Hello. Sorry for the late reply
I see you've been given some good advice already.
I've gone into many of these topics recently. Please peruse some of my posts in other electrical threads.
I will jump on the anti hot plate bandwagon. They are tremendous battery abusers.
Lets say that 1000 watts is continuous, and we will discount peukert, and inverter inefficiency and battery voltage drop under such a HUGE load.
volts x amps = watts
So 100 watts / 12.8 volts is 78.125 amps.
A 220 amp hour battery has 110 amps to give as one should not really drain them below 50% as a rule. So discounting the Peukert effect, and inverter efficiency, your healthy and fully charged battery( not likely) could power the hot plate at 100% duty cycle for a little over an hour and a half, before dropping to 50%
Now if we add 15% to the current for inverter efficiency, and do account for peukert, it is likely the low voltage alarm on the inverter will be sounding in about 45 minutes. So one or two hot plate meals, and your battery is at 50% and crying in a corner at the abuse you just subjected to. If it is not recharged quickly, and fully, it will get all petulant and decide it is not only a 175 amp hour capacity battery, then a 150, then a 120 and so on.
Please reconsider the hot plate idea. Also cooking inside with windows closed, even over electricity, will overwhelm you just with the cooking fumes and oil mist. COnsider foods which need no heat for city stealthing, and propane with the windows open partly at all other times
Now alternator recharging is not the magical panacea that most newbies consider it to be. While a well wired and capable alternator spinning fast can indeed make a lot of amps, once the battery reaches the 70% charged zone it will accept much less current. Once 80% is reached it will accept very little current, and that last 20% can take hours and hours of driving.
There is no way around this fact of recharging lead acid batteries. The last 20% takes hours no matter which charging source is used. Many will confuse surface charge( high battery voltage upon removal from a charging source) with actual battery state of charge. Most battery manufacturers say that voltage is only an accurate indicator of state of charge after the battery has not seen charging or loads for 24 hours or more. Shut off your engine and see 12.8+, means very very little.
Now as to your wiring diagram, the green wire is the stock vehicular wiring. This is undersized for the task of recharging even the single engine starting battery. It usually has a fuse somewhere along its length, and this stock wire is usually no thicker than 6 awg.
You basically are not charging the house battery off the starter battery. In your diagram the alternator is feeding the starter battery, and the house battery is feeding off the starter battery once the solenoid is engaged. There are issues with this method. One is the voltage regulator. Having the house battery tacked onto the starter battery through a solenoid, well the voltage regulator sees the nearly fully charged starting battery and will likely prematurely lower voltage greatly reducing the much wanted charging current
Number2 is that the original wiring is too thin for a large depleted battery tacked onto the end of the circuit.
This can be remedied by adding another 'green' wire in parallel from alternator the starter battery. You do not need to do anything to the original alternator circuit for this.
Or this wire can go from alternator (+) directly to starter battery side of the solenoid. Technically this wire should be fused at both ends as it will always be hot, even with the key off. Protecting this cable from chafing and shorting to ground is very important if one decides to forgo this fusing, which I am not recommending.
So If one unconventionally runs a wire from alternator(+) to solenoid to house battery, generally the circuit length is much shorter, and the voltage regulator will see the depleted house battery more than the nearly fully charged starter battery and allow the alternator to make more current, to feed the battery which wants, and needs it more.
The continuous duty solenoid Should be rated at, at least 90 amps. 200 is better.
The wire that triggers the solenoid only needs to pass at most, 2 amps of current. It does not need to be thick wire, it does however need to be fused. The solenoid might have two trigger wires, One (+), one (-). It does not matter which is which, really. One can just go the the mounting bolt, assuming it is grounded/ Other solenoids have just one trigger wire stud as it is assumed the solenoid will be grounded and it takes ground there.
The circuit you choose to activate the solenoid is another matter. I personally do not want the house battery assisting engine starting. This puts undue stress on the contacts in the solenoid, and exposes devices hooked to house battery to starter surges which might damage them. On my Van, and many vehicles, the blower motor circuit for the Hvac is deactivated during engine cranking. I would personally choose this circuit for activating a solenoid, if I used a solenoid.
The solenoid is the least expensive way to achieve automatic battery isolation and allow battery recharging, but far from the only product and method. I like the Blue Seas ACRs
http://www.bluesea.com/products/category/Automatic_Charging_Relays
The inverter should tell you at what size to fuse it. But you are fusing to protect the wiring, not the inverter, nor devices hooked to the inverter. The Inverter should be close to the batteries, but not in the same compartment with them, though with an AGM this is of less importance. Close for minimal voltage drop. use 120v household extension cords to reach distant devices as voltage drop over AC circuits in not really a factor in this circumstance.
