12V charging plates in 2008 Sightseer

[dennysbabe]

We have three 12V charging (cigarette lighter) receptacles in our 2008 Sightseer; one on the dash, one in the ceiling above the passenger seat and one in the dinette booth area. When we had our 5th wheel we checked our battery by inserting a digital 12V charging monitor but we can't determine whether these are reading the voltage on our chassis battery or coach batteries because they all register 13.5 when we either start the engine or run the generator. If the generator doesn't charge the chassis battery how come when it's running that these receptacles read 13.5 if they're connected to the chassis battery?

Phyllis

[Morich]

I have not looked at drawings for your specific rV but generally the Winnebago motorhomes have an item called a "mode solenoid" which automatically connects both bettery strings togetherat tow different times for different reasons.
On you rdash you are likley to have a momentray switch labeled something like "aux, boost, etc which will let you push it to connect the start and coach for a boost/jump start when the start bettery needs help. This solenoid also operates when the RV engine is starts to along the engine alternator to add some charge to the coach as well as the start battery as we drive to the next site!

When you see more than 12.8 on any lead/acid battery, it is not a true reading but shwoing what the charge is doing! If you are seeing that high on the start battery when only the generator is running, it can be one of two things going on.

One is that it is "surface charge" which is a false high reading until the chemicals in the battery settle and become stable after charging OR there may be a small item which passes some current from the coach to the start. Some RV came as standard, while others may have been added by previous owners as a way to keep both charged while stored and plugged to power.
These added items are often called by the brand name "Trik-L-Start".

Want to know which power point is on which battery? Try this, perhaps?
After the RV has not been plugged in, generator not run nor engine started, all the batteries will setleafter a couple hours, so that you can get a better clear answer.
If you check the voltage at a power point and it comes out near 12.8, turn on somethingtodraw power from the coach batteries like a few lights, vent fans, etc. and see if that power point shows a dip. Motors tend to draw more power when first starting so the water pump is likely to let you see a bigger startup drain---if that point is on the coach power.
If not noting a drop, try turning on the RV lights or honking horn as a drain on the start battery without starting the engine.

Note that starting the engine will show as a big drop on the start battery but it immediately comes up to show way higher than 12.8 as the alternator is already trying to charge that battery as well as the coach, so that will blow the testing idea!

This is a snip of the drawing for your RV mode solenoid and how it works.
Click to get a better view?

Green and red are the two battery connects to the solenoid, yellow are the positive battery and ground from the dash to make the solenoid operate. When the solenoid operates the red and green traces are connected togehter so that both batteries act as one!

If not familiar with this solenoid, it is just a "switch" which is electrically operated to open or close the connection!

Note:
I only see one powerpoint on the drawings for the coach, perhaps this will be a start to locate which? But also be awre that folks tend to add these for all kinds of reasons that are not shown on any drawing!!