FT817 external batteries; what is your latest recommendation?

kb3guz 2017-05-09 17:01:28 UTC #21

One online source says the current capacity for an EC5 is “capable of more than 120A continuous current with 10-awg wire.” I don’t know what the manufacturer says. I’ve drawn more than 50A through an EC5 flying drones with no problem. The cross sectional area of the connector appears to be as much as a 10awg wire. In any case, I don’t plan to draw more than 20A through them for ham radio.

I assume there is some RF noise (haven’t checked), but only during charging. The charging circuit isn’t used when discharging from the 12v port.

WA7JTM 2017-05-09 19:59:50 UTC #22

I have an 18000 ma hour version of one these and it will start your car (this one is rated at 450 amps for a short period of time). Not sure what they are doing inside the box to get that current, but they appear to charge “something” up.

They can be used for other things as they have multiple outlets for 5 volts, 13.8 volts, etc. It comes with AWG #4 very short jumper cables.

They deliver extremely high currents for a short period of time, and they do work. I have not actually used it for the radio yet, but others have. We have started cars with them.

Pete
WA7JTM

G4OIG 2017-05-09 22:22:59 UTC #23

I experienced connection problems with the battery boxes I use to house the NiMH cells that boost my LiPOs to provide 13.8v. The boxes are fine for low current applications, but can exhibit connection issues at higher currents. The solution was to modify them by using thin brass sheet normally used for modelling to create a larger contact pad for the button end of the cells to make contact with. Mine are only single cell boxes, so it was an easy mod. Multiple cell boxes will require some thought.

S52FT 2017-05-10 05:29:06 UTC #24

http://www.ka7oei.com/ft817_roar.html

73’s

kn4bbc 2017-05-10 15:01:08 UTC #25

I used 2 Zippy 3S lipo batteries 1 2.2Ah and 1 3.0Ah. I used a Turnigy Accucell-6 to change them

Battery

Charger