Adding a Flightpower 3s LiPo to the DX7

[allanQ]

Originally Posted by traeside

AllanQ did you ever get an answer to your question? i read this post long ago before i put my Rhino 2660 with diode in. but i wanted to do the same as you. as it is now if my voltage reads around 10.3 or 10.4 i am at about 16% when i put the pack on the charger. i don't like taking it that low so i also wanted to be able to set the low voltage alarm to 10.6. i would think that setting it to 11.6 would be to high with a diode. 10V might save a fire but i am not sure the battery is going to be very happy.

i never got an answer ...
however ... i put 2 diodes in series ... lowered the voltage about 0.8v to tx (actual output to tx after the diodes) and re-calibrated the dx7 voltage reading via service menu to about 1.2v .lower than actual battery reading (plugged in my batt checker at the balance plugs while tx is ON and batt plugged into tx)
i then set the low voltage warning to 10v (this is the max the dx7 allows me to set)

so ......
actualy MAX voltage to tx will be 12.6-0.8 = 11.8v
at MAX batt voltage ... tx reading will show 11.4v
when batt alarm goes off in the tx when reading is below 10v ... tx is still getting 10.4v from the lipo ... batt will be at around 11.1-11.2v (which is just nice to recharge the lipo)
i put back around 1800ma into the lipo

so far i have not faced any problems ... tx is cool .. lipo is cool ... no fires here
lasts me more than 3 weeks b4 i recharge again unlike the stock batt which gets me about 1 week+ b4 the alarm goes off

[traeside]

Nice work around i like it. if i am thinking right the reduction in voltage should cause the radio to draw a bit more current but all in all the wattage should be the same right?

[nexgen]

Originally Posted by marcgode

LM2937-3.3

400mA and 500mA Voltage Regulator

Generic P/N 2937-3.3
Contents

General Description
Features
Datasheet
Package Availability, Models, Samples & Pricing


Positive Voltage - Fixed Family
Parametric Table
Multiple Output Capability No
On/Off Pin No
Error Flag No
Input Voltage, min (Volt) 4.75
Input Voltage, max (Volt) 26
Output Current, max 400 mA,500 mA
Quiescent Current, typ (mA) 2
Output Voltage (Volt) 3.30
Watchdog No

it only looses little power and has max 26 volt input

I have a 9303 and run a 'naked' lipo. Based on these specs above, I should be able to just charge and go. I still however just charge the lipo to about 11.5-11.9 (3.83-3.96 per cell) and leave it at that. when I see the battery read 11.1ish on the tx, I charge.

[jinxjx]

Hi there, lets see, so if you don't fully charge the lipo, it will be safe to use in DX 7 without modifications?....thank you...i guess this one will do?

http://www.espritmodel.com/index.asp...D&ProdID=12032

[jimgrant]

Originally Posted by traeside

Nice work around i like it. if i am thinking right the reduction in voltage should cause the radio to draw a bit more current but all in all the wattage should be the same right?

Strange thinking..totally wrong .. voltage goes down, current goes down , wattage goes down

[tribe3]

I'm using a Hyperion LIFE 3s 2100mAh (part# 9HP-FG305-2100-3S) and it lasts a LONG time.

I put some Dean connectors and it fits snug but well

[Ron~FordTech]

I know - an ancient thread. But I looked around a bit and didn't see a more appropriate place to put this, so...

I have a basic un-modded DX7 except that I raised the voltage alarm point to 10.0v. I picked up a 11.1v/2600mAH LiPo for it with the proper connector. Before installing it I asked HH/Spektrum their official position on this idea and they said this:

"The tx will work fine for awhile, then you WILL crash. For sure. And you or someone else may be hurt. We say don't do it."

yikes.

I realize there are liability issues, but from a 'will-it-fry-the-radio' standpoint...is it true? Will it fry the radio? And if the answer is "yes" or "likely" or even "possibly", can I perform a mod [without the skills of an electrical engineer] that'll protect my transmitter?

Thanks!

[Schelli]

Hmm, i am using a Rhino Transmitter Pack, it is a 2620, 3s Lipo. It had the connector to connect it directly to the dx7 when i bought it.

Been using it for 2 years now, i didnt do anything to my dx7 whatsoever and i didnt have any problems at all, no crashes, no lost conns, nothing.

hope links work, this is the thing on hk.

http://www.hobbyking.com/hobbyking/s...idProduct=7346

[Ron~FordTech]

Right. I bought essentially the same thing, and it too has the necessary/tiny connector. I realize that just because somebody sells it -- and that it even has the appropriate connector -- does not automatically make it acceptable/safe/smart. But if hordes of people are using it without issue...well...it would be reassuring to know that.

OR...

If indeed it CANNOT be described as acceptable/safe/smart...if there is a [u]simple[u/] alteration that basically guarantees it'll be safe I'd like to learn it.

[Rodney]

Well I still make Ions to fit and work with no issues, drop in and fly. Perfect fit.

[jcflyer]

When doing this mod to your DX7 how do you recharge the battery? Do you have to disconect it from the TX? Will you loose your settings in the TX if diconected?

[aerocal]

Yes you will probably need to remove it from the radio to charge unless it has a separate lead. You will not lose your programming by unplugging the battery.

[dennis22g]

If you are really smart you will charge your lipo by the balance lead. It is really easy and you can leave the battery in the radio. If you are unsure how to use your normal charger for this method it is pretty simple. You will need a balance lead extension. The large positive and negative leads are placed one on each end of your balance socket. Some chargers are already connected in this manner. I think HK sells the leads already made up. I have used this method for about 3 years and have no problems. I have charged up to 6 amps using the balance leads. Hope this helps.
Cheers.
Dennis

[pache11]

Been using a lipo mod on my dx7 for over 5yrs and have no issues other then almost never charging my transmitter. I have to only charge it once or twice a season! The battery life is over 16 hours with the dimension engineering regulator and Turnigy 2650mAh 3S 1C Lipoly Tx Pack (Futaba/JR) pack. This lipo has such a low self discharge rate that after 4 months of use it has only dropped .1v. I now use my dx7 as a wireless trainer with my dx9 and charge only once a year. I charge it with the balance lead. It runs safe cool and efficient!