Hello,
I recently purchased a Cermark Extra 260 EP55 with the suggested power pack which included a neodym .25 outrunner and a castle Thunderbird 54. They want a 3S 4000-4400 LIPO for this, and as all my other planes take 3S 2200's I bought the Castle parallel deans cable that runs 2 3S 2200mah batteries in parallel for combined 4400 3S. I am using Sky Lipo 40C packs for this. The first time I ran it up, it seemed to work fine on the bench, and the maiden went well though it was a pretty light and short maiden. The next time I went to the the field I opened it up a bit more and had it in WOT for longer, and after maybe a minute and a half in the air it went dead stick. Fortunately I brought it in fine and once on the ground I found the throttle to be working again. I got the castle link module and upgraded the firmware on the ESC (it was at like 1.5 so I upgraded it to the very latest). Now when I run the motor up once I get to over 1/2 throttle the motor makes a horrible squealing sound and loses power. I'll have to double check but I almost feel like the ESC is detecting the 2 packs as 4S instead of 3S, has anyone seen that? Otherwise I'm at a loss as to what the problem might be, any ideas?

Tom

Quick update, it's definitely NOT seeing them as 4S, and it happens even with 1 of the batteries direct. I'm really confused here, as the only changes I made were updating the ESC firmware to latest and putting a slightly larger prop on it. Basically it spools up to about 55% or so and then the motor starts making a really horrible high pitched squealing sound and loses power. Love to hear some input here as I'm at a loss and I don't see much to adjust on this ESC. Others I'd try changing the timing, but for some reason on these castle thunderbirds you can't? Help!?

Tom