2700 MaH NIMH for Raptor V2  
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All Forums >> RC Helicopters >> RC Helicopter General Discussions >> 2700 MaH NIMH for Raptor V2
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2700 MaH NIMH for Raptor V2 - 11/3/2003 8:22:26 PM   
mfranzyshen


 

Posts: 6
Joined: 9/1/2003
From: Somerset, NJ, USA
Status: offline 		I've been running a 1400 JR MaH - 4.8V (4 cell NiCds) in my Raptor V2. Everything is fine except the JR digital servos (DS811)seem to draw ALOT more than the JR 537s I used to use. I get 4 flights (about 13 minutes) from a fully charged pack. I purchased a 2700 MaH 6.0V (5 Cell NiMH) and am concerned about balance. Does anyone have any recommendations/concerns about the use of this pack with regards to balance/performance. If so, what's the best way to balance the heli with the additional weight (about 2-3 oz).

Anyone running a battery pack this size? One last question, is there really any performance benefits to running a 6V pack as opposed to the 4.8V?
       Post #: 1

RE: 2700 MaH NIMH for Raptor V2 - 11/4/2003 12:51:01 AM   
taildraggerdave


 

Posts: 957
Joined: 8/30/2002
From: Sun Valley, CA, USA
Status: offline 		I can share my recent experiance. I have a 30V2 and was using a 1500mah nickel metal battery 4.8volts. My Voltwatch would start to get in the yellow on the second flight. I would check it after the flight at around 5.3 volts. Ball links are not tight and I can see no binding anywhere. The heli flies great. Maybe the Voltwatch is at fault.
Just to be safe, I bought a 4.8volt 2700mah nickel metal battery from Expert (JR) and it weighs a bit more than the 1500mah. I had no obvious change in CG on the heli. Didn't compare CG before and after but did not need to change any trim settings. Got 3 flights on it Sunday and it was still solid green

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(in reply to mfranzyshen)
       Post #: 2

RE: 2700 MaH NIMH for Raptor V2 - 11/4/2003 3:43:09 PM   
mfranzyshen


 

Posts: 6
Joined: 9/1/2003
From: Somerset, NJ, USA
Status: offline 		Thanks - I didn't realize they made a 4.8V 2700 MaH pack. If I had known this, I would have purchased that pack since it would be closer in weight and probably wouldn't affect the CG. I'll probably end up purchasing the 4.8V pack anyway and using the 6.0V pack in one of my airplanes. Thanks for the insight!

(in reply to taildraggerdave)
       Post #: 3

RE: 2700 MaH NIMH for Raptor V2 - 11/8/2003 9:51:43 PM   
w.pasman


 

Posts: 367
Joined: 4/23/2002
From: ----, NETHERLANDS
Status: offline 		I have only 4 cells and that already requires putting the pack on top of the tank to get the stuff balanced.
http://graphics.tudelft.nl/~wouter/helipage/tips/lengthwisebal.html

If you use NiMH make sure they can deliver enough amps. Furthermore NiMH have higher internal resistance, voltage drops quick when in use, and when you stop using the voltage seems still OK. taildraggerdave this must be your problem too. NiCd have much less internal resistance, but then the problem still is there. I now have 1700 NiCd cells because I had problems like this with NiMH. Allows some 6 flights. Then they are still half full but again, if loaded the voltage drops too much. But better than two flights.

(in reply to mfranzyshen)
       Post #: 4

RE: 2700 MaH NIMH for Raptor V2 - 11/9/2003 12:54:14 PM   
mfranzyshen


 

Posts: 6
Joined: 9/1/2003
From: Somerset, NJ, USA
Status: offline
How many flights do you think I should be able to get from the 2700 MaH pack and still be able to fly safely without risk of battery failure? I use an onboard Voltwatch - can this properly display the status of the battery accurately?

(in reply to w.pasman)
       Post #: 5

RE: 2700 MaH NIMH for Raptor V2 - 11/9/2003 8:47:30 PM   
w.pasman


 

Posts: 367
Joined: 4/23/2002
From: ----, NETHERLANDS
Status: offline 		mfranzyshen

I have not done this nor read about something to test this, but I just thought of the following method.
Discharge the pack at say 3A (assuming a 60 size machine, see the RR thread on amp usage of helicopters) or 2A for a 30size, and keep an eye on the voltage. Stop discharging when the voltage (during 3A load) drops below 4.5V. The amount you got out is the safe zone, you probably should not fly with batteries further discharged with that.

Then, you have to determine how many mah you use per flight. Again, see the RR thread on this to get an idea. Divide the two and you have the number of flights you can make.

BTW Make sure you load the servos during readout of the volt watch, unloaded the batteries thw voltwatch will usually show everything is right.

(in reply to mfranzyshen)
       Post #: 6

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