Replacing Capacitor on Main Control Board With A Watch Battery Housing?

[Dwassner]

For years I have not used the Night Set Back feature on my Lochinvar WHN055 because when we have power outages, the date and time needs to be manually reset, which is kind of a pain...

Per the Lochinvar rep, the capacitor on the board is bad, otherwise the unit would remember what time it is during the outage.

Has anyone here replaced a capacitor on a control board? And as a further thought, would there be a way to solder on a watch battery socket in place of the capacitor instead, so as to make it easier to change out? I don't know why they would not have done something like this in the first place...

FWIW, I actually have two control boards for this boiler, and surprisingly, even the BRAND NEW board has a bad capacitor...

 

[Dwassner]

here is the board:

 

[Sponsor]

 

[Reach4]

I am not familiar with your unit or anything like it. Is there a piece that goes on the wall, that you read and adjust? That is what I would think would have the memory stuff.

 

[Fitter30]

Wouldn't the new board have a warranty?

 

[JohnCT]

You do not want to install a watch battery in place of a capacitor unless you intend to change the circuitry as well. A capacitor only stores a charge, so that means during the time the board is powered up, the board is placing a voltage across the capacitor. Batteries do not like having voltage placed across them unless they're rechargeable. If the voltage is higher than the cell's voltage, it will damage it. If the voltage is lower than the cell's voltage, the cell will discharge until it meets the level of the capacitor charge. You can add one or more diodes from the battery to the board to keep the battery from discharging until the power goes out.

A quality capacitor used for memory will last a good ten years or longer. A watch battery will have a shorter life than that.

John

EDIT: I don't see anything on that board that looks like a memory cap, but there is something that does look like a small lithium battery soldered on the board. If you can host a large file pic of that board we can get a better look.

.

 

[Fitter30]

You do not want to install a watch battery in place of a capacitor unless you intend to change the circuitry as well. A capacitor only stores a charge, so that means during the time the board is powered up, the board is placing a voltage across the capacitor. Batteries do not like having voltage placed across them unless they're rechargeable. If the voltage is higher than the cell's voltage, it will damage it. If the voltage is lower than the cell's voltage, the cell will discharge until it meets the level of the capacitor charge. You can add one or more diodes from the battery to the board to keep the battery from discharging until the power goes out.

A quality capacitor used for memory will last a good ten years or longer. A watch battery will have a shorter life than that.

John

EDIT: I don't see anything on that board that looks like a memory cap, but there is something that does look like a small lithium battery soldered on the board. If you can host a large file pic of that board we can get a better look.

.

Is that the battery far left middle of the board silver in color? That make more sense than a cap being that having two bad boards. That board has been replace with a new number in 2017 according to a.part search.

 

[JohnCT]

Is that the battery far left middle of the board silver in color? That make more sense than a cap being that having two bad boards. That board has been replace with a new number in 2017 according to a.part search.

What I'm seeing as the battery is on the right edge of the board (opposite side of the four white connectors).

John