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HeliHobby . Ron’s HeliProz South . Century Helicopter

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e-Electric Batteries & Chargers > Battery problem?
 
 
Tin Pusher
Heliman
Location: Surrey, BC

I am an owner of a Century Hummingbird which is powered by a 7 cell 600 mah NiMH battery, called the Bird Seed. Many Hummingbird owners have complained about the helicopters flying for 30 seconds then not being able to get out of hover. I have the same problem and did a few tests. After the brief period that heli would actually fly it returned to the reduced power hover only phase. At that time I took it inside and hooked it up to my microlader orbit. I noted the volts produced under certain amp draws.
2.8amps=7.5 volts
2.0amps=7.8volts
1.2amps=8.1volts
.6amps=8.4volts
0amps=8.8volts

Is this normal or a bad battery?
Do volts usually drop as more amps are needed?

From talking to others it seems that for the heli to fly it needs approx. 2.5amps and 8+ volts to fly. I am formatting the battery again as we speak and I have Li-Polys on the way but I would like to understand what the problem is.

Thanks
Doug
05-18-2003 Over year old.
 
 
Ben74
Senior Heliman
Location: Long Beach, CA

hi doug. it's normal for a battery's voltage to drop under load. it sounds like you may simply be using the wrong battery for that heli. find out what other people are successfully using, and go with that.
05-29-2003 Over year old.
 
 
W|ngz
Heliman
Location: Montreal, Qc

This seems about right (the bird seed IS the correct battery for the hummingbird), and yes the voltage will drop under load... the difference is that the current that can be output over time (hence the maH - miliamp-hours) is severely reduced.

I have no idea why though

My theory would be that it needs a good charge/discharge cycle (for nimh cells, usually up/down three times for peak battery efficiency) which century does NOT mention in their documentation at all.
05-29-2003 Over year old.
HOMEPAGE  
 
 
Ben74
Senior Heliman
Location: Long Beach, CA

fyi, manufacturers of electric helis frequently recommend power systems and battery packs that provide only the bare minimum of power required to fly (and sometimes even less than that). you can usually be sure that the stock/recommended power system is going to be a dog. that's why i suggested that you check to see what other people are *successfully* using in their hummingbirds

w|ngs brings up a good point about breaking in the pack though. NiMHs usually need to be cycled a few times before they start performing up to their full potential.
05-29-2003 Over year old.
 
 
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MTA Hobbies . Model Rectifier Corp . RCHover

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e-Electric Batteries & Chargers > Battery problem?
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