(25-Jan-2021, 06:26 AM)Skavage Wrote: Looks like it is still in stock at RDQ.  https://www.racedayquads.com/products/fl...77df&_ss=r

Hi Skavage,

Thanks. I  have just ordered it    

The other day when I tried, it looked like it was in stock, but when I tried to add it to the cart is said "Out Of Stock"; go figure. Maybe it was some glitch with the website or maybe they just got more in; no matter; it is ordered now. 

Thanks Again.  

(25-Jan-2021, 04:13 AM)V-22 Wrote: I got one from RDQ, came in a few days. I'm using it on my Phantom HD build. Looks like it's still in stock:
https://www.racedayquads.com/products/fl...1849&_ss=r

Hey V-22, Dose BLHeli_32 seem to rectify the 7volt LVC/BLHeli_S issue??
If so I’ll be happy to pay the $70.00 for this AIO...

(26-Jan-2021, 03:13 AM)Joshua_A Wrote: Hey V-22, Dose BLHeli_32 seem to rectify the 7volt LVC/BLHeli_S issue??
If so I’ll be happy to pay the $70.00 for this AIO...

I'm planning on soldering up the motors tomorrow night! I'll do a test with a benchtop power supply to see how low it will go. I also want to verify RDQs claim that the 9V output for the DJI VTX will work on 2S...

(26-Jan-2021, 05:22 AM)V-22 Wrote: I'm planning on soldering up the motors tomorrow night! I'll do a test with a benchtop power supply to see how low it will go. I also want to verify RDQs claim that the 9V output for the DJI VTX will work on 2S...

Have you found anything yet, V-22? I’m excited to see what you discovered.

Hi Joshua,

My research indicates that BLHeli_S does NOT limit the lower voltage. If an ESC is using BLHeli_S and is being "clipped", then it has been implemented elsewhere; either in Betaflight or hard wired in the ESC or flight controller. Thing is, you can't tell without testing. Some boards that are running BLHeli_S clip the the voltage and some do not. Now, we are back to guesswork. Oops, I mean testing   

My presumption is that BLHeli_32 will override a hardware implementation, but I'm not 100 percent sure that it will;
we just have to take a chance, try it, and see what happens.

I am putting a Flywoo F411 stack with BLHeli_S in my Phantom-X and will be testing to see if I can drain a battery below 3.0 volts. I think this stack is used in the Flywoo Explorer...and...reviewers are draining the 18650 packs to 3V or less, so I am hopeful.

By the way, this little stack is really SWEET. It has pads for SoftSerial that is already set up in Betaflight. Plus, Betaflight is almost completely set up including the ports {GPS is assigned to hard UART2 and SmartAudio is assigned to SoftSerial}, the Modes, Rescue mode, and the OSD screen {has more stuff than I use}. This baby is ready to go. I am assuming the tune is for the 4 inch Flywoo Explorer. I am excited to get this upgrade completed and get the quad in the air.

Also, I now have 3 boards with BLHeli_32. One of these will go in the Quest250-LR build since I am working on the "Challenge" and don't want any LVC clipping the lower voltage.

(31-Jan-2021, 04:01 AM)Joshua_A Wrote:  Have you found anything yet, V-22? I’m excited to see what you discovered.

Had to make an unexpected trip out of town, so I won't be able to get to it until next weekend. Everything is hooked up and sitting on the bench though, and it already passed a smoke test

Hi V-22,

When you get time, could you run a couple eCalc metrics for me...Specs are in this Post.

Thanks  

(31-Jan-2021, 06:48 PM)V-22 Wrote: Had to make an unexpected trip out of town, so I won't be able to get to it until next weekend. Everything is hooked up and sitting on the bench though, and it already passed a smoke test

No worries man, I was just interested...

So let’s collect: There are three ways to fix the 7volt cutoff (I think)...
1). Move to three cell
2). Buy an ESC with BLHeli_32 (this “fix” is unverified, although if there’s someone who can verify this, let me know )
3). Remove the Voltage regulators power resister (this has been done -with success- although I presume it’s tricky to find the right resister...)

