[Thunder Chicken]

Hi guys, thanks for all the tips and advice. So the batteries have been cycled several times, under load, as per the instructions that came with them.....(helps to read the instructions!)
Now, as to some trouble i was having.....the ESC does not detect odd number of cells it seems. So.....running 9s, the LVP was kicking in almost right away, cause the ESC thinks there is a 10s hooked up. No way to change this it seems, even with the programming card. I got what I paid for. However if I disable the LVP, I can run fine.

Now, to go over the set-up again.....
50-65-275kv motor
15" 4 blade prop, set to 9" pitch.
9s, 5000mah 35c batteries.
This morning, the test run gave me this:
37.5v no load.
after a bit of running, it averaged out to about:
34-31v under load,
54A, 1600-1700watts.
After a 6 minute run time at various throttle settings, mostly 1/2ish, 27 amps, under load voltage went down to about 3.42-3.45 v/cell. Once shut down and 5 minutes after running, they settled to about 3.68-3.72v/cell.
Now, to get 9s, I have a 4s pack, and a 3s and 2s in series with a homemade y harness.
It'll take me a while to charge the batts up to see how many mah go back in as I only have a 50watt charger (bigger one on order)
I think this set-up will fly a lot better than it did last year on 7s. It flew fine, but was not overpowered by any means. However, it is a 16 pound airplane!

Thanks again for all the info on electric set-up! It is both fun and frustrating trying to get all this right!!

[fixer]

I would expect some losses would occur in all the extra connections and wire involved with using 3 batteries in series to create 9S, as compared to using a 9S. Glad to hear you have it running Ok.