Good Sam Club Open Roads Forum: Need help replacing charging circuit solenoid.
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Need help replacing charging circuit solenoid.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next
enblethen

Moses Lake, WA

Senior Member

Joined: 01/05/2005

View Profile






Posted: 01/21/20 07:29am Link  |  Quote  |  Print  |  Notify Moderator

Yes, all non-essential is disabled as Mailemaker item two suuggests.


Bud
USAF Retired
Pace Arrow

2003 Chev Ice Road Tracker


BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 01/21/20 07:51am Link  |  Quote  |  Print  |  Notify Moderator

When non-essentials are cut off with Start, how does the solenoid power stay on when in MOM, but not otherwise?


1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

maillemaker

office

Senior Member

Joined: 09/08/2009

View Profile



Good Sam RV Club Member

Offline
Posted: 01/21/20 08:16am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

When non-essentials are cut off with Start, how does the solenoid power stay on when in MOM, but not otherwise?


The ignition switch only energizes the solenoid when the switch is in DUAL position.

When the rocker switch is held in MOM the ignition switch is not involved at all. The house batteries are used to energize the solenoid.

This is my understanding, anyway.

The rationale is this:

When holding MOM, you are jump-starting the presumably dead engine battery using the house batteries. So clearly you need to energize the solenoid from the house batteries. And you only want them ganged as long as it takes to finish the jump-start, hence the momentary nature of the switch.

In Dual, the goal is to charge the house batteries, but not run down the engine battery if the engine shuts off. Thus the ganging is only going to happen if 1) the switch is set to DUAL and 2) the key is in RUN. This way if you arrive at camp and have had the switch in DUAL to charge your house batteries and you shut off the engine you won't accidentally leave the house ganged to the engine and thus possibly deplete both sets of batteries while you are camping, and then find yourself stranded.


Steve


1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"



maillemaker

office

Senior Member

Joined: 09/08/2009

View Profile



Good Sam RV Club Member

Offline
Posted: 01/21/20 08:37am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

Somehow I got the notion that when you turn the key to Start, that cuts off the blower motor etc including the power to the solenoid from the engine battery.


That is correct. When you turn the key to start, usually all RUN accessories turn off. If the charge solenoid is powered by this (mine is), then it won't be on when switch is set to DUAL and the key is set to START.

Quote:

With MOM you get house battery power to the solenoid, not any engine battery power if I got that right.


That is how I understand it, yes.

Quote:

So with MOM when you turn the key to Start it can cut off Engine battery power to the blower and solenoid, but that power is now from the House, so it all stays on is what I assumed.


No.

With MOM all you are doing is ganging the house batteries to the engine batteries. The charging solenoid is being powered by the house batteries. But everything else normally run by the chassis system (blowers, radio, etc.) are controlled by the ignition key being in RUN. So they will be off in START even though the house batteries are ganged to the engine battery.

Quote:

You are saying that with MOM, the key in Start still cuts the house power to the blower, but leaves the power to the solenoid on so it stays closed.


Yes.

Quote:

So even when on engine battery, all normal, turning the key to Start cuts power to the blower as one event and separately somehow on a different line somehow also cuts the power to the solenoid.


Generally, all non-essential accessories are turned off when the key is set to START. This includes the charge solenoid. But when you are holding MOM, it "overrides" the ignition switch power and instead uses power from the house batteries to energize the charge solenoid.

Quote:

MOM is able to distinguish between these two events and only cuts the power to the blower and not to the solenoid?


MOM doesn't cut the power to accessories - your vehicle's electrical system does (ignition key). All MOM does is gang your house battery and engine battery together. What electrical things are cut off when the key is in START is up to your vehicle.

You can think of MOM as simply a set of jumper cables from your house battery to your engine battery.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 01/21/20 08:41am Link  |  Quote  |  Print  |  Notify Moderator

Going from Run to Start cuts off non-essentials and the power to the solenoid normally. So there are switches of some sort responding to the key position. You try to start normally but the engine battery is too low.

You push MOM and try again using the key to Start. Non-essentials are still switched off same as usual, but this time power stays on to the solenoid (or there would be no power to the starter).

If the house battery power is just passed through to the engine side via solenoid, the brain that gets the power to run and switch off the non-essentials would not know the difference which battery bank is supplying the power. Seems to be the case.

