Low voltage alarm 30sec after spool-up. Could be the motor?

[McBrain]

Hi Guys,

So I've had some issues with my 450, tried a number of things last year and had a break for 12 months as we moved to the states. Now I just brought the heli back to the states after a visit to Aus and want to get it going again (been flying planks the last year)

Equipment:
Tarot 450 FBL. Tarot gyro, Platinum Pro 50A ESC, Tarot 450M 3800kv motor

Problem:
The heli spools-up to full head speed fine, but within about 30 sec the low-battery alarm sounds. It appears to be a genuine low battery problem.

The head speed might be lower than normal but I have no way to measure this. The only reason I think this is that it seems to need more collective (70% up-stick vs 50% previously) to get off the ground.

Solutions tried:
Tried different batteries
Replaced ESC
Replaced battery alarm

I guess the only thing left is to try a new motor. Any opinions before I fork-out for a new one? I'm running out of options, seems the motor is the only thing left?

[TR450ZS]

Have you checked the main pinion to main gear mesh? If it is us too tight then you will pull too many amps every time you spool up.

[Crash3D]

I would most certainly borrow a motor from someone to eliminate that as a possibility. If you have too serious of an issue with a motor, you could over-amp your esc and then nasty things happen. Your esc will become one of the most efficient fire starters ever.

[McBrain]

Originally Posted by TR450ZS

Have you checked the main pinion to main gear mesh? If it is us too tight then you will pull too many amps every time you spool up.

Thanks Allan,

I think I did check that, but I'm going to re-check as it makes sense.

Nick

[McBrain]

Originally Posted by Crash3D

I would most certainly borrow a motor from someone to eliminate that as a possibility. If you have too serious of an issue with a motor, you could over-amp your esc and then nasty things happen. Your esc will become one of the most efficient fire starters ever.

Borrowing a motor is not an option as no one at the club here in Charlotte NC flies helis!

I could borrow a watt-meter and check the current draw though.

I will check the pinion mesh again and then do a watt-meter check.
The test needs to be done with the blades on though, without the additional torque there is no low voltage alarm if I run it up with no blades on.

Nick

[Smoggie]

You said that you tried different batteries but were they all the same age? It sounds very much like a battery problem and if the batteries are all similar age and have been treated the same then they are likely to be in similar condition. If the batteries were stored for a year fully charged that would be a pretty sure way to kill them.

So if you haven't done so already try a new battery.

[McBrain]

So I tried re-setting the pinion mesh...

Sucess!!

I must have fitted a new pinion last year and not meshed it correctly.

I'm 99% sure that's the problem but I couldn't fly it tonight, just ran it up on teh ground. I'll fly it tonight and know for sure.

Yes the batteries may be a little tired but I have an number with different ages and different capacities.

I will fly tomorrow and know for sure.

Thanks for the help.

[McBrain]

Still not right. Got the low battery alarm again today at the flying field.

Funnily enough, when I switched to idle-up the alarm stopped. Hovered at a couple of feet to burn-up the battery and got another couple of minutes.

Then I tried another battery (Zippy 3S 20C 3000mAh) this is newer but still old and normally gives an extra couple of minutes flight time than the 2200mAh.

But with this battery I didn't even get the motor beeps on initialisation and rotor would not spool up at all.

Back to the bench to investigate further.

I have a new battery coming too.

[bad007]

After 12 months and now this. Battery , motor and wires getting warm? Tried multiple batteries but hold old?
If the motor was pulling too much a simple touch and feel would tell lots and in just 30 seconds it would be real hot. A battery charger where you could measure internal resistance isn't mentioned and still a indicator only.
I too took a brake for awhile and ended up with a bunch of batteries taking a salt water bath as they wouldn't work. Some with low resistance still would not work. Lift off and 30 seconds later loss of power and rushed to land. Even my 550 with a 1 year old battery would do that for some reason but a new one fixed it every time.

[macdad]

What is the low voltage setting for your warning?

How many mah are you putting back into the batteries?

Sounds to me like old tired batteries. Does anyone at your club have some newer 3S batteries that will work to test?

[McBrain]

Apologies for the delay in getting back on this.

I finally got to the airfield on Sunday with a brand new battery pack to try.

Works fine with the new battery!

So you guys were right about this. At one point I suspected the bullet connectors - and there may still be a resistance issue there. But it is pretty much solved.

Thanks for the help

[Crash3D]

Glad to hear you got it sorted out and it's working well now

[bazsound]

from what i understand the as well as the a batteries capacity changes with age, its internal resistance also increases with age/use.

You might have had 1 cell go bad but still show a full charge, but once under load would suddenly drop the total pack to lvc.

similar thing happened to my car battery. all of a sudden 1 day it didnt start, bumped it and it would start fine unless you left it over night. 1 cell was bad and not holding charge.

I left some 1s batteries charged for over a year (obviusly wernt charged when i dug them out) they worked but started dying 1 by 1 quickly after i started using them