I have installed second battery (parallel dual) with the factory cables.
Also installed a 220A alternator. Stock setup is a 145/160 amp alternator, with a 175A fuse.
Sounds like I'm supposed to add a larger fuse (250A?) but am worried the battery and alternator cables maybe too small?
What if I wire a SECOND CABLE from the alternator to AUX battery with ANOTHER 175A fuse?
The batteries (+) would then be connected through both the starter and alternator cables.
Alternator could output full power if needed going through two 175A fuses.
I know many upgrade the battery cables, but with two batteries/cables, I'd prefer to leave it stock if one or two extra cables can achieve the same thing. (I like the stock battery terminals)
Or will this create radio noise or other problems, or just not work like I am thinking?
I wasn't planning to uprate fuse on stock wiring (unless people tell me stock is large enough, but all the Big3 upgrades make me think stock wiring is borderline)
I just don't think you can get the full 220A potential on a 175A fuse.?
Therefore I am thinking about adding a second alternator cable to the aux battery.
Worried there will be some negative side-effects I don't know or understand..
I would like the ability to power a 2000W or larger inverter if possible. Sounds like they can draw around 170A, and a 3000W around 250A..
A power inverter, but I am worried about the fuse limiting the alternator power. I want to hookup accessories to aux battery because it's more convenient to access, and if I ever install an isolator, I want the accessories on the aux battery. Not sure if adding a secondary alternator cable to aux battery would work or cause issues. Trying to read up on battery hookups, ground loops etc. now my head hurts!
The fuse is to protect the load. It is to fail to cut power should the load exceed a set amperage. A higher amperage fuse won't blow as "easily", meaning the load (everything downstream of it) will be subject to the higher amperage and it, in turn, will act as the fuse.
Just like a higher amperage battery, a higher amperage alternator doesn't "push" amps into a system. It's just the amount that's available should the system (load) need it. So, the 175A fuse isn't choking down 45A of your 220A alternator. Your system is still drawing the same amperage it was before. With the 220A alt, you now have 60A more headroom for loads if you previously had the DR44 160A.
The stock wiring is barely adequate at best in a stock setup. You'll have twice (or more) the power requirements so upgraded wiring is absolutely necessary or you'll be having even worse voltage fluctuations and deficiencies than you have now (and might not even realize). Rather than adding a bunch of extra wires, I think upgrading what's there would be simpler and cleaner. But, yes, "doubling up" on power and ground wires would technically double the conductivity. A circuit is only as strong as its weakest link. You can have all the 1-, 2- or even 4/0 power cables you can cram under the hood but they won't do any better than stock if the ground isn't as good.
Honestly, a 2000W inverter needs its own battery bank. I think you'll be okay since you have that second battery. But, the batteries will be doing most of the work. It'll come down to the factor of time. If you're not using all 2,000 watts for more than a few minutes, then that 220A alt might keep up just fine if you're not running a lot of other high-amperage devices.
The inverter, or any other high-amp load should be connected directly to the battery(ies) with their own fused power cable, just like how an aftermarket audio amplifier is done. They do not go on the factory circuit downstream of that 175A main fuse. That is strictly for protecting the factory original equipment. Any other high-amp device you add should get its own power cable with its own appropriately-sized fuse.
