Ralph L. Fullenwider
05-28-2007, 02:55
Good morning everyone:
A question was asked, why is there ac voltage on 12 volt batteries. Let
take a quick and dirty look at what a battery is and does, which is more
than just being a power source.
I electrical or electronics there is always an ac ripple voltage present of
some form or another. ac powers the chargers for instance and of course the
alternator puts out an ac ripple voltage as well. These are small amounts
of course but the ac voltage rides on a dc carrier sign wave.
batteries: 1. source of 12 vdc power as we all know, but they actually do
more than that too.
2. A battery is like a huge capacitor and what does a capacitor do? It
blocks ac ripple and passes pure dc voltage.
3. The ac ripple riding voltage is passed off to ground through the
batteries and pure dc voltage goes out to our various coach systems.
It is a little more involved than that but basically, the above is what
happens. That is why a small ac voltage can be read with a meter on the 12
vdc system but is filtered out by the batteries so no ac passes to the dc
systems. That is pretty much the long and short of it. So need to go any
deeper than that in my opinion.
Safe travels,
Ralph and Charolette Fullenwider
84FC35
Duncan, Oklahoma
A question was asked, why is there ac voltage on 12 volt batteries. Let
take a quick and dirty look at what a battery is and does, which is more
than just being a power source.
I electrical or electronics there is always an ac ripple voltage present of
some form or another. ac powers the chargers for instance and of course the
alternator puts out an ac ripple voltage as well. These are small amounts
of course but the ac voltage rides on a dc carrier sign wave.
batteries: 1. source of 12 vdc power as we all know, but they actually do
more than that too.
2. A battery is like a huge capacitor and what does a capacitor do? It
blocks ac ripple and passes pure dc voltage.
3. The ac ripple riding voltage is passed off to ground through the
batteries and pure dc voltage goes out to our various coach systems.
It is a little more involved than that but basically, the above is what
happens. That is why a small ac voltage can be read with a meter on the 12
vdc system but is filtered out by the batteries so no ac passes to the dc
systems. That is pretty much the long and short of it. So need to go any
deeper than that in my opinion.
Safe travels,
Ralph and Charolette Fullenwider
84FC35
Duncan, Oklahoma