New owner question: Heaters - dash switch

There is no fire hazard, there is an in line fuse, 5 or 10 Amp I believe.  It's a pain to use because you have to hold it down.  That (having to hold it down) is a safety feature to prevent your coach battery from drawing down the engine battery.

Starting an engine can easily draw 400 amps or more which is why battery cables are typically 2/0 to 4/0 gauge.

I hate to be argumentative but there is a lot of misunderstanding about this momentary switch.
The switch is meant to be like a jumper to bring your starting battery voltage back up, then you turn it off to actually start.
When your engine is running all batteries will charge from Alternator.
If you change the momentary switch to an on-off switch nothing bad will happen since as soon as you turn on your ignition it is out of the circuit.
You can leave it on if you want your engine battery to charge from your coach batteries, either if you have solar or are plugged into 120 V power.
See this sketch of wiring system especially on the right side of schematic.

You can leave it on if you want your engine battery to charge from your coach batteries, either if you have solar or are plugged into 120 V power.
See this sketch of wiring system especially on the right side of schematic.

On the right side. Let me see if I am reading this right, sure looks safer already.

The momentary switch on the dash energizes the coil of the relay (shown as a resistor) and allows charge to flow from the coach batteries to the starting battery. This is breaker protected.

 I see there is a diode that permits the flow of charge to go from the alternator to replenish the coach and engine start batteries. This is breaker protected.

I dont see any unprotected flow of current that can start a fire regardless of operator input. I knew that had to be so. 



But, as drawn, what stops the coach batteries from drawing current all the time from the start battery? It appears to have an uninterrupted path from the + start terminal, through the diode, and on to the coach battery.



So in the event the coach batteries were being drained and not replenished (eg: boondocking with solar charge fail) , and the motor was not running, what stops the starting battery from draining along with them?


On my 2007, there is a relay that closes (makes the circuit)  when the motor is running. When the IGN+ goes dead (engine turned off) it opens the relay (breaks the circuit), making a hard disconnect of the coach and start batteries.



As I see it, there is not a safeguard like that in the schematic above.   

When the engine is not running the start battery will not charge the coach batteries, the relay interrupts that flow of current. The alternator must be supplying the current for the coach batteries to receive the current.
I may have left that off.

Thanks for that elec schematic, wish PC would provide it and a manual (not that hard to do...)
Dougn

Our PC-2350 is electrically unmodified, is electrically the same as when we bought it new in 2007.  I installed two volt meters, one each for the chassis battery and house batteries.  When I turn on the E350-V10 engine, the meters read nearly the same 13.8V and stay that way until I turn off the engine.  That is when driving with the generator off and obviously not plugged into 110V.

I never compared voltage readings under different scenarios.  It would make for an interesting experiment.

1) engine on, generator on
2) engine on, plugged into 110v and inverter on
3) everything off, hold in the dash button
4) engine off, generator on (with and without holding in the dash button)
5) engine off, plugged into 110v and inverter on  (with and without holding in the dash button)

As keelhauler might be implying, changing or modifying the intermittent dash switch to a constant-position switch, you might be able to maintain the chassis battery when maintaining the house batteries.  Keelhauler, did I understand you correctly?

I changed to an on/off switch and it does charge the chassis battery on solar or plugged in, or generator.  I turn it off boondocking to assure not depleting the chassis battery if there is little sunshine and at night.

I changed to an on/off switch and it does charge the chassis battery on solar or plugged in, or generator.  I turn it off boondocking to assure not depleting the chassis battery if there is little sunshine and at night.

That is a very good point.  What you hope maintains the chassis battery will also deplete it when the demand exceeds the charge-rate.