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