| Re: [GMCnet] Readings on Isolator [message #166552] |
Mon, 16 April 2012 21:15  |
Richard Brown
Messages: 281
Registered: May 2009
Karma: 1
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Senior Member |
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On my Eleganza SE, the wires from the isolator connect to the battery connections on the boost relay. That didn't strike me as much of a plan so I lengthened them & connected them to the respective battery clamps. Boost relays are like older Ford start solenoids in that they seem to be the first place to look for bad connections. To me, every connection is another place to have trouble.
Richard & Carol Brown
1974 Eleganza SE
"DILLIGAF"
Lindale, Tx. 75771
903-881-0192
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Richard & Carol Brown
1974 Eleganza SE
1174 Hickory Hills Dr.
Murchison, TX. 75778
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| Re: [GMCnet] Readings on Isolator [message #166585 is a reply to message #166583] |
Tue, 17 April 2012 07:34  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Mr ERFisher wrote on Tue, 17 April 2012 07:41 |
not quite
with 300 amps cranking current, every connection can drop about 3 volts.
What this does is connect the starter directly to the battery, eliminating 3 to 4 connections (depending upon if you have dis-connect switches) and connecting the battery ground, directly to the engine (mother of all grounds in the GMC), and the chassis.
Gene Fisher -- 74-23,77PB/ore/ca
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Gene,
If I followed what Richard wrote correctly, he reconnected the charging cable from the isolator to the battery terminal. This will not change the available cranking power at all, but will add a maintenance issue as that connection is not at the battery and subject to the issue that are common in that case.
As to starting cable issues:
If the 3 volts per junction were even close, most electric starters would never work. If you are seeing that level of potential loss at your connections, I suggest that you review your maintenance practices.
I have never had that level of voltage drop in any of my starter cabling. When I last measured the GMC (just after replacing the chassis battery):
Chassis battery at rest 12.8
Chassis battery while cranking 11.6
E Starter main to block 10.8
System current at battery cable 343 amps
Choke closed crank time 8.6 seconds
The above three are the averages before the first cylinder hit
I did not record the cranking speed
This was measured done with recording and averaging instrumentation that I still own.
This was with a new battery, but it probably not yet at full density as I brought it home, dropped it in, enabled the instruments and cranked.
In the whole time I have owned the coach, the only time I use the boost switch is to make the suspension compressor run faster.
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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