| Couple of electrical questions [message #95123] |
Mon, 09 August 2010 14:51  |
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JShot
Messages: 485
Registered: October 2006
Location: NW Ohio
Karma: 0
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Asking these for me, but also think there are a lot of lurkers that don't ask questions - maybe these can give them some insight on how we do the coaches -
1. Going down the road with the generator running and the roof a/c on because the dash air doesn't work (well). With the generator going, 110v is supplied to the PD converter/charger, which in turn, because of a combiner across the isolator, is charging the engine starting battery (I know, don't get on me about this setup!)
But the alternator is also charging the starting battery. So does the battery get charged by both systems in this case?
2. When the coach is home and plugged into shore power, the above setup keeps the engine starting battery charged up and supplies power to the interior 12v lights. If you unplug the coach after a couple hours, the combiner cycles on and off every few minutes for a while (if you still have a 12v light turned on, it goes on and off with the cycling). What's happening here?
At the moment, the ONLY battery in this coach IS the starting battery.
Inquiring minds want ......
John
John Shotwell
Ridgeville Corners, OH
78 Royale Center Kitchen
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| Re: Couple of electrical questions [message #95125 is a reply to message #95123] |
Mon, 09 August 2010 15:09  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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I'm not an engineer, but I'll through my hat into the ring on this one.
1) With two charging sources, the one with the higher voltage out will be delivering the charge current. When the engine is at idle, this will likely be the converter, while at hyway speeds its more likely to be the alternator.
2) A combiner connects the two batteries together when the voltage on either battery exceeds a "connect" level (13v or so). While on charge from the convertor, the convertor output voltage is about 13.8v and the battery is at the same voltage. When you pull the plug on the convertor and only the engine battery connected, the battery voltage will start to drop and will eventually stabilize at its charged open circuit voltage of about 12.8v. With no house battery and a light on in the house, the engine battery will power the light until the battery voltage drops below the "connect" voltage of 13v mentioned above. Now there is no load on the battery so the battery voltage will creep back up until it exceeds the connect voltage and the light comes back on. The extra load of the light loads the battery down and it soon falls below 13v and off goes the light.
This will seesaw back and forth until the battery voltage stabilizes under 13v at which time the combiner stays off.
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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| Re: Couple of electrical questions [message #95126 is a reply to message #95123] |
Mon, 09 August 2010 15:13 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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No house battery? Then what is the combiner combining with? If one side of the combiner is connected to the engine battery, where is the other leg connected? Questions, always questions.
Tom Phipps,
75 GMC, with combiner and a bunch of batteries.
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Couple of electrical questions [message #95128 is a reply to message #95125] |
Mon, 09 August 2010 15:22 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
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2. When the coach is home and plugged into shore power, the above setup keeps the engine starting battery charged up and supplies power to the interior 12v lights. If you unplug the coach after a couple hours, the combiner cycles on and off every few minutes for a while (if you still have a 12v light turned on, it goes on and off with the cycling). What's happening here?
At the moment, the ONLY battery in this coach IS the starting battery.
Inquiring minds want ......
John
_______________________________________________________________
LarC ( Keeping the search on for MY PO's electrical traps in my GMC )
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
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[Updated on: Thu, 12 August 2010 09:41] Report message to a moderator |
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| Re: Couple of electrical questions [message #95137 is a reply to message #95123] |
Mon, 09 August 2010 16:32 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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I believe Larry C is confusing an ISOLATOR and a COMBINER. I "think" Bruce is correct. Why no house battery ???????
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: Couple of electrical questions [message #95196 is a reply to message #95123] |
Tue, 10 August 2010 06:33 |
Glenn
Messages: 92
Registered: February 2004
Location: Northwestern Ontario
Karma: 2
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I wired my PD converter through a switch. With both generator and engine running I shut off converter,letting the alt. take care of the charging
HTH.........
Glenn
76 Glensbroke
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| Re: Couple of electrical questions [message #95200 is a reply to message #95123] |
Tue, 10 August 2010 07:25 |
Luvn737s
Messages: 1106
Registered: June 2007
Karma: 2
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I thought one of the selling points of the PD units was the Smart Charging feature. All my charging sources put out about the same DC Volts (converted or not), so I don't really care which is performing the charge at any given time. I should put in separate battery Ammeters to monitor battery health, though.
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
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| Re: Couple of electrical questions [message #95207 is a reply to message #95200] |
Tue, 10 August 2010 08:04 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Luvn737s wrote on Tue, 10 August 2010 08:25 |
I thought one of the selling points of the PD units was the Smart Charging feature. All my charging sources put out about the same DC Volts (converted or not), so I don't really care which is performing the charge at any given time. I should put in separate battery Ammeters to monitor battery health, though.
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Randy,
As much as I love operational instruments it pains me to say this but, ammeters do tell you much anymore. Back when generators (the kind with a commutator) were hard pressed to make a 15 amp charge rate, they were important so you could see which way the current was flowing.
In recent years I have seen -60<0<+60 ammeters that do not indicate any drain or charge at less than 5 amperes. Even if it did, this still would not tell you what you really need to know.
A volt meter for each (at least on the house) battery will give you much better information as it can tell you the effective state of charge. If this is a cheap 0-15, it will be very hard to interpret, but if it is an expanded scale (10-15) or better still a digital (3-1/2 digit)a it will yield information of significant value.
The meter in the GMC's OE monitor panel would be great, but the wiring to mine is pretty much worthless.
There are battery monitors that are frequently installed in cruising yachts that continually monitor the current into and out of the battery bank and can indicate a state of the bank with great confidence, but these are relatively expensive to purchase and install. Some experience and a repeatable high resolution instrument will tell you as much (IMHO).
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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| a flow chart [message #95209 is a reply to message #95208] |
Tue, 10 August 2010 09:56 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Maybe we could talk Gene into posting a flow chart
of this set-up? And some of the popular variations?
Bukzin
1977 Palm Beach
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