Capacitor battery - suitable replacement?

[OpenCedar]

I have a .047uf 5.5v capacitor acting as a battery. It's corroded, so I want to replace it.

Strangely, nothing comes up on mouser... is this an obsolete item? What should I replace this with?

The ones I am finding are silly expensive.

Can I slot a different value cap in? Is it the voltage rating that really matters? Does it have to be a special kind of cap, or can I use an electrolytic or film cap?

Many thanks!

 

[KlausST]

Hi,

I guess it´s rather a 0.47F than 0.047 mircofarads. Please check. In doubt post a photo (100kBytes should be sufficient)
Try: "goldcap" or "supercap", "supercapacitor", "ultracap" "EDLC" ..

Klaus

 

[OpenCedar]

Hi,

I guess it´s rather a 0.47F than 0.047 mircofarads. Please check. In doubt post a photo (100kBytes should be sufficient)
Try: "goldcap" or "supercap", "supercapacitor", "ultracap" "EDLC" ..

Klaus

I double checked when I had issues. It is indeed a .047.

Mouser has the type here:

https://www.mouser.com/c/passive-components/capacitors/?voltage%20rating%20dc=5.5%20VDC&sort=capacitance

I found it odd there was nothing in this uf range. Is there something I am doing wrong?

 

[KlausST]

Hi,

0.047 ... but what unit? Check this.

1F = 1 Farad = 1000 mF = 1,000,000 uF
mF = miilifarad
uF = microFarad

Supercaps, Goldcaps are in the region of several thousand to several million microfard.

0.047 F makes sense,
0.047uF makes no sense

Klaus

 

[OpenCedar]

It says microfarad in the service manual screenshot I red circled.

 

[stenzer]

Hi,

to act as a "battery" 0.047 µF ( = 47 nF) are for sure way to low. The voltage rating of 5.5 V are indicating a super capacitor, but without a picture including the dimensions of the capacitor, which should be replaced, we can not give an adequate answer. So we can only guess, and according to the shown values you even migth use a MLCC in a 0201 package.

Is C305 the correct reference designator? I assume, as you have the BOM, you also have the schematic, which you might also share, at least a snipped including the capacitor in question.

BR

 

[KlausST]

Hi,

I just checked the mouser link
I agree it also says microfarad.
But the darasheet of the supercaps says 10mF ... 1000mF which is 10,000uF ... 1,000,000uF or 0.01F ... 1F.
There is a lot wrong information theree
But be sure: the datasheet is correct.

If you've read some of my posts: I always recommend to use the datasheet directly from the manufacturer.

It's 0.047F supercap at 5.5V.
Farnell lists about 20 of them.

Klaus

 

[OpenCedar]

Hi,

to act as a "battery" 0.047 µF ( = 47 nF) are for sure way to low. The voltage rating of 5.5 V are indicating a super capacitor, but without a picture including the dimensions of the capacitor, which should be replaced, we can not give an adequate answer. So we can only guess, and according to the shown values you even migth use a MLCC in a 0201 package.

Is C305 the correct reference designator? I assume, as you have the BOM, you also have the schematic, which you might also share, at least a snipped including the capacitor in question.

BR

Hey, sure. See attached. The cap is arrowed. It shows the same value.

 

[betwixt]

That has nothing whatsoever to do with a battery, it is a supply decoupling capacitor. It is also very unlikely it is corroded and equally unlikely to be rated at 5.5V.

Are you sure you are looking at the correct component.

Brian.

 

[stenzer]

Hi,

please share a picture of your "corroded" capacitor, and give us some dimension information. The symbol in the schematic looks like a electrolytic capacitor, but the polarity information is missing. The schematic would indicate a capacitance of 47 mF. For comparison, have a look at capacitor C307 and C308 which are indicating a capacitance in (p) pico farad. Further, the voltage rating of 5.5 V is quite unusual.

BR

 

[KlausST]

Hi,

Here wrong data, there wrong information.
A photo, like already requested in post#2, shows the reality.
Photo of the part of the PCB, photo of the capacitor with all it's markimgs.

Klaus