Thor Motor Coach - drivers (chassis) radio on house batteries

[kubricky]

Hello all, new to the forum and a first time RV owner.  I lived on a boat many years ago so I understand the perils of 12v living in a movable environment (it seems harsher though).  I have a decent amount of mechanical and electronic knowledge and don't mind tearing into something to fix it correctly.

I picked up a Thor Four Winds 28z on a 2017 Ford chassis.  I talked to Thor customer service and was told that the chassis is delivered without a radio or door speakers and the radio is added.  When I told the person I spoke with that the screen does not come on, he suggested I replace it (I've read that the brand is junk).  The RV has the Axxera (spelling?) radio in the dash and I'm going to replace it with something a little better (and with navigation).  The radio is connected to the house batters and does not have a "park" switch (something I learned about here).  There are three sets of speakers in the unit: two in the main living area that are powered by the drivers radio (there are no speakers in the doors or dash), two in the back sleeping area, and two outside.  The speakers in the back sleeping area and on the outside of the RV are control by a head unit in the sleeping area ("A" and "B" speakers).  The "master" switch or house switch needs to be on for the driver radio to operate.  I can't find any blown fuses (it would be on the RV panel even though the radio is wired to the factory Ford audio plug.  It just appears the radio is not the best.

I understand that a radio can drain the chassis battery, but if it is only used while driving (is the alternator/stator removed from a truck chassis - that is sort of a rhetorical question as I do not think that is the case) there should be no issue.  I also realize that house batteries are wired to the charging system so they are "topped off" when plugged in.

My question:  Is there a definitive reason why the driver's (chassis) radio is not mounted/wired in a standard fashion?  I'm considering putting door speakers back in the unit and wiring it to the chassis battery.  Is there a reason why this is not done?  I'm here to learn, not argue.  I am considering the internet and this forum my friend so I'm not here to argue with anyone and welcome any input or feedback to help me understand.

I've got another (probably pretty basic question, but I'll save it an not make a nuisance of myself just yet).

Thanks again, look forward to learning as much as I can.

 

[darsben]

The radio may well be powered by the house batteries. The parasitic draw may have been a concern if the unit was left parked for long periods as the genny usually will not charge the chassis battery. There could also be an inline fuse blown

 

[Larry N.]

as the genny usually will not charge the chassis battery

That is coach dependent, since in many rigs it will charge both sets of batteries.

 

[Gary RV_Wizard]

 

as the genny usually will not charge the chassis battery

That is coach dependent, since in many rigs it will charge both sets of batteries.

It's actually about 50/50, so neither type qualifies as "most".  Fleetwoods and American Coach do, late model Winnebago Class A's do but older gas A's did not, the older Monaco's did not, etc.  The design of the charging system varies by year and model, so no general rule applies.

 

[Gary RV_Wizard]

My question:  Is there a definitive reason why the driver's (chassis) radio is not mounted/wired in a standard fashion?

No, and many mid or upper tier models have them, often in conjunction with the "park" switch you mentioned that shifts the radio power source from chassis to house.  Modern radios have two power leads, one for "stand-by" (keeps memory and clock alive) and one for the receiver/amplifier. The standby power stays with the chassis but receiver power gets switched to house when parked.

You could even wire a relay to the "ignition on" side of the chassis power such that it switched on automatically when the engine alternator is running.

 

[blw2]

I think that is the Thor way. Mine is, and it seems a lot of folks on the Thor forum bring this up.

oh, and mine is set up to charge both battery systems.

Drives me nuts once in a while, but I haven't done anything to change it.  What bothers me even more, is the fact that my radio (different brand) has a light that can't be turned off....it's a low draw led no doubt, but  still a parasitic draw I don't want when we are 'boondocking'.  I keep thinking about putting a simple power switch in the circuit, but low priority I suppose.

 

[Gary RV_Wizard]

The background power keeps the memory (station presets, etc) alive and the clock displayed (if you care about that).  I suspect it is on the order of 0.25 amp-hours per day, but of course each radio will differ somewhat.

 

[Old_Crow]

The park/travel switch on my coach does not switch the radio to the coach batteries.  It just switches the ignition feed for the radio from ignition switch power to the same source of power that the B+ keep-alive lead uses.  This allows the radio to run with the ignition key off. 
The keep-alive lead isn't switched at all.

 

[Gary RV_Wizard]

That's ok in your Bounder because Fleetwood coaches charge the chassis battery from shore power. Brands that do not do that should switch the power to house batteries to avoid killing the chassis battery by playing the radio all day.

 

[Old_Crow]

That's ok in your Bounder because Fleetwood coaches charge the chassis battery from shore power. Brands that do not do that should switch the power to house batteries to avoid killing the chassis battery by playing the radio all day.

Yup, that's what happened in my old P30.  Radio ran off the chassis battery no matter what.  First time we were parked for more than 3 or 4 days at a time, I killed the chassis battery.  When they replaced the roof air on that coach, the new a/c had a small solar panel on it.  I wired it to the chassis battery, and never had another problem running the radio.

 

[skydivemark]

My Thor dash radio is also powered by the house battery. Fortunately - thru experimenting and luck - I found the unlabelled button that turns it off -- it was bugging me.