FT817 Battery Upgrade

With an overseas trip coming up, thought it was a good idea to upgrade the battery in the FT-817.  I have been using a very tidy solution for nearly 5 years now consisting of a Hobbyking 3 cell 2500 mAh pack.  This is still working well, although I like to use 18650 batteries if the gear is transported in an aircraft.   The end solution isn’t as tidy as the Lipo one, but works fine.

For this trip, I obtained some 3400 mAh protected Panasonic cells from Ebay.   These cells have an inbuilt circuit that limits the discharge current to 5 amp or so and also controls over discharge, a condition that can ruin the cells.  The cells worked out at about $10 each delivered.  The first thing I did was check the rated capacity.  On a 1 A discharge, the measured capacity was 3000 mAh, not bad, maybe a 0.5 A it would have come close to 3400 mAh.

Then the battery was fitted or should I say attempted to be fitted to the 3 cell carrier that I use in the FT-817.  The battery would not fit, it was too long by about 2mm (70mm long compared to 68mm).  This was sort of expected, as the protected cells have a small PCB at one end that is encapsulated with the battery.  Jaycar electronics have two 18650 cell holders, a single cell and a dual cell holder.  The single cell holder takes the longer battery, but not the dual cell unit.

The dual cell holder was dremel’d out (is there such a word?) around the positive end to remove some plastic that was jamming on the collar of the battery.  It fitted after this modification, so the single and dual holders were glued together with Polyurethane glue.  This resulted in a strong three cell carrier.

It all fits (sort of) in the FT-817.  The battery and holder are a couple of mm too high for the battery flap to go back on.  This is not a big deal as when the leather case is on, the batteries are covered.  I will have to come up with a better long term solution though. Yesterday the battery was used in an activation at Mt. Ritchie, and the volts held up well, with plenty of capacity remaining.


Cells Installed

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5 Responses to FT817 Battery Upgrade

  1. Paul Taylor says:

    There is such a word as dremel’d, and if there isn’t, there is now. Good luck and good DX on your trip!

  2. VK3XPT says:

    Hi Glenn,

    I hope all is well. I just came across this post so thought I would see how they are going? I’m still using the Hobbyking packs in my 817, and they have been fantastic, but I do like the idea of the 18650’s though. Two quick questions for you:

    1 – Are you not powering the 817 via the internal battery connection plug?

    2 – Have you considered just taking to the battery door with a heat gun to “make it fit”? You can buy new doors fairly cheap online.


    (FYI – I also need to catch up with you at some stage to ask about your NBS tilt over tower – I think I need one of those!)

    • vk3yy says:

      Hi Perrin,
      For the 18650s, I was connecting to the rear external DC power socket. Can’t remember why this was, possibly because I didn’t have another internal DC plug.
      Yes, it might be possible to reform the original battery door. Someone has posted a 3D printed design of an 18650 battery holder for the 817 on Thingiverse. Would be good to try it out. https://www.thingiverse.com/thing:2527434
      I haven’t used the 817 for ages now as the KX2 works better for SOTA with lower current consumption, higher power and lighter weight.
      Yeah, the NBS tilt tower was worked out well, easy to maintain your antennas.

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