Dualsky 2500 mAh Transmitter Pack With Built-In Cell Balancer Review - RC Groups
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Dualsky 2500 mAh Transmitter Pack With Built-In Cell Balancer Review

Advertised as "the pack that will allow you to fly all month," Dr. Dave finds that this LiPo actually lives up to the hype!



I know this has happened to you: You get home and realize the weather is perfect for a quick flight. You grab up your gear and head to the flying field only to find out that your transmitter battery is weak. Even worse, you planned a full day of flying over the weekend at the club. You think you charged up your transmitter few weeks back and hardly used it, but without use, NiMH and NiCd batters lose their charge over time. Should you fly with a low battery? You decide no, no flying for you that day.

I must say I was skeptical; my beloved Hitec Optic 6 that has been stalwart throughout the last few years of flying, and I wanted to be sure putting the LiPo inside my transmitter would not damage it in any way. I did a quick test of Dualsky’s new transmitter battery distributed by 2DogRC, and after a few hours, I realized that this product is the real deal! No longer will I be caught with a weak battery!

Transmitter:Optic HiTec with Spectra Synthesizer
Transmitter Battery:Dualsky 2500 MAh LiPo
Available From:2DogRC

The Test

I really felt the only way to test the battery was to compare it to my original 600 mAh battery, a 2000 mAh I purchased and the 2500 mAh Dualsky LiPo. Because I use a Spectra module I knew there was draw on the transmitter as evidenced by the heat that builds up when the transmitter is operating. I started with the NiCD. The criteria for stopping the test was the 8.7 volt low battery alarm.

Spec Weight Size Starting voltage Duration
600 mAh NiCd
600 mAh NiCd
6.3 oz. (179g) 10mm x 2.8mm x 2.8mm 11.6 Volts 1 hours 54 Minutes
2000 mAh NiMH
2000 mAh NiMH
8.2 oz. (233g)11mm x 2.8mm x 2.8mm 11.3 Volts 4 hours 22 Minutes
2500 Dualsky LiPo
2500 Dualsky LiPo
5.1 oz. (144g)9.7mm x 2.4mm x 2.8mm12.4 Volts 9 hours

The Results

The Dualsky 2500 mAh battery wins out with nearly twice the hours of useable service, a lasting charge and lighter weight. I was really impressed that as the battery was winding down, it went literally hours before it reached the available power I had at startup with my two previous batteries.


One thing you have to be sure of is that you no longer try to charge the battery in the case, it has to be removed. More importantly, NEVER plug in your old charger while the LiPo is in the case.

You will likely also have to develop some type of male plug for charging. I took a standard JST plug and removed some of the plastic to expose the prongs. Just really be careful you do not get polarity off when you plug it in for charging. I have found this works well, and I use it to charge all my batteries with a non-typical plug.

You can see there are three different female plugs that I have used. All fit into the male receptacle of my Hitec Optec 6.


The question here is not why, but why not? If you are like me, you want to make sure your plane is set up perfectly before the first flight. With Dualsky's 11.1 volt transmitter LiPo you can take all the time you need. After two hours of leaving the transmitter on, I still was above 11 volts! I now have a transmitter that does not feel like a brick in my hand. By making the switch I have shaved off over three ounces! As transmitter packs get bigger they seem to grow slightly while the space in your transmitter stays the same, but the Dualsky LiPo fits with room to spare.

I can't say enough good things about the Dualsky 11.1 transmitter battery. You save weight, gain time, get cell balanced circuitry that also protects overcharging, and with all of that, you get the security of knowing you have plenty of flight time. I love it you get something that lives up adverting hype. 2DogRC and Dualsky have a winner here.

As with all electronic additions, make sure you check your warranty and follow all the directions provided.

