Let's Talk Batteries, Isolator and Voltages

[gt350ed]

Howdy! This is my 3rd thread on this GENERAL subject. When I started oh so many months ago here, I had an alternator that did not seem to be working, and I seemed not to have any charge going to my coach batteries (2 Golf cart 6-volt) either with the engine running OR when plugged in to shore power. Two presumably separate problems. And you folks here were extremely helpful in guiding me along.

Since then, I replaced the alternator and I now have a good charging system from the engine. I also checked the Magnatek convertor. It has 110volts coming in and over 14.15 volts coming out as of this afternnoon. So, no issue there.

Once I figured out that the solenoid-looking thing above my engine battery was probably the isolator, I started evaluating it. It had the alternator/starter cables coming in and the coach battery cables coming out. Although I had voltage coming TO it, I could not get a voltage reading coming out of it, as if a charge were going into the storage batteries. And I never heard any clicking sounds.

So I bought a replacement and installed it today. At first, it seemed to do nothing. Then, all of a sudden I heard a click with the engine running AND shore power hooked up. I connected my volt meter to a ground and touched the positive probe to the ear on the isolator that goes to the storage batteries. It was reading 13.2 volts. WOOHOO!! The static voltage of the storage batteries earlier in the day was about 12.65v.

Since then, I have plugged and unplugged shore power and again had the engine running, but no click and the voltage reading from the storage batteries side of the isolator is 12. 6 volts+/-.

SO...I guess my question is...does the isolator turn itself off and on? And if so, what triggers it?

I would think that 12.6 volts on deep cycle golf cart batteries WOULD NOT represent a full charge. So I'm wondering if I still have something wrong, or maybe my NEW isolator stopped working after one click. I had earlier traced wires and there are no fuses to blow.

Do I have a problem? Heck if I can tell.

[pwf16129]

if you have the same basic set up i have the isolator will be turned on when you have a key on hot connected to it or it could be wired so that the alternator has to have out put to energize it.
i had to replace mine right after i got it due to the fact the previous owners used a starting solenoid instead of a constant duty solenoid.
ck to see if you have a good ground going to the ground post,i wired mine to the battery and has worked well.
as for 12.6 volts that is very close to 100% state of charge look for a web site call the 12 volt side of life it has tons of good info to make your life easier

[gt350ed]

Originally Posted by gt350ed

I bought a replacement isolator (same type) and installed it. At first, it seemed to do nothing. Then, all of a sudden I heard a click with the engine running AND shore power hooked up. I connected my volt meter to a ground and touched the positive probe to the ear on the isolator that goes to the storage batteries. It was reading 13.2 volts. WOOHOO!! The static voltage of the storage batteries earlier in the day was about 12.65v, which I guess is near FULL CHARGE.

Since then, I have plugged and unplugged shore power and again had the engine running, but NO CLICK and the voltage reading from the storage batteries side of the isolator is 12. 6 volts+/-.

SO...I guess my question is...does the isolator turn itself off and on? And if so, what triggers it?

I'm wondering if I still have something wrong, or maybe my NEW isolator stopped working after one click. I had earlier traced wires and there are no fuses to blow.

Do I have a problem? Heck if I can tell.

BUMP!!

[tompen]

Did the relay look like one of these ? They kinda do the same thing but are controlled differently. The one on the right is bigger than it looks in the pic. The one on the left, using a BIRD can be bidirectional. The other will allow the Alternator to charge 2 batteries at the same time while separating them when the engine is not running. If you checked coach battery voltage while on shore power you should read convertor voltage. You would have to unplug to get battery voltage. You have had your share of problems with this. Hope you get it.

Tom

[gt350ed]

Originally Posted by tompen

Did the relay look like one of these ? They kinda do the same thing but are controlled differently. The one on the right is bigger than it looks in the pic. The one on the left, using a BIRD can be bidirectional. The other will allow the Alternator to charge 2 batteries at the same time while separating them when the engine is not running. If you checked coach battery voltage while on shore power you should read convertor voltage. You would have to unplug to get battery voltage. You have had your share of problems with this. Hope you get it.

