65F super capacitor as short time power backup

I use 13.8V DC DC regulator to power a 110V inverter that can take 11-15V on input.

When DC-DC converter is on, the 65F capacitor charge through the resistance.
If the DC-DC converter goes of, the capacitor power the inverter input through the diode. It will be a short among of time but enough for the need.

My question: Does the tension apply on the line by the capacitor can damage the output of the DC-DC regulator when it is down ?

DC-DC regulator: B62SR13722CC / partNum

Super capacitor: XVM-16R2656-R / partNum

Interesting in your opinion on this circuit.
Thank you!

Hi GaelDV,

Welcome to the Tech Forum.

That is a very good question. The datasheet does not specify whether the B62SR13722CC can tolerate a voltage on the output when it’s input supply is off (zero volts). However, at least for short-term conditions, I believe it can tolerate this state, since this is a common occurrence when powering a capacitive load. With a capacitive load, when the input supply is cut off, the output voltage will always be higher than the input voltage for some period of time before the charge in the capacitive load is dissipated.

Even though it should be able to handle the short-term conditions described above, it does not guarantee that it could handle this for longer-term conditions. I will send an inquiry to the product manager for Delta to see if they can get an answer to this question definitively.

There is a means of guaranteeing protection to the B62SR13722CC by placing a diode in series with it’s output. Unfortunately, this would result in a diode voltage drop to both the the capacitor and the load.

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thank you very much for your quick answer and for asking Delta about this!

Your answer confirms what I was thinking.
In first option, I think to the protection diode too, that would indeed solve this question of the DC-DC converter output.
The additional voltage drop of the diode would be OK for the inverter as it can take as low as 11V.
But the problem would be that it reduce the capacitor full voltage and so it’s ability to be used as a backup as long as possible. Also the Schottky diode between the capacitor and the load would be constantly “leaking”, no ?

Looking forward to have feedback from Delta.

Thank you!
G. Della Valle

Hi GaelDV,

Yes, the second diode would reduce the voltage to the capacitor, which would reduce its maximum charge storage. It would also reduce efficiency and produce additional heat .

Regarding leakage, I believe that the relatively high diode reverse-mode impedance would be sufficient to protect the DC-DC converter.

One other indirect clue to the internal characteristics of the B62SR13722CC is that the datasheet states that it is capable of operating in parallel mode with another B62SR13722CC without any special circuitry to synchronize their operation. To do this safely, it SHOULD be designed in such a way that if one of the two were to either fail or be turned off, that the other would not be damaged. This does not prove that it can handle such conditions, but it strongly implies so.

As soon as I hear back, I’ll let you know what I find out.

Best regards,

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Hi GaelDV,

I received confirmation from Delta that the B62SR13722CC can tolerate a voltage as high as its nominal output voltage where its input is off. So, it should not require that extra diode for protection.

Best regards,


Great News!
Thank you for your efficient support.