DIY 9X battery...

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DIY 9X battery...

Postby ThePoeko » Wed Jul 14, 2010 4:14 pm

I have a few unused 7.4v high C rating Lipos that I'm not using. I'd like to try the 9X battery mod with one of these. Is the high C rate (30 in this case) a problem? Can these batteries be used? I know they don't have the built in protection as the batteries suggested do, but they are already here and I'd like to put them to use if possible.

Thanks in advance for any advice.
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Re: DIY 9X battery...

Postby RCModelReviews » Wed Jul 14, 2010 11:40 pm

The mod will work just fine with a 2S lipo pack and the high C-rating won't matter at all.
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Re: DIY 9X battery...

Postby ThePoeko » Thu Jul 15, 2010 12:03 am

That is great news indeed!

Much thanks!
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Re: DIY 9X battery...

Postby JBC » Mon Jul 26, 2010 2:55 am

I did this DIY battery mod to my both of my 9X's and it works a treat, you're a legend Bruce THANKS! :mrgreen:
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Re: DIY 9X battery...

Postby ScottSails » Sun Nov 21, 2010 4:29 pm

Stupid question - doesn't the 9x use a MC7805 regulator that requires a minimum of 7.0 volts to achieve the regulated 5V? This could potentially cause some questionable operation if voltage gets below spec with 2 Lith cells.
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Re: DIY 9X battery...

Postby RCModelReviews » Mon Nov 22, 2010 6:57 am

The regulator dropout voltage is 1.5V at the current the transmitter draws (it is higher at the full rated current).

That means the 2S lithium can drop as low as 6.5V from its nominal 7.2V. By that time it's pretty near flat anyway -- having reached 3.25V per cell.

So in practice, not a problem.

The transmitter alarm will sound when the lithiums drop to 3.3V per cell -- still leaving the dropout voltage plus a safety margin.
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Re: DIY 9X battery...

Postby ScottSails » Mon Nov 22, 2010 7:14 pm

Thanks - I haven't had a chance to measure the operational current yet, happy to hear it is not pushing the regulator. I suspect with the Fly Dream unit installed, it will be quite low. I am quite excited about the ability to update the transmitter code - I intend to optimize for fixed wing electric use (removing some mixers, adding a throttle mixer (with offset), eliminating all heli stuff) so that I can fit the most amount of MY models.

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