Sudden Power Loss

[Dex Olson]

I've been flying my sr 120 now since mid December of last year and have really enjoyed it since the weather in Minnesota has allowed me to fly outside. Early in February the heli started acting really bizarre, like it would suddenly go to full throttle and climb out of control into the ceiling or without warning suddently pitch left or right or spin out of control.
I inspected the 5 in 1 connections, battery connections, motor connections and changed the tail boom and motor just in case there may have been a short there but nothing helped. I finally bought a new 5 in 1 and the bird flew beautifully again.

Now, last week all my batteries (6 of them) were suddenly lasting about 30 seconds before flashing low voltage. Now the heli flies for about 10 seconds and suddenly completely losses power and falls out of the air (obviously trashing the landing gear.) Again I've inspected everything and can't find any connection issues. Am I looking at another 5 in 1?
This little critter is getting kind of expensive! I just don't understand how a solid state device like this can go boobs north so quickly.

[Heli-cat]

I'll betcha anything the wiring is loose in your board to battery JST plug.

[Imzzaudae]

It's funny how these batteries go down. Pick up a new one and see if that may be the problem.

I'd put money on the other problems being TX in origin rather than onboard the helicopter.
What are you flying the 120 with?

[Dex Olson]

I have tried new batteries. As a matter of fact, the last new one lasted just 20 seconds before flashing "low voltage". I charged it and the second time it got the heli 6 feet in the air and then.... Power OFF, crash landing!

[Pfloyd]

Check the battery wires at the 5n1....most like attatched by two or three strands.

[Dex Olson]

Sorry, I forgot to answer your question regarding the radio. I'm using a DX6i that has been flying the heli really well. So much finer resolution than the original "toy" radio that came with it. I also use the DX6i on my Hausler 450 clone collective so I'm reasonably sure it's not the radio. I can try resoldering the battery connections to the 5 in 1 but I was unable to get any response, positive or negative, by moving those wires. The heli will just set there, without being touched, and power-on and off repeatedly without any apparent pattern. By that I mean that I can't discern any obvious timing to the issue. I'm going to contact E-Flight to see if they can suggest anything.

I appreciate your help guys.

[GLACIERBAY]

When you find out, post it, I am having the same issue!

[temtnf8]

My guess is also the power connections on the 5-in-1 board. I had a similar problem with the tail motor.. Intermittently it would work for a while and I'd think it fixed itself, then I'd get it in the air and she'd start spinning faster than any pirouette I've ever intentionally attempted...

[Pfloyd]

Originally Posted by Dex Olson

I've been flying my sr 120 now since mid December of last year and have really enjoyed it since the weather in Minnesota has allowed me to fly outside. Early in February the heli started acting really bizarre, like it would suddenly go to full throttle and climb out of control into the ceiling or without warning suddently pitch left or right or spin out of control.
I inspected the 5 in 1 connections, battery connections, motor connections and changed the tail boom and motor just in case there may have been a short there but nothing helped. I finally bought a new 5 in 1 and the bird flew beautifully again.

Now, last week all my batteries (6 of them) were suddenly lasting about 30 seconds before flashing low voltage. Now the heli flies for about 10 seconds and suddenly completely losses power and falls out of the air (obviously trashing the landing gear.) Again I've inspected everything and can't find any connection issues. Am I looking at another 5 in 1?
This little critter is getting kind of expensive! I just don't understand how a solid state device like this can go boobs north so quickly.

Check the red and black wires where they attach to the main motor. They are notorious for breaking strands.

[Chris.S.]

Also, the wires inside the jst at the battery end of the heli can break, that's what caused this issue for me. Put a new plug on and it was fine again. The wire was just broken enough that current could get through, but not enough to fly.

[Helikav]

This has been a problem with a lot of 120's and I'm surprised that there is no definitive answer to it yet. The common suggestions are to try new batteries, change the wiring and plugs, and as an extreme, replace the board.
I had the same issue with mine and the only thing I didn't do was replace the board. Replacing wires and the plugs worked, but only temporarily.
Perhaps the real problem is deeper and lies within the circuit board.

[Pfloyd]

Originally Posted by Helikav

This has been a problem with a lot of 120's and I'm surprised that there is no definitive answer to it yet. The common suggestions are to try new batteries, change the wiring and plugs, and as an extreme, replace the board.
I had the same issue with mine and the only thing I didn't do was replace the board. Replacing wires and the plugs worked, but only temporarily.
Perhaps the real problem is deeper and lies within the circuit board.

It's basically inferior wire and crappy soldering.

[buzzingbird]

I have the same problem. I remember reading somewhere on these boards to unplug tail motor or main motor to see if problems persist to determine if either is at fault. I dissconected my main rotor and no more cut off. I'm on my way to buy a new main motor and hopefully this will fix it. This happened on my msr. I had it chalked off as done blaming 5 in 1, however, I did same procedure described above and it was main motor. Changed out and msr flew again.
Let us know if you correct the problem by whatever means.

[in2win]

I'm thinking a touchy connection also but, just for the heli of it try re binding.

Mike

[Keldar]

oddly enough, there is a U-toob video that suggests that charging the battery at .7 causes odd issues such as this. According to the author, .3 is the charge rate needed.

[SurferOfTheSkys]

How do you know the magic number is .3 if I have a 500mah battery I charge at .5 isn't this acceptable. I haven't had a problem yet.

[SurferOfTheSkys]

Excuse me , I wonder how he came up with that number?

[Keldar]

Here is the video. There was no comment as to the "science" behind the claim.

[ame]http://www.youtube.com/watch?v=ARdc1wmIvls[/ame]

[jackovart]

it is not the charging or the rate of charge. i had the same problem. thought my batteries all died all at once. i was getting maybe a minute per flight then it got worse it started doing hard shut offs, just crashing to the floor. for me it was the wiring at the plug so i clipped the wires and stripped them back and just fed the leads directly into the battery. i flew like this for months, until i finally retired that heli due to servo issues. i got a new 120 this week, and have noticed that my batteries are much hotter after six minutes of flight using the plug connector v/s just feeding a stripped wire into the battery plug sockets. i think there is a lot of resistance in that plug. the plug may not be the problem for everyone though