House battery not charging properly. Bypass solenoid?

[mdecorso]

I am having some difficulty getting my house battery in my 1992 Ford E350 Class C Four Winds to charge properly. I think the solenoid between the engine battery and house battery is failing.

On the engine battery side of the solenoid, with the engine running, I get a 12.7 volt reading with my tester, with the positive tester lead on the solenoid post and negative lead on the engine negative battery post.

On the house battery side of the solenoid, with the negative lead on the engine negative battery post and the positive lead on the post on the house battery side of the solenoid, I get an 11.7 reading.

With my Onan generator running, I get a 13.8 reading at the engine battery and engine battery side of the solenoid, and an 11.8 reading at the house battery side of the solenoid.

Does this mean my solenoid is failing? Both batteries are brand new.

I am in Europe and it may be difficult to find an appropriate soleinod. Can I bypass the solenoid to get my battery to charge until I find the proper replacement part if I need one?

ThaNks.

[Salvo]

There shouldn't be any speculation whether solenoid is bad. Place voltmeter probes across the two big lugs of the solenoid.

With engine off, voltage will be greater than 1V. Depending on which probe goes where, measurement may be greater than -1V.

With engine running, voltage will be less than 1V. If voltage is greater than 1V then solenoid is bad.

[Harvey51]

Easy to tell if a poor connection or wire is dropping the voltage - disconnect the charging wire from the house battery. With no current flowing, a resistance will not cause a voltage drop between the solenoid and the end of the disconnected wire. Connect again and a drop in voltage indicates current flowing through a resistance between the measuring points. Could be in ground connections.

Looks like alternator trouble to me, too. I would put a voltmeter across the engine battery and watch while someone starts the engine. The voltage should initially be well over 14 for a few minutes.

[RJsfishin]

I wouldn't turn a hacksaw to anything. I would find the problem. You have a bad/poor connection somewhere. Once you find the problem, the solenoid will more than likely be fine.
You need 12v power now ??? Jumper the 2 batteries together, and you will have power to the house.

[Sam_Spade]

mdecorso wrote:
With generator on I am getting 13+ at the car battery, and then fluctuations of 11.82 to 12.04 at the house battery.

I think this means that your house batteries are DEAD and you don't have a good connection at or near them somewhere.

In order to get things back to a workable situation you may HAVE to charge your house batteries with an external charger somehow to be sure that they will take and hold a charge.

[Sam_Spade]

mdecorso wrote:
I get the same voltage reading coming off of that, 12.7.

I sorta need the battery to charge NOW or I can't start the generator

You are missing out on a critical point:
With no voltage readings above 12.7 present, NOTHING will be charging very much or at all regardless of what you do.

You should be able to start the generator with another vehicle battery and jumper cables but you might have to leave them connected for a few minutes before starting.

I have a STRONG urge to comment on "shipping" an RV to Europe.....but that's a subject for a different thread.

[Salvo]

That still doesn't make any sense.

With engine off, and gen on, you get 13+V at the chassis (car) battery and only 11.8V at the house battery? Sounds to me you have chassis and house battery mixed up. Instead of measuring at the solenoid, measure directly at the chassis and house batteries.
Get solid measurements.

Is this how your solenoid looks?



If it is then you're in luck. Disconnect both chassis and house batteries ground and remove solenoid. Take a hacksaw and cut the aluminum cover just below the electrical connections all the way around. Don't cut deep, just the cover. Now you can see the contacts that need cleaning. Get some fine sand paper to remove the pitting. Duct tape the cover back on and install. I've done this, it works.

mdecorso wrote:
With generator on I am getting 13+ at the car battery, and then fluctuations of 11.82 to 12.04 at the house battery.

[YC_1]

Wolfe is on the trail. You have bad connections. Ditto on the solenoid only needing one small terminal. However, make sure you clean the mount where it is bolted in place because that is the ground connection,.

[wolfe10]

Turn everything off, clean and tighten connections at battery and also ground connections to the chassis.

