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HelicopterRadio - JR DMSS › JR 9303 2.4 Battery Voltage Display?
06-08-2009 05:20 AM  8 years agoPost 1
David Blain

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Mt. Dora, Florida (USA)

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I own several JR 9303 radios, something seems off on the voltage display on the screen, it never reads correctly (?)

If I need to accurately check my voltage/Mah after charging, I use a Multi-Meter (as Electricians use) at the battery plug tail,(This is done with battery removed from radio) somehow the voltage I read at the plug versus what I have on the display always varies!

I was told not to use the JR display on radio as the "true voltage" of the transmitter battery for they tend to be off/inaccurate.
(Note; I am using a JR 2500 Mah factory upgraded battery in a 2.4 setup)

Any input guys?

David Blain
T.O.R.C.H.S. Orlando Member

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06-08-2009 05:24 AM  8 years agoPost 2
Dood

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Wescanson

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My 9303's voltage display seems dead nuts accurate.

Your multi meter isn't putting a load on the pack, that would explain why they're different.

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06-08-2009 11:20 PM  8 years agoPost 3
David Blain

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Mt. Dora, Florida (USA)

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I understand that there is "no load" on in when I check the voltage, But is the display the actual voltage that is in the battery or the voltage with the transmitter load due to the internal electronics?

Kinda see my point?
I charge the batteries up (.5 typical rate) and let's say after a full discharge/charge the voltage I read on the battery plug tail fails to match the voltage by at least half a volt (.5)!

So your saying that my voltage displayed on the JR 9303 2.4 is NOT the voltage available in the battery pack?

OR, are you saying that what I may actually measure for voltage at the battery tail is not what is available for fly time?
If so I wasted the money for the larger batteries for radios I run....

Man, I don't want to go li-po and gamble with voiding the factory warranty
(I know you know the Horizon game by posting all about it)
but it is starting to look better than this "old school" short life NiM batteries

David Blain
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06-09-2009 12:31 AM  8 years agoPost 4
JuanRodriguez

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The Villages, Florida

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If the battery voltage you're reading with your meter is higher than what is displayed by the radio then I would say that the radio's display is "under actual load", which is my understanding .... if so, that's the reading you want to go by.....

As I understand, the transmitter operates at about a 250 ma load....

So, why not put your meter under that same simulated load and see how they compare ??

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06-09-2009 01:00 AM  8 years agoPost 5
creepin

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louisville, ky

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you must use the meter when it's connected under load. find metal on both wires when its connected to the bett. and recv. and then get your true measurement.

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06-09-2009 04:36 AM  8 years agoPost 6
David Blain

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Mt. Dora, Florida (USA)

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Thanks....
Juan Rodriquez
creepin

Now that's what I was looking for, someone to give me some sort of information on the load the radio runs/draws on!
Now I can load test and confirm the battery with the meter!
(Juan where did you get the number from? Just curious)

Presently when the JR 2500 Mah batteries are charged all the way I get a display of 11.7 volts, it will fall off fast on the first flight, to the low 11 volt area, then settle in around the mid/upper 10 volt area then fall off.
About five/six 9+ minute tanks doing mixed flying...
I will not fly below the 10 volt mark, just too close for me
(Batteries are less than six months old with about 75+/- cycles)
I use at least two in one day to get a full gallon flown.

Anyone else use the the JR 2500 Mah battery and what is your display reading at peak/full charge prior to the first flight???????

I know I am not the only one with them for the JR Radios.

David Blain
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06-09-2009 04:39 PM  8 years agoPost 7
JuanRodriguez

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The Villages, Florida

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Hey Pull,

That figure has been thrown around for a long time but I have no definitive "source"..... that's why I began my statement with "As I understand...."

I'm sure a quick call to Horizon Tech Support can nail it down for you with more authority..... and besides, I'm not sure that figure applies to the 2.4 radios.......

Here's another thought......... I'm not sure that it would matter that much if you load the meter at 250 vs say 500 ma load to check your radio's meter with a full charge on the battery..... I'm guessing that a load anywhere in that range will do for what you're attempting to establish.....

