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Topic: Alternator not charging house batteries (Read 1545 times) previous topic - next topic

Alternator not charging house batteries

The alternator is charging the chassis battery normally but is not charging the house batteries.  I have checked both of the large outputs of the "isolator" and the chassis side has 14.5V at idle but the house side has no voltage.  That's about the extent of what I know to do for trouble shooting.

The DC side drawing we have shows the isolator board wiring but what we have in the coach looks a bit different than the drawing.  The components on both look similar but there is a lot more wires in the coach than what is shown.  I'm not for sure if what I checked was the isolator, the start solenoid or some combination of the two.

In one of the pictures it shows where I took a voltage reading from. 

What is it that i'm looking at in that picture?  Is checking the voltage there a good way to check the voltage output or is there a better way or place to check.

Thanks in advance,
Tyler

Re: Alternator not charging house batteries

Reply #1 –
That is the BATTERY COMBINER/BOOST, not battery isolator.

If you turn on the boost switch on the dash, voltage should be the same on both large lugs.

The battery isolator, if OE will be approx 4X12" with fins. The OE isolator may be entirely gone-- may have been where the two screws are on the upper part of the board.

Trace the wire from the Alternator B+ terminal and see where it goes.

Re: Alternator not charging house batteries

Reply #2 –
above the solenoids is a colored bar with 3 or 4 studs the 2nd one is alternator the left looks like the house batteries and far right is the coach(motor) batteries I believe  if u don"t have the same voltage to ground on these 3 posts your isolater maybe bad
this bar is to charge the batteries by the motor and prevent back charging from gen or house current
hope I did not confuse u

Re: Alternator not charging house batteries

Reply #5 –
Tyler,

Photos below show the original red finned battery isolator that came with our coach.  My photos show the same panel as does your first photo.

If you still have a OEM isolator, it should be mounted on your panel just above the two solenoids (the 2 round metal objects).

Re: Alternator not charging house batteries

Reply #6 –
The factory isolator is no longer there.  I tracked down the B+ cable and it is the the top red cable on the right side in the picture.

Does that mean the boost switch has to be on to charge the house batteries?

Re: Alternator not charging house batteries

Reply #7 –
Yes.

Re: Alternator not charging house batteries

Reply #8 –
Quote from: oldguy –
Yes.
Is that ok to do?  When we first got the coach, we had to use the boost switch to charge the chassis battery from shore power and I thought there was a lot of agreement on here about not doing that for risk of damage.

Re: Alternator not charging house batteries

Reply #9 –
On your photo it clearly shows the shadow of the isolator above the two screws, I wonder why it was removed?

Re: Alternator not charging house batteries

Reply #11 –
Quote from: The Soft Boulders –
Is that ok to do?
Using the boost switch to charge the coach (house) battery is OK as a temporary solution, until you get around to replacing the missing isolator.  We understand if money is a little tight right now - we've all been there at one time or another.

Remember: when the batteries are tied together by the boost switch, it would be possible to run both batteries down so low that you would not be able to start the engine.  You must pay attention to the voltage readings when they are combined.

The boost solenoid may get a little warm when left on for long periods, but it should not be damaged if it is correctly sized and rated. 

In your photo, the boost solenoid looks rather crusty.  I suspect it has been is service quite a while.  If you decide to keep using the boost solenoid to charge the coach battery, I would at least recommend you replace it with a new one.  It is important that the boost solenoid be continuous duty rated, and also of sufficient capacity to handle the required amperage.  The Cole Hersee 24213 has been used by many Forum members for this application.  It meets the requirements, and is not too expensive.

Shop around (online) for the best price.

Cole Hersee 24213 12V 200A Continuous Solenoid - Boat and RV Accessories

Amazon.com: Cole Hersee 24213 Hose: Automotive
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Alternator not charging house batteries

Reply #12 –
That solenoid consumes 3 amps of power to make it connection.  Gets warm.

Re: Alternator not charging house batteries

Reply #13 –
Quote from: Chuck & Jeannie –
Using the boost switch to charge the coach (house) battery is OK as a temporary solution, until you get around to replacing the missing isolator.  We understand if money is a little tight right now - we've all been there at one time or another.