Tom

Thanks Tom! The old one AND the one installed last weekend look just like the one one the left EXCEPT mine is a 3 terminal versus a 4-terminal. As I am the only owner and the isolator had never been touched, I'm confident that the wiring is correct to all terminals. Although the old isolator was found to be barely grounded, I insured that the new one IS grounded.

The replacement came from eBay and, frankly, I only paid $14.95 for it INCLUDING free shipping. So, I suppose one could NOT have a high degree of confidence in it. With this thread on the forum, I was trying to get answers to how it is supposed to work (voltage readings where and when, key on or off...that sort of thing). I'm still trying to figure out why there are so many wires on the storage battery side of the 3-terminal isolator (3 small wires and the battery cable).

This week, I have ordered a Cole Hersee isolator similar to the one on the right. It will be delivered this Friday or so. At a discounted price of $101.00, it is presumably a MUCH better unit. And this Cole Hersee isolator is designed to work most appropriately with CS series Delco alternators, which is what I have.

As for "share of problems", it really has not been that bad. Mostly relating to an alternator that apparently went bad, since replaced and working, and this isolator issue. I cannot ignore the possibility that the non-charging of coach batteries and the alternator having failed MAY be related. I've been operating on the presumption that the isolator may have failed at some point, and in my looking for what the problem was MAYBE I somehow shorted the alternator, adding to the problem.

Anyway, if you saw this coach, which we have owned since new, it almost looks like it just came from the factory. Well worth sorting out.

[tompen]

OK. The solenoid you described is usually a constant duty relay. Yours is internally grounded for the coil that closes it. 12V from the chassis battery will be on one large terminal, and 12V from the coach batteries on the other large terminal. The terminals often get used as a junction point. That explains the extra wires. The relay is normally open. When 12V is applied to the small terminal it closes the relay and connects the two large terminals. The object is to provide a boost or charge to whichever battery needs it. It is also used with the emergency start switch if you have one. The big question is where the power comes from to close the relay. That is the small terminal. Applying 12V to it should close it with a click. The relay may be controlled by a BIRD or IRD or just the boost switch.
However, the isolator that you have ordered would normally be used to allow the alternator to charge both battery systems using diodes so they do not discharge each other when the engine is not running. If you have both than I would believe the relay is either used for emergency starting or controlled by an IRD to charge the chassis battery when on shore power.
With your voltmeter check the two large terminals. Unplug from shore power for now. You should hade chassis reading on one side and coach on the other. This is assuming the relay is open. The small terminal should have no power on it. Next put 12V on the small terminal. The relay should close and the voltages will be the same on both batteries. If so, you need to find out what is powering the small terminal and when. Start with the boost switch if you have one. Try plugging in shore power and see if the small terminal is powered then. You may need a difference in voltages to trigger it if it has a BIRD or IRD. Draw some power from the chassis with the headlights so the voltages are different. Lots of info ot the site about how a BIRD works so I wont go into it again. I don't think you gave a BIRD if you have the isolator system for charging both batteries with the alternator.
Hope I haven't confused you too much. It just seems that there is too many different ways to put the things together.
Good Luck.
Tom

[Old Scout]

A $14 dollar solenoid is probably a simple switch that reacts to some sort of logic/signal that is stored/located elsewhere in the coach. Usually, the logic has a high setting that activates the solenoid when the bat bank being charged is above 13 volts [a 12v bat or two 6v bats in series that is/are fully charged and at rest is usually around 12.8v]. The lower end setting keeps one bank from draining the other bank when there is no charging source, eg, something under 13v.

Somewhat older coaches use the bat isolator to distribute charging from the alternator, and use a solenoid to control charging from the inverter and to provide a switch for the bat boost function. Newer coach designs often combine all three functions via the solenoid route. You need to figure out exactly how both the alternator and the inverter charging sources are controlled before you swap-out or add components.

Not sure how/if the bat isolator has any on/off logic built in. Do know that most alternators have build-in diodes that control charging output.

[Dave78Chief]

Based on the description on page 26 of the Owners Manual for your rig (http://fleetwoodrv.com/partsandservi...YR_BOUNDER.pdf) AUX Battery relay should be energized when the engine is running. If memory serves me correctly, Fleetwood products use a Battery Control Center (BCC) normally located under the front engine access hood. While this drawing is not entirely reflective of your setup, it would be close:


The fleetwood BCC would take the place of the BIRD controller shown. The silver relay you replaced (isolator relay) is used to cross connect the separate battery systems (coach and chassis). With the relay de-energized (no voltage on the small pin), you should see chassis battery voltage on one large post. You should see Coach battery voltage on the other large post. Again, this may not be identical to your setup but is very close.

