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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Jewel System and RX battery.
08-07-2011 08:12 PM  6 years agoPost 1
Malc1

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EVESHAM,UK

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I've been talking to Raja for a few weeks now regarding a problem I have with my Spectra and the onboard charging system.

As he's on his way to IRCHA I thought I'd try to get some input from any of the gasser guys who are still around who run the Jewel system on their gassers.

I have a 6.9v version Jewel and a 6 volt 2700mAh 'AA' NiMh RX pack on board.

I have a problem with the system not being able to keep up with the current drain on the heli.
The optional green charge indicator on the Jewel is always on but I lose the full green LEDs on the battery monitor after less than one flight.
Initially with the heli idling the monitor does should green.

A couple of flights in and I have the monitor sat in the amber/red and it leads me to abandon flying.
This is with the heli in flight.

I have,with the help of Raja done various tests and we seem to think all is looking OK with the system.

Regarding the radio gear on board,there are 3 JR DS8717's,a DS8711,a DS8900,a JR 770 gyro and a Futaba GV-1 governer.
All in all quite thirsty maybe.

The RX pack has not yet been changed,but it will be to elimate it.

I was wondering if there is an issue with the type of battery pack I am using with the Jewel and the listed radio gear.

Is there a different type of RX pack that I would be better using with my setup?

What are you guys using?

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-07-2011 08:33 PM  6 years agoPost 2
rc3po

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Danville, Illinois

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How is your jewel connected to the system. Straight to the battery or to the receiver?

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08-07-2011 08:42 PM  6 years agoPost 3
Malc1

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EVESHAM,UK

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Connected via a Y lead and switch straight to the battery - I think.
Its been a long time since the heli was put together.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-07-2011 09:33 PM  6 years agoPost 4
rc3po

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Danville, Illinois

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pm sent

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08-07-2011 10:28 PM  6 years agoPost 5
turboomni

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East of the Equator

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Have you tested the battery??

Setup is everything, All my heli's can fly far better than I can pilot them

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08-07-2011 10:48 PM  6 years agoPost 6
Malc1

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EVESHAM,UK

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I have done a test with a voltmeter and used a plug in tester which puts a load on the pack.

It looked OK - I think.

I can charge/discharge/cycle the pack on the charger but really what sort of thing should I be trying to look for?

As mentioned I am planning to swap the pack over to eliminate it but was wondering whether to swap it for the same type again.

Probably not.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-07-2011 10:55 PM  6 years agoPost 7
rc3po

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Danville, Illinois

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No...
Get a different higher output pack.. the 8717's definately require a good power system.. and in my opinion, nimh will not cut it...

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08-07-2011 11:07 PM  6 years agoPost 8
Malc1

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EVESHAM,UK

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OK,worth a try if I'm going to change it out - nothing to lose.

A123's sound a good idea - RX packs are available.

Any problems using my 6.9v output Jewel with these then?

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-08-2011 08:03 AM  6 years agoPost 9
gboden

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Chugiak, AK

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My 2 cents. I have a dual jewel gen on my Radikal and have hooked it up with a couple of Y-harnesses as well. I think that if the generator works still, which it obviously does given the fact that your LED continues to operate, then there is probably a broken wire someone between the AC/DC converter and the battery. I always test my generator by isolating my battery after startup to ensure power is being sent to the ignition module and the receiver by switching off battery power. I feel safe doing so because the engine will die if power is not being provided.
With all of that being said, I think there are two possibilities:
1. A wire is broken.
2. The Jewel cannot provide enough continuous power to the system resulting in additional power being drawn from the battery.

I don't think the type of battery should have anything to do with this fault. I am interested to know though. My current setup is below with a single 2700 mAh NiMH battery instead of the 1500 mAh shown in the diagram.

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08-08-2011 08:12 AM  6 years agoPost 10
Malc1

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EVESHAM,UK

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More Testing....

The heli is on the bench again with the wiring accessible and the AXI motor off the bracket.

With the battery unhooked and directly into the Jewels output plug I am getting the correct 6.9V out using the Dremel

With the RX battery still unhooked but all plugged back into the system again, connected to the Dremel I see 6.88 - 6.91v at the Jewel output plug and 6.86 - 6.87v at the RX battery plug.

