Head Speed & THR % relation

[arnika]

I have 3020-1000kV Scorpion and HW60A ESC. Pinion is stock 19T. I have my head speed set up comfortably so I can do some 3D maneuvers but nothing crazy. The throttle channel is at 58%. Should I put smaller pinion and increase the throttle % to achieve the same head speed?
I am asking because it seems the HW governor doesn't work properly. I tried both, StoGov and ElfGov. The head speed is always decreasing towards the battery end. So I don't get it. Once in governor mode, the RPM should remain the same and shouldn't matter on thr. % (once obove 50% let's say) and until the battery is cut off. It looks to me that the governor feature is not implemented properly, from technical point of view speaking.

[JimJW]

The Hobbywing Store and ELF gov. work properly.

When setup properly, the throttle percentage should give an RPM that is very close to the fraction of the max headspeed. This is simply checked by the following:

[Motor Kv] x [Pack Voltage] x [Throttle Percent] x [Pinion Teeth] / [Main Gear Teeth]

For your motor that works out to :
1000 Kv x 22.2 V x 0.58 x 19T / 110T = 2,220 RPM

This is pretty slow of an RPM for the Oxy 4 Max. Do you know what Headspeed RPM you are running?

If you have any ESC telemetry it would be very helpful to look at: RPM and Throttle Out.

[jrman83]

Where have you checked to confirm this? What FBL are you using? Does it have logging capability and if so, have you looked at those logs?

[arnika]

Originally Posted by JimJW

The Hobbywing Store and ELF gov. work properly.

When setup properly, the throttle percentage should give an RPM that is very close to the fraction of the max headspeed. This is simply checked by the following:

[Motor Kv] x [Pack Voltage] x [Throttle Percent] x [Pinion Teeth] / [Main Gear Teeth]

For your motor that works out to :
1000 Kv x 22.2 V x 0.58 x 19T / 110T = 2,220 RPM

This is pretty slow of an RPM for the Oxy 4 Max. Do you know what Headspeed RPM you are running?

If you have any ESC telemetry it would be very helpful to look at: RPM and Throttle Out.

Yes, something around that number, I am guessing +- 2400rpm. I have FrSky rpm sensor coming next week so I will know the exact number later. The THR% is above 50% in my case, as written in the manual it should keep constant RPMs till the battery end, But it doesn't.
I am using Microbeast Plus but the THR output is taken from FrSky receiver, it doesn't go through the MB FBL.

[arnika]

Originally Posted by jrman83

Where have you checked to confirm this? What FBL are you using? Does it have logging capability and if so, have you looked at those logs?

I didn't look at any LOGs. I don't think I can. It is connected from receiver CH3 to HW ESC.

[arnika]

OK, so the headspeed measured by the RPM sensor is 2350rpm, it is my regular headspeed I am comfortable with. Should I go higher is this too slow for the governor to work properly?

[fiddle]

Originally Posted by arnika

OK, so the headspeed measured by the RPM sensor is 2350rpm, it is my regular headspeed I am comfortable with. Should I go higher is this too slow for the governor to work properly?

If you like the headspeed, it is fine. I have three headspeeds setup on mine:

2350
2550
2750

You'll want to use a headspeed calculator to figure out what your ranges of headspeed can be: http://calc.kfmconsulting.se/ There is also the IRCHA app on your smartphone , if you have one. That is my favorite.

[ini_]

arnika,


The headspeed you have is just fine. You are able to go up to 3200 RPM with your setup.
When using HW 60A ESC, make sure you active freewheeling on. Otherwise the headspeed is on the low side and will load the ESC unnecessarily.


In many cases you are first happy with a relatively low headspeed. After some time though, you will gain skills and tend to become more active and consequently end up using more headspeed. Nothing wrong with that.

[JimJW]

If you’re still seeing headspeed dropping at the end of flight, can you tell us what voltage your packs are at? (If you have telemetry, what are the min voltage while flying and what voltage after your flight?

Years ago, I drove my old RC car NiCad packs until the battery sagged. And those old batteries kept on going... A modern LiPo would be ruined very quickly if you flew it out to similar levels of discharge.

[arnika]

I have alarm warning set up at 21V (6s) and at this level there is not much capacity left, maybe 10% (I can still get like 2min on slow head speed). From that point the voltage starts dropping down rapidly. I have soft cut out and 18V programmed on HW. Anyway, the governor feature start lacking - headspeed dropping somewhere around 22.5 volts. So at the end it doesn't work for sure. I wonder why it doesn't work since it is based on PWM, it should have nothing to do with DC voltage level. I may try BeastX governor feature instead.

