| [GMCnet] House electrical system not all that complicated [message #346256] |
Thu, 08 August 2019 19:01 |
glwgmc
Messages: 1014
Registered: June 2004
Karma:
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Senior Member |
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As Emory and others have noted there have been many new items come to market with features desirable for a GMC owner. I will cover many of those in the October presentation.
Here I just want to cover a couple of things that trip up even long time owners and leads to incorrect diagnosis or change out of perfectly good components.
First is the fact that the existing stock battery cables in many of our coaches have been exposed to the corrosive fumes given off from lead acid batteries for 40 years. When GM built the coaches they used the smallest battery cables they could since copper costs money. With all the exposure to corrosive fumes those cables are corroded even up under the insulation where you can’t see it. And every cable end is corroded both where it attaches to the cable and where it attaches to the aluminum superstructure, or the frame or the engine block.
Corrosion keeps those cables from flowing the quantity of electrons they did when new and fewer electrons flowing means less useful work can be done. Watts (the measure of how much useful work electricity can do for us) equals amps (the number of electrons in a cross section of the cable) times voltage (the pressure with which those electrons are being forced through the cable). Anything that impedes or resists the flow of electrons reduces the useful work.
So, virtually every GMC would benefit greatly by removing all the old battery cables and replacing them with new, marine multi-strand cable at least one wire gage larger than stock. Make sure to use factory applied cable ends and apply an anti corrosion chemical every where the cable connects to anything metal on your coach. Avoid like the plague those premade 4 gage cables hanging on the rack in your auto supply store. They are right for something like my Mini Cooper tow car, but are not right for your GMC.
Second is the nature of lead acid batteries. They begin loosing voltage the minute you start to use them! And, the harder you use them the faster the voltage drops. So, the very act of using your lead acid batteries causes them to be able to do less and less work for you. In a high draw environment like turning on the microwave powered off your batteries through an inverter in your coach causes the battery voltage to drop like a rock. That prevents the inverter from supplying all the power the microwave needs so it moans and groans, puts out less heat than you expect, and may even shut off all together. No wonder so many have gone to bed with the furnace on for a cold evening only to wake up in the middle of the night freezing because the battery voltage dropped below the level required to power the furnace.
And, to cap it off, you can only access less than half the capacity you paid for. Draw them down below half and the battery life in terms of charge/recharge cycles will also drop like a rock. Yes, the charts you see say a lead acid battery should last 1000 cycles if used only half way, but in most GMCs the owners regularly discharge them far more than 50% much of the time without even knowing it. That battery that died on the cold night powering your furnace was totally depleted, not just drawn down to 50%. Normal life in a Gmc is more like 200 to 400 cycles. Real world tough love stuff.
In short, a lead acid battery is not well suited to powering the house portion of your GMC unless all you do is use a few LED lights and maybe power an LCD TV for an hour or two. But, that is all that was available when our coaches were built.
Everything has changed for the better and it is now possible to give your GMC a heart/lung transplant that will forever change how much you and your family enjoy being in your GMC. And, it is now possible to do that cost effectively, at least for many owners. More in October.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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