House battery not charging properly. Bypass solenoid?

Yes but a casual reader might ask--How do you start a generator when you are in Europe?

Well, I push the button on it and it starts. It is mounted on the vehicle. Is that answering you question? And does that yes you posted mean I can bypass like I am thinking? Thanks again.

mdecorso wrote:
Well, I push the button on it and it starts. It is mounted on the vehicle. Is that answering you question? And does that yes you posted mean I can bypass like I am thinking? Thanks again.

Yes, you can bypass the solenoid. My curiosity was about the distances but now that you've explained that your arm reaches from Europe to Alaska, I'm all good.

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.

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.

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.

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.

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.

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?

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.