Key ignition solutions

[jgetma]

I purchased a Sabvoton controller with the LCD screen - apparently the LCD version does not come in the ignition lead to the controller. Id like to use a key switch to toggle electrical power to the ebike. Key in off position - no electrical power. Key on = power on. I was going to use the BMS for this, but my BMS does not have a hard on/off switch either.

The main circuit will carry peak ~200A @ Nominal 72V.

Relays in this range appear to be hundreds of dollars.

I believe a contactor can also serve this purpose but, again, one with the right specs cost many $$$$

What is the best-practice solution for toggling the main power circuit using a key ignition switch?

 

[qwerkus]

I purchased a Sabvoton controller with the LCD screen - apparently the LCD version does not come in the ignition lead to the controller. Id like to use a key switch to toggle electrical power to the ebike. Key in off position - no electrical power. Key on = power on. I was going to use the BMS for this, but my BMS does not have a hard on/off switch either.

The main circuit will carry peak ~200A @ Nominal 72V.

Relays in this range appear to be hundreds of dollars.

I believe a contactor can also serve this purpose but, again, one with the right specs cost many $$$$

What is the best-practice solution for toggling the main power circuit using a key ignition switch?

Don't know about Sabvoton - don t have one. But I can tell you that most controllers come with a simple unlock mechanism, where the Vbatt+ goes out to the display and comes back to the controller (blue line) before reaching the 5V subsystem that powers the microcontroller and tributaries. That way powering on the display shorts those two lines and effectively powers on the controller at the same time
Most key locks are placed in series on that Vbatt+ line before it reaches the display.

 

[Balmorhea]

https://www.ebay.com/itm/300a-Auto-Car-Boat-Battery-Disconnect-Safety-Kill-Cut-off-Switch-2-keys/223531939079

This kind of switch for RVs, boats, and equipment isn’t usually rated for 72V, but some are rated for 60V. Unless there's a load on it when switching, or a very aggressive capacitor spark, I doubt that your voltage would be a problem.

Heres one that claims 60V 300A, but it’s shipped from China.

https://www.ebay.com/itm/60V-300A-Battery-Isolator-Disconnect-Cut-Off-Power-Switch-with-Removable-Key/312776976035

 

[Super-Ev]

I have the same issue here, I too ordered the Sabvoton and received the modified ebike version without 3-speed-switch or ignition.

From what I have read online, it seems like the controller also runs slightly modified software. But then again, I have seen people splice cables into sabvoton with varying success.

Now, I don't have a picture of the original 72200 PCB but I do have my own Sabvoton 72200 and some pictures of 72150 which seems to have the same PCB and wiring layout.

From first glance, it seems like the obvious orange wire that goes across the whole board to the positive pole could be our culprit. I know that the orange ignition wire needs to be shorted to positive for the controller to turn on.

I also know that the TFT display uses the blue cable for the middle on/off button.

This is my controller now, I'm holding the display plug cable and showing where the blue cable leads.

I have already spliced a cable into it, before posting here, I guess I've already committed.

However, in the 72150 picture, there are actually 2 orange wires, one goes to the C127 pin in front and the other goes right next to positive. I'm assuming that even if I got the right wire, this will not be effective due to software.

If anyone can stop me in time, please do. I will update shortly with the results. lol

PS. I am trying to install a key switch to my sabvoton without connecting the TFT display. (with Bluetooth).