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A good reason to keep your Isolator [message #347463]

Sat, 07 September 2019 08:26

RF_Burns

Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada

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Senior Member

Seems a lot of people want to remove the Isolator when they install a combiner. Here is a good reason why you should keep the Isolator and install the combiner across it.

A couple of days ago when I started the Murray, the GEN light stayed ON. Checked the DigiPanel and it showed only 12V. So I got out the voltmeter and checked the alternator voltage at the Isolator and it was near zero volts. My alternator was 11 years old, so I guess it had a good run.

I pulled the alternator and opened it up. The problem was clear, the jumper strap at the output stud was burnt off inside. The plastic insulating washer was burnt off inside and badly melted on the outside. I cleaned up the stud, replaced the insulating washers and replaced the jumper strap. Checked the bearings and brushes, everything else looked ok. Re-installed and we were back in business with a working alternator.

It was clear that the alternator output stud was likely (or would have) shorted to the case of the alternator. If I didn't have the Isolator, the battery current would have flowed back through the #10 alternator wire causing lots of current, smoke and maybe flames. Its what us electronic types call I Norton.

So you may want to keep your Isolator for just another layer of protection. The 0.7 volt drop across the Isolator that some say limit the battery charging is a red herring. The alternator uses a remote voltage sensing wire which is connected to the battery. The alternator's internal regulator uses feed-back from this wire and automatically raises its output voltage to compensate for any voltage loss.

Just my 2 cents!

Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

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[Message index]

		A good reason to keep your Isolator By: RF_Burns on Sat, 07 September 2019 08:26
		Re: A good reason to keep your Isolator By: 6cuda6 on Sat, 07 September 2019 08:35
		Re: [GMCnet] A good reason to keep your Isolator By: jimk on Sat, 07 September 2019 10:40
		Re: A good reason to keep your Isolator By: JBO on Sat, 07 September 2019 10:37
		Re: A good reason to keep your Isolator By: RF_Burns on Sat, 07 September 2019 10:52
		Re: A good reason to keep your Isolator By: JBO on Sat, 07 September 2019 11:21
		Re: A good reason to keep your Isolator By: Matt Colie on Sat, 07 September 2019 11:51
		Re: A good reason to keep your Isolator By: 6cuda6 on Sat, 07 September 2019 13:46
		Re: A good reason to keep your Isolator By: Matt Colie on Sat, 07 September 2019 18:52
		Re: A good reason to keep your Isolator By: JBO on Sat, 07 September 2019 13:30
		Re: A good reason to keep your Isolator By: JohnL455 on Sat, 07 September 2019 15:11
		Re: A good reason to keep your Isolator By: Rick Staples on Sat, 07 September 2019 15:24
		Re: A good reason to keep your Isolator By: 6cuda6 on Sat, 07 September 2019 15:59
		Re: A good reason to keep your Isolator By: jhbridges on Sun, 08 September 2019 07:48
		Re: A good reason to keep your Isolator By: 6cuda6 on Sun, 08 September 2019 07:56
		Re: A good reason to keep your Isolator By: jhbridges on Sun, 08 September 2019 08:03

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