| Re: Testing the battery isolator [message #189161 is a reply to message #189146] |
Sun, 04 November 2012 11:17   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
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Senior Member |
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| Kerry Pinkerton wrote on Sun, 04 November 2012 09:04 |
I split this from my "BATTERY OR STARTING ISSUES" thread because the isolator is a different component. The original thread is at:
<snip>
Dang Mike,
<snip>
If voltage does not increase at the battery (s) and the alternator is working, either the isolator OR the wiring is suspect. To test the isolator:
1- With engine running, check voltage at center lug of isolator. It should be 13.5 V or so (alternator output V)
2- Check voltage at the other two lugs. If voltage is not the same on the top and bottom lugs, then the corresponding diode has failed and the unit should be replaced (repaired??)
3- If voltage is present on the output lugs but not at the battery, the wiring or connection is bad.
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**=> Here is a problem <=** See below | Quote: |
To verify the shore power 120 to 12V power supply is working, shut off engine, plug into shore power (or start generator), and measure voltage at center terminal. Again, should be about 3/4V+ more than battery voltage.
OK, that is what I think I know. Until confirmed, please don't run out and rip apart your coach based on this process.
Now a question. How does battery condition effect measured voltage? Again, what I think I know is that the original BUZZ box converter will always put out the same voltage to the battery regardless of battery state (fully charged or not). I have a new 'smart' converter that is supposed to charge at lesser and lesser rates as the battery comes up to full charge. I THINK that the alternator will also charge at different rates but am not sure.
Ok, pass, fail, what?
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Kerry,
The converter is not typically connected through the isolator.
When charge the house bank with the AC power, the measured voltage of the house bank will go to charge level (13+), the alternator stay at Zero and the engine bank will see quiescent (~12.6).
Answers to questions:
A discharged battery should not be below 11.0V, and a resting full charge will get you to 12.6V~13.0 (depending on battery electrolyte density - put 12.6 in your head).
Typical automotive alternators maintain a constant output voltage of around 14.5V.
That help?
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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