999zip999
100 TW
Ok
Controller for Bafang 750 watt motor
- Thread starter bpmcallorum
- Start date
bpmcallorum
10 mW
It’s like I’m first person in history to pair a controller with a Bafang motor.
They are actually a very popular motor manufacturer.
Have zero people done this?
My own transportation is only whatever I build, so I feel you there.
My recommended longterm solution for this is to always have a spare of everything (and in your case, since you don't have pedal drivetrain as a backup, to have them with you already mounted on the bike ready to just switch over wires) critical. Motors don't usually fail without causes like overheating, etc., so you probably don't need a spare of that. But a spare controller (pre-tested to be sure it will work when you need it to), display (if your system uses one and the system wont' work without it), and if possible spare battery, all kept on the bike, would be helpful in the event of an on-road failure.
Short of that, we can help you find the right controller for your application, but before we go digging around, we should find out what your usage actually requires (which you can use the ebikes.ca simulator to guesstimate), and then see what other features you require, so we can work out the right type of controller and whatever other things it has to be able to for you.
For the moment, to get you going, have you considered repairing one of your existing failed controllers? It's a fair bet that unless the LVPS or MCU failed in them all, there are enough spare parts between several of them to make one good one. Might not be, but worth a look if you haven't already done so.
Something to keep in mind about Kelly is that there are some of their controller models with a known but never fixed problem where it will brick the controller if you do certain things (spin the motor, etc) while it's connected to the computer for setup. There is a warning in the manuals for these models, so you can at least check for this before using them, if it's an issue for you.
Some Kellys (and other brands and their clones) have been known to just blow up in usage. I have one here that did so for another member on their scooter, I didn't actually find anything visibly wrong with it inside, but it won't operate a motor, and it would destroy a motor attached to it trying to run the setup "calibration" (hall angle test), so it could be an MCU problem rather than drive section; I didn't get deep enough into troubleshooting to find out.
Unfortunately there's no single "good" brand or model of controller out there; they all have issues of one kind or another, either in hardware / firmware design, or QC, feature set, setup software. So it's kind of a set of compromises choosing a controller for a particular application.
FWIW, if that's the battery connectors, just a positive and a negative, it doesn't matter if they are plugged in at the same time or different times or even in what order. If there is only one current path (positive to negative, two wires), then current cant' flow anywhere until the second one is connected, regardless of when that is, and current will always still flow the correct direction (assuming the connections aren't accidentally reversed, which has happened to people plugging them in individually or with unkeyed systems), so no damage could possibly occur from order of operations.
If there is more than one current path because of other wiring already connected to the battery that is also connected to the controller, then order of connections may make a difference, but timing of connections would not.
There *is* something that can sometimes damage a controller, usually the capacitors, but more often causing problems with a battery's BMS, and that's the inrush current charging the caps upon connection to the battery--but it doesn't matter how you connect power to the controller for this. To prevent this type of problem, which is pretty rare, you can setup a Precharge circuit. This is very simple in principle--it is just a resistor in series with one of the battery wires (usually positive, but doesn't really matter), that slows down the charging via the RC filter principle, so you can calculate the resistor value on the time you would like precharge to take vs the total capacitance of the controller (and the DC-DC for your light if it also connects to the battery at the same time). If there is a current limit you need to stay under (like that of a battery's BMS, etc) you can instead calculate using the current maximum the circuit should see. Most often it will take less than 30 seconds to precharge a system even with a fairly low starting current. Once precharge is complete, the resistor is bypassed (via switch, breaker or connection of a larger gauge wire around it).(the resistor itself stays just as it is, as it is now not part of the current path it doesn't matter). There are quite a few posts and threads about variants on this system, if you find you need to do this.
I use a battery disconnect on my SB Cruiser trike that just hard reconnects (no precharge) the battery to the controllers every time I use it, thousands of cycles, without killing any controllers from this problem...so, it isn't always necessary (most ebikes do not use precharge; larger EVs and higher power systems often do).
As far as Anderson connectors vs sparking...it's not a problem because those connectors are *designed* specifically to handle this. The tips of the contacts for all of the SB and PP series do not provide any electrical connection once mating has completed. They are designed to be sacrificial, to be eroded away slowly over time by this. The actual connection is made by the flat portion of the contacts beyond the tips, and those won't be damaged by the sparking of connection at the tips. Andersons do have their disadvantages, but only if not properly used. Other posts of mine in other threads (including one from the last several weeks) detail those if you're interested.
The antispark types of connectors simply integrate precharge resistors into them as a third connector pin, or separate conductor "layer" at the tip of the contact(s) (something vaguely similar to the tip/sleeve (TS) type connectors commonly used on 1/4" audio connections. Depending on the capacitance of the controller / system being used with them, the XT types with antispark have been known to fail because the resistors are very small to fit inside the connector, and they or their connection to the contacts is too small to dissipate the heat generated inside them during precharge by high currents generated by higher capacitance of some systems or controllers...so the resistor or it's connections fail, and precharge stops working. THe connector still works fine, but it then starts sparking.
The other disadvantage is that all the antispark types I have seen so far are solder-only,, usually using short shallow cups for the wire to fit into to then be soldered to, and may not be as mechanically sturdy a connection as a well-crimped connection (like the Andersons and some other types use), for a variety of reasons.
Many of us have paired many different controllers with various Bafang motors (of which there are many types both hubmotor and middrive); there are numerous threads and posts with various levels of detail about that around the forum over the years.
Most of the people that have posted over the years aren't here now to see your thread and reply to it, however, and most of the other people here on the forum that have done so either don't visit all that often or may not reply outside their own threads....so you'll probably have to dig around for those posts and threads to find the ones by them.Whether anyone has paired the controllers you listed in the first post of this thread with this specific motor you are using, I don't know.
I don't know any reason that any typical controller wouldn't work on your motor. LIke any motor/controller pairing, you'll have to work out the wiring, as noted in a previous post, both that on your bike and on that controller to match them up, then work out the required settings in the controller (if it's programmable, especially for an FOC controller which requires a lot more setup than non-FOC controllers do).
bpmcallorum
10 mW
Amazing. Thank you for so much of your time and all your information.Many of us have paired many different controllers with various Bafang motors (of which there are many types both hubmotor and middrive); there are numerous threads and posts with various levels of detail about that around the forum over the years.
Whether anyone has paired the controllers you listed in the first post of this thread with this specific motor you are using, I don't know.
I don't know any reason that any typical controller wouldn't work on your motor. LIke any motor/controller pairing, you'll have to work out the wiring, as noted in a previous post, both that on your bike and on that controller to match them up, then work out the required settings in the controller (if it's programmable, especially for an FOC controller which requires a lot more setup than non-FOC controllers do).
I’ll try to write a bit more tomorrow.
bpmcallorum
10 mW
bpmcallorum
10 mW
It goes down to 1amp.
If you’ve spent a couple of years majoring in electrical engineering you should use that knowledge, go back to first principles and properly size the components you require.
Did you cover buck converters in your course? A speed controller basically functions like one in terms of battery current to phase current.
Did you cover buck converters in your course? A speed controller basically functions like one in terms of battery current to phase current.