No problem with a solenoid having only one small terminal. That means it is screwed to metal and the solenoid exterior metal serves as ground.

Don't know where you are in Europe, but you should be able to find a 12 VDC CONSTANT DUTY solenoid of the proper amperage/ So, a starter solenoid is NOT what you need.

Another option is a marine ON/OFF switch with alternator and chassis battery to one lug and house battery to the other lug. Switch ON= combined. Switch OFF= batteries not combined.

[mdecorso]

So the solenoid has been bypassed, with both wires (I only have one on either side) attached to the same post. Wit car running I am getting declining numbers as I move down the line from the car battery to the house battery, withe the house battery fluctuating slightly around 11.8. With generator on I am getting 13+ at the car battery, and then fluctuations of 11.82 to 12.04 at the house battery.

Perhaps the wiring from one to the other has corrosion in it. I am thinking of replacing it. Thoughts?

[mdecorso]

So I cannot find any battery disconnect switch anywhere. I bought this used with no run through, but I have all the manuals and have been through them thoroughly. I have also traced tone of wiring from front to back and saw no such thing. When the generator is running, I get a four light (all of them) reading on my monitor panel. When engine running, three. I know that is not right.

The solenoid I have between the two batteries (engine/coach) has the two main lugs/posts and one other, not two like on a startery solenoid. I get the same voltage reading coming off of that, 12.7.

I sorta need the battery to charge NOW or I can't start the generator and am dead in the water with wife and kids living in it. Not good. So the bypass is a temporary idea until I can figure out what is really going on.

I have the alternator and starter tested at an Auto Zone a couple days before shipping this thing over to the UK and it all tested good. I know 12.7 is a tad low, should be more like 13.5 or so. But here I am trying to make it work for a couple months.

Working on the bypass right now, kinda want to see what readings I get when it's done, just to know more....

Please keep the advice coming. I am digesting it all. Auto electronics are not my forte. Swapping parts, no problem. I'm all tooled up.

[wolfe10]

Agree, 12.7 VDC at the chassis battery with engine running means an alternator/regulator/wiring problem.

Same for no change in voltage on house battery when generator is on and presumably powering the converter, charger or inverter/charger.

And, yes after you solve either of the above, you can bypass the defective solenoid to charge both banks. BUT, have you confirmed 12+ VDC to the signal terminal of the solenoid. If no, disconnect the POSITIVE signal wire from the signal terminal and take a small wire (will be supplying less than an amp) from the large lug that has 12.7 VDC to the positive signal terminal. If solenoid closes, you know the solenoid is OK. If not the solenoid is bad.

Safest way to bypass the solenoid: Mark (tape, paint, etc) all the wires on one large lug. Remove them and ADD them to the other large lug.

Be sure to return wires to their original position when finished.

Do NOT use a jumper wire to do this with engine running or driving, as the jumper could "jump off" and create a dead short directly from a battery.

[Sam_Spade]

Salvo wrote:
This doesn't make sense. When the Onan is running, you should be getting more than 11.8V at the house battery.

First, be sure that a coach battery disconnect switch hasn't been accidentally thrown. That will stop it from charging from ANYTHING.

AND with the engine running, you should see more than 12.7 at the engine battery too.

I'm not sure that "bypassing" anything is a good idea, not knowing exactly what is wrong.

There may be more than one fault at work here.

[Salvo]

This doesn't make sense. When the Onan is running, you should be getting more than 11.8V at the house battery.

mdecorso wrote:

With my Onan generator running, I get a 13.8 reading at the engine battery and engine battery side of the solenoid, and an 11.8 reading at the house battery side of the solenoid.

ThaNks.

[YC_1]

First you must find out if the control voltage of the solenoid is there before you throw the baby out with the bath water.

Of course you can bypass the solenoid. Just pile up the big wires on one side or the other.

Before doing that check the small terminals on the solenoid. You should be getting 12 volts on one and zero on the other. This is the control voltage. If you have a blown fuse somewhere the voltage might not be there.