I’m going to do a long mountain hike this summer, which will consist of 10 different summits. I’m going to bring with me my ft-891 and mainly be running quick activations with limited power, probably not more than 20w unless the conditions requires more power to accomplish 4qsos. Today I operate with a 12ah lifepo4 battery. How much power do I need on my hike? Should I buy another battery to have maybe 24ah in total or a solar panel?
Pros for solar panel is that it can be attached to my backpack and it will produce some power during the hike. When I’m stationary I can adjust the panel to have right angle for top performance. A solar at 30-40w will be around 1kg/2lbs, which is slight lighter than battery.
I have some notes on the FT-891 where OH8STN measured current draw at various power outputs. He had 20W transmit drawing 8.3A. Receive current was 1A. It was probably a YouTube video from some years back if you care to look for it.
You can estimate how much transmit/listen time you’ll need for the activations and work out the Ah needed.
Relatively power hungry rig compared to some of the qrp type radios.
Depend upon how much on air time for each activation, If you get 4 quick QSO on each summit and not much calling or receiving time spent on each band you might get enough from 1 charge of your battery. Maybe once you establish enough chasers trying to work you cut your power to 5 or 10 watts it will be just as effective. Having your best antenna is probably more important not some tuned up “Wonder Whip”. Alert you intentions on SW3 and the chasers will try to work you I am sure.
My 20W solar panel is 36x54 cm. Maybe it is to big for hiking. On good sunny day it gives maximum od 1,2A. I am on 175m ASL. If you go higher (you would ) maximum current increases
It may not be possible, but my suggestion would be to consider a different rig… maybe on loan from a friend? The 891 is similar to its predecessor the 857 in that it has relatively high current draw on both transmit and receive, being a mobile transceiver where the power requirement is not an issue. For that very reason I changed from an 857 to an 817 plus linear amp. Less convenient, but less battery capacity required.
Earlier this year I did a multi-day hike in a remote part of the southern US. On several SOTA summits there was no cell coverage. I think you may face a similar situation.
Make sure you’re familiar with alerting and spotting options. In particular, check out the SOTAMAT app: https://sotamat.com It allows you to send spots via FT8 over HF. Getting spotted is key for a quick and successful activation.
Also, if your route includes nature parks, consider activating POTA as well. Sending a POTA alert can attract additional chasers.
You didn’t mention where you’re planning to hike. If it’s Norway, I wouldn’t bother with a solar panel—in my experience, you’d rather need a rain panel in Norway! As others have said, I’d go with a lighter, less power-hungry rig like an FT-817/818 or KX2—though it might be a bit late now to reorganize your setup.
I’ve participated in the Swiss NMD Contest—which lasts four hours—a few times using the FT-891. I use a 15 Ah LiFePo battery, which allowed me to operate at 100 watts SSB for the entire duration, calling CQ frequently with the voice keyer. After those 4 hours, the battery was almost empty each time. At 100 watts SSB, the average current draw is about 9 A while transmitting. I suspect that reducing the power to 20 watts will only lower the average current consumption while transmitting by about 30%.
My estimate is that you can make 10 activations with your battery if you make 4 QSOs per activation and don’t have to call CQ too much. A solar panel doesn’t provide enough power to justify the effort. With a spare battery, you’ll be on the safe side.
You can experiment with this online calculator to get a better estimate.
Based on the calculation and your rig expect about 3 hours operation time with a 12 Ah LiFePO4.
If you hike (without recharge option) 10 summits and you carry a FT-891 and 12 (or even 24 Ah) plus food, water (and overnight stuff ??) then you must be a hiking ham radio sherpa legend
Wondering which route in LA has summits lined up like that?
Looking at your QRZ page the FT-817 might be the better choice if you ask me. Here the 12 Ah are plenty for 10 activations.
I don’t think it’s the right radio at all and the Battery Runtime Calculator agrees.
If you are SSB only then having 20W from the 891 vs 5W from the 817 is about 1S point better. If you can use FT8 then you don’t need the power as a few watts will do fine. Likewise, 5W of CW would be fine.
If it was me, I wouldn’t be taking the 891 on a long walk.
I have practical experience, since I also use a FT-891 with a 12Ah battery for QRO activations.With 100W output, I ge3t around 3 hours constant operationg time. reducint the power to 20W increstes the time to 4 hours.
Not answering your question directly as I’ve no experience with the FT891.
I have, however, considerable experience of using only 5W as all my SOTA activations have used 5W or less. As has been suggested, probably less than an ‘S’ point difference between 20W and 5W. I’m sure that under marginal conditions, 20W will do better than 5W.
I used an FT-817 for the first 100 or so activations and have recently moved to a QMX. The disadvantage is that there’s no VHF/UHF on the QMX but I take a small 2m handheld.
Hi, Mark (AE1MS) and I use the FT891 for activations, and we are generally set on 35 to 40W. Our antenna is a Buddipole Buddistick. We always activate together and on SSB, so your proposed 10 activations would be approximately equivalent to 5 activations for us together. When we expect heavy battery usage, we carry a Bioenno 12Ah LiFePO4 battery and occasionally have run it pretty much continuously for 3-4 hours. We never have exhausted it, so I think you would be fine for 10 short activations at 20W.
For shorter activations, we carry a 6Ah LiFePO4 battery, which weighs 1 3/4 lb. Throwing one in your pack would provide a backup in case of a battery failure or exhausting your larger battery.
BTW, we carry a Garmin InReach Mini 2 just in case we can’t spot by normal means. It has saved our bacon more than once since we are often on remote summits with no cell or internet service.
I think the general feeling is that the efficiency often tracks with the power level - 100 Watt mobile rigs use a lot of current during RX and waste lots of current at low TX power settings. So really you need to run a mobile rig at a higher power level - it’s more efficient that way, or run a QRP rig. Running a 100w rig at 20 watts is very inefficient. This is why a lot of SOTA activators run a QRP rig or QRP rig with amplifier.
As mentioned above, that type of radio draws 0.7–1.0 A. If you’re operating CW, I don’t expect the average current consumption to increase significantly, while in SSB the average current draw will definitely be higher. In my opinion, most of the QSOs you could make with 20 watts could also be made with just 5 watts, this generally applies from 60 meters and up. The 80 m and 160 m bands tend to be noisier.
You’re better off using a well-installed wire antenna and running low power.
In addition to the above, check propagation and activity. They may be even more important than the radiated power. If you have got the time, try your setup locally, there may be a summit or another interesting /p QTH nearby.
) maximum current increases
??) then you must be a hiking ham radio sherpa legend 