FT-891 on Battery Power

I carry my FT-891 in a backpack as a hike to mountain tops for SOTA (Summits On The Air). SOTA is an enjoyable extension of the amateur radio hobby.
When you’re carrying a backpack with radio, antenna, battery, rope, a throw bag, a portable antenna mast, food, water, rain gear, emergency supplies, etc., ounces turn into pounds. So, we SOTA enthusiasts find ways to lighten our load every chance we get. That’s why so many SOTA operators, called Activators, use lightweight rigs that weigh a couple of pounds or less, or even QRP CW radios that weigh 8 ounces or less.
But I like the receiver in my FT-891, and I like having 100W of power available if needed. Plus, the FT-891 is much less expensive than some of the QRP radios.
In this video I test the power consumption of the radio on TX and RX for both SSB and CW, as I power it from a LiPo battery. The LiPo battery weighs less than the 3aH Bioenno battery I’ve been using, and it’s less bulky. The voltage is less so I wanted to see how it affects power out. I was getting my normal power output when the LiPo was near a full charge, at 12.28 VDC. It dropped by 4 watts as the battery neared 11.2 VDC. But it can still produce plenty of power for a SOTA activation.
I have been running a LiFePo4 3aH with the radio set to 45W. It draws a bit over 10A on TX. That provided enough power for 50 contacts. The only reason I was looking into the power consumption at lower power levels was to see if I could squeeze more contacts out of a 3aH battery. It seems that I can, if I run 20-25W but it’s not double the number of contacts. The radio is less efficient at 20-25W, but it does extend the battery life somewhat, contrary to earlier reports I saw before I purchased the FT-891. They said, anything below 48W doesn’t extend the battery life. This video just proves their information to be inaccurate. So, lowering to 20-25W will save the battery but not as much as a 50% savings over running 45W.
So, if I know I’m going to do a quick activation, I will run 45W and go for signal strength. If I do a long activation, I will run 20-25W and go for more contacts.
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73, de N4HNH