Electrical wiring - 12 volt

[Ohgoodiee]

Can anyone explain why there is a gigantic capacitor behind my electric panel. Thanks much in advance.

Doug

[NavySub761]

Looks like an A/C Fan Cap... I am new to RV's, but that would be my guess.

[tranquility]

I agree. Given the draw on the A/C units, a capacitor is required. Same on a residential unit. Extends the life on hermetically sealed compressors on start up.

[NavySub761]

There are a few reasons with adding a cap to a motor.. but the main reason is for starting torque on an a/c compressor..
Read this, it explains more than I could.

http://www.brighthub.com/engineering...les/44951.aspx

[Ohgoodiee]

Hi guys and thank you for taking the time to answer my question. It turns out that is to prevent spikes in the 12 volt system (see pic - it's on the 12volt side of the electric panel). An example would be if you had all of your 12v lights on and kicked on the furnace or if you plugged in your converter with the furnace on.

[EMD_Driver]

Thanks for letting us know what it is there for. I wouldn't think a 120VA capacitor would have bare terminals like that. Are there any part numbers on it? Looks like something I would like to have in our 5er...

[Engineer Guy]

I'm thinking it's a +12 VDC 'smoothing' Capacitor. They have a 'flywheel' effect by absorbing transient Spikes and DC perturbations. They're also commonly used in Audio Systems to coast the +12 VDC supply through brief, periodic power drops.

I can't find a 'good enough' Article to link right now.

Measure across the Capacitor and to Chassis to confirm the Voltage on it.

[wa8yxm]

Is (or was) your Converter a Magnatek 6300 (or your power panel)

Magnatek had an optional "Battery Simulator" for those who wished to run the unit without a rechargable 12 volt battery... What, you ask, is a "Battery Simulator" Well.. it's what is in your photo, a great big Condenser (Capacitor)

Also, if your converter does not have internal filterling (The Magnatek did not and though it is the only one I know for sure did not,,, It is very likely not the only one) Well... that "Hardening Capacitor" as they are now known.. Is the answer.

It takes the pulsuating DC out from some low end converters and greatly smooths it.

NOTE: In my younger days, I designed and built my own power supplies (Another name for Converters... only smaller) so I'm speaking from experience.

[Ohgoodiee]

It's a Magnatek TU-740-2. In my younger days, I used to mess with a lot of power supplies, etc, but didn't think about something like this. Thank you for this insight.

Doug

Quote:

Originally Posted by wa8yxm Is (or was) your Converter a Magnatek 6300 (or your power panel) Magnatek had an optional "Battery Simulator" for those who wished to run the unit without a rechargable 12 volt battery... What, you ask, is a "Battery Simulator" Well.. it's what is in your photo, a great big Condenser (Capacitor) Also, if your converter does not have internal filterling (The Magnatek did not and though it is the only one I know for sure did not,,, It is very likely not the only one) Well... that "Hardening Capacitor" as they are now known.. Is the answer. It takes the pulsuating DC out from some low end converters and greatly smooths it. NOTE: In my younger days, I designed and built my own power supplies (Another name for Converters... only smaller) so I'm speaking from experience.