sharpshooter223

in one of my planes i have a gws speed 350 or 400 brushed (i forgot which one), i have the appropriate gws speed control, and i have a gws 9.6 volt 750 mah nimh battery. just testing out the system to make sure it works on the ground, i had charged the battery with an appropriate charger and then proceded to plug it in. so i first tested out the servos and they worked fine and all that. then i went to test out the motor so i put it on full throttle and it worked good for the first few moments. then it just shut off, so i throttled down and then back on to half speed and it went for a little while longer but then shut off again, i kept doing this until at very low throttle it stayed on for a little while but not high enough power to even move a piece of paper behind it very much at all. when i went to test the voltage of the battery it read 9.2. So has anybody experienced this before or know what is happening?

ozrcboy

Hi sharpshooter,

Few things could be going wrong...

1. Under load the battery voltage is dropping so much that the Low Voltage Cut is activating.
2. You are pulling too many amps and the ESC is shutting down for the sake of self preservation.
3. The motor isn't working properly, or the ESC isn't working properly.

To tell which you really need to be able to measure volts and current. There are lots of power meters you can plug in between the battery and ESC which will give you a read out on amps/volts etc. There about $60 here in Oz, so maybe $40USD in the states. Once you can measure what is going on you will find your ability to figure out which of the 3 things is happening is very quick.

My suspicion is that your ESC might just think you are plugging in a 3s LiPo if it has auto-detect, so when the voltage gets to 9.0v (and your 9.2 would be 9 under load or lower) it is shutting down the motor to save the battery. You may be able to program it to have a different LVC - you'll need to check.

Cheers,
Oz.

sharpshooter223

the esc i have is a fairly basic gws one and i think it was made before lipos were really being implemented. i have a multimeter that might be able to test it, but i also think that these gws esc's shut off around 4 volts or 3 volts or something liek that.

ozrcboy

Hmmm <shrug>,

Do you have any other ESCs/motors you could substitute in to see if its a faulty component?

Maybe under load your battery's voltage is taking a nose dive - could you try it in another model and see if it seems to work okay?

That's about all the suggestions I have sorry []

Good luck.

sharpshooter223

i have the same thing happening in a lower power gws plane and im using exactly what the company recommends in that one also. i hope it isnt just the gws brand but do you think that its a possibility? have many people had troubles like this with gws brushed motor setups?

ozrcboy

GWS brushed motor setups are pretty reliable in my experience.

So if you are having the same problems with both planes then what is the common components you are using in both?

sharpshooter223

im using nothing in common except for the charger used to charge the batteries, and thats an electrifly dc 400 peak charger.

ozrcboy

So different Receivers? Different transmitter as well?

sharpshooter223

ok, well same transmitter and same charger but nothing else is the same except for brand of electronics which you already said gws usually is good.

Time Pilot

IMHO, I'd start with the batteries first--especially if you have a 400 motor which is a bit of an amp hog compared to the 350. I've flown GWS equipment for about 4 years now and the only thing I won't use of theirs are the batteries. I never even used the ones I bought because they performed so poorly on the ground.

If you can let us know what all your parts are (motor, gearbox & gear ratio, prop size, ESC) that might give us another clue.

soarhead-RCU

If you are useing a GWS ESC check and see if it is the LIPO model. On the unit it will have ICS-480LI or any of the LI series if it is lipo. If it is, your ESC is "seeing a 3 cell lipo and the cutoff voltage on this unit is around 8.5v I think. Therfore as soon as the voltage drops on the NIMH battery under load to this level you loose your engine Juice. You have to use the plain ESC with nickel batteries or you will have this problem and they are not programable to my knowledge. Just have to "pop another 15$ or so for the regular ESC!!!!

BTW the GWS 300-350 motors have a grey gearcase and the 400 has black.....and the regular ESC has a 5.2v cutoff for nickel batteries.

Bob

sharpshooter223

ok, then i have a speed 350 motor. but no it is not a speed control for lipos i know this for sure. its funny, both planes i am using exactly as recommended, both planes have the same problem, and so far nobody not even the company has been able to come up with an answer.

sharpshooter223

could switching to a towerpro brushless motor/esc set perhaps solve the problem?

