House Batteries are ULTIMA Marine GEL Batteries.

[not Exide as previously posted]

If I understand correctly, in the house circuit there are two 6V batteries in parallel, with a single 6V in series with that pair. That's a weird way to do it, and it should be eliminated.

If the two batteries in parallel are 12V, then the third battery in series with them definitely should not be in series, as that produces 18V.

As bill h suggests, many times parts-swapping is the best way to determine the culprit, and I'd put a known-good battery into the house circuit in place of the three now installed and see the reaction (both using the isolator and again with it bypassed), before I bought any new batteries. There are issues with batteries that don't always show on the usual tests.

I'd take your suggestion of eliminating that third battery, or doing that and then replacing the two paralleled house batteries with a pair of 6V golf cart batteries in series. Golf cart batteries are a bit taller than typical deep-cycle, so you might have to mod the holddowns (I did).

An alternative would be to replace the three house batteries with three 12V batteries in parallel, which would normally give more power (in terms of amp-hours), depending on how big the batteries could be and still fit.

"YES"

...there are 3 - 12 volt house batteries ...two sit in the starboard engine compartment and are wired in parallel.

-Then-

...a lead comes-off the positive [of the 2 house batteries] and runs-round to the rear of the vehicle where there is a THIRD "house battery"; and is connected to the positive side...

-Then-

...a lead comes-off the negative of the THIRD "house battery" and runs-round to the port-side engine compartment and connects to then negative side of the 2 "chassis batteries", which are wired in parrallel to eachother.

This seems-like a strange arrangement to me as well, but as I had stated, this is how I purchased the vehicle.

It's like the 3rd "house battery" and the "Isolator" are wired in a "series loop" with the 2 parallel "house batteries" and the 2 parellel "starter batteries".

I have NO space limitations, so I can mount ANY number of batteries, in ANY dimention, in several different locations.

Do you think my Isolator is "shot"???

-OR-

...do I just need to replace the "house batteries" [x2 Golf Cart]; and in what number [of batteries] and in what configuration [wired] to the chassis batteries and the isolator???

I am not there, and do not have a diagram of your coach, so I may not have the big picture here.

How long do you stay out in your coach with no hookups?

Do you use the furnaces in winter?

If you need to run your genset to charge the batteries, can you do so without being hated?

Do you have a good charger onboard so genset runtime is short?

These questions are leading somewhere. I am trying to help you decide how many batteries you need and whether you really need alternator charging at all.

You might not even need a diode isolator. Unless you buy or build one using Schottky diodes, they rob valuable voltage from both coach and chassis batteries, limiting their usefulness and shortening their life. You might not even need an isolator at all.

I do not like parallel charging of dissimilar batteries, which is what most alternator charging systems end up doing. This is incredibly inefficient, taking hours and hours to charge, since the alternator is reading the well-charged chassis battery more than the lower-charged coach batteries.

If you must use the alternator to charge coach batteries in parallel, consider the Winnebago system.

The Winnebago system uses an interesting method of battery isolation and paralleling. The dash switch is an SPDT CO on-off-(on) It has three wires, with the momentary side getting power from the coach battery, the on side getting power from the ignition (or acc terminal of the ignition switch), and the center being the output to the coil of the paralleling relay.

So..Start the engine with the switch in off. To attempt to charge the coach battery while driving, you move the switch to the on position, which ties the batteries together while the ignition is on. You would use the momentary position to tie the batteries together when the starting battery is low. The off position is used for normal starting or to charge the chassis battery only. If the switch gets its power from the acc terminal of the ignition switch, then it can be left in on for all normal use, as the acc terminal is usually not energized until the starter is released, but that would vary with ignition switch suppliers. The batteries are not paralleled when the ignition is off.

This system combines the function of the isolator and the paralleling solenoid without the reduced charging voltage of the isolator. And there are fewer parts and connections than a system with both an isolator and a paralleling relay.

However, it does not address the issue of charging a low and a charged battery in parallel.

Warning: Rant follows.

