-1
$\begingroup$

I've just burnt out an L298n H bridge, not surprising, but I thought it'd be ok for low load testing. Apparently not.

I'm considering ordering these to replace them - Hilitand DC 5-12V Motor Controller, Dual-channel H bridge Motor, Driver Board Module 0A-30A

Only problem is my chassis is running on a 4S pack - maximum voltage 16.8 V and these are limited to 12 V.

My theory is that if I limit the duty cycle to 71.5% they should work...

However, I know that PWM duty cycle is not actually the same as an analogue out. My question is, does the community think these will get burnt out too?

$\endgroup$
2
  • $\begingroup$ The load (a motor) is inductive, so i'm leaning towards "it will be fine"... But then again the voltage is still on the input. $\endgroup$
    – Ben Bird
    Commented Aug 14, 2022 at 20:24
  • $\begingroup$ Also, people that spend their time editing minor grammatical errors and hyperlink format for reputation points, need to have a long hard look in the mirror. $\endgroup$
    – Ben Bird
    Commented Aug 15, 2022 at 18:25

1 Answer 1

0
$\begingroup$

The L298 part is rated at 50V abs max so hitting it with 4S is probably not why it burnt out. The peak output current rating is 2A abs max (continuous; 2.5A at 80% duty cycle). You didn't say what was your load, but I'd hazard the guess that it was sustained overcurrent that did the damage. Bear in mind that abs max ratings are not suggested design points.

However, the Hilitand part that you cited is rated for 13V, 14.6V max (if we can rely on what was published on Amazon). That's the max you can apply to the device, not the max voltage you deliver to your load. So, limiting the duty cycle won't work. If you hit it with your 16.8V 4S, I would expect a failure before long.

While on the Hilitand page, I noticed that it shows 30A max, far greater than the 2A L298. When I see an order-of-magnitude change in my designs, I reflexively look for a mistake.

$\endgroup$
2
  • $\begingroup$ Yeah the motor current is around 8 amps at stall. I presumed (incorrectly) that it would be fine for no load benchtop testing. If the Hilitand ones burn out after a few hours that's fine. I just need to get the PID loops tuned properly. Once that's done I can justify the project and get the contract. I considered BTS7960B motor drivers, but 4 of them won't fit in the chassis (even stacked in pairs) and i need closed loop control on 4 drive motors. Do you know of any ~8 amp max, 17V min H bridge drivers that arent too big? $\endgroup$
    – Ben Bird
    Commented Aug 15, 2022 at 18:24
  • $\begingroup$ Sorry, I don't know such drivers offhand. My next step would be a web search (broader than Amazon), but that would your next step too. $\endgroup$
    – r-bryan
    Commented Aug 16, 2022 at 2:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.