LiFePO4 Battery for JR 11X / 9503

The NiMH battery that comes with the JR 11X works fairly well, but if you want more time between charges and faster recharge options a LiFePO4 battery is a very good choice. This is also a good fit for other TX’s with 8 NiMH battery packs.

Horizon Hobby specifically advises against using a LiPO because it would carry a fully charged value of 12.6V which they warn could damage the electronics of the 11X.

However a LiFePO4 is a perfect match, and it doesn’t have any of the negatives associated with LiPO. The following combination works very well.


Hyperion did a nice job with this TX battery.

  1. The battery fits perfectly in the 11X without the foam spacer.
  2. You can use the Wall Wart ( included charger ) plugged into the transmitter because it has internal protection hardware.
  3. It can be charged at up to 4.8A, which is great if your TX is low and you have a long day of flying planned.
  4. LiFePO4’s are fine being stored at full charge unlike LiPOs
  5. LiFePO4’s don’t have fire or explosion issues like LiPO’s do.
  6. Advertised as having a 400 + charge lifespan.
  7. Tour TX will have a much more consistent Voltage than it typically gets.

Hey this voltage doesn’t look right!  ( but it is )

LiFePO4 is very different in how it works as it maintains a VERY consistent voltage over the majority of it’s charge. When this battery is called a 3.3V cell battery they are not kidding, it spends most of its useful operation between 3.3333V and 3.2V with a steep curve above and below this point.

Using my PowerLab 8 V2, I charged this as an A123 type battery. 3.65V per cell or 10.950V overall.  They suggest a maximum of 4.8A to charge this battery, so it can be topped off very quickly.

Just don’t be alarmed when you put it in your transmitter and it very quickly drops in voltage from 10.8V to 10.0V over the course of about 20 minutes. This is normal. 


It will sit at 10.0V for about  5 hours of TX use before dropping to 9.9V and then it will sit there for quite some time. So the voltage looks a bit lower than usual, but don’t let that alarm you.


This graph shows a 2.25A discharge curve starting AFTER exactly 5 hours of TX use.  It took another 1001mah discharge to get the battery from 9.9V to 9.3V or 3.1V per cell.


Here is a 3.5A charge after the discharge above.  So 1852mah – 1001mah = 851mah or how much storage is used in 5 hours. 

851/5 =  170.2mah per TX hour of use.



The other interesting point is that while it is safe to discharge this battery to 2.5V it pretty much drops like a rock a bit past 3.1V per cell, hence my battery Alarm set below.



11 Responses to “LiFePO4 Battery for JR 11X / 9503”

  1. 1 raj November 12, 2012 at 6:10 pm

    Hi there,
    can i use a 2s 1450 lifepo4 hyperion receiver pack in the DSX 11 transmitter at all please? the XG11 uses a 1400 2s lifepo4 pack as std and this makes it light weight compared to the DSX11/11X by at least 100 grams. the battery you specified is 155 grams (only 50 grams lower than the std nimh battery that comes with the tx.

    • 2 raj November 12, 2012 at 6:13 pm

      my plan is to use a jr banana plug and charge the lifepo4 receiver pack inside the transmitter using a pro peak charger under lifepo4 mode.

    • 3 mkovalcson November 12, 2012 at 6:31 pm

      I have never looked at that transmitter or battery.

    • 4 mkovalcson December 16, 2012 at 5:55 pm

      GABA, the Hyperion I listed is supposed to allow charging from the TX charger. The Nanotech may not have a protection circuit. I always charge mine using my PowerLab 8 V2 because it is much faster and balances the 3 cells.

      • 5 GABA December 16, 2012 at 6:20 pm

        So you take it out every time to charge?
        I was hoping not to have to take the battery out so I wouldn’t open the battery door again and again. Lol now the battery door is barely holding after the incident.. Is there a mention of the protection circuit on the battery or manufacturer page somewhere? I thought the charger or the Tx would have a protection circuit..

        Also .. Any ideas where I can find a replacement battery door for my x9503? 🙂

  2. 6 raj November 12, 2012 at 6:38 pm

    can i use a 2s lifepo4 in this one? may be not as voltage requirement is 9.6 volts I guess!

  3. 7 GABA December 16, 2012 at 1:02 am

    Hello sir

    Ok , so I bought a nanotech 2100 LiFePo4 battery from HK. I have used this brand so I wasn’t expecting this .. But today I go to check my charging Tx, and the battery is swelled up and has broken a battery door hatch and peaking out. How is that possible? Any explanations?

    It’s a dsmx 9503

  4. 8 mkovalcson December 16, 2012 at 6:24 pm

    I would contact Horison Hobby for a battery door. They handle all the warranty work for JR in the US, and yes I prefer to charge with my PowerLab 8 V2 because I trust it to charge the battery well and I can charge it in less than 20 minutes.

  5. 9 Raj December 16, 2012 at 7:39 pm

    We have had few incidents here in UK where the models were lost/ crashed due to the usage of lipo batteries in the transmitters. The problem with the usage of life and lipo is the slump in the power/signal ones the bettery is discharged and the residual charge left in the battery is not enough to land the model! Unlike the lipo/life with the NIMH the residual power left in the pack once the alarm goes off is enough to save the model. So unless you regularly charge the transmitter there is always a risk.

    • 10 mkovalcson December 16, 2012 at 7:53 pm

      I charge as soon as my JR 11X reads 9.8V. It normally reads 10.0-9.9 with LiFePO4’s. It will fall off fast from 9.8. I’ve had it drop from 9.8 to 9.6 very quickly so I charge it as soon as it reads 9.8 now. My new Jeti DS-16 that is on the way comes with a 3200mah LiPO and keeps track of the mah used, so it should be able to give me plenty of warning.

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