(08-Feb-2021, 06:40 PM)Joshua_A Wrote: So let’s collect: There are three ways to fix the 7volt cutoff (I think)...
1). Move to three cell
2). Buy an ESC with BLHeli_32 (this “fix” is unverified, although if there’s someone who can verify this, let me know )
3). Remove the Voltage regulators power resister (this has been done -with success- although I presume it’s tricky to find the right resister...)

1) First, it is not a 7 volt cutoff, it is a 3.50 Volt Per Cell cutoff. It is only 7 volts on 2S, but it is 10.5 volts on 3S not 7 volts, 
    which still DOES NOT allow you to drain an 18650 pack below 3.50 Volts per cell that we need to do.
    I have actual flight data to support this. 

    The goal is to be able to drain any given pack down to 2.5 volts per cell:
    Drain a 2S pack down to 5.0 Volts
    Drain a 3S pack down to 7.5 Volts
    Drain a 4S pack down to 10. Volts

    
2) Yes, buying a board with BLHeli_32 should solve the issue. {this assumes that it is not limited somewhere else in hardware}

    Interestingly, according to my research, BLHeli_S actually does NOT  have a Low Voltage Cutoff, 
    it just doesn't have the capabilities  to control or override the LVC. 

3) Good luck with that. In my opinion this is very risky, so I won't be doing it. 

    If a manufacturer has implemented a Low Voltage Cutoff in hardware, then don't buy those boards for long range.
    Thing is, I am not sure how to tell without actually testing the board.

(08-Feb-2021, 11:46 PM)iFly4rotors Wrote: 1) First, it is not a 7 volt cutoff, it is a 3.50 Volt Per Cell cutoff. It is only 7 volts on 2S, but it is 10.5 volts on 3S not 7 volts, 
    which still DOES NOT allow you to drain an 18650 pack below 3.50 Volts per cell that we need to do.
    I have actual flight data to support this. 

    The goal is to be able to drain any given pack down to 2.5 volts per cell:
    Drain a 2S pack down to 5.0 Volts
    Drain a 3S pack down to 7.5 Volts
    Drain a 4S pack down to 10. Volts

    
2) Yes, buying a board with BLHeli_32 should solve the issue. {this assumes that it is not limited somewhere else in hardware}

    Interestingly, according to my research, BLHeli_S actually does NOT  have a Low Voltage Cutoff, 
    it just doesn't have the capabilities  to control or override the LVC. 

3) Good luck with that. In my opinion this is very risky, so I won't be doing it. 

    If a manufacturer has implemented a Low Voltage Cutoff in hardware, then don't buy those boards for long range.
    Thing is, I am not sure how to tell without actually testing the board.

Well stated , although I believe there’s a little misunderstanding (partly due to hardware differences, I guess).
In reality we’re experiencing a “low voltage dropout” of some kind... not to be confused with “Low Voltage Cutoff” -as you have rightfully stated- is a software problem.
This problem persists no matter what the LVC is set to.
Eveilsteve did an interesting experiment (also I’ve repeated his experiments, with success), to show the “7volt Low Voltage Dropout”, in conclusion he shows that the FC only dropsout at 7volts (It doesn’t matter the number of cells, although in all likelihood this is only a problem on 2s...)
His post (the 9th post): https://intofpv.com/t-3-250g-10km-dji-di...ild?page=5
My fear is BLHeli_32 may still fall to the “7volt dropout” inspite for the firmware...
With all that said: testing is ever more important, and I will continue to test different “fixes” in the future.
And oddly enough I glad we have different results in our testing: it shows we’re getting closer, hopefully we can resolve this problem and advance the micro long range class for the better!!
Until then, continue testing, experimenting and having fun.
-Joshua

Hi Joshua,

Yes, I think that we are talking about different "7 Volt" issues.

I have heard that some FC's would not operate below 5 volts {I have done No Testing to confirm this, but if it is true that still translates to 2.5 Volts/cell for a 2S}.  However, I can find NO supporting information on the internet. 

