Hi, I'm hoping I can get some help. I had a brilliant idea to install a clock thermometer into my boat and hard wire it, I used a dc buck converter to drop the voltage to I believe 1.5v the issue is that every time I start the boat or trim the engine without the motor running the clock losses too much voltage and resets itself, I would like to install a diode and capacitor to power the clock during this voltage loss up to 5 mins basically I would like the clock to run for 5 mins after the boat battery its disconnected before it runs out of power, the clock draws very little amperage I don't think could even read it with my cheap harbor freight multi meter, the other thing is that the boat is only used once or twice a year and I need something that will repower when the battery is connected like the mem circuit of a car radio and be fine without power the rest of the time... If anyone could tell me what I need and how to make this work I would appreciate it.

 

You could likely put a "super Capacitor" between the buck converter output and the clock power. When you start or trim the battery voltage drops below the threshold of the existing buck converter so it drops out.

Ron

 

You could likely put a "super Capacitor" between the buck converter output and the clock power. When you start or trim the battery voltage drops below the threshold of the existing buck converter so it drops out.

Ron

Yes I think that's what's happening would I need a diode between the buck converter and the cap and what type of "super capacitor" would be sufficient to get me 3 to 5 mins, I really have limited knowledge in this any help is appreciated

 

Shouldn't need a diode there. I doubt the super cap would back feed into the buck converter. That is why I would put the cap there and not ahead of the buck converter on the 12 volt side. Most super caps I am seeing ate rated at around 5.5 volts so if you have about 1.5 volts it should work fine. I am guessing the clock / thermometer is very low current, pure speculation on my part. Even something like this would be overkill but if you are in fact running 1.5 Volts it would work. Two in series would get you a 5.0 volt rating and last hours. Again, less knowing the current needs it is a guess.

Ron

 

Battery backup. Put a diode in the feed line and put a 1.5V battery in parallel with the output of the converter. Change the battery once a year.

 

Battery backup. Put a diode in the feed line and put a 1.5V battery in parallel with the output of the converter. Change the battery once a year.

That's exactly what I am trying to by pass a separate battery

 

Shouldn't need a diode there. I doubt the super cap would back feed into the buck converter. That is why I would put the cap there and not ahead of the buck converter on the 12 volt side. Most super caps I am seeing ate rated at around 5.5 volts so if you have about 1.5 volts it should work fine. I am guessing the clock / thermometer is very low current, pure speculation on my part. Even something like this would be overkill but if you are in fact running 1.5 Volts it would work. Two in series would get you a 5.0 volt rating and last hours. Again, less knowing the current needs it is a guess.

Ron

Yes very low current draw if i remeber correctly cheaply multimeter wouldn't read the draw, would a n10041 diode before that cap you linked be sufficient as a precaution to not backfeed the buck? And also since I don't understand much about electronics in depth, will putting the cap create more of a power draw consistently or just while the cap is charging, thanks so much for your help

 

"That's exactly what I am trying to by pass a separate battery"

Does the statement mean that the whole point of this thread is to accomplish this task without a backup battery cell?

What could be faster, easier or simpler than installing a small battery once a year?

 

"That's exactly what I am trying to by pass a separate battery"

Does the statement mean that the whole point of this thread is to accomplish this task without a backup battery cell?

What could be faster, easier or simpler than installing a small battery once a year?

Yes exactly correct without battery backup, and nothing would be faster or easier or simpler, but I just want to hook up the boat battery and be done I don't want to have to screw with other little batteries around the boat... That was the point of the buck or I could've just used the clock as is and installed batteries in it once a year and avoided myself allot of headache lol I never thought of the voltage drop from the boat without the boat running but now I like the idea of no little clock batteries I like rons suggestion of a super cap it would be easy enough to do! Thanks for your ideas