Installed my CS-144 140amp alternator, knocked out my first hack at a dual battery system, and did most of the "Big 3" wiring yesterday. I need to build an upgraded negative wire for the block, but otherwise I'm all done.
The CS-144 alternator is meant for a 1995 Cadillac, but fits with little modification. A $16 pigtail adapter from ebay and few washers to space it properly and it fits. The factory alternator puts out about 40 amps at idle and 85 max, where this takes those numbers to ~85 and 140, respectively. Plus, I am all about replacing things on my 16-year-old rig before they can leave me stranded, so this hit two birds with one stone.
I grabbed a Dual Purpose Marine battery as the extra. Cost me $85 out the door, including the core fee (for not bringing in an old one). It is only 55Ah, but everything I want (fan, fridge, and some LEDs) will only use about 8-10 Amps per night. I dont expect to do any long-duration campouts with no driving during the day to recharge, so no worries. In any case, with the alternator putting out 90 amps at idle, Id only have to run the truck for 5-10 mins to full recharge the batteries.
The relay is from Powerstream.com. It is a simple product that closes the relay when it senses above 12.6 volts (i.e. engine running) to charge the 2nd battery. It was $75+chipping, and is rated for 150 amps steady state but they advertise that it can handle a 1500 amp spike. It is simply bolted onto the negative battery terminal, both out of simplicity and to keep the positive leads as short as possible. I might move it eventually, though I do need to get some rubber covers for the positive terminals.
I was worried that since the winch is only hooked to the 2nd battery, if I was winching with the engine running it could exceed 150 amps through the solenoid. For example, if the engine was running (relay closed) but the second battery was low, the winch might try to pull most of its 400amp draw from the main battery through the isolator. But, I called them specifically about this and they said such loads would not harm it at all.
Right now, the main battery has only the factory connections--though I combined all of the positives into one main lead (the thick black wire wrapped in electrical tape), and plan to add a cutoff switch down the road.
The second battery powers the winch and accessories. The red cable going into the fender is the positive line going to the back of the rig from the 2nd battery. It is on a 120amp fuse (which is just out of view) since the wire is rated at 150 amps, but I think I am going to swap in something like a 30 or 40 Amp fuse since 100 Amps could probably still arc enough to start a carpet fire without tripping the breaker. Plus, I will likely add individual fuses to each accessory. Right now only my compressor is powered by this wire, but eventually I will have a fridge, a roof fan, and some mild red LEDs powered off the same circuit.
I had to move the fuse box a good bit--it was actually about 1.5" further back, but I settled on this location after everything was done to minimize strain on the wiring harness. I was surprised I was able to fit the coolant bottle back in place, but it worked. I used a simple flat piece of scrap steel as the battery tray.
I'd like to say the ratchet strap is only temporary, but let's be real...
I really hate those blue hoses... I got em as a cheap set to replace some cracked vac lines, but I wish I'd have spent $10 more to find a black set :P .
Installed a few nicknacks like a synthetic winch line, finished the swing-out tray with expanded metal, and built a crude tool tote to fit in the cargo drawer. Now all my wheeling and wrenching gear is in one drawer, and I am slowly starting to fill out the other side with camping gear.
