JR 12X & LiPo battery

[John Cook]

(then again, Ive seen one 12x radio with direct lipo, so it might work for some question if you want to risk it)
hehe heck no. I'm not risking it. I ran one step down diode instead of 2 though, and the voltage seems to be in the low 11's to mid/high 10v range for most of the pack. Also, I think I only charged to about 90%.

I just thought JR was trying to avoid warranty claims with users stuffing fully charged lipo packs in there.

I could see 12.4+ volts maybe causing issues down the road, but 11's should be safe as a fully charged NiMh will hit or touch on 11v. Then again, my stock NiMh even properlly broken in like is recommended was a TURD of gigantic porportions. I would get high 10's for about a few mins, then low 10's for maybe 30mins to 60mins then high 9's for a few flights, then I would get nervous. Not what I consider acceptable for such an expensive radio.

[MrMel]

I found one heck of a conversion though :)

http://www.rcgroups.com/forums/showpost.php?p=11098350&postcount=81

[John Cook]

I found one heck of a conversion though :)

http://www.rcgroups.com/forums/showpost.php?p=11098350&postcount=81

I like your mod better. I can take the lipo out to charge it once every month or two ;)

[billyd]

What about changing out the internal voltage regulator like in this mod for the DX6 or DX7????

http://www.dimensionengineering.com/appnotes/spektrum_mod/spektrum_mod.htm


Does the JR 12x and X9303 have the same vr as shown in this example?

[MrMel]

Currentdraw of the 12X is actually very low, so I bet they already have a good regulator in it.

[billyd]

Well if that's true, then why can't you just use a 3s LIPO? The regulator that I was linking is good to like 32volts input I think. I thought the problem with these Tx's is their built in regulators overheat when exposed to the higher voltages of a LIPO???

[MrMel]

Havent seen the schematics so you cant be sure, but as I understand it, on 10X and 12X its not the voltage regulator that goes, its the transmitter boards that fry, some of those that ran 10X on lipo and switched to 2.4ghz got a poofed module where as the 72mhz had no problem.

[billyd]

Havent seen the schematics so you cant be sure, but as I understand it, on 10X and 12X its not the voltage regulator that goes, its the transmitter boards that fry, some of those that ran 10X on lipo and switched to 2.4ghz got a poofed module where as the 72mhz had no problem.


Ok but as I understood it, the onboard transmitters run on 3.3v taken from that regulator, so if you have a regulator that can handle the higher input voltage (e.g 12.6v LIPO), you don't have a problem.

[MrMel]

Logic doesnt make sense though.
On the x9303 it is the volt reg that fry, not on the 10 and 12x, must be some other design on those, sep volt reg on the tx board?

[billyd]

I'm not an EE. What happens when you overload a VR? Does the output increase (prior to failure)? For example the VR could be putting out 4v (for example) instead of 3.3v when overloaded with a LIPO, frying the transmitter before burning out the VR.

[MrMel]

Might be, but as I saw in one of the reports of a failed 10X the radio itself continued to work, but the model dived down and crashed since transmission ceased.

Well, someone perhaps can explain all this to us :)

[billyd]

Perhaps the 12x uses multiple VR's for different circuit boards in the radio.

[rkeith2]

I put 2 diodes in series and the voltage shows 11.8 at the battery and when tried in the 12X the screen shows 10.8, seems like the internal regulator is really dropping the voltage.

[rolexcomex]

I have been using a 3s 2400 LIPO in my JR 12x for the last 8 months.

The Radio meter reads 12.6v when fully charged. No issues. I love that I dont have to run home and charge all night for a couple of hours of flying..

Here is details and photos on this easy modification
http://www.helifreak.com/showthread.php?t=157656

[dyecocker1]

has anyone tried just using a castle bec to regulate the voltage down to 10v or so before it hits the radio? i realize that it would have to be unplugged at the end of the day so it doesn't draw on the battery but i could handle that...

a day after posting this i realized cc bec's only go to 9v my bad

[MrMel]

I switched over to Hyperion LiFe packs, works great.

[rolexcomex]

has anyone tried just using a castle bec to regulate the voltage down to 10v or so before it hits the radio? i realize that it would have to be unplugged at the end of the day so it doesn't draw on the battery but i could handle that...


I am still using a 3s.. at 12.6v no step down... no problems

The "12x cant handle 12.6v" might be an urban myth.. probably started by the manufacturer to keep you buying their crappy "8hr 2000mah" batts... We know that is also an urban myth..

[QYT001]

I wonder that noone made the Step-down Voltage Regulator for LiPo battery yet.:dontknow

[QYT001]

There is a nice Webench Power Designer tool at the National Semiconductor web site, www.national.com (http://www.national.com/), that can be very useful at determining switching regulator devices as well as supporting components.

[nairbg]

See Post #6

http://www.rcgroups.com/forums/showthread.php?t=1281844&highlight=dx7+lipo

[rolexcomex]

more long term follow up...

...over 12 months.. using the setup above and the same lipo battery... NO ISSUES..

[nairbg]

I don't believe that using a 3S lipo will cause any problem with this radio in that JR uses the LM2937-3.3 linear voltage regulator which is the part responsible for feeding power to the rest of the Tx. Here are the specs for that voltage regulator. Note in particular the input voltage limit. As 3S lipo isn't even 1/2 way there.


Paramaters / Values LM2937-3.3

Output Current.........500, 400 mA
Output Min................3.3 Volt
Input Min Voltage.....4.75 Volt
Input Max Voltage....26 Volt
Adjustable Output....No
Quiescent Current....2 mA
On/Off Pin................No
PowerGood / Error Flag....No
RegType...................LDO
Temperature Min.......-40 deg C
Temperature Max......125, 85 deg C
Output Max................3.3 Volt
Output Voltage.........3.3 Volt

[khymlawrence]

i have a JR xg7 with DMSS.. im using 3s lipo without any diode,straight 12.6v on it.. i opened my tx and check the voltage thats going into the rf board, its 3.14 and is regulated separatedly.. from switch, its 12.5v and regulated on the second board and when it goes up to my rf its 3.14v more or less. turned on for 30mins and nothing on the parts of the board goes hot.. so i think nothing will happen if you use lipo.. but you should take the risk for the advantage the lipo will give..

http://i1184.photobucket.com/albums/z336/Lawrenceanthony_Caluza/IMAG0240.jpg

http://i1184.photobucket.com/albums/z336/Lawrenceanthony_Caluza/IMAG0241.jpg

i just dont know with other jr if the inside looks the same..

[Valkyrie_1520]

I've been using a 3S Lipo in my 12X for over 2 years now. No issues what so ever. I pulled the original battery pack and removed the battery connector with the charge port. I then soldered a JST connector to positive and negative terminals to connect the Lipo for easy removal for charging. The battery connector already has a diode so nothing else is needed. My display voltage with a fully charged Lipo is 12.6V. I typically get about 3 days flying on 1 charge. I'm currently running a 2500mah Lipo but want to upgrade to a larger if I can find one to fit in the battery compartment.

Here's the link:

http://www.helifreak.com/showthread.php?t=157656