General electrical info on modern vehicles?

[Myself]

I'm looking at setting up a dual-battery system for myself and possibly a bunch of other cars, friends of a friend who need to run a lot of accessories with the engine off and don't want to risk draining the starting battery. RVs usually have these setups, and they're very straightforward.On one hand, the vehicle's electrical system is pretty simple. Alternator makes power, accessories consume power, battery smooths over the ripples and stores some for next time. But that's the way it's been for nearly a century. If my @$%^@ door-locks are any hint, there's no longer anything simple about cars.One alarming case sticks out in my mind: A friend's Dodge Shadow had a severe overvoltage condition, measured 28 volts at the lighter socket. Simple enough problem, replace the regulator right? No such luck, the alternator is shunt-wound and the regulator is actually part of the PCM in this car. Luckily he found a junkyard PCM!My general question is this: Is there anything weird that I should be aware of, with regard to starting and charging systems on modern vehicles? Are there any good books that'd bring me up to speed on the elaborate crack the automakers have been smoking in the last 5 years or so? I'm specifically curious about:"retained power" accessories and the relays that control themweird alternator setups like the one described aboveany circuits that might be affected by installation of a second batterykeyless entry, remote start, and other electrical nightmaresgeneral tips on getting wires through the firewallfinding wiring diagrams for any vehicle that might roll my wayand anything else you think I should know!

[ragingfish]

Well, a service manual would probably be a good start...But talk to maddigital on matrix owners...pretty sure he set up a multi-battery systme...he has TONS of a/v equip and needs a lot of power to run it all...

[Myself]

Yeah, a service manual would be a great idea if I were only working on one type of vehicle, but I might end up under the hood of everything from a honda to a jaguar. I'm looking for general information.

[joatmon]

Buying the service manual for a bunch of cars you may only see once can be expensive. I know alldata.com can sell you the info on a specific vehicle, do they have some deal for a repair shop that gives you access to whatever rolls into the garage?

[threekrows]

Yeah,we have alldata in the shop for info on all the stuff that isn't GM.(but it has GM on it too)It has pretty good info and is updated quarterly I think.But I'm sure it's not too cheap.And if you can't find info on it,you just give them a call and they will walk you to it or fax it to you if it's not on the dvd's(oh,yeah it comes on dvd,like 10 of them)

[JohnC]

This would be a good question to ask a manufacturer of battery isolators. They must have alot of experience/knowledge of "potential" problems.