isolator

Topic: isolator (Read 1259 times) previous topic - next topic

isolator

April 21, 2023, 05:17:57 pm

Having alternator charging issues, had mine replaced @ FOT 2 years ago, but now output is only 2.9V. I have had conversations w/ Red Tractor for diagnosis and it points to the alternator. The isolator and corresponding solenoids look pretty rough, I'm thinking they are original. Going to take the alternator to a local shop for testing and repair if neccessary. Looking @ Victron isolators- I have 2 AGM Deka house batteries and 2 start batteries. I have @ '93 280 with the 8.3. My boost solenoid appears to be bad so I ordered a new one. The whole isolator area looks weathered and worn so it's overdue for replacement components. Looking for advice for the isolator replacement- the ones I looked at say 2 batteries? do I need 4 battery isolator? I've been studying the forum to educate myself plus the invaluable help from Red Tractor, but it can be a little overwhelming! TIA

Re: isolator

Reply #1 – April 21, 2023, 05:35:05 pm

My isolator was a 200 amp isolator and I thought they go by amps and you size them according
to the amps that the alternator put out.

Re: isolator

Reply #2 – April 21, 2023, 05:36:30 pm

The standard factory isolator setup requires 3 posts on the isolator. One post is for alternator input, and the other two output posts are for your start and house battery banks. Victron is an excellent choice, especially if you pick the Argofet 200A (2 bank) model, which is much more efficient than the diode based isolator originally fitted to your coach.

The "alternator energize input" feature is useful if you ever want to upgrade to a high output Delco alternator.

https://www.victronenergy.com/upload/documents/Datasheet-Argofet-Battery-Isolators-with-alternator-energize-input-EN.pdf

Amazon.com: Victron Energy Argofet Battery Isolators 200-2AC (2 Batteries...

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Re: isolator

Reply #3 – April 21, 2023, 05:45:49 pm

If you are ever considering going to Lithium battery setup now might be a good time to look into a DCtoDC charger to replace the isolator?

Just to put another log in the fire?

Re: isolator

Reply #4 – April 21, 2023, 05:47:41 pm

Mine has four posts on it

Re: isolator

Reply #5 – April 21, 2023, 05:53:05 pm

Quote from: mikerox – April 21, 2023, 05:17:57 pm

Having alternator charging issues, had mine replaced @ FOT 2 years ago, but now output is only 2.9V. Going to take the alternator to a local shop for testing and repair if necessary.

If you can provide a photo of the rear connection panel on your alternator, or tell us the make and model number, then we can tell you if it is worth your time and money getting it worked on. If it is the incorrect type of alternator for your application, then spending money on it is a waste.

Re: isolator

Reply #6 – April 21, 2023, 05:56:02 pm

Quote from: mikerox – April 21, 2023, 05:47:41 pm

Mine (isolator) has four posts on it

Yes, it has 4 posts, but you will notice that two of the output posts are connected together with a jumper cable. This was the standard Foretravel configuration back in the day, but is no longer necessary with a modern replacement isolator such as the Argofet recommended in my post above.

Numbering left to right in your photo:
Post #1: House battery bank
Post #2: Alternator input
Post #3: Connected to Post #1
Post #4: Start battery bank

Re: isolator

Reply #7 – April 21, 2023, 05:57:56 pm

LN-A0012824LC

Re: isolator

Reply #8 – April 21, 2023, 06:00:20 pm

I believe it is the correct alternator. It has served me well for 2 years

Re: isolator

Reply #9 – April 21, 2023, 06:01:55 pm

Oops, wrong picture before. This is the alternator

Re: isolator

Reply #10 – April 21, 2023, 06:04:27 pm

Oops, wrong picture before. This is the alternator

Re: isolator

Reply #11 – April 21, 2023, 06:07:18 pm

Quote from: mikerox – April 21, 2023, 06:01:55 pm

(LN-A0012824LC) This is the alternator

OK, that is a good quality alternator, and more importantly it has the correct DUVAC design features.

Prestolite Products

It would be very unusual for that alternator to fail after two years. Before pulling it out you should do some trouble shooting to verify it is getting the proper SENSE and EXCITE signals that are required for it to work.

The EXCITE post (marked IGN on the alternator) should be hot (12 volt) only when the ignition switch is in the ON position.

The alternator post marked SENSE should be hot all the time. The other end of that SENSE wire should be connected to the START battery post on the isolator.

Re: isolator

Reply #12 – April 21, 2023, 06:12:39 pm

Sense wire matches battery 12.1- batteries are charging, ign wire the same when ign is turned on. I'm open to other test. Checked the 2 posts on the ends when it's running, 2.9v

Re: isolator

Reply #13 – April 21, 2023, 06:15:09 pm

Dash volt meter shows 10 when running

Re: isolator

Reply #14 – April 21, 2023, 06:17:12 pm

Quote from: mikerox – April 21, 2023, 06:12:39 pm

Sense wire matches battery 12.1- batteries are charging, ign wire the same when ign is turned on. I'm open to other test.

