| OEM isolator rating [message #194439] |
Mon, 31 December 2012 10:47  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Senior Member |
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What is the rating on the 1974 OEM alternator isolator, the blue one from Sure Power Products? The nameplate has corrosion where it lists what size alternator the unit is rated for.
The alternator has been upgraded to 100amp and I don't want to have the isolator crap out because the uprated alternator fried it. It is much easier to change it now rather than later.
Probably the best information would be the experience of those who have upgraded to a 100amp alternator. Eventually two 6volt batteries will be installed for the house side so that needs to be part of the equation.
Has the original isolator survived the upgrade?
Please note I have all the info on combiner (which I have) vs isolators (which I plan to keep) and have made my decision so I'm just looking to get the above question answered. I.E. I'm not looking to start another "oil thread".
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] OEM isolator rating [message #194455 is a reply to message #194443] |
Mon, 31 December 2012 12:10  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Senior Member |
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| James Hupy wrote on Mon, 31 December 2012 11:13 |
Steve, go large or stay home. I am presently installing an upgraded
alternator on an early coach. It had a 66 amp alternator and a small
footprint 75 amp isolator. The output lead is too small to carry the
additional amperage and must be replaced with one large enough to prevent
any voltage drop. I went with an isolator that is rated for 130 continuous
amps. It is mfg offshore, so names don't mean much. Hope this helps an old
dc wise electrician like you.
Jim Hupy
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Well I can make out the last digit as a "5". I can't make out the first digit. It could be a "7" or a "9". I am/was hoping it was a 95 like this one on Applied's site:
http://www.appliedgmc.com/prod.itml/icOid/986
as mine looks exactly like that one, right down to the color, fin configuration and mounting method.
I'd be willing to keep it if it was a 95amp unit. If it's a 75amp it will have to go.
Yes the wiring is being upgraded.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] OEM isolator rating [message #194481 is a reply to message #194455] |
Mon, 31 December 2012 17:20 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
I thought I'd take this opportunity to further my "electrical" education. I vaguely remember someone mentioning that batteries will
only "accept" charging power at a limited rate and it was under 100amps.
Did I misunderstand, or just mis-remember?
Regards,
Rob M.
-----Original Message-----
From: Steve Southworth
James Hupy wrote on Mon, 31 December 2012 11:13
> Steve, go large or stay home. I am presently installing an upgraded
> alternator on an early coach. It had a 66 amp alternator and a small
> footprint 75 amp isolator. The output lead is too small to carry the
> additional amperage and must be replaced with one large enough to prevent
> any voltage drop. I went with an isolator that is rated for 130 continuous
> amps. It is mfg offshore, so names don't mean much. Hope this helps an old
> dc wise electrician like you.
> Jim Hupy
Well I can make out the last digit as a "5". I can't make out the first digit. It could be a "7" or a "9". I am/was hoping it was
a 95 like this one on Applied's site:
http://www.appliedgmc.com/prod.itml/icOid/986
as mine looks exactly like that one, right down to the color, fin configuration and mounting method.
I'd be willing to keep it if it was a 95amp unit. If it's a 75amp it will have to go.
Yes the wiring is being upgraded.
--
Steve
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] OEM isolator rating [message #194488 is a reply to message #194481] |
Mon, 31 December 2012 18:06 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Rob, depending on the battery construction, the acid content of the
electrolyte, temperature, connector lug sizes, plate area, and probably a
few more that I have left out on purpose for brevity, there is a finite
charge rate that is POSSIBLE as well as one that is ACTUAL. Once the
electrons exchange places from the sponge lead plates to the electrolyte,
actual charge rate (potential difference) is less and not as much current
flows. So a brief answer to your query is yes. Charge rates are self
limiting by those factors. If a person insists upon jamming more electrons
per second into a wet cell battery than it can handle, they will outgas
hydrogen. If the temperature is high enough to reach the auto ignition
temperature of hydrogen and the ratio of hydrogen to oxygen is within its
combustion limit, bad stuff can happen with explosive results. Arcs can
also initiate the combustion sequence with explosive results. FOR SAFETY'S
SAKE, LIMIT CHARGE RATE TO AROUND 10% OF MAXIMUM AMP HOUR OF THE BATTERY IN
USE. In case I haven't mentioned it before, Happy New Year to you and
Helen. Or is it Happy OLD year down under?
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Dec 31, 2012 at 3:21 PM, Rob Mueller <robmueller@iinet.net.au>wrote:
> G'day,
>
> I thought I'd take this opportunity to further my "electrical" education.
> I vaguely remember someone mentioning that batteries will
> only "accept" charging power at a limited rate and it was under 100amps.
>
> Did I misunderstand, or just mis-remember?
>
> Regards,
> Rob M.
>
>
> -----Original Message-----
> From: Steve Southworth
>
> James Hupy wrote on Mon, 31 December 2012 11:13
> > Steve, go large or stay home. I am presently installing an upgraded
> > alternator on an early coach. It had a 66 amp alternator and a small
> > footprint 75 amp isolator. The output lead is too small to carry the
> > additional amperage and must be replaced with one large enough to prevent
> > any voltage drop. I went with an isolator that is rated for 130
> continuous
> > amps. It is mfg offshore, so names don't mean much. Hope this helps an
> old
> > dc wise electrician like you.
> > Jim Hupy
>
> Well I can make out the last digit as a "5". I can't make out the first
> digit. It could be a "7" or a "9". I am/was hoping it was
> a 95 like this one on Applied's site:
>
> http://www.appliedgmc.com/prod.itml/icOid/986
>
> as mine looks exactly like that one, right down to the color, fin
> configuration and mounting method.
>
> I'd be willing to keep it if it was a 95amp unit. If it's a 75amp it will
> have to go.
>
> Yes the wiring is being upgraded.
> --
> Steve
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: OEM isolator rating [message #194531 is a reply to message #194439] |
Mon, 31 December 2012 22:48 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I have had a 100 amp alternator using the original isolator for years. No problem. Lots of people have done this.
The 100 amp alternator will seldom if ever put out 100 amps. It can only do so when it is cold and there is enough load in both sides to accept it.
That isolator will supply it's rating to either side (house or engine side). I looked at mine one time and I thought it was 80 amps but that was a long time ago and you may be correct that it is 75 amps (per side).
Some people replace the lead from the alternator to the isolater and make it larger. It won't hurt anything but they forget to also replace the wires from isolator on to the appropriate batteries (engine or house). I say why bother. If there is some slight voltage loss in the existing wiring, it is made up by the remote sensing of the alternator so who cares. You aren't going to be pulling 100 amps very long because the alternator can't do it and the batteries cannot accept a charge at that rate for more than 30 seconds or so.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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