DX9 Lipo options?

[Sugar]

I've had a search on the world weird web for a suitable lipo battery for the DX9 but all I can find is the 7.4v 4Ah ones that are all over the place for sale.

I find it hard to believe that I can't find a 9.6v lipo to suit the DX9 given that I have a 9.6v lipo for my DX7.

I understand that some black magic must be happening in the 9.6v lipo as you cannot get lipo's to equal 9.6v without some sort of regulator or whatever inside the packaging. More than likely a series of diodes to reduce the voltage.

So based on that, why can't I find one for the DX9?

I guess that the 7.4v one will work well enough and it's got heaps more grunt to boot.

I've heard of people using a 11.1v lipo and not having any issues but at the replacement cost of a DX9, I'm not taking any chances.

[flightengr]

The stock battery for the DX9 lasts quite a while - it's much better than the stock battery was with many other Spektrum transmitters. There may not be enough demand for bigger DX9 batteries.

[Smoggie]

The manual says that the DX9 takes a LiPo, you just need to set to LiPo in the system settings to give the correct low voltage alarm value. I'm pretty sure it will then take the same 2s, 4000mAh LiPo as the DX8 uses.

[Xrayted]

Originally Posted by Grumpy_Old_Man

The manual says that the DX9 takes a LiPo, you just need to set to LiPo in the system settings to give the correct low voltage alarm value. I'm pretty sure it will then take the same 2s, 4000mAh LiPo as the DX8 uses.

It does. The DX9 and new DX6 use the exact same 2S lipo the DX8 uses.

https://www.hobbyking.com/hobbyking/...ter_Pack_.html

or

http://www.helidirect.com/plutx-4000...eywords=pulse/

will both work, and both have the needed internal shut off circuitry so that you can charge within the TX using the stock charger.

[Sugar]

I think my point was missed.

My question is...why do they not make a 9.6v equivalent lipo?

Why do I have to settle for a 7.4v one instead?

Why is it that I can get one for the DX7 but not for the DX9?

Would a 7.4v lipo be any less of a bettery than a 9.6v lipo (if the 9.6 lipo was available). I suppose that the 7.4 being 4amps, that would last about a million years between charges.

[aerocal]

The new generation of radios is designed to run on 2S LiPo or 4cell NiMh. The DX7 was designed to run on 8cell NiMh. Internally the radios now are running in the 3.5 volt range.
Theres no need to run anymore voltage overhead and then regulate it down that much more.
A 2S LiPo is 7.4 nominal or actually 8.4 fully charged.Its being regulated down to 3-4 anyway so 9.6 or more is just going to make more work for the regulator.
The 4000mah 2S LiPo will run the radio for about 25-30hrs.

[drunkenclam]

Will the logo backlight go off with the 4000mah pack? I had a 7s before it, and read on here the battery charge symbol didn't reflect correct charge with lipos, is this the same for the 9? I charged it at my shop with just a terminal plug off of their hitec x4, it was still going after almost 3500 mah. Was my pack undercharged? I believe it drained almost all the way in my carry on bag, and may have never been fully charged. I would plug it in for an hour or two before flying. Anyone know how long the 4000mah pack will take to charge on the stock charger that the dx9 came with?

[aerocal]

The blue led should go Off when the LiPo is charged if it is the OEM type pack.It charges at around 200ma so you can do the math for how long it will take to charge.16 hours or so from discharged.

[drunkenclam]

Okay, yeah I definitely wasn't leaving it plugged in long enough. It should be close to topped off now, but I guess I don't need to worry about overcharging it in the future. The voltage should read 8.4v when completely charged, correct?

[Smoggie]

Originally Posted by Sugar

I think my point was missed.

My question is...why do they not make a 9.6v equivalent lipo?

Why do I have to settle for a 7.4v one instead?

two reasons:

1. There is no such thing as a 9.6v LiPo. LiPo cells are 3.7v (3.7v nominal voltage, 4.2v fully charged) so any lipo has to be a multiple of 3.7v.
2. Why would you want more voltage? There is a voltage regulator in the Tx that reduces the voltage to something around 4v (I dont know the actual number but it is regulated way down). There is absolutely no advantage whatsoever in running a higher voltage battery, it just gives the regulator more work to do, it doesn't increase Tx performance in any way at all.

[Xrayted]

Originally Posted by drunkenclam

Okay, yeah I definitely wasn't leaving it plugged in long enough. It should be close to topped off now, but I guess I don't need to worry about overcharging it in the future. The voltage should read 8.4v when completely charged, correct?

Yes it will, and as has been stated, it takes quite a while for the battery to be fully charged and the light to go out, but the good news is you wont have to charge very often.

[crashcopterman]

I found a charge adapter, takes far too long to charge with the stock setup. So long, in fact, I initially thought my brand new radio was pooched.

http://www.spektrumrc.com/Products/D...ProdID=SPM6834

[Smoggie]

Yes, the stock charger is very slow. If you charge overnight then it's not really an issue but this does go against the old rule not to leaving LiPos charging unattended. I still do it though because realistically you cant be 'in-attendance' for the 12 hours it takes to fully charge.

[FrankFuss]

Charging unattended is probably not a good idea if you are charging a lipo at 1-3 C. However, you are charging the 4000mAh DX9 battery at about 1/20 C with the internal charger.

[Smoggie]

I'm not sure charging slowly is necessarily any safer than charging at 1c... Providing the charge rate is within the rating of the battery the risk would IMHO appear to be the same either way. Only difference is if bad things are going to happen they will probably happen sooner if charging faster.

The one thing that gives me some reassurance on charging the Spektrum Tx liPos is that they are protected cells, that is they have a little circuit built into the battery that prevents them from either being over-discharged or over charged. Even if the charger malfunctions the cells wont go over 4.2v.