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HelicopterRadio - Servo - Gyro - Gov - Batt › JR R700 rec. batt. prob.
01-19-2003 08:09 PM  15 years agoPost 1
bwyatt

rrNovice

Woodward, OK

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Hello to all.

I have a Raptor heli. and seem to be having low voltage proglems. My radio is a new X-378 with an R700 rec. The batt. pack is a 4N1100, which is also new. The first 4 or 5 trips to the field were normal, usually getting 4 to 5 flights with no battery problems. However, the last 3 trips have been less enjoyable. The first of the last 3 yielded only 3 flights then the servos began twiching, an early sign of a weak battery. Sure enough battery voltage checked below 5.2 volt.

The second of the three was after a normal 20 -24 hour recharge a couple days before flighing and a quick 3-4 hour top off the day I flew. I arrived at the field, turned the radio on for pre-flight, servo twitching and batt. voltage around 5.4 vdc. Field charged and made one flight before problems returned.

Third flight, 20 hour charge over night then to the field, pre-flight went good. Heli. flew about 10 min. becoming more and more iratic as the flight went along. I landed and you could see the rotor blades twitching, the voltage problem was back.

I came home pulled the pack and began checking each cell. Cell voltage was at 1.31 volt and with a 100ma. load would drop to 1.2 and hold pretty steady for several min., testing shows all cells to be strong. It is currently on the cycler showing a charge of 300ma and still discharging. I have checked the battery capacity several times and it always checks over 1100 with a full charge.

First of all, I was wondering is anyone has seen this problem and second, should I buy a 5 cell pack. I really don't think the pack is the problem, I am leaning toward the R700 needing just a little more voltage to remain stable. In every case, keeping the voltage up around 5.6 has stopped the servo twitch. Also, I am running a solid state gyro. JR 550.

Thanks for reading this and thank you for your help.

Bill,

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01-19-2003 11:12 PM  15 years agoPost 2
G.Man

rrProfessor

Bristol

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how often have you cycled the pack?

always fully discharge before charging

Don't Email me as I wont reply - PM Only (spam countermeasures)

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01-19-2003 11:32 PM  15 years agoPost 3
bwyatt

rrNovice

Woodward, OK

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Galifrey, thanks for your answer.

I usually discharge my battery every 2nd or 3rd time I charge it. However, since the problem I have cycled it 3 times and each time it was good for slightly over 1100 ma. I just got through discharging the battery pack after flying for about 10 min. and having the same servo problem. The result, over 800 ma still in the battery.

Also, while I was checking out the original pack I used a 1000 ma. pack to check the heli. I turned on the transmitter and receiver, they ran for over an hour with no servo problem and the GEM finally came on solid.

I'm about to think I may have a wire routing problem or somthing else causing the srevos to twitch. Everything about the receiver power system seems to be fine.

Any other ideas, I'm pretty much lost on this one.

thanks, Bill

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01-29-2003 01:20 PM  14 years agoPost 4
SteveH

rrProfessor

Texas

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Battery Problem?

BWyatt,

I was looking thru the posts looking for info on NMHI batteries and ran across this one and just couldn't keep my mouth shut. You state that if you maintain battey voltage above 5.6, the servo does not jitter. The rated voltage of you flight pack is 4.8 and the entire system should work with no problem down to 4.6 minimum. I'll bet by now you have found that the problem is NOT your battery, but your servo(s). Battery cyclers are set to pull the battery pack down to 1.1 volt per cell, or 4.4 volts.

I fly my systems routinely down to 4.6 volts with no problems, and you should be able to also, unless of course, you have a problem in the switch harness on the radio side that is dropping voltage. The way to check this is to first check your battery voltage normally thru the charge jack after several flights. Then check the battery voltage again with the system turned on and the volt meter plugged into an unused servo outlet on the receiver. If the voltage at the receiver is significantly lower, more than .1 volt, you have a problem in the switch harness.

Hope this is of some help.
SteveH

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01-31-2003 02:29 AM  14 years agoPost 5
bwyatt

rrNovice

Woodward, OK

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I think I have found my problem and a big thank you to all that helped me. Steve, you really set me in the right direction. I had left the older Futaba switch in my heli. when I installed the new JR radio. It seems the connection was loose on the receiver side of the switch and the switch was not in the best condition.

A week or so back my flying buddy pickup my bird and shut off the receiver. When he did, he commented, that switch seems loose. I thought he was talking about the mounting screws, he was not. It looks like the loose connection and the switch may have combined to cause the problem. As I think back, the only time I would have the problem is when the heli. was flying or when I had it sitting on my table, turned on and the wind was blowing fairly strong. Maybe 10 to 15 mph.

This may have been just enough to cause the switch and connector to open and cause the servos to jitter. And, that is why when I put in a different battery pack the problem went away. Yes, I did verify that the second battery pack had a much tighter fitting connector. I'm not sure why it seemed the battery voltage was causing such a fuss. I guess it just seemed the logical thing, until you really think about it.

Anyway, I have 3 good trouble free tanks of fuel through it and a new switch. With temperatures expected to be near 70 this Saturday, I am sure the helicopter will get a good check out.

Again, thanks to everyone who helped.

Bill

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HelicopterRadio - Servo - Gyro - Gov - Batt › JR R700 rec. batt. prob.
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