Ford Starting /House Charging Question UPDATE Test

I will re-check whether my charging solenoid closes when the key is turned to "on" and not yet turned to "start"

Yesterday I had the voltmeter on the small wire that goes in the middle (sometimes seen called "ignition wire") and it only showed battery voltage coming onto it after the engine started, but I will re-test. I had the pos probe on the ignition wire terminal in the middle of the solenoid and the neg probe on the battery neg post.

This time I will also compare battery and house voltages to see if there is any action once the key is turned to "on" and left there.

When the starter is started the blower etc quit to reduce the draw on the engine battery and then the key goes back to "on". So it seems that power cut to the other things includes cutting power to the "ignition wire" on the solenoid to open it, and then it closes when the key goes back to "on" and power is restored to the other things too.

So even if the solenoid is closed when you go to "on" that still leaves only the engine battery to start the starter and then after that the house batts are put in parallel with the engine battery.

I saw no voltage drop on the house batteries when the engine is starting, only the rise after the engine got going. If the solenoid does close when just in "on" and engine not running, then I would not see that at the house batts, because there would be no load from the starter.

Perhaps it would achieve the same thing if the solenoid's ignition wire got its power directly from the alternator.

I remember that you are not supposed to leave the key in "on" with the engine off because it will burn out the points. AFAIK there are no points anymore but vague on that. So I hope today's test does not burn my points if I have any. I will report results of the re-test later today.

If my house batteries are very low and will not turn my generator over, can I engage the "engine emergency start" button to start the generator?Not trying hijack the thread, but it seems to be related.

I think so. But I can't do it on my rig because my arms aren't long enough. :)

My 3-way rocker switch with MOM (emergency start) is on the dash by the driver. The generator start switch is either on the generator or back on the stove vent hood.

My generator starts from the engine battery. I would have to get a helper to hold the MOM switch in order to start the generator from the engine battery.

A better solution would be to use the house batteries to start the engine, and then start the generator using the current provided by the alternator (and let the alternator charge up the engine battery).

How can the key be in run and the engine not started?

If the engine were running and died by some other means than using the key to turn it off, (out of gas, pop clutch, etc.) then the engine could be off but the key in RUN.

In normal operation, however, the engine will be running when the key is in the RUN position. But there is also a START key position and this is different from RUN. Many times things are disconnected in START that are connected when in RUN. This is so the engine starter motor gets all the current. You might notice your radio turning off when starting, for example.

If my house batteries are very low and will not turn my generator over, can I engage the "engine emergency start" button to start the generator?Not trying hijack the thread, but it seems to be related.

Here is what I think:

On my RV (1990 Winnebago Warrior, Ford E350 chassis), the Charging Solenoid, which gangs the house and chassis batteries together, is activated 1 of 2 ways:

FIRST WAY:
Momentary Position of rocker switch:
This uses power from the HOUSE BATTERIES to energize the solenoid. This is a "jump start position", and is to be used when the engine battery is dead. Thus logically you would want to use the house batteries, and not the engine battery, to energize the solenoid.

SECOND WAY:
DUAL position of rocker switch:
This uses the engine battery (or alternator if engine is running) to energize the Charging Solenoid. But, it is hooked up to the RUN position of the key.

When you START the engine, typically all other accessories are OFF. I can see this when I start my engine as all of my aftermarket gauges turn on when I switch to RUN, but turn OFF when I keep turning to START, and turn back on again when I let go of the key and it goes back to RUN.

My guess is that the Charging Solenoid is only energized when:
* Rocker Switch is in DUAL mode.
* Key is in RUN position.

1991.
1. FORD does NOT install any Coach charge relay's at all. The Coach Maker installs the Coach Battery charge system
2. Even as old as 1991, there can be 2 types of Charge systems for the coach battery. The Older 80/90's style on C body was a standard silver continuous duty solenoid. It was activated by the Ignition side of the Key switch. When you turn the Key to START the engine, the Ignition side of the Key switch is opened until the engine starts and you release the spring load of the key. Yes, If you have an Ignition side charge solenoid activated it WILL close for both battery banks when you turn the key to the Ignition indent, but NOT to the 2nd spring loaded Engine start indent.
3. Other systems back then used a Dual Battery alternator Isolator. NOT to be confused with current Intellitec type BIRD system. Here is a link to that older type system. https://www.sterndrive.cc/product/battery-isolator-130-amp-bi-1203-3a.html?gclid=EAIaIQobChMIuOnWhaiS5wIVBdvACh07UAuBEAQYAyABEgJe6vD_BwE
This link shows a 3 battery but they make the 2 battery system.

Hi BFL13,

My 1987 Ford E-350 Diesel had only one solenoid but it did have a Diode for isolating and charging the "house" battery bank.

Most people would not know if the charge/isolator energizes. They would normally proceed right by the on position and go for start.
Older rigs did not have the electronics. My 1993 has electronics to delay the energizing. Some had the Mom/off/dual switch. That is what we had in my old 1986 Itasca. It sort of worked! Switch failed then connectors on relay and finally relay corroded internally.

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

BFL13,

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