OK, sense and excite inputs seem satisfactory.

With engine running, what is the voltage on the alternator B+ (positive output post) and on the alternator input post (Post #2 in your photo) on the isolator?

Re: isolator

Reply #15 – April 21, 2023, 06:25:51 pm

I'm not getting anything

Re: isolator

Reply #16 – April 21, 2023, 06:35:24 pm

Well, if alternator has a good SENSE connection, and a good EXCITE connection, and is not putting out ANY voltage when turning, then I guess it must be bad. It might be a problem in the voltage regulator...

I've exhausted my ideas, so unless other members have other suggestions then I guess take it to the repair shop and see what they say.

Be sure you tell them this alternator is used with a two battery bank charging system and must be configured as a DUVAC model.

Re: isolator

Reply #17 – April 21, 2023, 06:39:46 pm

While you are working on the battery/charging system, be sure you clean up the end connectors on ALL of the wires and cables. They should all be shiny clean metal when you put it back together.

Re: isolator

Reply #18 – April 21, 2023, 09:16:35 pm

The pic of the isolator shows that the isolator has been some kind of hot. Some of your readings could be bleed through the diodes in that isolator. Those wires also need to be checked and cleaned as they look like they have been hot also. Now this rambling leads to the alternator, If it was having to run at full load and is what cooked the isolator then you could have either burnt up a brush and/or it is stuck in the brush holder. In like manner it could have killed a diode in one of the rectifiers. If I was betting on a rectifier with a bad diode I would put my $ on it being the Neg. one. Yes the alternator has a Pos and Neg rectifier. Any good old school shop can check it out and fix your problem. Now a name brand parts store

?

Mike

Re: isolator

Reply #19 – April 21, 2023, 09:32:08 pm

I found an old school shop not far from me, I have high hopes they'll make it right

Re: isolator

Reply #20 – April 22, 2023, 08:20:10 am

Should I replace these or just clean them up? If replace, what are they and where can I get them?

Re: isolator

Reply #21 – April 22, 2023, 08:57:44 am

Quote from: mikerox – April 22, 2023, 08:20:10 am

Should I replace these or just clean them up? If replace, what are they and where can I get them?

Definitely replace them. They are auto reset circuit breakers. See if you can read the "size" (15A, 20A, etc) imprinted on the metal case. If not, the B-2126 12 volt wiring diagram for your coach may list the required size. On our '93 U280 they are 15A. They are available at most auto parts stores and online.

Bussman Automotive Circuit Breakers - Wiring Products

Short Stop Circuit Breaker 15A Metal RT Bracket Type 1 12V (BP/CBC-15B-RP):...

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Re: isolator

Reply #22 – April 22, 2023, 09:34:52 am

Quote from: mikerox – April 21, 2023, 05:17:57 pm

My boost solenoid appears to be bad so I ordered a new one. The whole isolator area looks weathered and worn so it's overdue for replacement components.

I see one relay in your photo. I would replace it also. Starting out with everything fresh is good!

Amazon.com: ONLINE LED STORE 12V 40/30 Amp 5-Pin SPDT Bosch Style Electrical...

I don't know what solenoid you purchased. The one below is highly recommended by Forum members. Can be used as both AUX START solenoid, and as BOOST solenoid.

Amazon.com: Cole Hersee 24213 12V 200A Continuous Solenoid : Automotive

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Re: isolator

Reply #23 – April 22, 2023, 10:00:19 am

Chuck, thank you for sharing your wisdom with me, that solenoid IS the one I ordered from Amazon, I'll need to order another one and thanks for including the relay. My plan is to get all this replaced including the isolator. I have a new grandbaby about to be born and we're supposed to travel to their house, in the MH, to help with the other previously born offspring. I just want it roadworthy enough to get us to Athens GA about 2 hours away and will address more items as time allows.Your assistance is priceless. Thanks again.

Re: isolator

Reply #24 – April 22, 2023, 10:17:35 am

Quote from: mikerox – April 21, 2023, 06:12:39 pm

Sense wire matches battery 12.1- batteries are charging, ign wire the same when ign is turned on. I'm open to other test. Checked the 2 posts on the ends when it's running, 2.9v

I am going to start by assuming you mean the positive and negative battery posts on the alternator.
2.9V across these two terminals means that you have a high resistance connection and 2.9V is the difference in voltage, which can be thought of as electrical pressure.
Careful probing is the order of the day.
Everything on the negative terminal, post, copper terminal and wire should be 0V to a good ground.
On the positive side you should have battery voltage to ground. I have gone so far at times in the past to run an independent wire from the battery negative terminal to where I can reach it to measure the voltage on that battery wire, when looking for the location of the high resistance connection.

When you find battery voltage load it down with a 12V light bulb and measure again. Used to be you needed a vacuum tube volt meter to get into that kind of trouble but noooo!, all you need is to spend $8 at Harbor Freight for a VOM with high impedance input. The cheap Radio Shack Micronta analog VOM sucked up current at the rate of 20,000 Ohms per volt automatically loading down the circuit under test.

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