Theory behind converter operation?

[AlbuqHenry]

Sent: 1/16/2008

Hello everyone, newbie question here....

I was wondering how the operation of the converter goes.  I have a 77 brave the converter is a Colman .  Every thing is working just wondering how it works.    What I'm not sure about is when you are using your 12 coach stuff and plugged into shore power, is everything powered by the battery then the converter maintains the battery.... kinda like an alternator on a car, or do the lights and stuff get powered by the converter only? then there is a separate circuit  to charge the battery?  At first I thought it was just like the car and alternator.  When I was on shore power the other day I noticed the lights kinda dimming a bit and getting brighter,  kinda blinking but not going all the way off just dimming a bit.  It was happening when the charge light on the converter was blinking, on the converter it says blinking meaning the batteries are almost charged.  So after I saw this I now  think there are two separate circuits, one for power to the loads , 12 volt lights, and another circuit for the batteries.  Now the last thing I am not sure about is, why are you not supposed to run the alternator to charge the coach batteries when the converter is also charging the batteries?...... the way I understand how the alternator works is it told by the voltage regulator to charge based on what the voltage regulator sees from the batteries... if the coach batteries are being charged by the converter wont the regulator see the higher  voltage that is being supplied by the converter and simply tell the alternator not  put out as much charge. ?  Not sure if this makes sense? Just trying to understand how it works and why it works that way... LOL ... Any comments?

[ClydesdaleKevin]

Sent: 1/17/2008

A converter uses a transformer and other little technical goodies to convert 120 volts AC to 12 volts DC.  When you are plugged into shore power, your converter is supplying the 12 volts to run your lights and whatnot, and it also acts as a power distribution center...it sends the 12 volts it converts to where it is needed, and then it sends unconverted 120 volts AC to where THAT is needed, like your outlets, fridge, etc.  Some older converters don't charge the batteries, but yours is a 77, so that should send a 12 volt trickle charge to the batteries as well.

I have run my converter with the engine running on several long road trips when it was very hot outside...with the genny running, and the roof air blasting.  I've never had any ill effects on the batteries or charging components.

Kev

[Slantsixness]

Sent: 1/17/2008

If you have a Dual/MOM switch (most do) The converter will work fine off the genny. If you don't have the switch then you have a battery isolator, which does not allow the alternator chassis charging system to charge or be affected by the running alternator.

When you have the Dual switch, and you're not running the genny, then the dual position allows you to power the 12 accessories and charge the coach batteries as you drive. If you leave the switch in "dual" when parked, you will drain the chassis battery as well as the coach battery(s). MOM is only for a "jump start" when the chassis battery gets run low.
Unfortunately, even if your converter charges the Coach battery, leaving the switch in the dash to "dual" will only shorten the life of your alternator or regulator, because it remains connected, effectively shorting the field to ground on the alternator, and causing it to eventually fail. so:

driving, no genny: switch to dual.

Driving with the Genny: turn the dual mom to the center (off) position.

Parked, switch to center off. (however the chassis battery can be jump started or quick charged by holding down the MOM switch, but never for more than a minute and not while cranking the engine over.)

The Dual/ MOM switch was Winnebago answer to eliminating the rather large and expensive Battery isolators commonly seen in motorhomes. Even the most expensive isolator has some trickle discharge effect to them. Relays and automatic charging systems are the way to go.... if you want to spend the money.

Tom

[AlbuqHenry]

Sent: 1/17/2008

Cool, thanks.  thats pretty much what I was wondering.....  thanks again- Henry

[AlbuqHenry]

Sent: 1/18/2008

Hello again...

Tom,  now that I read this again quote- {leaving the switch in the dash to "dual" will only shorten the life of your alternator or regulator, because it remains connected, effectively shorting the field to ground on the alternator, and causing it to eventually fail.}....I am not quite understanding what you mean.... when the switch is set to duel there is basically one ''big'' battery right?  wouldn't the regulator see the same with one little one or one ''big'' battery?  just more work to charge it.  Maybe I misunderstand what you are saying...... I am not for sure but I understand the alt. and regulator get power to operate only when the ignition is on. -Henry

[denisondc]

Sent: 1/18/2008

Well; the voltage regulator only gets the 'reference voltage' when the ignition is on, so it can only energize the armature in the alternator then. The output terminal of the alternator is always connected to the battery.
As far as I know, on my 72, the battery connecting switch (dual-off-mom) only works when the ignition is on. The solenoid in the battery compartment is what actually connects the two positive cable together, and that solenoid only gets powered when the ignition is on & I operate the rocker switch......and if the engine battery isn't dead. After reading that in the 'momentary' position the switch would connect both batteries, I went looking for the wiring to accomplish that. I think it would have needed a wire from the coach battery to that switch. But I only found a wire from the ignition "1 circuit" feeding it. This wiring isnt reflected in the Dodge chassis wiring diagram, nor in the 'coach' wiring diagram that came with it from Winnebago - a one page copy of a hand drawn diagram.
So if I forget and leave the dual-off-mom switch in the 'dual' position when I shut the motor off - it wont hurt anything. Other Winnies may be wired up differently of course, even if a prior owner didn't do any of his own wiring mods.
When our engine battery refused to cooperate one day after stopping in a rest area, I just reversed the two positive battery cables to the 'engine' and 'coach' batteries.

[AlbuqHenry]

Sent: 1/18/2008 5:02 PM

OK I get it now.... On mine, when I got it all the rocker switches were out of it and I  had to rewire them.  I put the power to the solenoid through an on/off rocker using coach batt. power.  So basically I have just connected or not connected no matter if the ignition is on or not...  I hadn't thought about the solenoid getting power only when ignition is on...  Thanks- Henry