If you call Horizon, please let us know what they say (just out of curiosity)....

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06-10-2009 01:58 AM  8 years agoPost 8
dkshema

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Cedar Rapids, IA

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You could open your manual and read the specs of the transmitter...

Below are the specs from the XP9303 (72 MHz version of the 9303) manual:

and the X9303 (2.4 GHz manual):

Current drain is clearly shown for both radios, including the X9303 when operating in DSM1 and DSM2 modes.

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Batteries need to be checked under a reasonable load to gauge their true output voltage. Open circuit into a high impedance voltmeter won't tell you what you think you're supposed to see.

And while you're at it, if you have a multimeter handy to measure the battery VOLTAGE, it does not take a rocket scientist to use that same multimeter to MEASURE the ACTUAL operating current.

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Nicad/NiMh cells have a nominal output voltage of 1.2 volts per cell over most of their discharge cycle. If you stop flying at 10 volts, you're still have a whole bunch of capacity left.

That 2500 mah pack will go for almost 9 hours (8.93) under the 280 ma load of the X9303 in DSM2 mode.

That same pack will last for 12.5 hours under the 200 mah of the XP9303 system.

The batteries are fully discharged when they reach 1.1 volts per cell under load. That means 8.8 volts when the pack is exhausted.

The low battery alarm of the X9303 AND XP9303 is set to trigger at 9.0 volts. Stopping at 10 volts is leaving a good deal of charge in the pack. It will stay in the area of 9.6 volts for most of the normal discharge curve.

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The peak, fully-charged voltage reading of the pack is not a function of it's mah capacity. A healthy 8-cell 100 mah NiMh pack will have the same full-charge voltage as your 2500 mah 8-cell pack. Voltage is a function of the chemistry and the state of charge, not the capacity.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-10-2009 02:19 AM  8 years agoPost 9
copperclad

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NY

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Hi Pull-n-Pitch
it is interesting , and not too hard , to use your multimeter
to measure the voltage of the battery , while in the TX and turned
on , this lets you see exactly how the display compares to the
actual battery voltage while in use

.

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06-10-2009 04:46 AM  8 years agoPost 10
David Blain

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Mt. Dora, Florida (USA)

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Okay, I relinquish under correction!
Juan- Thanks for the replies to the post!
copperclad-Thanks for the photo and the information!

dkshema-
1) Your correct I am not a rocket sciencetist, Just a Commercial G.C.
2) Yes I have read the manual (nice scan of pages though) but I was needing some minor clarification on reading of the voltage at the battery pack versus the display on the screen.
-To you I say "Thank You" for the information provided on the 2500 pack.
3) I will be out pushing the Raptors this week and it's good to know I was taking it "too" safe at 10 volts and will push the into the 9.6 nominal discharge curve you referred too.
4) I flew by "Better safe than sorry" marginal doesn't cut it with me!

Now in closing, I will have tested my voltage (per photo by copperclad) and it is dead on (Thanks Dood! Your always there also)

dkshema, what kind of radio is a XP8013 as in your profile? (XP8103 similiar?)
(couldn't resist bustin' your chops, after you busted mine)
seriously-
dkshema, Thanks this is why I am a active member of RR for clarification on points we sometimes just don't understand!

David Blain
T.O.R.C.H.S. Orlando Member

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06-10-2009 04:54 AM  8 years agoPost 11
dkshema

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Cedar Rapids, IA

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XP8013 -- must be a typo. It's an 8103. I'll go fix it right now.

Edit -- all better now.

BTW -- I'm not as mean and evil as some of my posts would lead you to believe...

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-10-2009 06:02 AM  8 years agoPost 12
David Blain

rrKey Veteran

Mt. Dora, Florida (USA)

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dkshema-
Never thought that about you...
Somehow you ALWAYS come back with the correct answers though...
Must go with the RR Professor title.

I do appreciate the help!

David Blain
T.O.R.C.H.S. Orlando Member

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HelicopterRadio - JR DMSS › JR 9303 2.4 Battery Voltage Display?
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