What external battery do I pair with the Icom IC-705?

I typically pair my IC-705 with a 6 aH Bioenno LiFEPo battery pack (the blue battery between the transceiver and tuner above).

Many thanks for QRPer reader, Ron, who writes:

Dear Thomas, thank you for the great videos and information on POTA and QRP work. I’m very inspired.

Thomas, I received an Icom 705 recently and I was wondering about power. In your videos, is your battery 12 volts? This works okay? I wonder because of the 13.8 volt requirement in the manual.

Thank you for your time. I’ve already picked out a park that I will try to activate one day when I’m up to speed on POTA. 72 Ron

Thanks for your question, Ron. I’m very happy to hear you find the videos useful.

I almost exclusively use Bioenno LiFePo 12V batteries which actually output closer to 13-13.5 volts in use and can even briefly be a bit higher immediately after charging.

Most amateur radio transceivers (including the IC-705) typically have a bit of voltage flexibility and will operate a below 12 volts and tad higher than 13.8 volts. QRP radios especially. You’re wise, though to always check (the MTR-3B is a notable exception as it prefers a max of 12V).

In fact, I just checked the IC-705 specs and its voltage requirements are 13.8 V DC ±15% (12V – 15.87 volts). The IC-705 can actually run on much lower power because the Lithium Ion pack that is supplied with the IC-705 (BP-272) is only 7.4 VDC when charged.

I would suggest you check out a 4.5 or 6 aH LiFePo battery like this one at Bioenno. Either would have the capacity to carry you through a few hours of heavy use.

Of course, there are many, many more battery options out there, but I’m a fan of LiFePo batteries for their longevity, capacity, and stability.

Hope this helps!

7 thoughts on “What external battery do I pair with the Icom IC-705?”

  1. Can I connect the aforementioned batter directly to the radio or do I need to run it through something else first?

    1. Hi, Christopher,

      Since the power cord that accompanies the IC-705 has two in-line fuses, you can connect directly to the battery. I typically bring a small Powerpole distribution panel so I can connect other 12V devices if needed.


  2. Dead wrong.
    That radio will default back to 5w transmit if there is not enough power.
    It wants a 16v battery.

    1. Actually, Brad, the IC-705 wants 12 VDC +/- 15% to run a full 10 watts. 16 volts is *way* over the amount the IC-705 can handle and could very well damage it if overvoltage protection doesn’t kick in.

      All of the Bioenno packs I mention are 12 volts, so ideal for the IC-705 and most of the portable transceivers on the market today. The amp hour rating has everything to do with capacity and nothing to do with voltage.

      The IC-705 will also run on 7.4 V DC with the BP-272 battery pack, for example, but maximum output power is decreased to 5 watts.

      Please don’t try to feed your IC-705 16 volts. You might let the smoke out.


  3. Hi Thomas.
    As far as I know we can’t get Bioenno batteries in the UK. Do you use a dedicated Bioenno charger? I ask because I’ve spotted 6Ah Bioenno equivalent but it’s not clear how I would charge it.

    I really appreciate your brilliant site and the effort involved in putting it together.
    Thanks, Bern G8KVM

  4. Brad, have you used the IC-705 with a 16V battery? I would assume the HI Voltage warning would show on the starting screen?

  5. Hi folks. I am having a weird issue with my 705; after I finished charging the Bioenno 12V 6Ah battery (BLF1206A), when using the PO scale on the 705, it would switch rapidly between 5W and 10W on receive. This wasn’t the case a few days ago. Any ideas?

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