How To, 50A BBSHD Controller Mod

[fechter]

Nice to see the insides. Thanks for posting the picture.

I can't make out the numbers on the chips very well.

What's this one?

BBSHD display board.jpg (148.17 KiB) Viewed 4213 times

[E-mil]

I knew you'd gonna ask about that chip, which definitely looks a buck converter.
Unfortunately I don't have a better or clearer image, not even the original hi-res pic enhances it.

And I'm not going to open it up again now.

[tomjasz]

Well, here's to the rescue, Fechter:

I can detail how to safely break it apart if you wish.. I rubber-glued it together, and it's without problems since.

Please?

[fechter]

Which model of display is that?

[E-mil]

The display is the DPC-14 aka C850 .

Here are the pics and description from my memory. Have to say I managed to break a corner of the front glass, but luckily it doesn't affect anything.

Display assembly description:
The display is surrounded by a square removable plastic rim which is held in place with several plastic notches - 3 on the sides, 2 top and bottom. Under this is the edge of the displays' glass, which is not glued but rather sticky tape is used, put between the glass plate and the cabinet's plastic. Important to know is that the flat LCD cable sits in the right side of the display, so you have to be careful not to open this side too wide or cut too deep!

How to open:
The plastic rim is quite easily pried off. Look at the pics for location of latch points.
The difficult part is now the glass. I used a narrow blade/scalpel to carefully work my way around the edges, making sure I didn't press too deep inside. In hindsight it could be a good idea to oil the blade and seal, as the tape tends to stick to the knife. As I found out, the glass is likely made of .. glass. Be careful. Work your way around the edges until it starts to lift.
When glass is lose, open from LEFT side, and dont twist it. Else the flat cable can break.

Inside of the cabinet is the backside of the circuit board visible. It is held in place with some screws IIRC.


Flat cable can be seen inside. Don't open this side any further!
The plastic rim is already removed here. Notice the broke glass corner:

DPC-14 C850-1.jpg (78.65 KiB) Viewed 4173 times

Bottom side view:

DPC-14 C850-2.jpg (68.01 KiB) Viewed 4173 times

Left bottom side view:

DPC-14 C850-3.jpg (150.12 KiB) Viewed 4173 times

[tomjasz]

The display is the DPC-14 aka C850 .

Here are the pics and description from my memory. Have to say I managed to break a corner of the front glass, but luckily it doesn't affect anything.

Thank you!

[sc5252]

Excellent thread.

Taken the plunge and ordered new shunts.

Will report back.

Many thanks to all.

[espresso]

This is presumably the modification that Luna does when they supply the BBSHD with the Ludicrous controller?

[fechter]

This is presumably the modification that Luna does when they supply the BBSHD with the Ludicrous controller?

Yes.

[espresso]

This is presumably the modification that Luna does when they supply the BBSHD with the Ludicrous controller?

Yes.

Does anyone besides Luna sell this commercially?

[racingame]

Hello, how do I know if my BBSHD controller has the 3077 MOSFETS? Also, in another article regarding replacing MOSFETS for old BBS02 (https://electricbike-blog.com/bbs02-controller-mods/) it was suggested to replace with these other types:
https://www.digikey.com/products/en?x=1 ... PP034NE7N3 (mid quality)
https://www.digikey.com/products/en?ven ... SD19536KCS (high quality)
Expecially the latter, I think it should be better than the 3077, right? I would like to get the least possible heat from my controller, also possibly building a totally new housing for better dissipation. I don't know if anyone else already thought about that as well.

[fechter]

I don't know how to tell without taking it apart and looking at the markings on the FETs.

I have seen an enhanced housing with extra cooling fins that Luna makes. Not sure if they are sold separately or not.

[tomjasz]

Hello, how do I know if my BBSHD controller has the 3077 MOSFETS? Also, in another article regarding replacing MOSFETS for old BBS02 (https://electricbike-blog.com/bbs02-controller-mods/) it was suggested to replace with these other types:
https://www.digikey.com/products/en?x=1 ... PP034NE7N3 (mid quality)
https://www.digikey.com/products/en?ven ... SD19536KCS (high quality)
Expecially the latter, I think it should be better than the 3077, right? I would like to get the least possible heat from my controller, also possibly building a totally new housing for better dissipation. I don't know if anyone else already thought about that as well.

