Philip shares battery sizing calculator spreadsheet and POTA radio survey results

Many thanks to Philip (KA4KOE) who shares the following two notes:

Battery sizing calculator

I developed the following spreadsheet as a response to all the folks asking “what size battery should I get“?

That’s one of those questions one can’t answer accurately without more information, so I created a spreadsheet.

Click here to download the spreadsheet (Rev 1 updated Feb 1, 23).

Popular POTA radios

I also recently ran a poll on the Facebook POTA group asking what radio they primarily used for POTA. The sample size was 1,148 votes.

Here are the rankings by percentages:

1. Yaesu FT-891: 25%
2. Xiegu G90: 9%
3. Icom IC-7300 and IC-705: 7%
4. Yaesu FT-857D, FT-991A, FT-817/818: 4%
5. Xiegu 6100, Yaesu FT-897D, Elecraft K/KX series: 3%

I cut off the poll at below 3% as there were 60 entries for various radios.

I’m not really surprised by the top 3 rankings.

13 thoughts on “Philip shares battery sizing calculator spreadsheet and POTA radio survey results”

  1. Thanks Philip! I’d be interested to see a broader equipment survey. Perhaps, including Antennas, Coax, Batteries, Keys, Speakers/Earbuds, Logging Software and Mechanical Pencils (Thomas ?).

    de W7UDT

  2. Philip, your Facebook survey pretty much confirms what I’ve been telling others these past few years (thankfully, I should say, it confirms!): The FT-891 and G90 are the two most popular radios for POTA. According to your poll, over one third of the respondents use one of those two radios–pretty darn amazing!

    It’s also a reminder to me that I live in a wee bit of a QRP bubble. I sometimes assume that other activators are also QRP, but I realize that we low-power ops are likely in the minority at least in POTA. I think we’re in the majority with SOTA where weight and size are so critical.

    Fascinating stuff! Thanks!
    Thomas (K4SWL)

  3. This is a great spreadsheet Thomas, thanks for passing it on from KA4KOE. I’ll have to take some current measurements on my Penntek TR-35 for use as a comparison. Depending on your VSWR, transmit currents can vary considerably. I noticed this while doing some tests at the RV Park using a dummy load at the picnic table. The received QRN made operating worthless. While out in the field trying a half-dozen resonate and none resonate antennas I noticed every antenna load naturally had a different transmit current depending on that perfect match, without regard to actually how efficient an antenna was at converting my QRP amps to a radiated signal.

    For the summer I am centered in the San Isabel USNF for my work, so this year I have promised myself to have actual days off. So in addition to working more on building my Two Tinned Tunas ][+ station of QRPp tx/rx & station accessories, I want to pick some epic peaceful spots for POTA hunting & eventual activations. If I can get into enough of a daily routine, I will be able to bring my TR-35 for a lunch activation also. What more fun to have after delivering a load of firewood or after several hours of weed-eating? Last year I had a mountain lion trance past me in one of the remote campgrounds, she was on a mission so may not have even noticed me … but I did her, LOL.

    Anyway, spreadsheets like this keep us engaged and help to calibrate who we are so we feel like one connected world when we sit down at the picnic table to operate POTA/SOTA.

    Cheers, Davey – KU9L

  4. Very cool battery calculator spreadsheet. Something that I’ve pondered…but not studied…is the behavioral component: empirical observations on actual (vs anticipated) transmit time per hour. I’ve thought about collecting data via a data logger during my portable ops team events but the prep always seems to push that back.

    We guess about this percent TX time. But it likely varies by transmit mode, too.

    Thanks for posting the spreadsheet!

  5. I was surprised by the percentage rankings of radios used for POTA as some are quite large radios. Was the results from Activators, Chasers, or a mixture of both?

  6. No distinction was made on whether the op was a hunter or activator.

    I may run another poll for portable antennas in the future. I think the folks on the POTA FB group may be tiring of me due to my many posts….and I will not get into a battery brand poll. That subject is almost as contentious as the old Ford vs. Chevy debate.

  7. Thank you for posting this! I found this very helpful to calculate the correct size battery (LiFePO4 battery) I will need to purchase for my POTA FT8/FT4 Activations when I use my 7300 as the transceiver. I have been using a Xiegu X6100 at 5 watts with a small 12vDC cooling fan for my FT8 POTA activations using a 10Ah LiFePo4 battery. I found with that battery and radio I could do 3 to 4 park activations on one charge per day. 73 es TU, Jeff K9JP

  8. It seems like every other day someone asks this question on the FB POTA group. I have bookmarked this page and now cut and paste it as needed. There is a LOT of disinformation out there. I believe I took a reasoned approach to this. I could tweak this spreadsheet even more but I think it is “good ’nuff”.

  9. If anyone notices any errors, I would welcome your feedback! This spreadsheet is open to revision if needed.

  10. Thanks for the great work on the spreadsheet. I think I did find one minor error in the sheet. B25 text “Ampere Draw Per Hour” isn’t amps/hr but “total amps needed”.

  11. 16 January 24: I have a revision to the calculator. You cannot size a battery smaller than the 1C charge rate vs. the radio maximum current drain. For example, if your radio draws a maximum of 10 amps in transmit, then the minimum battery size is 10 AH. This assumes a specified maximum charge rate of 1C. If the manufacturer states 0.5C, then your battery size in this example would be 20 AH. Personally, I’d get a different battery if faced with this option.

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