Dave

[gt350ed]

Dave: Thank you for the schematic. Now here's where it gets really stupid. I have always discounted that photo on page 26 BECAUSE I have never seen THAT convertor ANYWHERE in my rig. If it is there somewhere I will plead STUPID. I've never seen it. In MY coach, a 31 footer, the convertor seems to be above the dinette and looks NOTHING like the "convertor" in the photo. It is above the dinette that I receive 110v power and that is where converted voltage goes out thru the wires at the bottom of the panel. When I'm plugged into shore power, I can hear what I believe is the charger at the same location.

There IS an unmarked box out front in the battery area RIGHT NEXT TO the so-called 3-terminal isolator. There are no markings on it that I can see. But it DOES have mutiple wires all leading to a single connector. It looks similar to the BIRD Relay Control in your schematic. I will post a photo of it. Probably not before Saturday. The coach is back in storage, coming to the house Saturday.

Also, MY 3-terminal isolator is not wired as the schematic shows. And since I'm the original owner and the cables/wires have not been touched previously, HOWEVER it is wired was working for 20+ years.

One other thing, the "AUX START" push button on the dash does nothing when I push it. Just here a click as if it's not making a connection. It also has never been disconnected. Perhaps there is a clue here.

I'm going to be using the voltmeter to see where I have voltage and where not and otherwise tracing more wires not previously traced. Then I will post again.

[gt350ed]

Originally Posted by tompen

OK. The solenoid you described is usually a constant duty relay. Yours is internally grounded for the coil that closes it. 12V from the chassis battery will be on one large terminal, and 12V from the coach batteries on the other large terminal. The terminals often get used as a junction point. That explains the extra wires. The relay is normally open. When 12V is applied to the small terminal it closes the relay and connects the two large terminals. The object is to provide a boost or charge to whichever battery needs it. It is also used with the emergency start switch if you have one. The big question is where the power comes from to close the relay. That is the small terminal. Applying 12V to it should close it with a click. The relay may be controlled by a BIRD or IRD or just the boost switch.
However, the isolator that you have ordered would normally be used to allow the alternator to charge both battery systems using diodes so they do not discharge each other when the engine is not running. If you have both than I would believe the relay is either used for emergency starting or controlled by an IRD to charge the chassis battery when on shore power.
With your voltmeter check the two large terminals. Unplug from shore power for now. You should hade chassis reading on one side and coach on the other. This is assuming the relay is open. The small terminal should have no power on it. Next put 12V on the small terminal. The relay should close and the voltages will be the same on both batteries. If so, you need to find out what is powering the small terminal and when. Start with the boost switch if you have one. Try plugging in shore power and see if the small terminal is powered then. You may need a difference in voltages to trigger it if it has a BIRD or IRD. Draw some power from the chassis with the headlights so the voltages are different. Lots of info ot the site about how a BIRD works so I wont go into it again. I don't think you gave a BIRD if you have the isolator system for charging both batteries with the alternator.
Hope I haven't confused you too much. It just seems that there is too many different ways to put the things together.
Good Luck.
Tom

Tom: Thank you for the detailed info. It is very much appreciated. You mentioned "Yours is internally grounded for the coil that closes it." The specs indicate that the isolator is EXTERNALLY grounded thru the mount and needs to be attached to metal, which it is.

You also mentioned "The relay may be controlled by a BIRD or IRD or just the boost switch." As I mentioned in a reply to "Dave", I'm going to post a photo here of something that MAY be a BIRD. Not sure.

As for the AUX START button (boost?), it is either not working or the wire at the other end is not triggering anything. It just makes a click, as opposed to what I would presume would be to use the coach batteries to engage the starter. Maybe this leads back to the isolator?

Beyond this, I will follow your suggestions for checking things and report back.

