beagleboneblack don't restart after power fluctuation.

I’ve connected beagleboneblack to my car power supply with 24V to 5V step down. when I power on my car the BBB starts but when I ignite the engine BBB stops running and don reboot though the power led is on. Can I fix it with software change mentioned at!msg/beagleboard/aXv6An1xfqI/mURD3LfQ5dMJ?

The reason it powers off is because your ignition switch is not providing constant power when you turn the key to start. I would try to find a power source that has power when key is set to on and start.

Ya I got that! But I am looking for some aiding reactive circuits or some magical software fix!

Ok so why not add a cap to the circuit to keep it powered while you start the car.

cap? is it some electronic circuitry? I donno much abt electronic circuits but i can solder few resistors, capacitors and diods on a board. Any help is a gr8 favour…
Thank you.

Cap = capacitor. Just make sure that it is the right size for where you put it in your circuit. If it is too small i can explode and possibly start a fire. In your original post you stated that you have a 24V to 5V step down, so if you place it before the step down make sure it is at least rated for 24V or if you place it after it has to be at least 5V. You may also consider a voltage monitor circuit to safely power down your BBB to avoid corrupting the file system.


Thank you. I will give a try. As per the post here!msg/beagleboard/aXv6An1xfqI/mURD3LfQ5dMJ? the power source should have proper rise time. I’m afraid a capacitor will increase the rise time. Any way I’ll give a try.

I think you should be fine as long as you don’t use a value that is too high or too low. Too high may cause problems with rise time and too low may not keep enough power supplied for the board to stay powered up. Also caps aren’t like batteries, the charge almost instantaneously where as batteries need time to fully charge so as long as you can get the cap charged fast enough the board should power up without any problems.


I’ve connected beagleboneblack to my car power supply with 24V to 5V step down.

24V “power supply” in a car? If this means you’re this from the accessories circuit, you’re doomed. Accessories are turned off while the car is being started, and a cap won’t be enough to power the beaglebone, since they stay off as long as you’re turning the engine. Another problem is, you’ll corrupt the filesystem with an out-of-the-box beaglebone. You’ll have to use a read only file system.

You could tie the beaglebone directly to the battery (with a fuse of course) and use some circuit to monitor when to turn it on and off.

Not necessarily , my car is a 95 3kgt and it starts within 1-2 seconds of turning it over. A cap big enough should be able to handle that. As for the 24v idk how I didn’t catch that, but then again who knows it is possible.


A cap big enough should be able to handle that.

Not sure if I did my math right, but for 2 seconds at 2W (beaglebone will be booting), and assuming his 24V to 5V regulator can regulate with an input voltage all the way down to 12V, that’s around 20mF. I guess that’s doable with $$$.

It wouldn’t be as simple as connecting the cap to the accessories line, since this would absolutely destroy your relay contacts from the inrush in charging this gigantic cap from 0V. And, you would have to throw a diode in so you didn’t power all of your accessories with this cap.

Very true. So I guess even just using a li-po or li-ion on the bone would be much easier.