Premature Low Battery
07-16-2002, 03:30 AM
#1
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Premature Low Battery
The Morris 60 SuDoKhoi in my Avitar seems to flatten a battery in no time.
Specs are as follows...
Weight 7 pounds.
Aileron Servo's (2x) JR2721's
Elevator and Rudder JR4721's
Throttle JR537
Receiver JRPR549
Receiver Battery JRPB4440 1800Mah (NEW)
I have atleast 40 degrees of throw on each of the control surfaces in high rate but mostly fly slow or hover in low rates except for elevator. Normally I have the flaperons on most of the time.
After approximately 40 minutes flying time receiver voltage is down to 4.7/4.8 v checked immediately after landing. This equals 4 flights usually.
I had a 2000Mah Nickel Metal battery in the plane as built but flight times degraded to about 1/2 hour. I cycled the battery to get a good idea of its capacity and it was pretty short (1/2) of capacity. I then replaced the battery 2 weeks ago with the 1800 sub-c pack.
I patterned the battery for 24 hours @ 100mA and immediately cycled. It's capacity was around 1600 mA. I have been flying for a couple weeks now with this new pack, always checking voltage before each flight.
Total flying time always run around 40 minutes before reaching the lower voltages.
Tonite after flying this afternoon I cycled the battery down to see what the remaining capacity was. It cycled with about 580mA. This was down to 1.1v per cell. I think I did the right thing to quit after four flights.
Is my new battery pack doing what it should?
Does the 2721's or 4721's draw that much more current than the standard 517's or 537's.
I have other fun fly planes that I can fly for 80-100 minutes with 1200mA packs using R700's and 5x 537's.
Thanks in advance!
Note: I also posted this message on the JR Ask Danny Forum...but I would like other input from fellow flyers.
____________
DoubleD
Specs are as follows...
Weight 7 pounds.
Aileron Servo's (2x) JR2721's
Elevator and Rudder JR4721's
Throttle JR537
Receiver JRPR549
Receiver Battery JRPB4440 1800Mah (NEW)
I have atleast 40 degrees of throw on each of the control surfaces in high rate but mostly fly slow or hover in low rates except for elevator. Normally I have the flaperons on most of the time.
After approximately 40 minutes flying time receiver voltage is down to 4.7/4.8 v checked immediately after landing. This equals 4 flights usually.
I had a 2000Mah Nickel Metal battery in the plane as built but flight times degraded to about 1/2 hour. I cycled the battery to get a good idea of its capacity and it was pretty short (1/2) of capacity. I then replaced the battery 2 weeks ago with the 1800 sub-c pack.
I patterned the battery for 24 hours @ 100mA and immediately cycled. It's capacity was around 1600 mA. I have been flying for a couple weeks now with this new pack, always checking voltage before each flight.
Total flying time always run around 40 minutes before reaching the lower voltages.
Tonite after flying this afternoon I cycled the battery down to see what the remaining capacity was. It cycled with about 580mA. This was down to 1.1v per cell. I think I did the right thing to quit after four flights.
Is my new battery pack doing what it should?
Does the 2721's or 4721's draw that much more current than the standard 517's or 537's.
I have other fun fly planes that I can fly for 80-100 minutes with 1200mA packs using R700's and 5x 537's.
Thanks in advance!
Note: I also posted this message on the JR Ask Danny Forum...but I would like other input from fellow flyers.
____________
DoubleD
07-18-2002, 10:29 PM
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1800 battery pack
I have a 4.8 volt 1800 mah pack in a lanier cap 232 running 6 JR 8411 digital servos. I get about a 15 minute flight before my expanded volt meter says the pack is in the caution area. This is a brand new pack! I've checked the servos for end point bind ups. All of my servo extentions are of the heavy duty type. Heavy duty switch from cermark. I don't get it ! I can take my Wild Thing with a 1100 mah pack and put about 6 flights with no problems. The Cap is my first large gasser. Any ideas? Would a 6 volt battery pack do any better? Help!
rbeck
P.S. My battery cycler says the pack is right where it should be!
rbeck
P.S. My battery cycler says the pack is right where it should be!
07-18-2002, 11:14 PM
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Premature Low Battery
I would recommend that you guys purchase your packs from Radical RC. I have 2 6v-1300maH packs in my 1/4 scale Giles with 9202 and 9303 servos and I get about 20-15 minute flights before I am down to 6.1 volts. I usually run out of fuel before I run out of battery. I think your packs have issues.
07-19-2002, 12:24 PM
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Premature Low Battery
Just to add to what the others are saying about bad packs; could there be a high impedence short somewhere?
Something is drawing an excessive amount of current to drop your packs so quickly.
It does sound a little fishy that two different packs are showing the same symptoms in the same aircraft.
If you don't feel like going through each wire with a meter to check them out you could replace thngs one at a time to find the problem. I'd probably start with the switch harness. Carefully check for servo binding with a little finger pressure on the control surfaces.
Good Luck,
Jeff
Something is drawing an excessive amount of current to drop your packs so quickly.
It does sound a little fishy that two different packs are showing the same symptoms in the same aircraft.
If you don't feel like going through each wire with a meter to check them out you could replace thngs one at a time to find the problem. I'd probably start with the switch harness. Carefully check for servo binding with a little finger pressure on the control surfaces.
Good Luck,
Jeff