Time Pilot

You can't say that until you've ruled out the solutions.

This is all we know:

Motor: 350
battery: GWS 9.6V 750 mAh battery [:'(]
Propeller: Unknown
Gearbox: Unknown
ESC: "Appropriate" This isn't really helpful, because there are people, dealers even, who will sell you the wrong thing and tell you that it's the right one.
Charger: Unknown

- We don't know if the ESC is incorrect (please provide a number)
- We don't know if you've over propped and causing your own problems.
- We don't really know if your battery is fully charged. A fresh off the charger 8 cell, 9.6V battery should read around 11.5 to 12V.

From flying GWS components for 4 years, your problem really sounds like a battery problem. Two planes, different components, the only common variable: battery.

sharpshooter223

the battery isnt common, i have seperate batteries for each, also the propeller and speed control for the other plane is EXACTLY what gws said to use.

the charger is an electrifly dc 400
the gearbox is a, er, i dont have the package anymore and the gear isnt labeled
the prop is a 10x7 slow flyer prop
the esc is an ics300

the battery does in fact charge to 11.1 or 11.2 volts each time. i am unconvinced it is the batteries because the chance that 2 completely different batteries would have the exact same problem is rather extremely unlikely. by the way if you want to hear of a third plane doing this, the first electric i bought was a flyzone park pilot arf. it came with the motor, speed control, battery, and charger. it did the same thing, and at the time my friend had bought the same plane and his did the same thing. now that i think about it we bought the same radio sets also, is it possible that a futuable 4yf transmitter could be causing all of this?

ozrcboy

Is the second battery 8.4v sharpshooter?

sharpshooter223

the second battery is a 6 cell 7.2 volt 150 mah, the speed control to that system is an ics100 and its running the indoor power system that comes with the gws pico j3 stick

Time Pilot

That's the Tx I have, and it's highly unlikely that it's causing the problem.

If the Rx cuts out, but then back in again at full power, it could be rf interference, but unlikely the way you describe the symptoms.

If you were testing the 150 mAh battery with the larger motor, that's the kind of performance you would expect from a battery like that. In general, the larger the battery, the happier it is providing current/juice/amps to the motor.

The battery is your weakest link in your power system. If you can borrow a bigger one for ground testing even, you'd know if that was the problem.

Time Pilot

What GWS plane are you flying that uses the 10x7 prop?

sharpshooter223

ok, the 10x7 is on my ultrafly outrage and im using the motor that ultrafly suggested, and im using the system to that motor that gws suggested. i use a 9.6 volt 750 mah battery on my outrage, i do not use the 7.2 votl 150 mah. i also have a gws pico j3 stick that i use the motor that comes with the plane and i am using an ics100 on that plane with the 7.2 volt 150 mah. the ONLY thing in common is the charger and transmitter.

Time Pilot

I looked up the specs on the Outrage, and if we've got the same documentation, they do not recommend a 10x7 prop. They recommend a 10x4.7 prop on a 2S lipo with a 5:1 gearbox.

GWS doesn't even recommend using a 10x6 on a 9.6V battery with that kind of a gearbox.

http://www.gwsus.com/english/product...em/eps350c.htm

You are overpropping your system.

That may be the beginning of your problems. Start by using a smaller prop: an 8x6 and see if you have the same problems. If not, try a better battery.

sharpshooter223

well, im probably gonna be upgrading to brushless soon. ill have to see if i have money for lipo batteries and a charger after that. i probably am overpropping the system then, but i highly doubt that it would limit it to 10 seconds, nothing overheats or anything either.

soarhead-RCU

Its not the idea of anything overheating, its when you draw too many amps the battery is not able to handel it so the voltage sags way down and the ESC low voltage level cuts in and you lose your motor. The ESC is just doing its job!!!!!!!! Get the right prop and I bet it will work, unless you have damanged the battery.

Good Luck
Bob

Time Pilot

With all due respect, I do not recommend that you start experimenting with lipo batteries until you've learned the basics of setting up power systems (or use recommended ones).

sharpshooter223

is it possible to suck almost all of the amps from a battery but still have full volts?