But now for some reason the brain running the power to the solenoid can tell the difference?

Maybe the MOM by-passes the solenoid to parallel the house with the engine batt some other way, and it all acts the same as when on engine battery, but the solenoid being open in Start does not cut off the house battery power, because it by-passes the solenoid when in MOM??

I don't know. The schematic posted earlier was too complicated for me.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 01/21/20 09:50am Link  |  Quote  |  Print  |  Notify Moderator

More coffee, new plan.

Maybe the wire coming from the solenoid middle post that powers it, goes down to where it forks with one fork going to the switch controlled by the ignition key, and the other fork going to the MOM.

You push MOM and that powers that fork. You turn the key to Start and that cuts power to the switch on the other fork as usual. BUT that does not cut power to the solenoid since the other fork is "live" from the MOM.

maillemaker

office

Senior Member

Joined: 09/08/2009

View Profile



Good Sam RV Club Member

Offline
Posted: 01/21/20 01:37pm Link  |  Quote  |  Print  |  Notify Moderator

Quote:

Going from Run to Start cuts off non-essentials and the power to the solenoid normally. So there are switches of some sort responding to the key position. You try to start normally but the engine battery is too low.

You push MOM and try again using the key to Start. Non-essentials are still switched off same as usual, but this time power stays on to the solenoid (or there would be no power to the starter).


Yes. The MOM switch uses the house batteries to energize the charge solenoid.

Quote:

If the house battery power is just passed through to the engine side via solenoid, the brain that gets the power to run and switch off the non-essentials would not know the difference which battery bank is supplying the power. Seems to be the case.


Yes. That "brain" is the ignition switch.

Quote:

But now for some reason the brain running the power to the solenoid can tell the difference?


I don't know how it works, but the when the ignition switch is in START, accessories are turned off. This is going to be true in pretty much any car.

Quote:

Maybe the MOM by-passes the solenoid to parallel the house with the engine batt some other way, and it all acts the same as when on engine battery, but the solenoid being open in Start does not cut off the house battery power, because it by-passes the solenoid when in MOM??


I don't understand what you are saying here.

I think it is really very simple.

MOM is just like taking a pair of jumper cables and hooking up a second battery to your engine battery. That's all it does. The difference is instead of jumper cables it's a solenoid operated from the house battery juice.

DUAL does the same thing, but it uses the RUN switch juice.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 01/21/20 02:26pm Link  |  Quote  |  Print  |  Notify Moderator

"I don't understand what you are saying here.

I think it is really very simple.

MOM is just like taking a pair of jumper cables and hooking up a second battery to your engine battery. That's all it does. The difference is instead of jumper cables it's a solenoid operated from the house battery juice."

You need a way for the solenoid to stay powered when the key is turned to Start or it will cut off the house battery supply to the starter so you can't start.

One way would be as in my previous post using a Y in the solenoid's power line to by-pass the switch from the ignition key and power it from the MOM.

DrewE

Vermont

Senior Member

Joined: 08/23/2014

View Profile


Online
Posted: 01/21/20 03:36pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

"I don't understand what you are saying here.

I think it is really very simple.

MOM is just like taking a pair of jumper cables and hooking up a second battery to your engine battery. That's all it does. The difference is instead of jumper cables it's a solenoid operated from the house battery juice."

You need a way for the solenoid to stay powered when the key is turned to Start or it will cut off the house battery supply to the starter so you can't start.

One way would be as in my previous post using a Y in the solenoid's power line to by-pass the switch from the ignition key and power it from the MOM.


The MOM (momentary emergency start switch) is the Y in the solenoid's power line. There's no other Y at all. The switch is a single pole, double throw momentary pushbutton switch. The common connection on the switch goes to the solenoid's control wire, the normally closed to the chassis run circuit, and the normally open to a circuit powered by the house battery.

It is quite simple indeed.





BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 01/21/20 04:52pm Link  |  Quote  |  Print  |  Notify Moderator

OK thanks. I get it at last! Oh well.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next

Open Roads Forum  >  Tech Issues

 > Need help replacing charging circuit solenoid.
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2020 CWI, Inc. © 2020 Good Sam Enterprises, LLC. All Rights Reserved.