Poll

Update: I'm going to use two-three 6 amp rectifier diodes in parallel and then the same set again in a series. So it'll be a 12 series dropping voltage 2 x ~ .9 = ~ 1.8 V Theorectically it'll drop the voltage to ~ 11.1v - ~1.8v = ~9.3v. Didn't check the specific voltage drop of the rectifier but should be around there. Of course you could add another set in the series and get a better (and closer to what heli should be at) voltage. (8.4V) In theory this should work, I'll be trying it around christmas and will update. =) Hope this helps someone. Maybe save some burnt out tail motors =)


P.S. Also based on Honey Bee 2. I figure it drains a 1.8 amp/hr battery at most in 20 minutes. Avg. of a 5.4 amp current. So, personally I'll be using a 12 amp series with 3 sets.


____/¯¯| diode |¯¯\______/¯¯| diode |¯¯\____/¯¯| diode |¯¯\___
¯¯¯¯\__| diode |__/¯¯¯¯¯¯\__| diode |__/¯¯¯¯\__| diode |__/¯¯¯
12 amp, ~ -2.7 V series.
Diodes are cheap and can be bought at your local radioshack. 50V, 6 amp variety.
____ = the same wire
¯¯¯¯

tnd2000

I think the diode you're referring to is 1N4006 (going by memory here). The voltage drop of a silicon diode is .6 to .7 volts.

You should measure the voltage with the motor running (take off the blades and spin up the motor). You are going to find the voltage is alot lower then rated. And if you are using lipo, you should know 4.2V is the top off voltage. If you fly the heli for 10 minutes after it's fully charged and then measure the voltage you may find it's now at 3.9V per cell and am still able to get another 10 minutes of flying before it is completly drained.

On my XRB Dragonfly which uses 8.4V 2 cell lipo (900mAH). I bypassed the battery and replace it with a power source (only 8.0V) with near infinite mAH for its purpose. It smoked my board when I upped the throttle, the cheap board needed the drop in voltage at full load.

Poll

That is interesting that 8v smoked it. Well, it should cost me $3 for these parts to try this, and if it doesn't work no harm done =). I'm going to try it at around 8-9 V and see how it works, if I need to take off some diodes then it'll be np. I'm just trying to throw an idea out there since I've read a lot about tail motors being burnt out by the 11.1v lipos. Also I can't actually test this till christmas =\. This would be cool if it worked though, I'm a freshman EE in college so I don't have $10 a pop for a motor.

P.S. the rectifier I was thinking of was the 6A05.

tnd2000

Cool you're studying EE. Then you'll understand the reason 8V smoked it is because with batteries, the voltage drop significantly with such high load demands of the heli. Using my PS with no voltage drop, it was too delivering too much power :<
I'll bet you'll smoke the tail motor even if you just hooked up 8.4V directly it. Those things are rated at much lower voltage.

Poll

lol, good point. Maybe I'll throw one or two of these in series by themselves heading to the motor ;-) . . . not a bad idea, ah . . . when I get my bird I guess I can fiddle around then and see what works. This probably does waste some batt. power, but I cant' imagine it being too much... + I'd rather have a 25 minute flight with working motors than a 35 minute flight with everything hot and toasty.

-- I think I read somewhere the motor is 7.6V. I guess this would be a good spot to use the 1n400x you mentioned earlier. I just want to be able to sustain flight w/out having to worry about stuff burning out, maybe someday when I'm decent I'll up the voltage for more performance.

vanman

My Feedback: (2)

We have been flying the E-Sky Honey Bee for several weeks now on an 3S1P 11.1v 700mah and 1200mah packs and have not burned out a single motor yet.

We have been flying this thing in the living room and to put it to the test, we flew in the golf dome this weekend. Friday night we flew it for an hour solid....landing just long enough to change batteries. We went back on Saturday and flew it CONTINUOUS for over 2 hours, again only landing long enough to change batteries.

What did we do to our Heli? We peeled the label off the motor ( to allow the thing to disapate heat) and put a heat sink on the main rotor motor and also one on the tail motor......that's it.

The theory that we have been going with is that while the 4-in-1 controller see's the 11.1 volts, the motors never do....at least I have never seen anyone hovering at full throttle anyhow.......

The one that we are flying is the fixed pitch version.....can't see why the others would be much different.

By the way, the heli overall has well over 20 hours of actual flying time now.....no problems from Li-Po usage and no burned motors........

Just thought I would give our experiences and possibly save you some time......

Bill

Poll

Yeah, I guess it's somewhat of a mixed bag, or maybe that tail motor stuff is exaggerated. I did order a heat sink. I enjoy screwing around though, and doing that mod wouldn't be hard so why not..

tnd2000

You should not mod the tail motor directly with diodes. Remember if you drop the voltage to only the tail motor, it'll spin lower and you'd end up compensating with more rudder trim. The net effect is you end up gaining nothing but wasted energy.

Poll

Yeah, that would put more strain on the esc, more worried about that than a lil motor..

tnd2000

Yes that's true about the esc, but my point was you are not going to save your tail motor neither. Say at 1/2 stick, the tail esc is pumping 5v to your tail motor in order to keep it stable. If you reduced the voltage to 3.8V using 2 diodes. The lower voltage won't keep it from spininng. In order to regain control, you need to raise the output of the esc to 6.2V so you are still running the motor at 5v. Power is just wasted by the diodes.

Poll

Yeah I got your point there, the only real point of lowering the voltage is so I can't go too high even if i wanted too..... Well, anyways, got bored in chem so I did some math. If I lowered the voltage from 11v to 8v (probably won't lower it this much) and saying my heli would normally fly for 35 min on 1800 mAh, the new time would be ~27.4 min. Or, put another way I'd waste about ~400 mAh into heat with the diodes but still have 1400 mAh, which is still a good bit.

I do think about vannman's post about how this may be frivolous, but, I guess I'll do it for fun. Just gotta hold on long enough till easter, I live from holiday to holiday =). I've been looking at some brushed motors from the dreaded helihobby that are supposed to be able to handle the voltage of lipos.

tnd2000

Sorry I was not very clear. I should've said RMS voltage instead of just voltage. If you did use the diodes, you will reduce the peak voltage to the motors but the RMS would remain the same.

Also my on honeybee 2 the main motor runs hotter then the tail motor.