DIY Electric Skateboard

Well if it's going bad when your on it, it could be that the load (motor) is creating a lot of heat to start turning. Maybe put on some heat sinks or try a similar motor. If nether work, try a different circuit design for your h-bridge

>>1215411
I thought that too, but the MOSFET didn't feel hot at all after it blew up. I just heard a pop and it stopped working.
I'm actually just using a single MOSFET to control the motor, not a complete H-bridge. I need something simple to work before I make it more complex.

Note: I am using a flyback diode with the motor.

Are your mosfets on heatsink? Normally mosfets need heatsink to stay at their rated amp draw for any period of time. Also the data sheet indicates that package limits the mosfets max current to 78A, see foot note 4. The new ones should work.
As for the motor, it will draw near stall current briefly while starting up. You can use the performance chart and table to estimate running current at various loads. Ofc if your fat ass is too heavy and stalling the motor you might need to add some gearing or belting for more torque at the wheels.

>>1215425
Read before posting. It's possible that your mosfet is being overpowered. If you have a multimeter check the active (while motor is spinning) current draw. Check the specs of the mosfet to see if it can handle such power. Might find something that way

Consider a soft start?

>>1215425
Lol thanks for the response. I believe I did put a heatsink on it. I have a 3:1 pulley ratio.

Not sure if this info is relevant, but in the first test run, I had a single mosfet and after it popped the motor just went full power.
The second time was with 3 mosfets in parallel, and there was just no response when one of the mosfets popped. I tried to see if I could still use the last 2 (with the popped one removed) without load and it failed spectacularly.

I think the next time I try I should give it a push first so that it doesn't have to move me from a complete standstill.

>>1215434
I thought PWM = the pulsed drain current specification.
My multimeter showed about 3-4 amps when spinning (without load, but connected to the pulley and wheel). I won't be able to measure it with me on it since that would be going way over the 20 amps max my multimeter can handle.

>>1215459
How are you limiting current on this?

>>1215459
Get a rag and wrap it around the wheel and grip the rag with your hand, or twist the rag to get more friction. The Amperage should go up

I haven't seen your wiring diagram but it sounds like you're putting all the amps through a MOSFET. Use a relay. A high power circuit for power and a low power circuit for logic. Keep them separate.

File: P_20170724_184121_vHDR_Auto.jpg (1MB, 4656x2620px) Image search: [Google]

1MB, 4656x2620px

>>1215461
There's no current limit on this. I was thinking of buying a hall effect current sensor, but that costs like 15-20 dollars more.

>>1215486
Yeah, I've tested without me on it. The current does go up with increased resistance. But I can't measure the current without buying more stuff (as stated above). I kinda just want this prototype, and make upgrades incrementally.

>>1215492
I thought of using a relay, but they seem much bulkier if handling high currents like this compared to MOSFETs. I also want proportional control which I've done with an Arduino and Wii Nunchuk.

My circuit is really simple honestly, but here's a pic for reference.

>>1215454
Yeah, mosfets fail in closed mode. So if it blow the motor will go 100%.
Maybe try IGBT instead of mosfets, or 4 mosfets in parallel, maybe 4 40amp mosfets will run better.
Could be also, you have fake mosfets.

>>1215516
>driving the gate with 5V
Going to need more than that to make sure it saturates.
If you're driving it directly from an arduino the MOSFET is probably spending too long in linear mode causing massive heating (i.e. explosion). For something like this you'll need a gate driver than can push-pull a few amps.

>>1215698
I thought 5v wasn't enough too, but the MOSFET was is supposed to be logic level. I've let it freewheel for a few minutes and the MOSFET doesn't go above 40 deg.
But I don't know much about this, learning through trial and error. If I want more current to flow through, would I need to increase the gate voltage or current to make sure it saturates.
I've tried powering it with 3.3v before and I can see that it heats up a lot when that happens.
Would a logic level converter (from 5v to ??voltage) be sufficient? Thanks

>>1215698
I see a lot of "@ 10v" on the datasheet, so I assume the MOSFETs work best at 10v and above. Correct me if I'm wrong.