[gt350ed]

Originally Posted by Old Scout

A $14 dollar solenoid is probably a simple switch that reacts to some sort of logic/signal that is stored/located elsewhere in the coach. Usually, the logic has a high setting that activates the solenoid when the bat bank being charged is above 13 volts [a 12v bat or two 6v bats in series that is/are fully charged and at rest is usually around 12.8v]. The lower end setting keeps one bank from draining the other bank when there is no charging source, eg, something under 13v.

Somewhat older coaches use the bat isolator to distribute charging from the alternator, and use a solenoid to control charging from the inverter and to provide a switch for the bat boost function. Newer coach designs often combine all three functions via the solenoid route. You need to figure out exactly how both the alternator and the inverter charging sources are controlled before you swap-out or add components.

Not sure how/if the bat isolator has any on/off logic built in. Do know that most alternators have build-in diodes that control charging output.

Old Scout: Thank you for your assistance. One thing that I mentioned in an earlier thread is that I actually have two of these "solenoid" looking things. One is a 4-terminal mounted on a bracket in the engine compartment directly above the alternator. I've done nothing with it, presuming it is operating as a true starter solenoid. It seems to be wired that way and since the alternator is working fine and the ignition switch cranks a good starter, I have ignored it.

In other replies to Tom and Dave, I have mentioned an unmarked device next to what I'm calling the 3-terminal isolator. I'm going to be postiong a photo of it. I'm wondering if THAT is where the "logic/signal" might be coming from IF that is how things work on my rig.

[bruceisla]

Originally Posted by gt350ed

Tom: Thank you for the detailed info. It is very much appreciated. You mentioned "Yours is internally grounded for the coil that closes it." The specs indicate that the isolator is EXTERNALLY grounded thru the mount and needs to be attached to metal, which it is.

You also mentioned "The relay may be controlled by a BIRD or IRD or just the boost switch." As I mentioned in a reply to "Dave", I'm going to post a photo here of something that MAY be a BIRD. Not sure.

As for the AUX START button (boost?), it is either not working or the wire at the other end is not triggering anything. It just makes a click, as opposed to what I would presume would be to use the coach batteries to engage the starter. Maybe this leads back to the isolator?

Beyond this, I will follow your suggestions for checking things and report back.

If you use the "Aux Start" switch the only thing I would expect (audibly) would be a "click". The "Aux Start" switch picks the solenoid (that you replaced) .... that solenoid, when picked, connects the House bats to the Chassis bats. It DOES NOT engage the starter. In normal use of the "Aux Start" you would operate the switch AND crank the engine using the ignition switch.

As Tom said, assuming you have a BIRD or IRD, that device determines when and if it will pick the isolator solenoid. It's usually an electronic device that samples House Battery voltage, Chassis battery voltage, the position of the ignition key, and sometimes whether the hour meter on the Genset is running. The BIRD is usually a small black rectangular box that is about 4" X 4" X 1" thick .... often manufactured and labeled by Intellitec.

[Dave78Chief]

BIRD isolator for a gas rig looks like this:



As far as the converter, if you can start with picture of what your coach DC fuse panel looks like. The one that feed the fridge, water pump, water heater, 12VDC lights, etc. Even a name off it would help.

Dave

[tompen]

Originally Posted by gt350ed

Tom: Thank you for the detailed info. It is very much appreciated. You mentioned "Yours is internally grounded for the coil that closes it." The specs indicate that the isolator is EXTERNALLY grounded thru the mount and needs to be attached to metal, which it is.

You also mentioned "The relay may be controlled by a BIRD or IRD or just the boost switch." As I mentioned in a reply to "Dave", I'm going to post a photo here of something that MAY be a BIRD. Not sure.

As for the AUX START button (boost?), it is either not working or the wire at the other end is not triggering anything. It just makes a click, as opposed to what I would presume would be to use the coach batteries to engage the starter. Maybe this leads back to the isolator?

Beyond this, I will follow your suggestions for checking things and report back.

The relays with two small terminals have one grounded externally to complete the circuit. This is just an electromagnet. Yours has the circuit grounded inside the relay so only one terminal is required. They work the same. You need to see if applying 12V to the small terminal closes the relay. Then we can go about finding out why your coach isn't doing it.
Also if something else, BIRD for example, has closed the relay, it will noclose with the aux start switch because it is already closed. Don't forget to check for 12V at the small wire. Check with the aux start button and with the ign. on.