The max green LED on the system battery monitor is fully on at this point - as it should be.

At this time with out boost charging the pack the voltage across the RX pack without the Dremel spinning up the motor shows 5.89 - 5.91v with flucuations on the monitor and no max green LED.

System all plugged in and switched on.

With the Dremel running I am seeing 6.3v across the pack with a full green LED.

You can feel AXI motor slowing up slightly when loaded up.

Still all looks good but the heli is only sat on the bench at this point.

I've got another RX pack on order and will check things further.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-08-2011 09:01 AM  6 years agoPost 11
pgkevet

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Wales

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I've reported my own findings before but worth repeating:

I found on my setup that a single 4.8v subC pack gave obvious fluctuations on a battery monitor when working the sticks hard on the bench...despite the fact that subC's are supposed to be able to deliver as much as 30A. The reason has to be voltage drops across servo plug/sockets and it's recognized that one loses around 0.2v across each of those. Bypass switches and connectors and you lose flexibility. Work a servo through direction changes and they can pull huge currents (some reported as high as 2A in stalled states). I decided that potential was worrying.

My answer was to go to 2 AA 4.8nihms and 2 switches both directly into a Rx to avoid Y-leads adding to the connector burden. That way the generator is parallel charging and the connector resistance drops dramatically and voltages hold.

Dual AA packs that only have a potential for some 8-10A each still hold that voltage when working the sticks on the bench for that reason.

Prior to flight I test by switching each switch on in turn to check the voltage on each pack through one monitor. You can also check the charge capability of the generator by observing the monitor at a decent engine rpm (but well below take-off pitch) by seeing that monitor hold voltage to max led indication and be assured that the dual capacity would run a full flight independently of the generator... and then recheck each pack prior to the next fligt to confirm their charge is holding.

Eneloope type cells are available as AA but not subC so it also means one doesn't need to worry about recharging nihms before a session if it's been several days since one last flew...eneloopes are supposed to hold 80% for upto 12mths (albeit drop-offs can be quick at the end)..so if one can assure oneself that charge levels as indicated are near full and generator is pushing that to max voltage before takeoff then you're good to fly.

I suspect the most fashionable answer would be to use HV sytems based on LiFe cells and use a plug/socket rather than on/off switch and solidly crimped bullets or soldered junctions anywhere an extension is needed.

pgk

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08-08-2011 10:27 AM  6 years agoPost 12
Malc1

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EVESHAM,UK

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I've ordered a A123 2300 RX pack to try - to eliminate the NiMh one I have here.

Going to do some more tests on the system as is later on.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-08-2011 11:58 AM  6 years agoPost 13
rtdillon

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Huntsville, AL

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LIFE Charging
Please look into the charging requirements of the LIFE battery.
You are not going to be able to swap out the NIMH/NICAD packs with LIFE in your setup and go fly. When charging those packs they must be current limited as well as voltage. If set right, your voltage regulators will protect from over-voltage charging but there is still the possibility of pushing too much current into the pack when it is low. IMHO.

No,No..The other left!

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08-08-2011 01:28 PM  6 years agoPost 14
Malc1

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EVESHAM,UK

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My Bantam e902 charger will charge LiFE packs so not a problem there.

So It's the onboard charging with the Jewel that I'm going to have problems with?

As mentioned the Jewel is the 6.9v version, what do I need to do to make this work then?

The A123 RX pack I have ordered also doesn't have balance taps - is that also a problem?

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-08-2011 02:58 PM  6 years agoPost 15
lejon

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Las Vegas, Nevada

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Malc1, From what I have experienced I'd go with a larger capacity battery (4K +). Under normal conditions I have had batteries stay charged for months, then I have had them much like you are experiencing where I would charge them after every day because they were low.

Here's what has happened to me:

I had a battery going bad and since I don't have an on-board monitor I didn't know it. I started noticing that when I would power up the gyro to a long time to settle, and then the RX started flashing when I stir the sticks. Well although I should not have, I cranked it up and flew for 15 minutes or so. When I attempted an auto I noticed that the response was sluggish. I aborted and came in for a normal landing to check things out. When I went to pick up the heli I noticed the RX light was out. I checked the battery and although it came on it would die after stirring the sticks. Changed out the battery and all is well.

