At times get some great information through my email. It feels so compelling that I have to pass it on because I feel the information so valuable, not only to me but to others traveling this path. Thanks Joe / N5USR.
In BMHA@yahoogroups.com, "Joe Martine, N5USR" <n5usr@...> replied to Andy KF4SWS
How does the Battery hold up when the FT857 requires 22A to operate (I think that's right)... I have a Catrike recumbent tadpole trike, so the weight of a battery pack is not that important. So what kinda battery pack would allow best performance and for how long. Do you use a solar charger? I understand the ATAS120 works 2-160M does that mean you plug into both antenna ports on the back of the FT857? Do you use Twitter? See my Blog ajelliottjr.blogspot.com you may email directly if you will. Thanks. Andy KF4SWS
I've never tried full power on the little battery, 20W is about as far as I go. The rig doesn't quite get to 22A, mine pulls 18.5A on 6 meters at 100W FM. At 20W, in FM mode it pulls about 9A. Running on SSB, the average draw will be significantly lower.
The best size of battery is mostly dependent on how long you want to operate. I'm not a big talker, especially when pedaling, so the receive current predominantly sets my runtime. At 600mA or so, I'll pull the 12AH battery down to 50% discharge (the lowest I want to take a lead-acid) in 10 hours. At 20W FM the rig pulls 9A, so absolute worst-case is maybe 15-20 minutes of transmit time. Since SSB is usually around 30% of that number on average, I can probably get close to an hour of TX time.
That assumes the battery can handle the current draw and keep the voltage from dropping too much. I've found the 857 isn't too happy with low voltage!
If I wanted to be able to run 100W, I'd want something considerably larger, so it could handle the current spikes. I have a 100AH AGM that's about the same dimensions as a car battery. It would be okay, but it is VERY heavy! Runtime to 50% DOD with it would be on the order of 83 hours (!!!) receive-only, and a bit over 2.5 hours continuous TX time at 100% duty cycle. On SSB, maybe 4-5 hours TX time. Not too bad, if you can carry the weight!
The ATAS is only good for 40M thru 6M, and "works - sorta" on VHF/UHF. I'm not at all impressed with the V/UHF performance, but it's better than nothing. If I take the 857 with me, I generally just plan on being on HF (my normal "bike radio" is an FTM-10R) but I do have the diplexer to combine the antenna ports if I want. I also have a 6M/2M/440 tri-band vertical that I can use if I want better V/UHF and have 6 meters as well.
I do use solar, but I don't carry panels with me. I have two arrays on the house. I recharge my smaller AGMs with a set of Harbor Freight panels (have a nicer charge controller than the one they provide though) and have 540W in panels connected to a 660AH battery bank that runs my ham shack. If needed, I can charge other batteries off that system as well.
So far I haven't planned for any really long rides, when I go on those I am usually with a group so the radio doesn't go along. When I'm by myself and taking the ham rig it's usually just a shorter ride of at most a couple of hours or so.
Joe / N5USR