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Jet Cat help!!

Old 06-04-2009, 08:45 PM
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TED ANTON
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Default Jet Cat help!!

Hope some one can help me here,
My GSU reads" OC Batt Low" 4.4 is the voltage, when I test the battery it shows 8.4 off the charger
I even checked each cell with a volt meter and each cell shows 1.4 volts
My rx is a 2 cell A123 pack fully charged I am using a smart fly
I amfrustrated can some one please help !!!

Thanks
Ted
Old 06-04-2009, 08:53 PM
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FILE IFR
 
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Default RE: Jet Cat help!!

Have you checked the pack with a load tester? .500amp or even 1.0 amp.

A *bad* battery can (at times) read a healthy charge, but put under load will determine otherwise.
Old 06-04-2009, 09:01 PM
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SinCityJets
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Default RE: Jet Cat help!!

Something isn't right, A123's do not drop like that, even under load. Also, a 2 cell A123 will not be even close to 8.4 off the charge. If charging them with an A123 charger, they will be 7.2 MAX, and quickly drop to 6.9.

Chad
Old 06-04-2009, 09:07 PM
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rcjet lynch
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Default RE: Jet Cat help!!

The GSU is giving you the ecu voltage not the RX.
Old 06-04-2009, 09:10 PM
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rcjet lynch
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Default RE: Jet Cat help!!

Ted, what battery are you using on the engine,is it the Jetcat lipo?
Old 06-04-2009, 09:13 PM
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TED ANTON
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Default RE: Jet Cat help!!

I put a load tester on the pack ( Duralite ) 1 and 1.5 amps and the v drops to 7.2
Old 06-04-2009, 09:15 PM
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TED ANTON
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Default RE: Jet Cat help!!

Hi Rob
I am using Nickle metal 6 cell 3600ml
Old 06-04-2009, 09:20 PM
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SinCityJets
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Default RE: Jet Cat help!!

Ted,

You have named about three different battery types.

Is you ECU battery a 6 cell Nimh, a 2 cell A123, or a Duralite?

Chad
Old 06-04-2009, 09:27 PM
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rcjet lynch
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Default RE: Jet Cat help!!

Okay well fully charged you should be about 8.4 volts, if you are reading in the 4 range your pack is dead. I am asuming that your a123's are from duralite?
Old 06-04-2009, 09:47 PM
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TED ANTON
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Default RE: Jet Cat help!!

Hey Chad

My reciever packis A123 , my ECU battery is an Nimh and my battery tester is from Duralite
Hope that clears thing up
I just tried another ECU and the votage is almost the same 4,5 v ,
I tried2 different Nimh packs and they both register the same voltage but when I test them ( with 1.5 amp load )they are fine 7.2
The only thing I know for sure is I'm going to have a beer or tworight now before I toss the whole lot out the window
I will try a new pack
Thanks for the help guys

Ted
Old 06-04-2009, 10:10 PM
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Default RE: Jet Cat help!!

Is the ECU set up for a LiPo?

Check what the GSU says...
Old 06-04-2009, 10:25 PM
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Default RE: Jet Cat help!!

Id try a GOOD Ni Cad. freshly Charged.
Old 06-04-2009, 10:30 PM
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Default RE: Jet Cat help!!

Ted,

try a different GSU and see if you get the same reading

Mark
Old 06-04-2009, 10:44 PM
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SinCityJets
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Default RE: Jet Cat help!!


ORIGINAL: TED ANTON

Hey Chad

My reciever pack is A123 , my ECU battery is an Nimh and my battery tester is from Duralite
Hope that clears thing up
I just tried another ECU and the votage is almost the same 4,5 v ,
I tried 2 different Nimh packs and they both register the same voltage but when I test them ( with 1.5 amp load ) they are fine 7.2
The only thing I know for sure is I'm going to have a beer or two right now before I toss the whole lot out the window
I will try a new pack
Thanks for the help guys

Ted
Whew! I was getting worried about you for a minute there

Ted, switch to a 3 cell A123 for the ECU and forget these problems. (your ECU may need to be sent to JetCat for the A123 upgrade. I think it is $25)

Chad
Old 06-05-2009, 06:20 AM
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TED ANTON
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Default RE: Jet Cat help!!

Well it works now, I changed the black "phone line " from the engine to the ECU and all 3 ECUbatteries read 7.9 - 8.2
I never would have thought that it would work but it did
Thanks for all the help guys, this forum is great I posted a question and I received half a dozen replies with in 30 min
Thanks again and safe flying

Ted Anton
Old 06-05-2009, 06:45 AM
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Default RE: Jet Cat help!!

Ted this is very strange. The RPM/EGT sensor cable should not have any influence on the ECU power supply voltage ( unless you have a cable internal damage shortcuting the whole system ).

One thing you could check though: the grounding of the engine connection board. The board is held in position by 3 screws going in 3 aluminium dowels. One of these dowels is metallized on the board.
The lower side of the board will have a metallized strip at this dowel location. Check if this specific dowel is well fastened on both the board side and compressor casing side.
I have seen strange things like that happening with an intermittent connection board mass, including in flight flameouts.
Old 06-05-2009, 07:03 AM
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TED ANTON
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Default RE: Jet Cat help!!

Hi Oliver

I know it's very strange but it works now, I know there is no connection with the battery lo reading and the cable
I will check the board
Thanks for the input

Ted
Old 06-05-2009, 11:01 AM
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Default RE: Jet Cat help!!

Ted.
Ship the entire jet to me.
I will fully evaluate all systems and return it to you with my findings in December.
LOL.
Hope you sort it out. I look forward to flying with you soon!!
Old 06-05-2009, 06:16 PM
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ROMA-F1
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Default RE: Jet Cat help!!

THE BATTERY YOU NED TOO USID, IS THE .. [LIPO 5000 NIHM] DURATRAX FROM .. TOWER HOBBIE..... WWW.TOWERHOBBIE.COM.. ..ELTANO0503@HOTMAIL.COM
Old 06-05-2009, 08:01 PM
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Default RE: Jet Cat help!!

Hi Ted,

I would take particular note of Oliver's comments. That cable should have no influence on your ecu battery voltage. I would bet you have a dodgy NIMh battery pack. They are infamous for false peaking during charging because of their relatively high internal impedance. I never use them in aircraft for that reason. I only use them in rc cars and even then they are a pain.

I would remove that pack from your jet until you test it more. Is it a new pack?

Craig.
Old 06-05-2009, 08:16 PM
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rcpete347
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Default RE: Jet Cat help!!

HI, NOBS batteries, Nimh have very low impedance, especially if two are in parallel.
Rcpete
Old 06-08-2009, 11:10 PM
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Default RE: Jet Cat help!!


ORIGINAL: rcpete347

HI, NOBS batteries, Nimh have very low impedance, especially if two are in parallel.
Rcpete
That is correct Pete. NOBS sells good products. However these Nimh packs are particuliarly picky to charge.
Not everyone uses a high end charger with specific Nimh charge schemes and a temperature sensor to avoid overheating the pack.
I've stopped using Nimh packs a while ago now and I don't regret it...


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