coach battery master on/of switch voltage

tiinytina · March 16, 2012, 08:00 PM

The master switch to turn the coach batteries on/off was iffy most of last year.. turn on and then would come on when it chose.. this spring wouldn't turn on unless wiggled and jiggled.. so bought a new LED tipped 12V 3 prong toggle switch (old one is 3 prong but didn't remove it to read the microscopic imprinted verbage)... removed old switch and its a 125V/220V switch??? now I'm confused... this switch turns on the 12V batteries... don't know if this switch is OEM or PO change out...(or if it interacts with the shore power???) (I can do plumbing and carpentry but electric is just not on my learning curve...)

thanks!
Tina

ClydesdaleKevin · March 16, 2012, 10:16 PM

I wish I could help with this one...our switch is a complicated thing, with a built in volt meter (which only works now with the chassis battery), 2 toggles, one for each battery bank, and while it does work for the coach side (you can hear the solenoid click as it opens and closes, but no LED light and no volt meter), it works the way its supposed to for the chassis side, volt meter and LED indicator.

The one to ask is Dave...he's the electrical god of gods!

Kev

DaveVA78Chieftain · March 16, 2012, 10:31 PM

Being rated for 125/220 is no big deal. Just means it can handle higher voltage. However, most battery disconnect relays are based on a 3 position (MOM/OFF/MOM) switch. The polarity of each momentary position is reversed. The relay itself is a latching suc that once it switches position it locks in place. This way a constant voltage signal is not required to keep it latched. This way the latching circuit is not acting as a constant battery drain. Relays like the Aux start relay do require a constant voltage applied to the small terminal to remain energized.

The biggest problem people have with a Battery Disconnect Relay is that the heavy contacts inside the relay get pitted and weld together or do not make clean contact with each other due to the pitting.

Dave

tiinytina · March 17, 2012, 11:41 AM

The toggle that has been in since we bought her is 3 prong but only 2 are connected...to smaller red wires, one goes into charger/converter... the other to batteries I'm assuming. The switches are on the opposite side from the battery bank and the wires were put in place prior to the rig being undercoated with thick spray insulation. so tracing them is nearly impossible.

Gone has a MOM switch but this may be a straight connection into the coach batteries it looks like which works regardless of the interior on/off. I have found that the batteries are drained despite constant solar trickle charge so not sure whats up. Batteries are about 2-3 yrs old deep cycle Marine, kept charged via trickle when needed (usually when we are out in her and if she sits any period of time)...

Is the toggle switch the "relay" you are talking about? like I said electricity is my poorest skillset....
Tina

tiinytina · March 17, 2012, 08:16 PM

Yea.. replaced switch today.. and can hear relay click now.. and yea.. power! and put an electric trickle on the coach batteries and they were at 10v.. so charging.. hoping that the bad switch was draining them.. (propane detector)... but will check relay tomorrow just in case....
Tina

DaveVA78Chieftain · March 17, 2012, 09:31 PM

Tina,
Not sure exactly what your setup is. Here is a diagram of a normal latching Battery Disconnect circuit that uses a Intellitec 100 amp relay (http://intellitec.com/pdfs/BATTERY_web/bd.htm)

Of course on the newer fancy rigs this can grow to get rather complex

tiinytina · March 18, 2012, 01:11 PM

Thanks Dave.. of course today the switch didn't work until flipped a couple times.. the relay was not working, then was.. think I will go ahead and replace the relay.... it is also warm is this normal? going to check it in a bit so any chance of remaining warm is due to battery drainage, and not being in ON position.

Put a electric trickle onto main house batteries and reading 12.4... so we'll see if I have any drop in a day or so.

Generator also cranked fine from inside with batteries fully charged. yea...

Tina

DaveVA78Chieftain · March 18, 2012, 08:43 PM

My guess is the relay contacts are pitted and burned therefore not making contact. By cycling the switch the contacts are cleaned a bit until they make more or less good contact. I am curious what kind of a disconnect relay you have. Really should not be one of the Aux start relays.

Dave

tiinytina · March 19, 2012, 07:49 AM

Our MOM relay/solenoid is mounted on front of chassis. The master Battery relay is under dinette near where batteries are midship, 30amp Plug and electric fuse panel is in rear of RV in bedroom. There are a line of thermal fuses mounted under dinette as well, but sound goes to the larger Relay (round about 2" in length and 1.5" in diameter.

I'm guessing I will disconnect the house batteries before replacing the relay hate being zapped... assuming I can pick up a relay at local RV place.

I did find to small wires disconnected under rig by oil filter, and putting the two together activated the MOM solenoid... not sure to connect them or not need to clean and look to make sure they do go together (no other loose ones around though so its likely)....

Tina

DaveVA78Chieftain · March 19, 2012, 12:40 PM

Do not forget that the house battery voltage will be on one side of that relay and the converter power will be on the other side. You have to have shore power disconnected or you will get converter voltage at the relay. And last would be to ensure the Aux start relay is OFF.

Dave

tiinytina · March 19, 2012, 08:33 PM

bought new relay today.. wrong one.. bought 4 post have 3.. tomorrow will exchange. Planned on disconnecting batteries and no shore power for refit. been slammed to a wall from 110V, i do not touch live wires... N:(

my RV place will also test my water heater control board free.. igniter is on constant... but thats another forum post....

Tina

DaveVA78Chieftain · March 19, 2012, 08:51 PM

This sounds like a regular 100 amp AUX start relay. If so, then all you have to do is run a wire from one small post to the attaching bolt as a ground wire. Only difference between 3 and 4 post is 3 post is case grounded. The 4 post version was intended for those situations where the relay was not installed on a metal surface (ergo the need for a seperate ground wire).

BTW, that is not a normall Battery Disconnect style relay. Requires constant voltage to it to stay energized. A real Battery Disconnect does not require constant voltage to it.

Dave

tiinytina · March 20, 2012, 07:30 AM

This is mounted under our dinnette bench to wood (looks original to RV so also ASSUMED W% it is the right mechanism for the job) . is looks like a Pollack Solenoid switch, and it is controlled by on/off toggle by door. So it shouldn't draw any current when off .... or so I ASSUMED.. but know where that gets me... i'm going to disconnect both RV batteries, unbolt the unit, and transfer the wires going to each pole one by one, pole by pole.. so that I don't muck things up...

Should I change it out for a "real" battery Disconnect? I like the ability to turn it on and off with the switch by the door and no clue if what you suggest can be used similarly... don't want to have to rewire if I don't need to...

Tina

DaveVA78Chieftain · March 23, 2012, 09:09 AM

In your case, I would think the decision to upgrade is driven more by how you use the rig than anything. If you rarely boondock, then what you have should work fine. If you do boondock a lot, then by upgrading you prevent the extra load draw to keep the relay energized in order to use coach battery (normal latching battery disconnect relay does not require constant voltage to stay in either position). While you said there were 2 wires connected to the operation switch, you did not say if both wires feed down to the disconnect relay. A latching relay requires 3 wires (B+ from coach battery fuse, Signal A, Signal B) between relay and selector switch so that would dictate what you need to rewire.

QuoteI did find to small wires disconnected under rig by oil filter, and putting the two together activated the MOM solenoid... not sure to connect them or not need to clean and look to make sure they do go together (no other loose ones around though so its likely)....

When wires are connected, is the relay only energized when ignition switch is ON? (Provides charging of coach battery when engine is running therby bypassing the DUAL/NORM/MOM switch).

or is this the control wire for the DUAL/NORM/MOM switch?

Dave