I am not a fan of charging coach batteries by the engine alternator, particularly through an isolator. If I wanted to do that, I would have a Perko make-before-break switch in the charging line to allow the alternator to see only the coach batteries and respond to their needs only. When the typical motor home with an isolator tries to charge both truck and coach batteries in parallel it responds to the highest battery and the result is a long slow charge for the lower batteries, usually the coach batteries. A heavier alternator never really gets to show its stuff in such a setup. The Winnebago relay solution is elegant in its simplicity, and at least avoids the diode-induced voltage loss. An isolator drops the charging voltage by around .7 volts, which can result in a sulfated battery with a short service life unless equalized or at least three-staged after the trip. Batteries that are charged by an alternator and are not regularly equalized do not last as long as batteries that are properly fussed over.

I never parallel my batteries. The alternator charges the chassis battery, as God, Ulrich Zwingli and Charles Kettering intended, and the genset or solar panels charge the coach batteries.

End of parallel charging and isolator rant.

These are all very good points to consider in changing anything.

I am typically "plugged-in" where ever I go.

I will use the furnaces in Spring and Fall, but store the vehicle during the Winter... Again, typically plugged-in while doing this.

Rarely use the gen-set, as I am usually somewhere where there is power and most private or state operated parks or campgrounds do not allow the use of generators.

I have a Converter / Charger with an average charge rate of 7.5 amps [probably original equipment].

quote:

I am typically "plugged-in" where ever I go.

I have a Converter / Charger with an average charge rate of 7.5 amps [probably original equipment].

Since you are typically plugged in, batteries are not crucial. You can get along with one or two MATCHED 12 volt coach batteries.

I would suggest buying a good "smart" converter/charger. It need not be a biggie, but three-stage charging extends battery life. This is particularly true if you leave your coach plugged in for any time.

I would also suggest that you do not need alternator charging. Hence an isolator is unnecessary. If you must have alternator charging, eliminate the diode isolator and do the Winnebago relay thing.

An additional reason for my dislike of alternator charging that I did not mention is that it can lull you into a false sense of security, thinking that your batteries are fully charged after a trip. After a trip, batteries will really benefit from being fully charged with a three-stage charger before they sit.

quote:

most private or state operated parks or campgrounds do not allow the use of generators.

Music to my ears. Loud or long-running generators are one of my cranks.

quote:

It's the house batteries that are in question........Should I scrap the 3rd "in-series" house battery and replace the 2 "in-parallel" house batteries with Golf Cart Batteries; completly eliminating the 3rd HOUSE BATTERY???

Since your two matched coach batteries test 1.275, they should last a long time in parallel and properly nannied.



You don't depend on your batteries as much as we do (we have never plugged in our Barth) but it is good economics to do the best you can for your batteries.

quote:

I have a Converter / Charger with an average charge rate of 7.5 amps [probably original equipment].

First, all three of your house batteries are in parallel, not series parallel. As bill h mentioned, diode isolators drop voltage and never give the house batteries the 'kick" they need to be desulfated. However, my somewhat newer Breakaway apparently has a sensor/relay that switches charge between house and chassis batteries (There's a relay that seems to have no other purpose, but I'll have to remove it to read the nameplate data). After a run of a few hours, the house batteries are fully charged.

As far as the converter-charger is concerned, I'd be surprised if you had less than an Intellipower 9160 (60A 12VDC) (more likely significantly more output). With most older Intellipower 9xxx unis, a "Charge Wizard" can be added (I have one for the old design you can have for postage). This adds a desulfating cycle when connected to 120VAC.

If you don't have a "smart" converter/charger, I agree with bill h that it's a very wise investment.

quote:

Music to my ears. Loud or long-running generators are one of my cranks.

bill h, this is one main reason why I'm putting myself through the ordeal of replacing the Kohler Klunker with a Honda liquid-cooled RV genset. Just sitting on the cart at full power, the Honda is significantly quieter than the Kohler. I have full-soundproofing sheets coming for the enclosure (expensive stuff!)

quote:

However, my somewhat newer Breakaway apparently has a sensor/relay that switches charge between house and chassis batteries (There's a relay that seems to have no other purpose, but I'll have to remove it to read the nameplate data). After a run of a few hours, the house batteries are fully charged.

