How To, 50A BBSHD Controller Mod

General Discussion about electric bicycles.
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fechter   100 GW

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Re: How To, 50A BBSHD Controller Mod

Post by fechter » Dec 04 2020 11:26am

E-mil wrote:
Nov 29 2020 5:28pm
This old BBSHD controller is fulfilled. It is my fourth tuned controller and it got the full overhaul. Tuned to the max and ready for 22S 92V 55A.

It will be an absolute beast and probably the most insane BBSHD with an original controller 😎 .
What LEDs are you using for the voltage dropper? Do they light up?

If you have the plastic gear, that will be the weak link if you run it hard.
"One test is worth a thousand opinions"

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Re: How To, 50A BBSHD Controller Mod

Post by E-mil » Dec 08 2020 5:34pm

Hi Fechter, the LEDs are just standard 10W and 1W white or red, as in my example here.
In an old post I measured the Vf of different LEDs at different current draw. Seems like both the display and the controller logic are fed thru them, so display illumination level affects the draw.
Consensus was that current draw is around 75 mA, and a typical white 10W LED drops 8.9V while a 1W drops 2.9-3.3V (all depends on type/quality/bin).

Pictured is the sandwiched LEDs I used for the test, here powered at about 29V 80mA. It's enough for a backlight and the LEDs are running way under spec, albeit without a heatsink.
IMG_20201208_230729.jpg
IMG_20201208_230729.jpg (412.28 KiB) Viewed 329 times
I have a spare nylon gear. Let's see what goes first.

ChristianKi   1 µW

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Re: How To, 50A BBSHD Controller Mod

Post by ChristianKi » Feb 07 2021 3:49am

E-mil wrote:
Dec 08 2020 5:34pm
Hi Fechter, the LEDs are just standard 10W and 1W white or red, as in my example here.
In an old post I measured the Vf of different LEDs at different current draw. Seems like both the display and the controller logic are fed thru them, so display illumination level affects the draw.
Consensus was that current draw is around 75 mA, and a typical white 10W LED drops 8.9V while a 1W drops 2.9-3.3V (all depends on type/quality/bin).

Pictured is the sandwiched LEDs I used for the test, here powered at about 29V 80mA. It's enough for a backlight and the LEDs are running way under spec, albeit without a heatsink.
IMG_20201208_230729.jpg

I have a spare nylon gear. Let's see what goes first.
What about your bike? Does it run as you thought? Or are there any issues?
How much km/miles did you drive after this tuning?

I read nearly the complete thread. But what I don't understand is the voltage drop with the led's. Is this a reason of the controller or the display?
If it is because of the display, does it work at a 20S 72V without led's if I want to run a eggrider V2?
At the eggrider app I could select a 72V battery. 🤔

Image

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fechter   100 GW

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Re: How To, 50A BBSHD Controller Mod

Post by fechter » Feb 07 2021 12:11pm

With the stock display, it will cut off at about 61.5V. So it looks like maybe the Eggrider will get around that limit. What I'm not sure about is whether the 61.5v limit is monitored in the display or on the controller board. If it's on the controller then the Eggrider won't help.

The voltage regulator in the motor controller is rated for 80v max and as I recall, the stock FETs are rated for 75v. Even with the Eggrider, one of these other parts might not be happy at the higher voltage.
"One test is worth a thousand opinions"

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Re: How To, 50A BBSHD Controller Mod

Post by ChristianKi » Feb 07 2021 1:35pm

Sounds logical. I know about the fets. That isn't a big issue. Changing parts is the simplest part of the game. Destroying Prozessors is way more painful. 😁

So electrically it's like this? The full battery voltage goes to the display (brown) . The voltage for the Prozessor comes from the display (Pl-orange)???
But this normally couldn't be. Because if you aplicate the controller with the bafang tool, there is only the UART adapter (max. 5V) at the processor. If the processor (does mcu mean processor?) needs only 5V from the USB UART port, it normally doesn't get more from PL/Orange.

The Vdrop with the LEDs is only at the brown cable to the display, right? I bet there is a separate voltage regulator with 5/3.3V out for the processor.
If so, what does PL/orange from the display do?