My opinion is that the on-board charging system is working but is not able to charge a dead or dieing battery, or if it does charge it the battery will not hold the charge.

Not sure how your on-board voltage monitoring system is connected but is it possible that you are some how isolating the battery and instead of showing that the system voltage is low it is showing that the battery is low?

Good luck and I hope you find the problem,

Lejon

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08-08-2011 06:11 PM  6 years agoPost 16
Malc1

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EVESHAM,UK

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Regarding the battery monitor it is wired via a Y lead to the gyro gain channel of the receiver.

Using something similar to a Voltwatch.

So it's monitoring system voltage and not straight across the battery pack.

Also just checked to confirm the Jewel output.

It is on a heavy duty Y lead on the receiver side with the single end going away to the RX battery pack.

So it's battery,switch harness to one end of the 'Y' lead -----> Jewel output and Receiver.

I'm only using a 7 Channel RX so a bit of a shortage of channels I'm afraid.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-12-2011 05:06 AM  6 years agoPost 17
rbort

rrProfessor

Franklin, MA - USA

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At IRCHA having a great time
Just wanted to drop in a quick note to say that you can use a 2 cell LiFE pack with the 6.9v Jewel system. The generator will not overcharge the pack as it is a constant voltage charger and there are no issues with overcharging due to this.

On a side note after some extended use for bench setup or whatnot it is a good idea to keep the pack at least half full before flight as a heavily drained pack and take more current from the generator and tax it more than necessary. The generator regulator is designed to output 3 to 5 amps so use a pack that is large enough that can handle this amount of charge rate if necessary.

I'm heading off to bed as another full day tomorrow is on tap for me at IRCHA but I'll leave you with this quote from a recent PM that I received:
Hi Raja,

I'm back from my vacation and went out to the field to test my generator setup. I went through 6-8 tanks, atleast 1.5 hours of effective flight time. All went fine, in spite of a few engine tuning issues
I've charged the A123 after I got home. I put 58 mAh back in a 2300mAh pack I would call the test successful as the system is clearly able to keep the pack fully charged. The only drawback is that the regulator does not produce power until 7000ish rpm. But that is not really concern at the moment as the pack was kept fully charged all day.

Best Regards
Michael
-=>Raja.

MA 1005 Hanson 280, 4210 flts
Spectra 27 3DMax, 3280 flts
Whiplash V1-2 Hanson 300, 1555 flts
Whiplash V2 Hanson 300, 393 flts

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08-12-2011 07:24 AM  6 years agoPost 18
Malc1

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EVESHAM,UK

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Raja

Wish I was over there as well checking things out

New 2300mAh NiMh RX pack fully charged and fitted.

I could only get a pack without balance taps over here to try for starters but have ordered a A123 NoBS pack with the correct lead configuration from the US.

I'll feel happier this way.

Hopefully, weather permitting I'll try it out later on today to see how it goes.

One thing I did notice is that it is now quite difficult to get the Red PLV led come one when stirring the sticks around - thats a good sign I'm sure.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-12-2011 10:45 PM  6 years agoPost 19
Malc1

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EVESHAM,UK

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Hmmm, interesting....

Went out this afternoon with a full green LED on the battery monitor and came back with it the same.

Flew for four tanks of fuel and about an hour on a fully charged up pack and have just come back and topped the pack up.

Ended up putting 319mA back in.

At no point did I see any ambers or reds on the monitor and no PLV recorded either.

I'll try it for longer tomorrow to see what I get.

Minicopter Diabolo - Kosmik200,Pyro750-56
SpectraG + G26 3D Max

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08-13-2011 05:01 AM  6 years agoPost 20
rbort

rrProfessor

Franklin, MA - USA

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Sounds good
Looks like you might have solved it

-=>Raja.

MA 1005 Hanson 280, 4210 flts
Spectra 27 3DMax, 3280 flts
Whiplash V1-2 Hanson 300, 1555 flts
Whiplash V2 Hanson 300, 393 flts

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