PDA

View Full Version : speed 400 lipo ?


kc7rjt
08-10-2005, 04:47 AM
Hello,
I am brand new to electric, and a veteran glow pilot.
That said, i just got a Sig EP-42 with a speed 400 motor.
The motor is,by sig's desc, an "upgraded" speed 400.
Sig recomends a 1300 milliamp hour nicad, i bought one and it feels auhfully heavy, i think its made of "c" cells. What would i get in LiPoly
to run this plane?

tnx...
Tom..:o

jobu
08-10-2005, 02:28 PM
I use 1500 lipos. 3 cells 11.1 volts. How many cells in the NiCd. If it has 8, a 11.1 will be ok if it is less, think abot a 7.4 or 2 cell lipo.
A 2 cell = 7.4 volts and with the difference in weight should give you close to the power of a 7 cell nicd or nimh which = 8.4 but it will last longer.
If it where me I would go with 11.1v/1500 lipo (Kokam makes a good one,Cheap) just keep you eye on the heat of the motor and don't over discharge. This battery (depending on the plane weight and so on) shoul last about 12+ minutes. The nicd will last about 8. Also the plane will be alot lighter and much much faster.
That lipo is at least 1/2 less weight of an 8 cell "C" pack with 20% more power.

Do check the heat every few minutes the first time out. There are many replacement 400 motors out there most around $10. If you do stay with elecs, think about going brushless. Its like going from steam power to rocket fuel and pretty bulletproof.
Joe

rcers
08-10-2005, 02:30 PM
You will for sure need to prop down if you go with 3s Lipoly - that is what I would do, but get a watt meter and keep the amps to 12-13 and you will be good.

You will fry the motor if you use the same prop/gearing with a 3s LiPoly.

Mike

Lazyflier
08-28-2005, 06:00 AM
Hello,
I am brand new to electric, and a veteran glow pilot.
That said, i just got a Sig EP-42 with a speed 400 motor.
The motor is,by sig's desc, an "upgraded" speed 400.
Sig recomends a 1300 milliamp hour nicad, I bought one and it feels auhfully heavy, i think its made of "c" cells. What would i get in LiPoly
to run this plane?

tnx...
Tom..:o

Be very carefull using 3s1p 1500 Mah or higher Lipo with the stock motor. You are pushing the voltage limit on the stock motor with 12.6v starting voltage going into a motor designed for about 8v. The recommended nicad for the ep42 is 7 cells so I really woudn't use a 3s lipo. Suggest the 2s instead. Had a friend use the 3s he fried the motor If you go to lipo you will have to get an esc that has the correct low voltage cutoff for lipos. A 3s should cut off at 9v a 2s should cut off at 6v. The esc for nicad and nimh has a low voltage cut off of about 5v. The esc in the kit is for nicad/nimh. If you are aware of loss of power using the existing ESC and land right away you should be ok using the existing esc using a 2s lipo.
You might get away with this on a 2s lipo as it is close to 6v but get that low on a 3s lipo and the pack is ruined and 50 or so bucks down the drain. Reason is lipos should not be discharged below 2.5v per cell or they will not recharge.
There are add ons that can be put in esc wiring to set this lvc on an existing esc for about 20 bucks. Try FMA direct or Tower Hobbies.