The Inverter should be the last resort, not the first.
Laptop DC to DC "car adapters' are much more efficient. Almost every single laptop out there has one available. Mine was 22$ and is 3+ years old at this point. PWR+ brand.
Charging USB devices through an inverter might be the very definition of wastefulness in Vandwelling.
http://www.amazon.com/s/ref=nb_sb_n...ds=usb+car+adapter&rh=i:aps,k:usb+car+adapter.
Your record player might humm with a 60 HZ buzz when powered by the inverter. A pure sine wave inverter might cure this buzz, but they are 2 to 3x as much. The size and weight of records, and the player is not conducive to vehicular dwelling.
As for grounding, if you do go with a battery monitor, there must be a shunt installed between the batteries and all the ground wires. There will be two big bolts on the Shunt. One stud will have 2 wires attached to it, One going to starter battery(-) the other to house battery (-). On the other side of the shunt is the load side. All stock vehicular grounds must run here, The original battery to engine ground must be disconnected. it now becomes the engine to shunt ground. Same with the firewall ground. Many alternators are grounded to the engine through the mounting bolts, others have a wire from alternator to engine ground. IF the latter, run this wire directly to Shunt.
A buss bar should be hooked to the load side of the shunt. To this Bussbar you hook all (-) from your house loads. No (-) wire can go directly to either battery (-) without going through the shunt. If any wire does, then the shunt will not be reading all the current flowing into or out of either battery, and the battery monitor becomes inaccurate. Even if you are only monitoring the house battery, no other (-) wires can go directly to the starter battery that do not go through the shunt.
Properly terminating large cabling to hook onto battery or Solenoid or alternator is extremely important. It requires the right tools and the skills to use them. I recommend those without the tools and skills to have cables made for them. The store bought cables sold at autoparts stores are NOT made well. They have steel ring terminals just crushed over copper wire.
Stereo shops can make up fat properly terminated cables for you but be weary of aluminum cables or copper clad aluminum cablesas they are not rated for the same current as pure copper. Here is an online store that will make cables with high quality parts and workmanship. Do not skimp on these fat charging cables. At best skimping causes poor battery recharging, at worst your vehicle turns into a volcano.
http://www.genuinedealz.com/custom-cables
The fatter the wires you purchase, the better the alternator can charge the battery, upto the 80% State of charge range. However the fatter the wire, the harder the alternator will be made to work when the batteries are depleted. This can shorten the life of the alternator, and many choose thinner wire for this reason, and many choose thinner wire just because it is cheaper and easier to run.
Distance also plays a big part in how fat the wire should be, as well as the amount of connections.
Circuit breakers are a great option over fuses, but I suspect many cheaper fuses, and circuit breakers will not trip the circuit at their current rating. I also suspect the circuit breakers have more voltage drop across them than a good ANL fuse. Do not shop for these by price alone.
The starter battery and house battery can be completely different, but this is not ideal. AGM and flooded batteries do have slightly different charging current requirements, and this varies by manufacturer, and can vary widely. Right now I have both an AGM and a flooded battery. I try and keep the AGM battery from seeing voltages over 14.7, and I try to never leave the batteries in parallel without a charging source keeping the voltage over 13.1, which is the resting fully charged voltage of my Northstar AGM battery.
Many will say that one battery or the other will always be over or undercharged when charging in parallel. I have not found this to be true with the many different ways I have to measure current into or out of either battery, but I have not run every permutation of battery state of charge and alternator rpm either. What I have noticed is that the battery takes what it wants at the voltages allowed at what the charging source can provide.
One thing you pretty much require is a grid powered charger and some method to power it. You cannot rely on the alternator alone to fully charge a battery, not unless you are driving hundreds of miles after each discharge. If a battery is cycled daily below ~90%, every 7 to 10 days is needs a full 100% charge, or it will suffer progressive capacity loss, and die a premature, expensive death. The higher the state of charge you can keep the battery, the better it can perform and the longer it will last.
Solar can be very good at taking the battery from 80 to 97%. Many consider 97% fully charged, but really that last 3% takes longer than there is daylight available to get it there.
AGM's basically will be fully charged when they accept no more current where as flooded batteries will always take a little bit. One can stick a hydrometer into a flooded battery to see how it fares under any given recharge regimen. AGMs require an amp hour counter/ battery monitor.
Sorry that living off battery power is not simpler. It can be, as long as frequently replacing batteries is no big deal, but keeping batteries where they can perform well and live a long life can be challenging, so one must place a line in the sand between 'ignorance is bliss' and 'battery nerd'