You don't and several resellers were dishonest about when they transitioned. Many BBSHD did not have 3077, and that was not a problem until the motors were pushed beyond 30A. You could always buy a late version controller for around $100 and keep the original for an emergency spare. I always keep a backup. I hate downtime.

[fechter]

I know the BBSHD I'm running has the shitty 75NF75 FETs, but it still does amazingly well. I don't run 30A for long periods either, but the motor heating is more of an issue than the controller heating for me. Someone measured one with a FLIR and the temps around the controller are higher than the rest of the motor, so minimizing this is probably a good thing.

[racingame]

Has anybody tryed to use liquid metal pastes in place of the stock thermal grease on the MOSFETs plate? I think it should lower the temperature.

[espresso]

If I am going to be replacing mosfets with better quality and higher voltage ratings, would this be a suitable candidate for this kind of modification?

https://em3ev.com/shop/bafang-bbs02-48v ... ontroller/

[fechter]

If I am going to be replacing mosfets with better quality and higher voltage ratings, would this be a suitable candidate for this kind of modification?

https://em3ev.com/shop/bafang-bbs02-48v ... ontroller/

It will be potted, so difficult to replace the FETs. If it has the 3077 FETs installed, those are not bad.

[racingame]

From what I read on other threads, you cannot go over the standard 25A on the BBS02 since the circuit was not designed with enough room to withstand the extra power like the BBSHD.

[racingame]

Could somebody advise me which shunts to buy, possibly providing links both to Digi-Key and Mouser, both for 5mOhm and 3mOhm? Thanks in advance to anybody that will help.

[burner77]

Just to make a summary after reading everything twice.
For a 50A mod replace the 2x 5 mOhms on the rear side of the PCB with 2x 3 mOhms (Width: 3.18 mm Length: 6.35 mm, Height: 0.35 mm). Power can be lowered in programming software, for example 24A = 40A
Mouser WSLF25123L000FEA

original display goes only up to 61.4V using 15S
DPC14 is made by APT display, what about DPC18 made by Bafang? Is this really a problem of the display or the controller itself? Using a Cycle Analyst with shunt or shorting the orange and brown wire of the display wire (turns on controller, but level can't be switched anymore, throttle is fine)

Using more than 63V the 2 black caps have to be changed. But are maybe bigger and don't fit in the housing anymore.

Have you actually filled the controller again with silicone to protect it from water? Or is more air better for cooling?

[E-mil]

I'd like to share some thoughts and feedback on several of the recent posts. Good to see things are still going

Burner77's summary:

For a 50A mod replace the 2x 5 mOhms on the rear side of the PCB with 2x 3 mOhms (Width: 3.18 mm Length: 6.35 mm, Height: 0.35 mm). Power can be lowered in programming software, for example 24A = 40A

- Yes, exactly how it works. 30 A / 24 A = 0.8 => 50 A x 0.8 = 40 A

Math is not my thing, but according to parallel resistor calculations, and current set to 30 A:
1/Rt = 1/R1 + 1/R2 ... , Where Rt is total resistance.
To get the final current in below examples, simply multiply 30 A with the difference factor in circuit resistance, fx (2.5/1.66) = 1.5 =>
1.5 x 30 A = 45 A

2x 5 mOhm: 1/Rt = 1/0.005 + 1/0.005 => 1/Rt = 200 + 200 => 1/Rt = 400 => Rt = 1/400 = 0.0025 Ohm ---> 30 A

3x 5 mOhm: 1/Rt = 200 + 200 + 200 => 1/Rt = 600 => Rt = 1/600 = 0.00166 Ohm --->
Total current: 2.5 / 1.66 = factor 1.5 => 30 A x 1.5 = 45 A.

