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[GMCnet] Riddle me this one.....inverter [message #346134] Tue, 06 August 2019 23:49 Go to next message
glwgmc is currently offline  glwgmc   United States
Messages: 1014
Registered: June 2004
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Senior Member
At the GMCWS rally at Seven Feathers Casino at Canyonville, OR, in October I will give a presentation on whether and how to update your GMC to modern electronically controlled lithium batteries. In that presentation I will cover in detail things like converter/battery chargers, inverters, smart combiners and etc. if you can get there it might answer most of your questions.

The very short version is your GMC has both a starting battery that supplies power to start your coach, the chassis lights, and dash heater. You also have a house battery bank which could be anything from one to four batteries, some of which could be up front and/or in the rear. That house battery bank supplies 12vdc for lights in the house portion of your coach, the furnace, the refer if so equipped and other 12vdc appliances like roof vents, etc. you also have a power cord which can be plugged into a shore power source to supply 120vac for household appliances like a microwave and roof ac. When no shore power is available you can turn on your generator to supply 120vac for the same purposes.

Each of these are independent but can be combined in some circumstances. When 120vac are available a device called a converter/battery charger will keep the house batteries charged and also supply 12vdc to the house 12vdc circuits. GM never supplied an inverter but some POs have. That device takes 12vdc from you house battery bank to supply 120vac to power house appliances (but not the ac) for a short time. 12vac lead acid batteries are not well suited for powering an inverter for a bunch of reasons beyond the scope of forum post.

Inverters do not charge batteries. There is a lot more to it than this but perhaps this will help in your understanding of the two 12vdc systems and the two or three 120vac systems in your GMC. Best bet is to attend a rally and ask questions there.

Hope this helps

Jerry

Sent from my iPhone

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Jerry & Sharon Work
78 Royale
Kerby, OR
Re: [GMCnet] Riddle me this one.....inverter [message #346143 is a reply to message #346134] Wed, 07 August 2019 07:22 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Jerry,

Excellent short synopsis of the electrical systems.

One additional point that may be the source of some nomenclature
confusion, especially among those with past exposure to SOB's: Many large
coach come equipped with "Inverters" (Heart is one common brand which comes
to mind). Those 1000 Watt to 4000 Watt inverters are commonly also
"Converters" and include automatic "crossover switches" to select which
mode they're operating in. Such devices are not common in GMC's, primarily
because of their size and cost, plus the fact that most wanting an inverter
don't choose to replace the pre-existing converter at the same time.

HTH,

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] Riddle me this one.....inverter [message #346153 is a reply to message #346143] Wed, 07 August 2019 08:55 Go to previous message
Olly Schmidt is currently offline  Olly Schmidt   United States
Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...
Karma: 8
Senior Member
A small note: my 23' has three batteries. The Onan has its own battery.
--
Regards

P O Schmidt
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Best regards

Olly Schmidt
PGP Key ID: 0x18a9 3a1f 4196 bf22
'76a Eleganza II, VA
'73 Sequoia, SH, Germany
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