…thinking about…

…getting battery power hooked up to my Yaesu FT-7800R.

Right now, I have the 2M/70cm radio for my Jeep, but it is not installed. However, I’ve been eye-balling the new FTM-10R. That would be absolutely perfect for my Jeep. But, what to do with my 7800? How about putting it on my bike?

I can get a carry case made, like a saddlebag, that holds the radio on one side, and the battery on the other, is weather-proof, and easily removable and be able to mount it on the front rack. Or, I could rig it up on the rear rack in the trunk bag. Either way, the faceplate will go on the handlebar stem, and the antenna will be mounted to the rear rack.

Of course, none of this does any good without battery power.

Looking at the 7800, it has 4 power settings from 40/50 Watts down to 5 Watts. Any operation while bicycle mobile will need to be 5W to keep the battery size manageable.

The 7800 specs show a Tx current draw of 8 Amps at 13.8V (and max power of 50W). Since power is current(I) * voltage(V), 13.8 * 8 = 110.4W. And with an advertised power of 50W, this gives us about a 50% efficiency. That’s not too bad, and probably better than actual (they are advertising, after all).

So, at 5W and 50% efficiency (10W) and running 12.6V, I’d have a 0.8A current draw for transmitting.
(5W*2)/12.6V = 0.8A

Since another site uses a 33% efficiency thumbrule (which would give me a 1.2A current draw), let’s round it off to a compromising 1.0A.

Now, a 1Ah battery will give 1A for 1h. Active use of the radio for a 6 hour period would be an estimated total transmitting time of 2-3 hours (and that’s a lot of talking). So, I need a battery that will give me 1A for 3 hours, or a 3Ah battery.

Now, to start looking…

powerstream battery pack

This one looks promising! And they built it in a water bottle!
battery space

Well, any thoughts…?

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