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Old Mar 30, 2012, 09:42 PM
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9 volt battery upgrade to Skyfly 9x radio

Has anyone tried this and had success? I have done it and it seems to work fine. Wondering if I used a rechargable 9 volt battery, if I could use factory charging port on the side of tx. I'm new to all this, but I have made the er9x updated software.
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Old Mar 30, 2012, 10:49 PM
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What kind of 9V rechargeable would that be?
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Old Mar 30, 2012, 11:05 PM
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If you want to use the charge port, you need an 8-cell NiMH pack (nominal 9.6 volts).

A good alternative is the HobbyKing LiFe pack. Much cheaper ($7) and suitable voltage (9.9) but does require removal for charging and use of a proper charger with A123/LiIon/LiFe setting.
http://www.hobbyking.com/hobbyking/s...ter_pack_.html
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Old Mar 31, 2012, 01:19 PM
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Some 9 volt packs have been 6,7,8 cells. Either way you can use those voltages especially since you upgraded your firmware. You can also charge thru the stock charge port , but most 9 volt batts are tiny capacity like 150 mah - 250 mah and would only run the TX for less than 1 hr. Maybe 30 minutes to be safe.

(I like my 2000 + capacity)
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Old Mar 31, 2012, 07:55 PM
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Originally Posted by gulio View Post
Some 9 volt packs have been 6,7,8 cells. Either way you can use those voltages especially since you upgraded your firmware. You can also charge thru the stock charge port , but most 9 volt batts are tiny capacity like 150 mah - 250 mah and would only run the TX for less than 1 hr. Maybe 30 minutes to be safe.

(I like my 2000 + capacity)
There is no such thing as a true 9 volt rechargeable pack. Six cells NiMH gives nominal 7.2, seven gives 8.4 and eight gives 9.6. The small "9 volt" batteries are either six alkaline cells (9.0, non-rechargeable) or seven NiMH (8.4). In any event, they are totally unsuited to transmitter use, being incapable of delivering the necessary current, even for a short time (note that people do use the little 9 volt alkaline batteries to power transmitters with the RF section disabled as a buddy box, but that way the current drain is way down).

What you need for a transmitter is AA cells of at least 1000 mAh capacity. The best choice is Sanyo Eneloops, which have very low self discharge and capacity of about 2000 mAh. Avoid the very high capacity NiMH cells, like 2700.

Since you have ER9x, you can use 6, 7 or 8 cells and adjust the voltage warning accordingly. However, I would not use fewer than 7 cells to provide an ample safety margin above the minimum input voltage for the voltage regulators.
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Old Apr 05, 2012, 02:15 PM
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I have now took advice and put a 7 cell NiMH battery in my 9x. I did have to modify the battery compartment by cutting and lengthening the compartment with more doner plastic from a plastic light switch box. I juct cut one coener and then heated the other end to get the right shape na depoxied it inside the Tx. It's a good snug fit and I can use the factory charging port on the side. Thank you all for the advice and direction on this, keep flying and keep smiling.
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Old Apr 05, 2012, 05:17 PM
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I never really considered using 7 cells or even a 9 volt tiny pack. I can do it , but I don't like messing with my battery door. I have had some connection trouble before. How about letting us know how long the 9 volt pack lasts?
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Old Apr 05, 2012, 07:17 PM
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Originally Posted by gulio View Post
I never really considered using 7 cells or even a 9 volt tiny pack. I can do it , but I don't like messing with my battery door. I have had some connection trouble before. How about letting us know how long the 9 volt pack lasts?
Here are the specifications for a "9v" NiMh battery.

http://support.radioshack.com/suppor...bt-nimh-9V.htm

The capacity is 150 mAh, but that's at 150 mA discharge. At 300 mA you only get about 2/3 of that. Moreover, that's discharge to 7v, which is much lower than you'd want to go. So let's say 1/2.

Since the transmitter typically draws about 250 mA, you could expect 15-20 minutes operation.

There are big guesses involved here, so it could be half as much or twice as much. But the bottom line is the same -- forget 9 volt batteries for transmitter use.

By the way, alkalines have more capacity but are less able to deliver current, so they don't work any better.
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Old Apr 05, 2012, 07:27 PM
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I am not the one considering using a 9 volt battery for TX. I use the LSD like you suggest. I would only be willing to do this for a test. In fact if we can get an accurate consumption I'd be willing to graph a 7 cell NIMH on the CBA if it even goes that low.

I'm guessing the TX is 200 ma , maybe I heard that somewhere. I'm not even sure the cba goes down to 100 ma. Mine may be 1 amp minimum.

Apparently th OP has been using one and just wants to go to a rechargeable pack instead of a throwaway. I can see why.
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Old Apr 06, 2012, 02:22 PM
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Quote:
Originally Posted by gulio View Post
I am not the one considering using a 9 volt battery for TX. I use the LSD like you suggest. I would only be willing to do this for a test. In fact if we can get an accurate consumption I'd be willing to graph a 7 cell NIMH on the CBA if it even goes that low.

I'm guessing the TX is 200 ma , maybe I heard that somewhere. I'm not even sure the cba goes down to 100 ma. Mine may be 1 amp minimum.

Apparently th OP has been using one and just wants to go to a rechargeable pack instead of a throwaway. I can see why.
I realize than and should have been clearer.
FM transmitters were typically 250-300 mA, but 2.4 generally require less power. So 200 mA may be about right.
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Old Apr 06, 2012, 05:12 PM
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I do have some tiny 1sx130 and 1sx160 mah cells to do so maybe I'll try to find one of my old 9 volt rechargeable packs to test. Mine are 7 cells.
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