Transmitter Battery

The Iris transmitter is a FlySky ER9x and the manual does not say anything about batteries, voltage etc.

Currently I am using 8 AA energizer rechargeable batteries which when fully charged give me about 11.1 - 11.2 v total.

How low can I let the voltage go before needing to recharge the batteries?  Is 10.5 v a good cutoff?

Also, can you use other batteries such as a LifePo4 like this one

What do other people use in the transmitter for batteries?


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  • I had a Parkzone LiPo from flying other models, cut the end and added an EC-3. Tight, but fits fine.



  • I highly recommend using a LiFe battery over a Lipo. We used to sell these along with an adapter for the 9x radio, but no longer. I still fly with this battery though, and have for several years. The LiFe voltage is lower than a Lipo which brings it a little closer to the radio's operating voltage. This allows for a little less energy wasted to heat and a little less strain on the components. Also LiFe batteries have a flatter discharge curve, are not prone to self-disharge like LiPo's. That said, lots of people use Lipos. It's not a bad idea, just LiFe batteries are a better idea, IMHO. :)

    • Well, I would not use a Standard LiPO as well. The Turnigy LiCo Tx battery I proposed, behaves a bit different, drops pretty quick below 12V and does come with a very low self discharge.

      And the 9x Voltage regulator (1A type) sure does not get strained, since the current is only app 120-140mA (including backlight which I´d strongly recommend as well)

      But I know, that the LiFe pack works great as well. Its more or less a matter of taste.

      Btw: I recommended this as well, but the former IRIS charger did not have a LiFe setting:

      Some might prefer to use a 3s LiFePO4 bat instead, because of lower voltage and better behavior at low temperatures, but this battery chemistry requires another charger, offering LiFe settings. PS: The recent charger, supplied with the IRIS (see Update 5), offers a LiFe setting as well. Don´t forget to switch it back when done.

    • Good to know about this battery as well. I wasn't familiar with "LiCo" formulas. Thanks for sharing the details.

  • Just take the cheap Turnigy transmitter pack, no soldering required...lasts a lot longer and can be charged by the IRIS charger (at least one app for this slow motion item)

    Looks like this:


    More pics and description here:

    • Thanks gervais.  That's the information I needed.

  • I bought that pack for the Iris Radio and this banana plug adapter [ ]

    My AA haven't died yet though so waiting for those to go kaput before charging up the new pack.

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