Upgraded batts - now she don't wanna take off!!!!!!

[Rick Rotorhead]

Hi all, having decided that I have overrun my stock Lipos (3s 1000mah 10c 85g) and ruined their capacity, I decided to buy some nice new, bigger batts. I bought two Kokam 1250 mah 3s 15c packs 117g, but now my Twister(=Blade CP clone) needs full power (4in1 light just flashing red) to barely lift off at all. Ok, so shes' now about 30g over her stock airborne weight, but should that make so much difference? Theres no extra power in reserve to cope with random hieght loss etc. Does anyone else succesfully run on 1250 packs, should there be more power available? do I need to new motor or is it that 30g extra is simply too much for this small bird? ( I don't really want the expense of going brushless at this stage.) Any advice folks?
Rick

[nvr2low20]

only thing i can think of is maybe adjust the pitch on the blades a little but other than that like you said maybe the weight is just to much for the little motor, and you must have the upgraded motor with 9 tooth pinion already right

[Skiddz]

I run 3S 1320s on my CP and it's got plenty of oomph. I do run a 3600Kv brushless with an 8T pinion tho..

Can you flatten the pitch a little bit to get the headspeed up? More headpseed with less pitch still equals the same lift, *but* you may get the motor up into its "power band" which may provide a bit more "oomph" for the pitch you'll need to get 'er flying. I had to flatten mine out to get the headpseed up to around 2100 RPM.

[Rick Rotorhead]

Many thanks I'll give it a try. This bird was always pretty gutless even on 3s power.

[Rick Rotorhead]

Ok - its working now with the 1250 mah 3s batt (117g). I had to make an adapter to marry the Deans connector of the Batt to the JST connector on the heli. I must have had a dry joint, cos I resoldered it and now more power gets to the motor - not a huge difference, but enough to get her airborne. She needs near full power to lift this batt pack, but at least I can get full 15 minute flights now without over draining the pack (which has killed my stock 1000 mah 3s packs that came with the heli).

I see now that Kokam make a 1500 mah 3s pack thats a few grams lighter than the old 1250mah pack - gotta get me some........

[Danyboy]

Howdy, Rick!

I do not know exact values, but it appears that there's not much that you can add as extra weight.

I even fly with smaller batteries, only 700mAh, and fly 11mins until I get to the 9V-line (which still gives me plenty of time to get to the helipad and set it down...), but I have 3 batteries.
By flying just 10mins, than taking a small break, flying the next battery, small break, and so on, I can easily fly a whole afternoon "non-stop" while never exceeding the batterie's or motor's limitations.

If you want to fly long, take smaller batteries. Less weight means less energy needed to make it fly, therefore the motor won't get really hot and the breaks between the flights can be shortened.
So you'll be doing what all the managers want their employees to do: Do more with less... :lol:

As a hint, to discover that magic line of 9Volts, I installed a so called "LiPo-Saver" on the tailboom.
This is a little electronic with an LED which comes on when the Voltage drops below 9V. And since it is connected directly at the heli's battery-plug, you'll make sure you have the 9V under load.

Sincelery,

Daniel

[Rick Rotorhead]

Thanks Danyboy, I'm slowly realising that you're right about batt size - for all e-powered flight. The weight is the killer. One guy at my club flys a small plank - just 32 inch span with a CD Rom outrunner motor and a tiny batt (about 600mah) yet he gets 1/2 hour flights by giving full power vertical burns and slow glides back down - several times, its because his plank only weighs like 6 ounces (170g) that he get the performance. My little heli may do the same! (not glide of course :lol: ). I'll buy one small batt and see if it really helps...Cheers, Rick