[JimJW]

Originally Posted by arnika

I have alarm warning set up at 21V (6s) and at this level there is not much capacity left, maybe 10% (I can still get like 2min on slow head speed). From that point the voltage starts dropping down rapidly. I have soft cut out and 18V programmed on HW. Anyway, the governor feature start lacking - headspeed dropping somewhere around 22.5 volts. So at the end it doesn't work for sure. I wonder why it doesn't work since it is based on PWM, it should have nothing to do with DC voltage level. I may try BeastX governor feature instead.

So what’s the resting voltage after a flight?

Originally Posted by SeanM

Yes, no matter the size of the LiPo, the voltage after a flight should be no lower than 3.7v/cell. Any lower and you're most likely exceeding the 80% rule, which will effect the LiPo's life expectancy over time.

I've discharged mine down to 0% also, always on accident. While they still work, the internal resistance of the cells has gone up slightly and I believe they've lost a little capacity.

[fiddle]

Originally Posted by arnika

I have alarm warning set up at 21V (6s) ... I have soft cut out and 18V programmed on HW.

You shouldn't be any lower than 22.4v when you land and disconnect the pack and check the voltage. I'm shocked your charger will charge these packs again if they are lower than that. Mine will throw a fit and refuse to charge them.

[arnika]

After the flight the battery is around 20V, I drain it down to the bottom.
No problem with re-charging the battery since the 3V is the minimum voltage per cell, I am still above that and settings on HW let you adjust to 18V soft cut off, means 3V per cell.

I am using HRB batteries and SkyRC D400 charger https://www.motionrc.com/products/sk...rger-sk-100123
Looking at the table, I will re-adjust my alarm warning to 22V to stay around 15% capacity at the end. Thanks for the info.

[arnika]

So I did a couple of changes. I put smaller pinion, went from 19T to 18T, that helped me to increase the THD % while keeping the same head speed. But most importantly, I went from EflGov to StoGov and did the standardization procedure which I never did before. The governor seems to be working fine now.

[JimJW]

Originally Posted by arnika

After the flight the battery is around 20V, I drain it down to the bottom.[IMG class=inlineimg]https://www.helifreak.com/images/smilies/icon_biggrin.gif[/IMG]
No problem with re-charging the battery since the 3V is the minimum voltage per cell, I am still above that and settings on HW let you adjust to 18V soft cut off, means 3V per cell.

I am using HRB batteries and SkyRC D400 charger https://www.motionrc.com/products/sk...rger-sk-100123
Looking at the table, I will re-adjust my alarm warning to 22V to stay around 15% capacity at the end. Thanks for the info.

3.0 Volts after a flight is Way-Way-Way to low. Did I say it was too low? It’s tooooo low. After a flight it should be at no lower than 3.7V.

Under load the minimum voltage per cell is usually 3.2 to 3.3 volt.

From RCG: https://www.rcgroups.com/forums/newr...ply&p=26357340

Originally Posted by slipstick

What voltage you're looking for depends entirely on WHEN you're measuring the voltage :

The battery voltage drops when power is being taken out of it. 3V (or 3.2V or maybe 3.3V) is the minimum voltage the battery should ever see UNDER LOAD to avoid damage. I.e. when it's actually running the motor at full power. But you'll actually only know this voltage if you have some telemetry or similar in the plane.

When the load comes off, the battery voltage bounces back up. So 3.7V (or 3.8V or sometimes 3.9V) is the voltage OFF LOAD. I.e. what you should see AFTER a flight when you check the battery. That's considered a safe voltage off load to ensure that the battery never went as too low when it was under load.

Steve

You’ve probably already done irreversible damage to your batteries.

Please read:

https://www.promodeler.com/askJohn/H...for-LiPo-Packs

[arnika]

Originally Posted by JimJW

3.0 Volts after a flight is Way-Way-Way to low. Did I say it was too low? It’s tooooo low. After a flight it should be at no lower than 3.7V.

Under load the minimum voltage per cell is usually 3.2 to 3.3 volt.

From RCG: https://www.rcgroups.com/forums/newr...ply&p=26357340




You’ve probably already done irreversible damage to your batteries.

Please read:

https://www.promodeler.com/askJohn/H...for-LiPo-Packs

I did not. I am aware of "under load" or "no load" conditions. I have voltage telemetry and if I land around 21V it means 3.5V per cell. Still safe. Voltage then slightly climes up. I misswrote before, I meant the voltage when landing (under load) was 20V. I changed my alarm since.