5net wrote: ↑
Jan 10 2022 1:50pm
Yes, I did look around for a sensorless controller and only find 1 for ~$35 which is the same price with a ebike controller with "Product Description: The product according to market demand to do without Hall zero start, brushless dual-mode smart measure battery voltage, motor phase!"
If you link to it, I can see if it says anything on the page that indicates it may not work, or anything that helps us figure out a good wiring diagram/etc for you to hook it up to the mower.
BTW, I re-read the description of the controller you previously linked to, and it does actually support sensorless mode; they just have a badly-translated phrasing for it:
Double-Mode, controller can check the motor hall sensor condition automatically. If the motor sensors are broken, controller will operate to None-Hall mode.
"None-Hall mode" means sensorless.
That controller's description (where I foudn the above) specifies it's actually the 84v version. You probably want the 72v version it links there (this is the 1000w, they also link a 1500w)
because your battery is nominal 72v, and that's what that means on the controller specs.
It also says
First look at your e-bike battery voltage levels, corresponding to the selected voltage controller, look at the size of the current controller previously used, such as the 16A-18A 350W controller, 22A-24A controller is 450W, 28A -30A controller is 500W, 31A-33A is 600W controller, 33A-35A is 800W controller, 36A-38A is the 1000W controller, 40A-43A is the 1200W controller, 50A is about 2000W controller. If the original e-bike is 350W we recommend upgrading to a faster wattage, so you can take advantage of the best motor speed and power.
whcih all comes down to that the 1000w controller probably has a current limit of 36-38A, which is way higher than what your battery supports, so if the motor gets bogged down a lot while mowing, it could draw more current than the battery can safely output (more on that later in the post where you mention battery info). There are ways to lower this if necessary by manually modifying the controller inside, for many controllers.
I found out that Kobalt battery is limited at 5A max discharge. Also, ther are some selling custom parts that help the battery push out more with max 15~20A, so people do try to use this battery for e-bike. I dont think the discharge of this battery is normally at 20A.
If the battery is limited to 5A max, then that means the most power the mower could possibly draw from it when it's charged to 80V is only 5A * 80V = 400W, and past that the battery would shut itself off, if it has a protection board in it that does this.
If it relies on the mower to do the shutoff, which some of the power tool/battery systems out there do, then without the original controller the only limiting that will happen is whatever the new controller is able to do on it's own). In that case, you would need a controller that has a very low current limit (5A), to keep the batteries at the limit they would have been at originally.
If the battery doesnt' ahve any internal protection or fuses to keep it from supplying up to the 20A the cells can do, then you can try using them with a higher-current-limit controller, up to the 20A. If there is a fuse or other protection you don't know about on them that is below the limit of what the motor actually makes the controller pull from the battery, the fuse will blow or the protection will engage and the battery will stop working. (some of these protections self-reset, some reset when put back on the charger, and some are permanent "bricking" of the battery).
You can also bypass the protection, fuse, etc. if you have to, but this may prevent using the Kobalt charger (and/or using it with an other Kobalt tool).
I do have one "control motor torque (current)" speed control switch, and I will use it at first.
Just so you know, a switch doesn't actually do anything but switch things; it doesn't actually change motor torque or current, unless it is supported by the controller itself, no matter what the switch itself is called.
If you already have a sensorless ebike controller, that doesn't directly control the current (most don't, just the speed), then the switch doesnt' do what it says, it just controls the speed (assuming the ocntroller itself supports even that (not all do)).
Also, I can't not figure it out yet how to re-use the bail-clever and safe button to use with the ebike controller.
"Two ways to start:
1. hold button A and pull bail B
2. Pull bail B and press button A" (then I can release the button A)
with 3 wires coming out, in my guess is 1 of the wire is sending to signal to light up the battery indicator at the button.
It depends on how the switches work.
1 Set your multimeter to continuity or 200ohms. Put red lead on first pin of the switch connector that goes to the switches. PUt black lead on the next pin. The meter should beep or read a very low number for a connection, and OL (or whatever your meter manual says) for no connection.
2 While measuring that first wire pair, activate the bail and note the results.
3 Deactivate the bail and activate the safe button, and note the results.
4 Move the red lead to the next pin, and repeat #2 and 3.
5 repeat this until all combinations of pins have been tested and noted.
Now you have a chart that shows you which pins are connected or disconnected by activating or deactivating each of the two switches.
There is probably one common wire between them, and one wire that is the "signal" for each switch. If so, you may only be able to use one of the switches, unless you rewire each switch to be independent two wires. Depends on what you want to use them for.
If the bail is the hand control used to start the mower, then that is the one you use to pass the throttle's output signal wire to the controller's throttle input wire.
If the bail is just another safety switch, and you have a separate hand control switch to activate the mower, and the bail and safety button are wired to the same 3-pin connector with a common wire between them, and they both are "NC" or Normally Closed switches (shorted except when pressed or "on") then you can wire them both to the Ebrake input of the controller, so that they keep the controller disabled except when the safetys are turned off.
Using alligator clip leads will help hold them in place if you need more hands; there are also holders called "helping hands" that even harbor freight carries that help you hold stuff while you work on it.
If you can, I would recommend drawing up a wiring diagram for the parts on the mower as you test them, in a way that you will understand and be able to refer to as you change out and connect the new controller and do testing, etc. Then if you need to fix things later you also have something to refer to without having to remember why things are wired the way they are.
The battery indicator has 5 wires. What do you think?
The battery indicator 5 wires are probably four individual wires to each LED, plus a power or a ground, if there are four LEDs. There are battery meter chips out there you can buy and wire up to re-use them, but you do have to build some other circuitry around that to make them work.
If it uses something else, I'd need to know what that is before I could make much of a guess. You'd need to get pics of the actual battery indicator board, if it's accessible, for us to see what electronics it has on it (if any) to help determine how you might re-use it (if it's possible; which it probably is).
Originally the controller drove the indicator in some way, which makes sense since it has to have an MCU on it to do the motor controlling anyway. (if not driven by the MCU, it's probably a separate battery meter/indicator chip on the controller board, under that potting).
It is probably easier and cheaper to buy a separate battery meter, or use one already mounted in a throttle.
So far, the only part that I will try to replace is the controller, everything is there: battery, switches, motor. The ebike controller have 3 speed dial, I will play round to find out what is the best speed to run it.
The "speed dial" in most cases only changes the amount of voltage going to the mower motor (and blade), not the power going to it. Generally, you want the speed of the blade to remain at the same speed so it cuts correctly, and moves the cooling fan for the motor (if it has one; it's common) at the right speed to move enough air to keep it cool.
If you want to control the power of the motor, the controller has to be designed to actually be a torque/current control type (FOC controllers do this, but so do some "regular" controllers, in a different way), and that switch has to actually change what current the controller provides to the motor. Typical cheap bike controllers don't do this; just change the speed.
Changing the speed does change the power used, but it also changes the speed.
Changing just the current limit to the motor doesn't change the speed of the motor, *except* when the power needed by the motor to maintain that speed (like when hitting heavy grass, etc) is greater than the limit. So for this purpose, it's a more effective way to prevent motor overheating, excess battery drain/load, etc.
When it started to run for 3s, it actually gave a big torque that twisted the body of the mower a little bit, and since it doesnt have a hall sensor. I assumed that is a "ok" and not worry much about.
Most likely it means the motor is fine (since it gave you the voltages on the wires when you tested it spinning, it also means i'ts probably fine).