How many Amps on B50-8M / 5s Setup

[f5b@wannabe]

Hello !

I´d like to know if someone has a usefull prediction for me how many amps a B50-8M 6,7s would draw with a 5s LiPo Setup (with about 200A capability at 3.1V/cell) on a 16x16slim for example.

Best regards, f5b

[kyna]

f5b,

I would be happy to assist you, except we do not make a B50-8M. Perhaps the motor you are referring to is either a B50-8S 6.7:1, B50-8L 6.7:1 or B50-8XL 6.7:1.

Best Regards,

Kyna Veatch
Office Manager
Hacker Brushless USA

[f5b@wannabe]

Thanks Kyna !

Well, it is definetly a B50-8M, a formerly 24cell fai. Kv is about 3600 as i know, resistance and so on i noted somewhere, i´ll have to look for. (Perhaps Hacker Europe has the information, the motors are custom-built)
In this times they were flown with 24cell CP1700(?) i was told with 16x16wide on the 6,7:1 drive at about 130Amps.

Now i´d use 5s Packs and i´m awaiting a voltage at about 16.5 to 17 Volts.
I´d use instead of 16x16wide the slim variant to get amps down for the beginning, then switch to 16x17 and check what is possible with the cells.
But not too much, about 120-130 i´d define my maximum, because i´ll still use the HM125F5F for this (it´s just in my table and no further use for it) .. perhaps it would work fine ( it should take 6s as printed on the lable )

So, beside flying 24cells GP2200 on 180Amps the 5s lipo-version should make lots of fun.

I just need a little hint, if my predictions would be in the real range.



f5b,

I would be happy to assist you, except we do not make a B50-8M. Perhaps the motor you are referring to is either a B50-8S 6.7:1, B50-8L 6.7:1 or B50-8XL 6.7:1.

Best Regards,

Kyna Veatch
Office Manager
Hacker Brushless USA

[f5b@wannabe]

I took a look on my remarks,

KV=3600 RPM/V
No load current ~ 4,125A
Resistance ~0,0065 Ohm

Prediction with calculator says

157 A static (but i have no 16x16slim in calc)
16 V on battery (i know they´ll be a bit better)
7600 RPM on the blades with 6,7:1 gear
Motor efficiency about 82%

By interpolating with my recent experiences between 16x16 wide and slim i´d have to correct the Amps by 20-30A down

What do you think, especially for the 125F5F ?

[kyna]

Thank you for clarifying, we do not stock them as B50-8M but rather B50-F5B. Sorry for the confusion.

I'm getting predictions of 143 A static, but I also do not have the slim props in my calculator. Hacker of Germany reccomends the HM195-F5F for that motor combination. I would think that you would be taking a risk to use the 125.

Best Regards,

Kyna Veatch
Office Manager
Hacker Brushless USA

[f5b@wannabe]

Thank you for clarifying, we do not stock them as B50-8M but rather B50-F5B. Sorry for the confusion.

I'm getting predictions of 143 A static, but I also do not have the slim props in my calculator. Hacker of Germany reccomends the HM195-F5F for that motor combination. I would think that you would be taking a risk to use the 125.

Best Regards,

Kyna Veatch
Office Manager
Hacker Brushless USA

Hm, ok, no problem i just forgot that the motors are named at your country a little bit different, sorry for me, too.

That´s the point of my problem... B50-FAI(8M) was used with 24CP1700, with goos packs i wrote down the information of 18V under full work at around 130Amps in Flight with 16x16wide on twisted hub. Well, this was only with short duration, because the 18cell drives came in, even shorter for the 24cellGP2200 drives on more Amps. (but i can not 100% say they´re true, because this was at a time i didn´t masure my own)
So i hope i could get with 5s lipo on 17V with slim untwisted hub in the HM125 specs.

For the HM125. Are there any informations about the maximum power ? Ok, 125A an something more for short bursts (i used them already on 14cells and 145A without problems) But what will happen with more volts ? I personally think the best dimension to check would be max. watts for bursts etc ?
Sure, my climbs would be in the 3-4sec area.

[kyna]

The maximum on the HM125 is 125 amps. It was only intended for use in short bursts (15 seconds) up to 125A.