Last edited by Angela H; Oct 29, 2007 at 09:29 PM..
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Nov 04, 2007, 12:49 PM
iumop ap!sdn w,I
G.P.'s Avatar
Nice review. I've been using one of these all summer and it has been working great. I'm not sure about other transmitters, but on my 9C I can just charge through the normal charge jack without removing the battery. I know, I know. I've heard of problems with all types of batteries though, so I see it as a risk no matter what type of battery is in there. The best part is that I don't have to wait until the battery is dead to charge my T'x anymore. I can come home and charge it up for whenever the weather turns good. -Greg
Latest blog entry: R.I.P. (rest in pieces)
Nov 04, 2007, 01:58 PM
Registered User


Just to chime in... I have one of these as well and flew with it all this past summer with no problems whatsoever. I have a 9303 and I charge it in my transmitter as well with no problems. Good luck.
Nov 04, 2007, 03:06 PM
Trons and Fumes
wrightme's Avatar
FWIW, it is probably OK to charge it in the TX, IF you use a LiPo charge source. You do not want to leave a LiPo on "trickle" accidentally.
Nov 04, 2007, 03:15 PM
MaxAmps CMO
JAM's Avatar
No same rules apply to a Li-Po in a TX as a plane..........Remove from either to charge.

MaxAmps Marketing Manager
Nov 04, 2007, 03:31 PM
Registered User
Will this battery work in a Spektrum DX-6?

Nov 04, 2007, 05:19 PM
Dr. Dave
Davem452, check he 2dogrc or dualsky website. Seems to me there is an issue with the failsafe.
Nov 04, 2007, 05:52 PM
We shall serve the Lord
kingsflyer's Avatar
Been using one in my 9C for over a year and I LOVE IT!!! I can get over 7 hours of actual air flight time before I need to charge it. I doesn't even lose 1/10 of a volt from one week to the next. I just put one in my 9C that I just upgraded to Spektrum 2.4.
Mike McD
Last edited by kingsflyer; Nov 04, 2007 at 08:36 PM.
Nov 04, 2007, 09:28 PM
Registered User
efinkg's Avatar
I'm using a True RC lipo transmitter battery in my Optic 6, I love it too.
Nov 04, 2007, 10:04 PM
Registered User
I'm using a True Rc 2500mAh Lipo in my Spectrum 7 and it is great. It has a smaller form factor than the Dualsky or the Commonsence Tx Lipo and I can charge/balance the battery using my FMA balancing Cellpro charger.

I was going to buy the Dualsky but the battery cannot be charged using my FMA Cellpro charger because it doesn't have separate balance/charging leads.

Because the battery only has two wire charge leads, you can't use any external balancer like the Astroflight "Blinky" to check/balance the voltage on each cell.

Last edited by no stick; Nov 06, 2007 at 08:35 AM.
Nov 04, 2007, 10:33 PM
Flazo's Avatar
This review is SO! Late, I have been flying with this Lipo on my 9C Futaba since April....and bought it at


this lipo transmitter battery from DualSky is Way better than RCommonsense.
Nov 04, 2007, 10:35 PM
No Guts, No Glory
flyin C's Avatar
I hate getting only 45min of flight time on my JR XP6102. I really need to upgrade, looks nice.
Ill keep my eye out for a used one on sale.
Nov 05, 2007, 12:11 AM
Too little play time...
WarrrEagle!'s Avatar
Great review on a must-have item for the frequent (or infrequent) flyer!

I bought the 1800mAH version for my Futaba 9C about a year ago when 2Dog put them on sale. I can't recall how much I paid but it was not much. I consider it one of the best purchases I have made. I do wish I had the even larger capacity.

For charging I simply put a JST pair in between the batt and tx plug. I just leave the tx plug in and disconnect the jst for charging. One less charge lead to worry about...

My two brothers bought the reviewed pack from Grayson at SEFF this year and have been amazed at how infrequently they charge their tx packs. They too put a JST pair in-line.
Last edited by WarrrEagle!; Nov 05, 2007 at 01:32 AM.
Nov 05, 2007, 12:19 AM
Test your skills....fly IMAC!!
sun.flyer's Avatar
Nice review Dave, I'll have to look into getting one of these.

Nov 05, 2007, 02:19 AM
Registered User
I also have a Tx lipo pack for my DX 7, but i always charge it with the balance plug. It seems that many of you are charging the Tx lipo with two leads plus or JST, how do you guys do that? Does that mean you don't need to balance charge the pack thru balance plugs(and balance charger)? Please advice guys. Thanks

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