Battery Usage Profiles for 550L Dominator

[PaoloFCantoni]

So I've just got my 550L flying (coming from mCPX-BLs and 450Xs).

I've just broken in the batteries HK Zippy 5000 40Cs (x2).

This is my first large Heli and I'm still getting used to the craft and running (ungoverned) @ 75% in IU.

I've some questions regarding the battery voltage and current profiles I should expect.

Now that they've been broken in, I'm getting 4.5 mins flying - mainly level FFF (haven't tried any 3D yet - for me that would be flips and rolls mainly).

At the end of that time, both batteries come down at 23.5 ±0.1v with individual cells @ 3.92 ±0.3v. Recharge takes about 2000 mAH to give 25.1v with the cells registering 4.19 ±0.3v.

I know that LiPo cells have a "longish tail"; so, given my flying style how far can I push it?

Obviously, I'm nowhere near 3.7v per cell yet. How many mAH should I limit the usage to?

I'm going to be increasing the motor % shortly then switching to governed as I get more confident.

Any advice or information appreciated, TIA.

Paolo

[dogbreath]

A lot of people feel that 80% is a safe discharge, so if you put 4000mah back in you're there. That would equate to 9 mins at your current rate, but with lower voltage at the end of the flight I think it would wind up shorter. Bump to 5 1/2 and see what you put back in, then six, etc and see where 4000 mah recharge gets you.

Dan

[gstoneberg]

I'm more conservative than that. I try to have my cells end up at about 3.8v when I get back home from flying. On my helis (both 550 and 500) that equates out to around 4min. I'm putting back about 50%. If I take the head speed down to around 1700 on the 550 I can go to almost 6min, but I usually only fly part of the flight at the lower head speed.

[1am7h30n3]

I fly by the 80% discharge rule that dogbreath mentioned. His method is how I figure out my flight time as well, keep flying longer and longer, checking how many mAh you put back into the pack.

Just be careful though that if you're still getting used to the heli and flying conservatively you will be using less mAh than when you get to fly it harder, so leave yourself a bit of a margin of safety maybe or be sure to re-adjust your flight time when you start to push the heli more.

[PaoloFCantoni]

Thanks for the input guys.

I understand that when I "ramp up" the power, I'll need to revise the timings.
I was really after the end points you've mentioned.

In the mean time, I've upped to 5.5 mins and 2300 mAh @ 23.2v Cells: 3.87 ±0.3

Paolo