JeremySutton

Hello.

I am new to brushless motors and lipo batts. I bought a friend's plane as an RTF and I am concerned that the lipo battery is too much for my motor/esc. Here is my set up:

Hacker A20 20L
Phoenix 25 amp ESC
Thunderbird 3-cell 11.1v 2100 maH

Gear is all used in a Copperhead Extra Stiffy:
http://www.copperheadaviation.com/co...p?idProduct=69

My next question is, without a computer usb cable how do I program the ESC not to drain my lipo too much?

Jeremy

Fliprob17

The motor should be fine with that battery, it is spec'd for a 3 cell LiPo 1200mah-2100mah, so you are within the range. The ESC should also be fine with that battery. You need to get the instructions from the person you bought it from or try to download them online to program it for the LiPo low voltage cutoff. I assume the battery is a Thunder Power, not a Thunderbird. The battery is my only concern, a 2100mah pack may be a little heavy for that plane. They seem to recommend a 1500mah pack. Which would be around 2oz lighter. As long as it flies ok and the Center of Gravity is not off with the 2100mah battery, it should be fine.

Fliprob17

Here is the link for the manual, you will want to set the voltage cutoff at 9volts. http://www.castlecreations.com/suppo...er%20Guide.pdf

JeremySutton

Thank you!

Dang typo . . . ThunderPower not ThunderBird.

Spoke with previous owner/pilot about weight of batt, but he says that the discharge counters the weight.

Fliprob17

I would still make sure that your Center of Gravity is right on.

Dr Kiwi

I beg to differ - a Hacker A20-20L with 3s and a 10x4.7 or 11x4.7 prop - waaay too much for the motor (the battery pack will be fine!)!

Even with a 9x5 GWS HD that motor on 3s draws more than its rated 15A continuous. With a 10x4.7,or heaven forbid an 11x4.7, it is going to be drawing well over 20A. [burst max for the motor is 19A]. Heck, with an 11x4.7 it draws 15.30A at only 7.1v - probably 25A or more on 3s!

JeremySutton

Dr. Kiwi:

Previous owber ran Hacker A20-20L with 3s and a 11x4.7 prop.

Cooperhead aviation recommends that set up (with a 1500 mAH lipo).

www.copperheadavaition.com for their Extra Stiffy.

I am new to brushless and li-po . . . Are you saying that my motor will fry?

Jeremy

Fliprob17

Nothing says anything about what prop, except the Copperhead page??????? Just the electrical capacity of the setup was being discussed. Never trust the manufacturers recommendations Always do a test of your own for amp draw with a wattmeter, with several props before actually flying with anything. I am running a E-Flite Park 480 BL 1020 kv motor, more powerful, with a 11x7E APC prop and a 11.1 volt LiPo, and I am only getting up to 24.2amps at full bore, and about 10 amps at 60% throttle for a continuos rate. And that motor is spec'd at 22 amps continuous and 28 amps burst, way above the estimated pull of 6-15 continuous and 19 amps burst spec'd for the Hacker 20 20L. Anyway, I would think a 10X4 would be a good place to start. Maybe a 9x5 too. If the system has already been run with an 11x4.7 prop, 11.1 volt LiPo, same motor, etc.... I would think you will be fine, it didn't have black smoke marks on it when you bought it right You really don't know what is going to happen until you hook up a meter and it tells you exactly what you are pulling Always better to be safe and keep the parts as cool as possible while keeping a high performance level.

Fliprob17

If there are no differences in the setup since the previous owner flew it, why would it be any different? All that happens by going from a 1500mah battery to a 2100mah battery, is the battery is heavier, and you get more flying time. It is always a good idea to test the system, and just hook-up a wattmeter and see how many amps the motor/prop combo is pulling.

JeremySutton

Thank you Fliprob17. I have a lot to learn still.

No black smoke stains or smell or anything to tell me the motor isn't in mint condition. Hope to get a li-po charger for Christmas and then I will know all I need to know

The guy I bought it from is an honest and good guy.

He flew the 11x4.7 slow flyer prop for 3-D flight. Manufacturer recommends: APC 10X4.7 / 11x4.7 slow flyer prop.

I just check in with the previous owner again -- he did fly with the exact same set up he sold me. He had the 1500 maH battery, but sold me the 2100 maH for a good price and to give me longer flights.

Jeremy
www.quietflyer.blogspot.com