... The Actro 32-3 is used in the Ion helicopter with an Actro 32-3 motor with two 5s4p packs in series routinely. The speed controllers generally used with this set up have max amperages of 70 to 80 amps or so. It isn't obvious to me why the amperage draw of a 17X12 propeller should be more than a 1.5 meter rotor (though the rotor is geared, I understand) That is why I asked the question posed to start this thread.


I have emailed and left phone messages at Hobby Lobby for two days now with no reply...that's why I came to the forum here, looking for knowledge<G>

George

OK, here is some additional information:

My E-Focus II with a Pletenberg 30-10 with a 22X12 prop and Schulz 32.55 ESC on the same 10s4p battery draws 65 amps at full throttle

My Showtime with Actro 32-3 with 17X12 prop and Jeti 77 opto ESC passes 75 amps at half throttle...so I'm pretty sure that the ESC fried because it was pulling more current that it can take......

Now the big question is what do I need to do to fix the problem? Smaller prop, bigger prop, limit throttle curve, etc?????

I'll be looking through the FAQ's <G>

G

A little more experimentation shows that changing to a 22X12 prop, a 17X 10 prop and running the 17X10 prop on only one 5S4P pack all still result in reaching 75+ watts at about half throttle.

So, How do you adjust the current draw of the motor!?

Do you mean 75 AMPS?

It's no wonder the ESC fried. I can't even imagine how many Amps you were drawing with a 10S pack at full throttle... Scary.

There are only two ways to adjust the current draw of the motor:

1. Adjust the prop size. Smaller for fewer Amps, bigger for more.
2. Adjust the battery pack voltage. Fewer cells for fewer Amps, more cells for more.

There's nothing you can do to the motor or ESC to "limit" the current. Electricity has some of the same properties as water, but there are many major differences too.

Simply put, you're running WAY too large a prop or WAY too many cells on that motor. It works with the much larger heli rotor because it's heavily geared. What's a typical heli gear ratio? 10:1?

May I ask how you came to determine that a 17x10 was the "right" prop for this combination?

The Hobby Lobby website says the Actro 32-3 is for planes of 9 to 12 lbs running 16 to 26 cells (nicad I know but I fugured 1.4 volts per cell so about 39 volts) and 16 to 18 inch prop....so I thought I was sorta in the ball park-- clearly NOT....perhaps that is why I can't get anyone at Hobby Lobby to talk to me<G>! Following are the quotes from their web-site:

"Haul up a 13 pound sailplane at over 1000 feet per minute or perform unlimited aerobatics with a 10 pound airplane!

Actro 32 - 14 to 32 cell motors that swing propellers up to 18" diameter. Comes with fiberglass rear mount. Power output in the 550-2000 watt range. Will fly 8 to 18 pound airplanes and sailplanes."

Actro 32-3
"For 14-26 cells in propeller models and 28-32 cells in helicopters. Propeller range is 13" to 18" in diameter. This 3 turn motor has an RPM/Volt of 555, resistance of 34 mOhm. Maximum efficiency of about 89% in the 50-95 amp draw range. Power output in the 550-2000 watt range.

ACTRO 32 SERIES - The 32 series motors are designed for models with 14-32 cells and propellers up to approximately 18" diameter. Weight, 15.25 oz., 2-11/16" long without prop shaft, 2" diameter. A 1/8" thick fiberglass rear mount drilled for 3 M4 bolts is included. Choose the appropriate prop shaft for your model from the Actro adapters and mounts page. These high torque motors are designed to spin large props without a gearbox. For airplane and sailplane models from 8 to 18 pounds."




G