EVILsteve's  Post #69 of 3" 250g 10kkm DJI Digital Build is the only real information, empirical or otherwise, regarding the shut down limit of any Flight Controller that I have found. His results show a battery draw down quite a bit less than 7 volts; specifically 5.83 volts in one instance {1 volt is a lot in this environment}.  However, keep in mind that this is an extremely limited test with only a few boards and specific switching power supply {NOT a battery}. His conclusion, suggests that the lower operating limit for some FCs is about 6 volts. For me, this is approaching  the 5 volt limit that I had heard about {with no supporting evidence}.

I believe that this particular issue warrants additional testing; more FCs with various amp ratings, more tests per FC, different battery configurations, and both bench tests and actual flight tests. In fact, different FCs with different mosfets might have different results. 

I will say, that even getting to 6 Volts total, 3 Volts per cell, or less will be better than the 3.5 Volts per cell documented from my actual flight data. Since my Phantom-X has already logged over 21 minutes without any adjustments, getting another volt or so from the pack might get me to 30 minutes. Currently, she is being upgraded with a new BetaFPV Toothpick F405 AIO 20A V4 BLHeli_32 flight controller. When full reassembled, I will remove or reduce as many Low Voltage limits that I can find; both in BLHeli_32 and in Betaflight. Then we FLY. Yeah, I am not set up to test this on the bench {Yet}.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Quotes from EVILsteve's above referenced post:

Test 1: 7.5v at plug in and I reduced the voltage until the motors stopped spinning. This was about 6.3v it usually quit, flight controller and betaflight were still operating normally but I could not re-arm the quad until I increased volts to about 6.5v. If I reduced the voltage extremely slowly I could get a bit lower to 5.83V or 2.91v/cell. The motors did not stop at the same time if I went slow enough.

Test 2: 11.6V at plug in. I could reduce voltage well below 2.5v/cell without any issues. LVC not active on this esc.

My test show that I do not have LVC active but the mosfets cannot handle operating below 6v on any board I tried. I'm not sure blheli32 would do any better, moving to a 1-2s ESC might be the only solution. None of my blheli_S boards seem to have LVC but ifly4rotor's definitely seem to by his testing. Hopefully we don't have LVC issues with 1-2s boards.

This was with a switching regulator that was extremely noisy I did not try any tests with a blheli32 esc. I need a cleaner power source for any more tests.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Hey ifly,
I agree, information is hard to find...
So I went to Rotorbuilds to see if all 2s li-ion quad had this problem...
1). This build has the same problem, although note only on 2s, 3s “fixed” the issue...
2). This build has not noted if LVD (“Low Voltage Dropout “) was a issue... but interesting read nonetheless.
3). This build states that 2s is impossible to tune, although is the comments you see the “2s problem, 3s fix” a few times...
I have to make two points:
1). These builds are dropping out at 6volts, NOT 7volt in my case...
2). In bench testing, just because the motors are spinning doesn’t mean the quad will fly... in my testing the motors will not Dropout until 6volts, but in a real flight the quad drops a 7volts. yes the motors still spin, but to quad won’t fly...

Hi Joshua,

The way I see it, there is really NO definitive answer nor solution.
There are just too many variables that we can't really determine or don't have the details about.
When you look at the assorted results, NO clear conclusion can be drawn.

That said, the only place this comes into play is in Long Range and getting the Maximum Fly Time with 18650 packs. 
It just is not an issue for racing or acro flying; hard and fast in a very short time. 

Truth is, once I see if we can match the DJI "Challenge", I won't worry about getting 30 minutes of fly time either.
I do also want to get my 5k badge, but here the quad doesn't matter.

Hey ifly.
First the add to your point: the problem only -seems- to haunt 2s li-ion power systems, so the number of applications that will benefit from our testing (as I too will note) is extremely limited...
Although the dropout at 6-7 volts agitates me greatly (probably the engineer in me... ), and I -and hopefully others- will continue the research until the issue(s) has been resolved.

Edit: here’s a fix.