How are the electrical components connected?
- Thread starter juntjoo
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stancecoke
1 MW
For a dual motor bike you need a dual controller.
Each controller has three half bridges, that are triggered by a processor, to power the three coils of the motor in a way that the motor turns.
There are tons of literature about driving a BLDC motor....
e.g. here:
resources.altium.com
There is a big variety of dual motor controllers available.
Each controller has three half bridges, that are triggered by a processor, to power the three coils of the motor in a way that the motor turns.
There are tons of literature about driving a BLDC motor....
e.g. here:
How to Make Advanced BLDC Motor Controllers
In this project article, we’re going to be taking a different approach to my typical project. Driving a brushless motor is relatively simple from a schematic perspective; however, there is a large amount of theory about brushless direct current motors that you need to understand to be...
resources.altium.com
There is a big variety of dual motor controllers available.
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@stancecoke yeah, they look like mine
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@stancecoke and so how would you connect another battery?
stancecoke
1 MW
Hm, strange question. Just connect the battery to the controller. Often simple Japan bullet connectors are used.
red to red, black to black.
Some advanced Ebike drives need a communication by CAN or UART with the battery, but your photos seems to show a cheap chinese system. It will work with just + and - wires. Of course you must use a battery with the right voltage for the motor and the controller. Most run with 36V or 48V nominal voltage.
Your first question was pretty harmless, but once you move to batteries, it would be best for you to provide some background on what you are trying to accomplish. Nobody here wants their information or advice to lead to a fire or harm to anyone, since batteries can be dangerous, and there are more things to consider besides connecting them together (e.g. a safe charging routine, type of BMSs used, etc.).
I've read others saying you can add one of higher voltage just not too much. And I think you use a battery "mixer" or something. Not actually trying to, just wondering how it all works
Someone with my bike said they connected one extra battery to just one of the motors. But if battery power is to go straight to the controllers, which controller? I still haven't taken it apart enough to see how it's all connected. Not trying to add another battery. Just trying to figure out how it works
Just want to know how someone did it. I have other curiosities about these machines and what I may want to do with mine. Just trying to figure out what I'm looking at and how it all connects and works
Adding batteries in "series" will increase the total voltage (add the voltages of the two batteries). Adding batteries in "parallel" will maintain the same voltage, but increase the current capability (add the current capability, in amps, of the two batteries). A series connection is like an old flashlight where you have a couple of batteries in line with each other, positive to negative. A parallel connection connects the positive of one battery to the positive of the other, and negative to negative.
The boxes used to "combine" batteries in parallel, will not obtain these benefits, in favor or provided a greater margin of safety for the novice or for folks that worry about messing up when charging or discharging packs configured in parallel (like ensuring both packs are at the same voltage. the combiners allow them not to be at the same voltage, but don't provide the higher current capability).
The charging routine is important when you don't use a combiner, but most experienced folks will take to extra care to follow safe practices, in order to obtain the performance benefits. There are also technical considerations with respect to the battery pack BMS's used, which may or may not support series or parallel configurations.
stancecoke
1 MW
You have to tell us more about your system.
Do your bike has two controllers in two housings, like in my first link? Then it's easy to run one motor from one battery and the other motor from a second battery. If the two controllers are in one housing, it's more difficult, as the controller will share the DC rail for both motors.
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Yeah, two, double check the pic I posted above. They both fit in there with the bb.
So how does my battery connect to both my controllers?
Both controller need battery input, but it depends on whether you have two separate/identical controllers, or have two controllers that are designed to work in a dual configuration, in a master and slave setup. There are also controllers that have two controllers in one housing, like stancecoke posted above, so there's only one battery input.
If I were to guess, it looks like you possibly have a master/slave setup, or two identical controllers. But for your battery question, it appears that both controllers have battery inputs, since downstream of the XT60 connector below, from your pic, you can see both the red and black conductors split into two, with one red and black going to one controller, the others going to the second.
If I were to guess, it looks like you possibly have a master/slave setup, or two identical controllers. But for your battery question, it appears that both controllers have battery inputs, since downstream of the XT60 connector below, from your pic, you can see both the red and black conductors split into two, with one red and black going to one controller, the others going to the second.
@E-HP ah. Master/slave it seems. It's tight in there unless I take off the other side panel to get a better look at everything.
So the guy who said he connected an extra battery to one motor(someone in some YouTube video comments) disconnected that Y cable to the one motor and connected the extra battery to the one controller? It's a 48v system and he hooked up a 52v battery to one motor
Could he have connected it in parallel with the main battery to ensure even discharge of batteries? Would that be something a "combiner" helps with?
So the guy who said he connected an extra battery to one motor(someone in some YouTube video comments) disconnected that Y cable to the one motor and connected the extra battery to the one controller? It's a 48v system and he hooked up a 52v battery to one motor
Could he have connected it in parallel with the main battery to ensure even discharge of batteries? Would that be something a "combiner" helps with?
The combiner would be necessary when using two different battery voltages. The system would only draw from the battery with the highest voltage, and switch when it drops lower or equal to the second battery.
But from your description, it sounds likes like he’s powering one controller at 48v and the other at 52v, which is possible, but the 52v motor would be doing most of the work on flat ground.
So then would you get more even power distribution to the two wheels putting batteries together in parallel behind that Y splitter cable?
Chalo
100 TW
You can't put two batteries of different voltage in parallel, because the higher voltage one will dump current uncontrollably into the lower voltage one.
Isn't that what a battery blender is for?
Alternatively then two equal batteries can be straight connected in parallel, but with my master/slave controller setup would you then just connect each battery up to one controller each or would either way work equally?
ZeroEm
1 MW
No. The batteries are NOT in parallel when using the blender. The blender decides which battery powers the whole system based on which battery has a higher voltage. It won't affect power distribution between motors.
If they are connected in parallel (assuming the same voltage packs), then they are easier to manage since one won't run out of juice before the other, so you only need to monitor the combined charge level. As I mentioned before, you need to be careful and have a clear understanding of the dangers and how to mitigate them. I hope I never lose the healthy fear of managing my batteries. I have too much to risk to ever lose that.
Chalo
100 TW
A battery food processor doesn't put them in parallel. It uses the one with higher voltage by itself until it falls below the voltage of the other one. It's worthless; worse than using them one at a time.
stancecoke
1 MW
Depends on the controller. With FOC controllers normally the motor current (the torque) is controlled. If you demand a certain torque with the PAS level or the throttle, the voltage of the battery is irrelevant, a higher voltage would just lead to a lower duty cycle, to get the demanded torque.
