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 > Ford Starting /House Charging Question UPDATE Test

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BFL13

Victoria, BC

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Posted: 01/19/20 07:51am Link  |  Quote  |  Print  |  Notify Moderator

The one solenoid I can see would be the isolation one, with the wire going to the house batteries coming out one side of it. I get "alternator charging" with the engine running and not when the engine is off.

ISTR a test where I had a voltmeter on the engine battery during starting. Voltage first fell to 11.x then jumped to 14.x. So I will do that with the house batteries, which should answer my question, I hope. Plan is to turn the key very slowly watching house battery voltage. (with multimeter, not Trimetric, which has a smoothing delay to it.)

I should also be able to do something at the solenoid itself with the voltmeter and possibly hear something.

Will report later today.


1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
See Profile for House electronics set-up.

BFL13

Victoria, BC

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Posted: 01/19/20 08:48am Link  |  Quote  |  Print  |  Notify Moderator

This covers what everybody has been trying to explain. What I don't know about my rig (yet) is whether the isolator is energized in the key's (pre-starting) ignition position. or just after it starts.

https://expeditionportal.com/forum/threa........-isolator-versus-starter-solenoid.76484/

That says (scroll down) you can rig it either way to energize it.

* This post was edited 01/19/20 09:22am by BFL13 *

landyacht318

Near a large body of salty water

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Posted: 01/19/20 10:36am Link  |  Quote  |  Print  |  Notify Moderator

The Solenoid's trigger circuit controls whether the house batteries assist engine starting, or not.

Some vehicles deactivate the HVAC blower during engine starting or the headlights,or power windows, ect, but have it/them On, with Key to on, not start, so turning the key to on.... the solenoid closes, then opens when the starter is cranking, then closes right after the engine starts.

I'd prefer this, opposed to allowing house batteries to assist engine battery through solenoid during engine starting, but it cycles the magnet and slams and separates contacts twice as much within the solenoid, wearing it out faster. I also would not want solenoid passing starter current from house to starter battery, as that will also wear out solenoid contacts faster, and when these fail often the contacts fuse together leading to full time in parallel situation, which then cycles the starting battery with house loads.

The Ideal, in my opinion, Solenoid trigger circuit would close the solenoid contacts only after the engine starts. I often recommend people put an illuminated switch inline on the ignition activated trigger circuit, thus have the option of letting belts and engine warm up before tasking the alternator and belts with the 50+ amp loads depleted batteries can ask for. Some just use the illuminated switch and have the switch always powered live, connected to house or engine battery, that way if engine battery is dead they can flip the switch and house batteries assist, or if depleted batteries cause their belts to squeal on a cold damp morning, they can turn it off and allow things to warm before trying to feed depleted house bank.

The absolutely full starter battery right after starting on my rig, will briefly draw 90 amps and this quickly tapers back down to 0.5 or less in 45 seconds or so, and if I had a large depleted house battery bank they would be sucking huge amounts of amperage from the alternator at that point too.

I believe a delay in activating the house battery charging solenoid is wise. Less stress on a cold engine whose cold oil is too thick to circulate properly and a damp cold belt might more easily slip and glaze and perhaps cause issues down the road. Each 25 amps the alternator has to make requires one Engine HP, with all the losses through belts/pulleys/diodes, so I'd prefer the engine idle for a bit before asking it to feed house depleted batteries.

I've found a badly oxidized 12v quick terminal under my dash that is not live with KEY to ON or Start, but becomes live only after engine actually starts. After deoxidizing it, I use it for powering my aftermarket voltage regulator, but would use this circuit to trigger a solenoid, if I used a Solenoid and I'd have an illuminated switch on it to neuter it too.

BFL13

Victoria, BC

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Posted: 01/19/20 11:21am Link  |  Quote  |  Print  |  Notify Moderator

Confirmed in my rig that the isolator is not energized until after the engine starts running. Voltage on the ignition wire in the middle of the solenoid does not rise until after the engine starts.

Before that, as the key goes through its steps there are two loud clicks from below somewhere on the passenger side and then it starts. That must be the other solenoid I can't see.

Voltmeter on the house batts also shows no change until the engine is running--definite time delay there before voltage starts to rise.

Thanks everyone for explaining how all this works.

DrewE

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Posted: 01/19/20 01:49pm Link  |  Quote  |  Print  |  Notify Moderator

On my motorhome, the combiner solenoid is activated from the "run" position on the key, so it does combine if the key is in run but the engine isn't running--the same situation where the fan blower operates, etc. (It is also activated by the emergency start button on the dash, which is actually a SPDT switch. When pressed, it connects the control wire of the solenoid to a house battery circuit; when not depressed, it's connected to a chassis "run" circuit.)

There are of course any number of minor variations on how these things are set up by different manufacturers and with different models.





BFL13

Victoria, BC

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Posted: 01/19/20 01:55pm Link  |  Quote  |  Print  |  Notify Moderator

I am confused by all terms. How can the key be in run and the engine not started? Isn't "run" next after "ignition"? (1. release steering wheel, 2. ACC, 3. ignition, 4. run)

This one has "run" before "start"

https://dannysengineportal.com/ignition-switch/

I saw somewhere that run was after when the various warning lights on the dash turn off just after it starts. I think that is when my isolator is energized.

EDIT some more: In desperation I looked at the driver's manual [emoticon] and it explains there are five positions with my MH. Acc, Lock, Off, On, and Start.

"On" is when you can see if the dash warning lights work(except the brake) "Start" cranks the engine, then the key returns to "On" and stays there while the engine runs

* This post was last edited 01/19/20 03:13pm by BFL13 *   View edit history

DrewE

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Posted: 01/19/20 06:11pm Link  |  Quote  |  Print  |  Notify Moderator

"Run" and "On" are different names for the same key position, where the engine keeps running if it's started and where the idiot lights all illuminate when you first switch it there.

Typically you'd have some permutation or combination of Lock (lock steering column), Off (nothing happening), Accessory (Radio works but engine doesn't), Run or On (Engine works, idiot lights come on when first switched there, some additional accessories are alive), and Start (crank up the motor, often also disconnecting various non-essential accessories). You can have the key in On/Run without starting the engine, and in many cases that would activate the battery combiner solenoid.

If you have a BIRD sort of device, that works by detecting votlage levels, it might not connect the batteries under normal conditions until the engine is actually running and the alternator charging and the chassis voltage higher than some threshhold.

BFL13

Victoria, BC

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Posted: 01/19/20 06:36pm Link  |  Quote  |  Print  |  Notify Moderator

I suspected that the "combiner/isolator" (same thing) would energize before the starter got started, but in my case it does not, as described earlier.

If it did energize before the starter starts, then that must mean the house batteries always help the engine battery start the starter. LY gave some thoughts on that.

I have only long #10 wire to the house batts positive side (frame neg), so to take real advantage if the isolator energized first, I would need fatter wire on that path. So I like mine the way it is.

I don't know what the other MHs do for wire gauge on the house battery side of the isolator where they also have that dash rocker switch as described in the other thread.

pianotuna

Regina, SK, Canada

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Posted: 01/19/20 06:54pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13,

What chassis is it? Ford? GM? or other? What motor?


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BFL13

Victoria, BC

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Posted: 01/19/20 07:07pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

BFL13,

What chassis is it? Ford? GM? or other? What motor?


The rig in my sig, photo in Profile. In case you can't see that from where you are, it is a 1991 Ford E350 gasser. Called an "incomplete". They sell those to companies that make ambulances or RVs

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