Need advice on 12 volt electrical system 1981 apollo

[jondecker76]

Hello

I'm almost done on a full remodel of a 1981 Apollo 3300DB

Since I'm very close to being done, I finally purchased (2) new house batteries and a new start battery and installed them.

Up until this point, the 12 VDC system has been working fine off of the converter (there was no house battery installed prior to today).  Everything has been working great - lights, leveling system, water pump, etc etc.

Today has been the very first day that I have tried to "self contain" the coach.  With the newly installed batteries, I disconnected the shore line.  Without shore power, none of the 12VDC circuits work.


I traced the wires..  The house battery  end up going to the generator compartment and to a solenoid type relay to tie it to the start battery.  In the generator compartment, the lead (#0 black wire) ties into a #6 white wire that goes to the converter.  Everything matches the schematics in the manual.

That's when it appears to me, that according to the wiring and the schematic in the manual, the only way the 12VDC circuit gets power is from the converter.  This makes absolutely no sense for a self-contained motorhome!

Let me attach some images:




This is the 12VDC schematic in the manual.   If you look, both the house and the start battery go to a "battery switch" which allows you to tie the two together for hard starts or to charge both while driving or charge both from the converter.  (this has actually been replaced at some point with a solenoid which serves the same function and is controllable from a dash switch)
If you follow the common lead from the Battery Switch, it will eventually end up connecting to a #6 AWG white lead from the converter.  My assumption is that this is the lead that charges the batteries while connected to shore power.
If you keep following, you will see the 12VDC circuit in the lower right-hand corner of the page.  According to the schematic, only the #6AWG black lead from the converter powers this circuit! (this matches what I see physically in the coach)  So looking at the schematic, what actual purpose does the house battery even serve?  According to the manual, and to what I can see on the coach, the house battery only can go to the "Battery switch circuits" that allow you to operate things like the overhead blower, radio, etc...  It doesn't even go to the 12 VDC circuit that powers the important things like lights, water pump,  etc. that allow you to be self-contained.



Here is the part of the manual that describes the fuses in the 12 VDC circuit. (Remember, these are the things that won't operate currently unless you're on shore power, even though common sense tells you that the house battery SHOULD operate these things)



Lastly, this is what my gut is telling me...  Even though I can't find a manual ANYWHERE on this converter (a Baisler BEC 50), I'm thinking that whenever there isn't 115VAC present, the #6AWG white wire should jump to the #6 black wire that feeds the 12 VDC circuit.  Though, without any kind of documentation it's just a guess.  In any case, common sense says that this is how it SHOULD work (when taking schematics into account)

So now I'm kind of stuck..  Either A) the schematic in the manual and the wiring I see physically are wrong, B) The converter should backfeed from the #6 AWG white wire to the #6 AWG black wire to feed the 12 VDC circuits when shore power isn't present, or C) I'm going to have to tie in my own wire from the house battery to the 12VDC circuit (in which case it has to be on a selector switch so that when the converter is operating it doesn't try to overcharge the batteries)

Is there something that I'm missing?  I find it very hard to believe that the house battery originally served basically no purpose aside for a backup for the start battery (as the schematic is alluding to).  Something is making absolutely no sense at all.

Any help and ideas would be greatly appreciated!

[Stripe]

Jon are you sure your RV doesn't have a switch to engage the 12v power to the lights and such?

I know it's unrelated (I think) but my RV actually has a selector switch tat lets me choose between the inverter and shore power or I can put it in center. Although no mater what position that switch is in, all the 12v lights and appliances work..

[circleD]

Same here Stripe. If it works from shore power but doesn't from battery, there might be connection issue between the AC and convertor. Try to run a jumper wire. Nothing major just to try some lights. The ground is common. Hook it where the top fuse is.

[jondecker76]

Stripe:

I'm pretty sure that no such switch exists - I've had this coach torn down to the frame so it's very unlikely that I could miss something like that.  Plus, as I've pointed out, the actual schematic even shows that the only thing going to the circuit is a #6 AWG black lead from the converter, which I've also physically verified in the coach.


This is why I'm wondering if there is supposed to be some mechanism in the converter it's self which would allow the battery to backfeed through the white #6 AWG lead out to the Black #6 AWG lead, which would in turn feed the 12 VDC circuit.  If I could find a manual, I would know - but I can't find any manuals at all for a Baisler converter.

[jondecker76]

I just emailed Basler Electric.  They are still in business so hopefully they can send me some documentation on the converter.

According to the schematic, either the RV was never meant to be truly self contained (I.e. some 12 VDC circuits will only work on shore power), or the converter is supposed to make the connection whenever shore power isn't available.  It's very clearly displayed in the shematics.

Once I hear back from them I'll decide how to proceed

[DaveVA78Chieftain]

Many converters of that era have a transfer relay built into them that selects converter DC output when AC is available.  When AC is not available it routes battery power to the fuse panel.  The switching relay may be stuck in the converter position.

Dave

[jondecker76]

Thanks Dave.  It's good to hear something that's kind of backing up what I'm thinking (it's the only thing that makes sense looking at the schematics and at the wiring physically)


I'll crack open the converter tomorrow and see if there is an integral relay - I've got dozens of relays on the shelf for wind turbine projects, so if this is the case it would be a very easy fix!

[jondecker76]

Problem is fixed!


I took the converter apart, and as suspected there was an internal relay which would allow the battery to feed to the fuse panel to the 12 VDC circuit through the converter whenever shore power isn't applied.


The problem was a simple fix - construction debris from the teardown made it's way in and was preventing the relay contact from returning to it's normally closed position.



As you can see, the converter was quite a mess inside!  I cleaned it up, touched up the relay contacts with some emery cloth then put everything back together.  Now all of the self-contained functions are working off of the battery as they should whenever shore power isn't applied

[DaveVA78Chieftain]

 

Nuff said 

Dave

[M & J]

 

[Rickf1985]

Did you ever get a reply from Basler? It is always nice when a company acknowledges it's older products even if it can't help with them.

[fedcard]

 

[jondecker76]

Haha,  yeah got a reply that is very old and no longer produced

They did give me contact information to the company that actually produced them,  though i never followed up

[Rickf1985]

But they did get back to you and gave you a contact. better than a lot of companies out there.