| [GMCnet] Battery Isolator Schematic [message #150200] |
Sat, 19 November 2011 23:57  |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
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Not a wiring diagram. What's in the box.
Suggested testing methods too.
I suspect there are a couple of schottky diodes and some spike suppression.
What's preferred? Isolators or combiners?
Dolph Santorine
adolph@Santorine.org
Excuse me for not being my usual wordy and sporadically verbose self. This message is sent from my iPhone.
No trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.
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| Re: [GMCnet] Battery Isolator Schematic [message #150205 is a reply to message #150200] |
Sun, 20 November 2011 01:44  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| Dolph Santorine wrote on Sat, 19 November 2011 23:57 |
Not a wiring diagram. What's in the box.
Suggested testing methods too.
I suspect there are a couple of Schottky diodes and some spike suppression.
What's preferred? Isolators or combiners?
Dolph Santorine
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Based on the voltage drop through an isolator I doubt they are Schottky diodes. At least not in the OEM and common replacement units. Other than heat there is no real concern for low forward voltage drop the Schottky features as the alternator sense lead corrects for that.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] Battery Isolator Schematic [message #150206 is a reply to message #150205] |
Sun, 20 November 2011 02:42 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Functionally the isolator is just to high current diodes probably around 50 volts PIV mounted in a heat sink with some potting compound. You would have to take an old one apart to see if there is anything else inside one. I doubt there is much.
What is preferred? That depends on who you talk to. Actually the isolator should be considered part of the alternator. It's function was to allow the alternator to charge two (and in some cases more) separate and isolated batteries systems.
The combiner has a different function of allowing two (and only two) isolated systems to charge and power each other.
When installing a combiner, the alternator becomes part of the engine system. The converter is already charging and is part of the house system. The combiner allows cross connection between the two systems if the required voltage levels are present.
Which is a better solution? It is the old Ford vs. Chevy argument. "I bought a Ford they have to be better." "I own GM so it has to be better."
Then there is the fence sitters who buy one Ford and one Chevy just because they can't make up their mind or to keep their bases covered.
"GM might go out of business...No wait, Ford might go out of business.
Ford is better than GM....No wait, GM is better than Ford.
I do not know what to do so I'll just buy one of each."
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Battery Isolator Schematic [message #150207 is a reply to message #150200] |
Sun, 20 November 2011 03:07 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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> What's preferred? Isolators or combiners?
>
> BOTH ! ;>) see here,
http://goo.gl/RMHV9
I am not just a middle-of-the -road guy , but there are good arguments for
having both , the isolator and a combiner, on a GMC.
If you read this whole set of slides, I think you will see it is not an
either-or situation, but a best-of-all-worlds , to use both.
http://goo.gl/J4Uow
it is a 10 minute addition to add a combiner, and you still have that BMF,
heat-sinked, isoloator to carry the surge current of dead-flat start-up
loads and the fail-safe, multi-bank batteries, protection, of a combiner.
This just beats the heck out of a either-or situation...
JMHO
gene
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Battery Isolator Schematic [message #150211 is a reply to message #150200] |
Sun, 20 November 2011 06:53 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Dolph Santorine wrote on Sun, 20 November 2011 00:57 |
Not a wiring diagram. What's in the box.
Suggested testing methods too.
I suspect there are a couple of schottky diodes and some spike suppression.
What's preferred? Isolators or combiners?
Dolph Santorine
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Dolph,
You are giving them WAY too much credit....
I have actually removed the epoxy potting from several. It started because one was a special version for a marine ($$) application and no replacement was readily available. That one did have something more than a pair of diodes electrically isolated from the heat sink. That is exactly what all the others since have had. They are most often to two press mount diodes (just like those in an alternator bridge) in a good size aluminum block that has a long screw for a center post, that block is very often secured and isolated to/from the heat sink with a piece of thin double sided tape. The output terminals are just bedded in the epoxy, maybe with a large washer. I have never seen anything like a spike snubber and the times I have looked up the diode number, it was nothing special.
Testing is simple. But don't be fooled, sometimes the just blow out like a fuse, and sometimes they do go solid.
*Best Test - Engine Off - First measure voltage to ground at the center terminal - if not Zero, there is a problem. Then, undo all three connections (watch out as the battery leads will still be hot). Measure resistance (or forward drop - if you have a good meter) between center and both battery connections. You should get something one way and nothing the other. If not, you have a problem.
*Other test (you don't have time to take things apart or it is someone else's) - Measure center post engine off like above. Then start and look for the forward drop from the center post to the batteries of 0.6~0.75V. If you see more, that diode is open. (Less will have been covered by the center post to ground test.)
When you get are installing a replacement, PLEASE - look for the terminal identification (typically on the side of the heat sink sometimes marked in the epoxy) and confirm that if not identical to the old part, at least you understand the differences. Some parts have the "center" post at one end. There are also some strange parts that show up in marine service.
Why do you think they use black potting epoxy?
So we can't see how little is actually in there...
Do I like isolators or combiners more???
No
I have replaced many more isolators than combiners because combiners are still pretty rare as most cruising boats have installed multi-bank shore power chargers so a combiner would be a waste of time.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Battery Isolator Schematic [message #150222 is a reply to message #150200] |
Sun, 20 November 2011 08:48 |
shawnee
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
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| Dolph Santorine wrote on Sun, 20 November 2011 00:57 |
Not a wiring diagram. What's in the box.
Suggested testing methods too.
I suspect there are a couple of schottky diodes and some spike suppression.
What's preferred? Isolators or combiners?
Dolph Santorine
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Dolph,
I have been using the combiner for about 10 years. The good part about it is it combines the charging of the auto battery with the charging of the house batteries when on electric power. It also will separate the batteries when off electrical power when either one discharges below a certain level. I wouldn't be without one.
Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
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| Re: [GMCnet] Battery Isolator Schematic [message #150226 is a reply to message #150200] |
Sun, 20 November 2011 09:18 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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My advice, get the factory type (isolator) system working as it should. Buy the 100A minimum unit if yours is bad. Then buy the Yandina combiner (cheep money) and wire that across the isolator. Very easy. Then go have a beverage and forget about it. It's automatic. Also in my opinion, the combiner across the isolator may help "protect" the isolator in some situations by providing an secondary path. Once above 14V and straped by the combiner, the alt voltage regulator self corrects for the diode votlatge drop that was there when the combiner was open and now is paralleled. The reverse is also true when pluged in or on gen if you have a smart converter as in an Iota or other brand. It will charge both fully and safely (so they don't boil or sulfonate) and then maitain. Priceless.
John Lebetski
Woodstock, IL
77 Eleganza II
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