Why not using a voltage divider to drop the voltage? Then I could divide it to exactly half. The display shows 36V instead of 72. I could calculate the range like 36V battery and with a 60A shunt mod the power is shown exactly divide by 4. All pretty simple to calculate in the head. 😁
If my 13S battery is build, I have to measure the voltage at the orange cable. I'm waiting for cells and charger for now. 😔

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fechter   100 GW

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Re: How To, 50A BBSHD Controller Mod

Post by fechter » Feb 08 2021 2:45pm

The orange wire is switched pack voltage going from display to the controller board. On the controller board there is a voltage regulator that drops it to 12v and a cascaded regulator for the 5v.

The reason a voltage divider doesn't work well is the load current varies significantly so the voltage will be all over the map. If the voltage seen by the controller gets too low, it will trigger a low battery cutoff.
"One test is worth a thousand opinions"

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Re: How To, 50A BBSHD Controller Mod

Post by ChristianKi » Feb 11 2021 6:50am

fechter wrote:
Feb 08 2021 2:45pm
The reason a voltage divider doesn't work well is the load current varies significantly so the voltage will be all over the map. If the voltage seen by the controller gets too low, it will trigger a low battery cutoff.
Why should this be? There isn't any heavy load. Just a display, the controller processor and the processor at the display. I don't understand the alternating current.

But now I have another idea.
To be continued..... 😉

btw.... What about the eggrider? Das this work out of the box with 72V 20S at 84V full charged? You could select 72V in the app. 🤷🏻‍♂️

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fechter   100 GW

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Re: How To, 50A BBSHD Controller Mod

Post by fechter » Feb 11 2021 9:06am

The current draw on the low voltage supply does vary with operating conditions. Most of the change is likely due to the FET gate drivers. I measured between 25mA and 40mA depending on conditions, so a pretty significant variation.

The Eggrider itself may be fine at the higher voltage but I think you will still get an error if the controller sees over 63v.
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Re: How To, 50A BBSHD Controller Mod

Post by ChristianKi » Feb 11 2021 10:23am

In 5-6weeks I get the 750C display for the sabvoton controller. Maybe this would work.
I'm gonna test it.

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Re: How To, 50A BBSHD Controller Mod

Post by fechter » Feb 11 2021 5:14pm

With a Sabvoton, it should be fine at higher voltage. Then you'll have enough power to melt the plastic gear.
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Re: How To, 50A BBSHD Controller Mod

Post by ViriViri » Feb 15 2021 5:09am

Hello all!
I have been lamenting over the new 28A 52V BBSHD controllers being severely nerfed, only peaking at around 27A and rolling back to 25A. They are noticeably weaker than my old (now dead) controller from 2017. Yesterday I soldered a single 5mohm resistor from that dead controller to my weakling new one and all I can say is... I should have done this sooner. It was easy for me since I've pulled apart a dead one before. No need to pull the potting other than from the backside where the shunt is and the fet heatsink. There was no thermal paste, just the rubber potting between the fet heatsink and controller cover. Seriously, Bafang don't care.

Eggrider now reports max 1509 watts so 26A@58,5V which should translate to 39A/2281W peaks in reality. I need to get an ammeter for accuracy, those numbers can't really be trusted. It makes a nice and noticeable difference, but now I'm left wondering about that second resistor and if I should have gone for it. My battery can do 44A continuous and 55A bursts, so I would need to dial it down to those numbers so nothing crazy powerwise. The motor is coming apart for maintenance next week and I'll have to pull the controller, so I might as well solder a second resistor on the one I installed yesterday. I'll probably redo the phase wire plugs and add some conformal coating to the exposed board and around the wire harness entry.

Since there are no pics of two resistors soldered on top of the old ones, Is it as straight forward as dropping another 5mohm resistor on top of the one I already added?

But yeah, If you're on the fence about performing this simple 45A mod, go for it. Here's to hoping mine won't go up in flames any time soon, I have a spare but really don't want to use it anymore. I gained noticeable torque on all gears and almost 10kmh more top speed :bigthumb: .

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