Does that perform the same function as the Perko Switch I mentioned earlier? Sounds pretty nifty.

I think it does - I had, at one time, a website with a similar device (this is one such) - but it's not the one I remember in the Breakaway. I seem to have a great number of relays, but unlike Regencies with their neat Relay Farms, the Breakaway's are scattered all over. In any event, I have not discovered a diode isolator...anywhere.

I'll be getting to that before too long, as my quest for The Compleat Wiring Diagram is still underway.

Something is taking care of my house and chassis batteries underway (and the dash VM confirms something is loading the alternator); I just can't rule out Black Magic at the moment...

From their site:

"Voltage spikes generated by the coil of the solenoid are absorbed by protective circuitry built into the Battery Separator."

Hmmmmmmm............sounds like a lot of puffery over a standard clamping diode.

I think this one has a relay - a diode system wouldn't have a solenoid, to my knowledge - unless the solenoid is just to parallel the batteries for emergency start. The voltages noted do lead one to suspect that the thing is actually a diode-based isolator

Yeah, it has a relay. Good circuit design practices mandate the use of a clamping diode to cause the coil to dissapate countervoltage generated by the field collapse when the relay is de-energized, which they appear to be trumpeting as something special.

Or, they might have cheaped out and just used a resistor.

When I suspect a single-component standard design practice is being touted as "protective circuitry", it Makes me suspicious.

I also get a "full charge" reading on my house batteries after running, so things must be working correctly... Just still have the output voltage fluctuation to figure-out.

My Converter / Charger is a:

MagnaTec TU-775-2
B-W Manufacturers.

As-long-as their is a load present, the symptoms stop.

Have-had a busy week, so I have not yet made it back to the repair shop.

Greetings from Las Vegas.

I have tried to read thru all the post to gather what is happening. Got lost in a few but there are a couple of points I would like to make.

If the voltage is bouncing up and down AND the alternator is getting hot, I believe that you have a short somewhere or very high load that is being applied to the 12 V system. I believe that the bouncing is being caused by a circuit breaker going on and off to protect the system. I would look for and maybe try to feel the breakers on the panel or elsewhere and if you find a "hot" one, that is probably the circuit this causing the trouble.

Isolators (if there) would not cause this symptom.

I don't believe the alternator is defective, if it charges (output voltage > 13.3VDC minimum) and the bouncing stops with lights on, Then I don't believe that charging system is at fault. The alternator is trying to do it's job, maintain the charging voltage above 13.3 VDC and if a high current drain (or short thru a breaker) were applied, the voltage would be dragged down during the time the breaker was on and then would jump back up when the breaker over heated and turned off. The alternator will try to apply as much current (via constant voltage regulation)as it can per the RPM of the alternator, if it is working into a high load, it will get hot!

Suggest don't over analyze, look for the simple things first. During the problem--

Hot breaker(s)
Disconnect systems ONE AT A TIME, until the bouncing stops, go further down THAT circuit once this is located.

Warm or hot wires:
Same issue, follow to the source of the load or short.

Warm or hot switches:
Same.



HTH

quote:

Something is taking care of my house and chassis batteries underway (and the dash VM confirms something is loading the alternator); I just can't rule out Black Magic at the moment...

On my Breakaway, it had a relay that paralleled the chassis and coach batteries once the key was turned on. Going down the road did a nice job of keeping everything up. HOWEVER, The PO had AGM house batteries and I also do not like charging different technology batteries in parallel, doesn't matter what kind of charger you use. I also didn't like this system because at the very moment you switched the key on, before starting, the batteries were paralleled and starting load was applied to both house and chassis batteries.

When that relay failed I replaced it with an Intelletec system that parallels the house and chassis batteries together AFTER the alternator voltage has reached 13.3 VDC or more for 2-3 minutes. I have 4 golf cart batteries for house batteries and two wet style 12 V batteries for the chassis.

My alternator will normally run 13.8 to 14.2 volts depending on temperature and load, it is a 160 amp unit and will produce 100 am at idle.