4x 5 mOhm: 1/Rt = 200 + 200 + 200 + 200 => 1/Rt = 800 => Rt = 1/800 = 0.00125 Ohm --->
Total current: 2.5 / 1.25 = factor 2 => 30 A x 2 = 60 A.

2x 3 mOhm: 1/Rt = 1/0.003 + 1/0.003 => 1/Rt = 333 + 333 => 1/Rt = 666 => Rt = 1/666 = 0.0015 Ohm
Total current: 2.5 / 1.5 = factor 1.66 => 30 A x 1.66 = 50A.

3x 3 mOhm: 1/Rt = 1/0.003 + 1/0.003 + 1/0.003 => 1/Rt = 333 x 3 => 1/Rt = 1000 => Rt = 1/1000 = 0.001 Ohm
Total current: 2.5 / 1 = factor 2.5 => 30 A x 2.5 = 75A.


- 2x 2.5 mOhm is exactly the same result as 4x 5 mOhm.
On my BBSHD, I simply soldered one extra 5 mOhm on top of one of the original ones, resulting in 45 A. I did not change a thing in SW, as the PAS was already very low for the whole PAS range 1-8, but PAS9 has to be 100% assist for some reason, else the throttle won't go to 100%.

Original display goes only up to 61.4V using 15S
DPC14 is made by APT display, what about DPC18 made by Bafang? Is this really a problem of the display or the controller itself?

- Never thought about that! Of course it must the controller that controls that. If voltage is too high but still turns on the system (fx at 62 V), the controller just sends error code to the display.

Using a Cycle Analyst with shunt or shorting the orange and brown wire of the display wire (turns on controller, but level can't be switched anymore, throttle is fine)

- I'm not sure what you mean / no idea.

Using more than 63V the 2 black caps have to be changed. But are maybe bigger and don't fit in the housing anymore.

- Yes, they have to be changed. For the cap size fitting problem, I've displayed various examples in a previous post. I did not order 80 V caps, so maybe those would be ideal if not going over 18S. I maxed out the space, but added one cap outside as well. Hell, it works!

Have you actually filled the controller again with silicone to protect it from water? Or is more air better for cooling?

Seriously a good question! I have already feared that running my BBS in -5 C temps, and bringing it back inside has drawn moisture that settles on the circuit board and what-not. It's been over a month since I checked for that, where it was dry. I ought to spray it with something to at least seal the board.
Air cooling inside is irrelevant I think. However, I replaced the white cooling paste with some generic silvery paste. The connection between the FET plate and housing is askew, but I have had no heating problems with my NF75 FETs.

[fechter]

Using more than 63V the 2 black caps have to be changed. But are maybe bigger and don't fit in the housing anymore.

Have you actually filled the controller again with silicone to protect it from water? Or is more air better for cooling?

Adding a capacitor externally to the main battery wires just outside the housing should work OK. The resistance of the wires will be minimal compared to the ESR of the cap.

Potting the controller board will be slightly better for heat dissipation, but makes it a pain to rework if needed. I've seen some conformal coatings that can be peeled off fairly easily if needed that would make it plenty water resistant.

[burner77]

Thank you for all the helpful info.
About my previous display question: DPC14 is made by APT display, what about DPC18 made by Bafang? Is this really a problem of the display or the controller itself?
The question is, if the display DPC14 shows a lower voltage using a voltage dropper resistor, than only the display tells the controller the voltage is too high. So the display itself is the problem.
It could be run without display shorting the orange and brown wire of the display cable (for ON/OFF). But of course it isn't possible to change the assistance levels and only throttle modus is working. Or a Cycle Analyst with shunt could be used to replace the Bafang display.

[fechter]

I'm pretty sure the voltage is measured in the controller, not the display.

[Cobain Windsurfer]

The cap fitting problem can be easily solved by putting a DIY gasket between that can give several mm of headroom. Put a thin layer of oil on the contact area of the controllershell and stamp it on a paper to do a template. Cut the template out and draw on the material. I drilled the gasket out from an old LP, but perhaps black plexiglass or a better heatresistant material is better. Use a thin layer of sealant on of either side of the gasket to make sure water is kept outside.