Guys,

I have a AXI 2820-8 that I had run on a A123 3S2P pack. Since then I move to the AXI 2826-10 and a 4S1P Lipo pack. I have an old ship that I was thinking of putting the 2820 in and would like to use the 4S1P Lipo pack in. Can this motor handle this, I assume that as long as I load it similar to what I ran the 3S2P it should be fine, correct?

Best,      Dennis T

Dennis,

I see what you mean, the reason I wanted to use the 4S1P is I could get double duty from the existing packs. Might be easier to get one of the lower Kv value motors. The CC software that you spoke of is this the 3.12 release? Is the 70% limit in Fixed rpm mode or only in governor mode?

Best,     Dennis T

Dennis,

I see what you mean, the reason I wanted to use the 4S1P is I could get double duty from the existing packs. Might be easier to get one of the lower Kv value motors. The CC software that you spoke of is this the 3.12 release? Is the 70% limit in Fixed rpm mode or only in governor mode?

Best,     Dennis T

Like Crist said, the 70% limit is in 3.13.  The prior version, 3.12 gives a little more room, but still might not fit your 4S/1500kV combo.

Crist: I was using the phrase "70% throttle" interchangeably (and probably incorrectly) with the idea of "70% RPM".  In either case it might cause us a little pause in motor selection, as the bottom end of control range comes into play much sooner.  Example" I have some 1200kV motors that are now relegated to 5" pitch or below (with 4S) because of the new limit, even though we have flown these motors very successfully with 11x5.5's about 1000 RPM below the Phx 3.13 limit.

Stuntguy: I still think that ffffast Flite Streak would be fun!!!

From Joe Ford from Castle from the RC Groups Vendor section - Castle Creations - New Frimware - page 3

He is talking about head speed but I think it is all the same for our purposes.

"Guys...just because it's giving you a headspeed error does NOT mean that it won't try to do that headspeed. Click on the info button to the right. It tells you why it can't go up that high, but it does NOT mean that it won't try to do it. Just wanted to clarify that. There is NOTHING different about this than the old version other than we give you more info on why it WON'T WORK."

Notice what he says about the old and new versions.

From Joe Ford from Castle from the RC Groups Vendor section - Castle Creations - New Frimware - page 3

He is talking about head speed but I think it is all the same for our purposes.

"Guys...just because it's giving you a headspeed error does NOT mean that it won't try to do that headspeed. Click on the info button to the right. It tells you why it can't go up that high, but it does NOT mean that it won't try to do it. Just wanted to clarify that. There is NOTHING different about this than the old version other than we give you more info on why it WON'T WORK."

Notice what he says about the old and new versions.

That is interesting.  I was tempted to ignore the "warning" but did not trust my luck!

I did some messing around with various kv and cell counts just to see what I could see.  On the high end you can generate a "won't go that fast" comment easy enough using either version of software, but on the low end you get a "won't govern below 70%" message on 3.13.  HOWEVER version 3.12 will let you go quite a bit slower than 70% without generating the "too slow" comment.  Could be the governing is no different, and all they did was supplied a BETTER set-up guide.

Of course, for the reasons Alan mentions too slow is not a very good idea, under any case.

Today's dumb question: I thought we were supposed to be targeting operating speeds of roughly 75% of available RPM.  However, if 70% is the new "bottom" then maybe the 75% ROT needs updating as it only allows a few hundred RPM above that..? 

Dennis A.

I think the 75% target was a safe target--giving the overhead voltage, even at the end of the flight when the battery is getting pooped out.

The trick is to remember what voltage are you using in this calculation---the fully charged voltage (16.8V =4*4.2V) for a 4s pack), or the average loaded voltage during a flight (14.8V=4*3.7). To be honest, I don't exactly remember, and I bet that I have used both values in posts here!

Information from my data recorder shows that I fly level laps at about 280 watts, and in my overheads I peak (very briefly) in the 440 watt range. When I made the theoretical motor plots (posted some time back) for 4 throttle settings (I think 70, 80, 90, 100%), I noted my needed input power ranged from ~75% throttle (level flight) to 80% throttle at the peak 440 watts. So what I think I came away with was that it doesn't take much of a throttle change to really up the watts.

I see I used a battery voltage of 13.8V as the full throttle for that calculation This is what my loaded battery is putting out near the end of the flight. See there is another Voltage to think about!

So 70% throttle would be like having a battery with 70% of that value--about 10V at the end of the flight.