Since it is very difficult to accurately calculate what your exact amp draw in flight would be, I highly reccommend that you use at least the HM135 if not the HM195.

We both were calculating numbers that would pull around 135 amps.

Best Regards,

Kyna Veatch
Office Manager
Hacker Brushless USA

[f5b@wannabe]

That´s for sure.... no way to discuss about that, i know the risk.
But remember, HM125 is still fine for B50-7s with 14GP3700 on 16x16slim, just with calculating this combo is driving the prop only 500 rpm less.

see...

14cells B50-7s

Static Predictions
Current (A) 190,4
Motor Voltage (V) 11,3
Input Power (W) 2154,4
Input Power Loading (W/kg) 1411,2
Power Loss (W) 595,7
Motor/Gearbox Output (W) 1558,7
Output Power Loading (W/kg) 1021,0
Motor/Gearbox Efficiency (%) 72,3
Shaft Efficiency (%) 48,7
Motor RPM 46407
Propeller RPM 6926
Static Thrust (N) 53,36
Pitch Speed (m/s)46,9 Run Time (min:sec) 0:42

Definetely measured current is about 145A, Runtime is 45sec. with timemark, 500mAh left in GP2200, with GP3700 some more


5s B50-8M
Static Predictions
Current (A) 157,3
Motor Voltage (V) 16,0
Input Power (W) 2519,6
Input Power Loading (W/kg) 1627,5
Power Loss (W) 462,1
Motor/Gearbox Output (W) 2057,5
Output Power Loading (W/kg) 1329,0
Motor/Gearbox Efficiency (%) 81,7
Shaft Efficiency (%) 70,7
Motor RPM 50907
Propeller RPM 7598
Static Thrust (N) 64,21
Pitch Speed (m/s) 51,5
Run Time (min:sec) 1:40

Hard to say what will happen.....

[Kyri]

Did you try it? I will try B50-9M on 6S tomorrow.

[f5b@wannabe]

Oh sorry kyri, i just had no time to do it :-(

I´m unfortunately a little busy in my job, perheps next week it could be possible.

But i´d be very happy to hear from you and your experiencies with your combo.

I guess you´re using the HM135 or 195 ?

I´ll take a look in the big black box at home, if there is any HM195 left, the more i´m thinking about, the more i´m sure i´ll blow up the HM125, even if its loaded for seconds... just some watts too much. Perhaps only a bad feeling.

[Kyri]

I tried it yesterday, 6S with 9M and 16x17 was the biggest prop I tried and the batts were only mildly warm. I will try the same setup with a 17x18 red on 5 deg and maybe a Fun500-32 (a little hotter) if its not enough.

I used Master 99 which was fine with 24 GP2200 and 125A for quite some time. So using 6s which is a little lower voltage than the 24 cell setup, I figured that the controller would be fine - and it is. I have a 195 but its soldered to a 5L so I'll keep them together when I try 4 or 5S,

Regards

Kyri

[f5b@wannabe]

hm, ok, i formerly thought a 5s setup would be in 24cells range, cause they´ll just keep up to 16,5 or 17 volts under load. I believe 24cells would be at 18V or so.

Therefore i´d be very happy if 6s on 9M works witk the HM99... perhaps my HM125 would fit the 8M with 5s.

[f5b@wannabe]

Hi @ all

so, here we go, now i did some tests in the air with the combo.

First i have to say, i believe i should have used a 7M.

Why ? First of all, the cells are really great, they´re up on 17V as i guessed at 120A. But this current is very hard to achieve with the 8M. 16x16wide seems to produce lots of rpms, so much to take the 8M into a efficiency hole as it seems, it´s getting hot really fast. Hm, and the 17x18 is not working fine with the plane.

Can anyone tell me the true voltage of the formerly used 24CP-Cells or 18Cell packs under load with current ?

By the way, the HM125 could handle it, but i replaced it by the HM195

[f5b@wannabe]

I just turned to the 17x18, pretty hot for the 8M with the lots of runtime we have now on LiPo.

On a german board i found a video with similar drive but still on 16x16wide... as i asked the guy he is very happy with it and although it is not the best vid it shows clearly what massive performance you can get on just 5cells.