Remember: when the batteries are tied together by the boost switch, it would be possible to run both batteries down so low that you would not be able to start the engine.  You must pay attention to the voltage readings when they are combined.

The boost solenoid may get a little warm when left on for long periods, but it should not be damaged if it is correctly sized and rated. 

In your photo, the boost solenoid looks rather crusty.  I suspect it has been is service quite a while.  If you decide to keep using the boost solenoid to charge the coach battery, I would at least recommend you replace it with a new one.  It is important that the boost solenoid be continuous duty rated, and also of sufficient capacity to handle the required amperage.  The Cole Hersey 24213 has been used by many Forum members for this application.  It meets the requirements, and is not too expensive.

Shop around (online) for the best price.

Cole Hersee 24213 12V 200A Continuous Solenoid - Boat and RV Accessories

Amazon.com: Cole Hersee 24213 Hose: Automotive

Everything metal on Pearl is crusty and that's always a considering factor when it comes to spending money frivolously on her.

Would buying a new isolator be the correct way to fix the problem?

Would something like this work?
Cole Hersee 48090 Battery Isolator 90A 3 Stud
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Alternator not charging house batteries

Reply #15 –
As Mike says, a replacement isolator should have a rating of around 180-200 amps.  (Allows for future alternator upgrade)

The original isolator on our coach was rated at 190 amps.  See photo below.

SO, looking at the offerings from the supplier you linked, the Sure Power #2002 would be a better choice.

EATON's Sure Power 2002 Multi Battery Isolator | Waytek

Some Forum members tout the superiority of a "smart" battery combiner over the original diode-based isolator.  For example:

Cole Hersee 48530 200A Smart Battery Isolator

The Cole Hersee 48530 could actually take the place (physically and functionally) of your old boost solenoid.  It would work as a "smart isolator" and as a "boost solenoid" (using the optional start assist mode).

There are several different products that address the automatic management of dual battery banks in RVs.  Search the subject on this Forum for many opinions before you make your decision.

You can also do away with the automatic function, and take matters into your own hands with a manual switch.

Re: Alternator not charging house batteries

Reply #16 –
Correct.  You have a 160 amp alternator and diode-based battery isolator needs to be rated at that or higher.

If you go that route, you will need to be sure the wire from the alternator SENSE TERMINAL goes to the chassis battery lug of the new isolator.

And, if you are a KISS theory guy, you can replace all that with a simple, marine ON-OFF switch.  Alternator B+  and chassis battery to one lug and house to the other. Sense wire to chassis battery lug or any other place like the boost switch with good connection to chassis battery.  Here is a good one-- rated at 250 amps continuous: PERKO Inc. - Catalog - Battery Switches - Medium Duty Battery Disconnect...

With that switch:
OFF-- alternator charges only chassis battery bank.

ON--  alternator charges both banks. Also, allows on-board charger to charge both banks with zero amp draw from solenoid,etc. A very good high amp battery combiner/boost.

Re: Alternator not charging house batteries

Reply #17 –
All the new coaches are equipped with an auto battery combiner as far as I know.

Blue seas ACR?

ML-ACR Automatic Charging Relay with Manual Control - 12V DC 500A - Blue Sea...

If you do not run a wire from the relay to the switch it works fine just no light up in the switch.

The switch replaces the boost switch.  Magnetic latching. No power consumed.

Either bank gets a charge the relay connects them.  Auto disconnect if a draw occurs.

Separate post on relay to add a starter sense wire to auto disconnect the relay combining function when the starter engages.

Batteries can be manually connected. 

The start sense optional hookup shows the start batteries true condition if hooked up.

My auto combiner works perfectly from  our small solar panel setup

Re: Alternator not charging house batteries

Reply #18 –
Thanks for pointing out the proper sizing of the isolator,  I probably would not have thought of that.

I'm not fully understanding what's all going on so I need to do some more research.

I like the idea of a manual on/off switch but am having trouble picturing how it works.

Re: Alternator not charging house batteries

Reply #19 –
To ensure that you never have a run down start battery is why the ACR is installed where the isolator was.  100% reliable.

One mistake resulting in discharged start or house batteries can permanently damage them.  Replace

That's why the industry changed to the auto combiners years ago.