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[byronvoyle]

Hello, I am trying to upgrade my e-bike controller from 48V to 72V. I tried connecting a 72V battery to the 48V controller, but then one of the five large capacitors (740µF 63V) blew up. After checking the MOSFET specs inside I know they have a max voltage of 68V and a current of 120A. Is it possible to upgrade this controller to work stably with 72V?

Any advice from anyone. Thanks.

[Grauteufel]

No it is not likely possible with your controller. A "72 volt" battery probably sees peaks around 84v. Its not just the fets that need to be rated for this voltage, the isolation of all the traces and every component needs to be able to meet this. It would be cheaper, easier and more betterer to just replace the controller with an appropriately rated one.

[flynnstig82r]

The Endless Sphere forum is the best place to ask about e-bike components and mods, FYI. You might get a few people who know about such things here, but it’s not the main topic of the forum.

[hotsauce]

No, a 48V controller is made of parts to work with a 48volt battery. Different battery needs a controller intended to work with it. Additionally, your motor needs to be able to handle what the controller is sending to it, as do all the wires in between. So yeah upgrading your battery essentially means you have to upgrade your controller and motor as well

[Specter]

What about the drivetrain?  Will it be able to handle the extra torque?  There's not much over engineering in stuff like this, they make it cheap to keep prices down, not a lot of headspace and overspecs going on.

This is probably not a good idea, and the fact that you went and threw a 72 volt battery on a 48 volt system, shows you don't know nearly enough about how systems work, to do it properly.  What are you going to do to tame the flyback?

aaron