First thing, an isolator is a relay. It's either open (no current flowing through it) or it's closed (current flowing through it). It's an ON/OFF switch, nothing more.
Second, there's no such thing as 1 o/t cable.
Third, for a 10 foot cable, AWG #8 cable will handle 75 amps sustained, but with a 2-3% voltage drop. AWG #4 cable will handle the same 75 amps for less than 1% voltage drop. AWG #1/0 or #2/0 cable will handle it with virtually zero voltage drop, less than 0.1 volt.
Don't go get a $7 voltmeter and expect to read amps of more than a few milliamps unless you also have a shunt in the circuit. You need a ammeter (amp meter) to read amps greater than 10 amp in most cases. A battery monitor, like a Xantrex, will monitor volts, amps and lots of other things. But it's not cheap.
A 100 amp alternator will not put out 100 amps to an aux bank. The vehicle's electrical system will take what it needs first, and then whatever is left over goes to the house bank.
Do not try try to charge a house bank with a charger plugged into an inverter. When the isolator is closed (current running through it) all of the batteries in the vehicle are connected to together. When you plug a charger into an inverter and connect the inverter to the system, you are literally using amps from the battery to charge the battery. The alternator must charge the battery, and at the same time you are drawing those amps right back out to power the inverter and the charger. The inverter draws 1-2 amps, and the charger will draw 8-10. You're going backwards when you do that. You're also just murdering your batteries.
The cranking battery will recharge very quickly, because you draw out very few amps when you use it to start the engine. A few hundred amps, but for only a second or two. The cranking battery will recharge in a matter of minutes.
If you have a 150 amp alternator, then the vehicle is probably using close to 90 amps of that, so no matter what you'll never get more than 50 or 60 amps from the alternator to the house bank. You've got 190 amp hours worth of batteries. If you've discharged them to the point where the inverter won't work, then it'll take a 30 amp charger about 6 hours to get them back to 50%, and then another 12 hours or so for them to become fully charged. As they get closer and closer to becoming fully charged, less and less amps will flow into the batteries. The last 10 or 15 amps alone could take 5 or 6 hours.
The Espar heater will draw an average of 1.5 to 2 amps per hour, depending on how cold it is and whether your van is insulated or not. If all you run is the Espar and nothing else, you could run the Espar on a fully charged 190 amp hour battery bank for 48 hours before you got down to 50% DoD, and another 30 or so hours before the voltage dropped too low to run the Espar.
If you draw 50 amps out of your house bank, expect 8-12 of charging time to fully recharge the batteries. If you regularly draw the batteries down below 50%, or don't fully charge them (at least once a week), then the life of the battery bank will be 12-18 months, at most.
It appears that everything is connected properly, except for the isolator. A regular battery isolator (like a Sure Power Isolator) will not work with some alternators, Bosch in particular. If I knew exactly (brand and model) what kind of isolator you have, I can tell you if it'll work or not. More than likely you need a battery separator. Both an isolator and a separator are simple relays, but they work differently in how the pass current through the relay.
It's also better to connect the isolator/separator to the same terminal that the alternator connects to, or that fuse block where the alternator and the battery (and everything else) connects, rather than to the cranking battery's positive terminal. When you connect it to the positive terminal on the cranking battery, the house bank will draw it's charging current from the stored electricity of the cranking battery first, so it must be charged and then discharged in one brutal step to get current to the house bank. It'll work, but it'll reduce the life (and starting capacity) of the cranking battery significantly.
With the engine at idle, measure the voltage just before, and just after the isolator. The voltages should be the same coming out of it (going to the house bank) as it is coming into it (from the alternator). There might be a .1 or .2 voltage drop coming out of it, depending on the diode type that the isolator has within it. But no more than .2 volt difference. It should also be at least 13.2 volts going into the isolator. If it's not, there is a connection problem at the cranking battery.
"When I check if there is voltage coming from the isolator to the aux batteries, I don't know if I am reading a residual charge on the aux batteries or power through the isolator. I don't seem to know how to use the darn thing."
If the voltage shows in the lower 12.x range, or lower, that's the voltage of the batteries themselves. If it's higher than 13 volts, then it's the charging voltage.
On the voltmeter look for DCV (DC Voltage, instead of ACV). Turn the dial to 20. Plug the black lead into the COM hole, and the red lead into the V/Ohm/ma hole (not the 10 ADC hole). That should tell you the voltage.
Second, there's no such thing as 1 o/t cable.
Third, for a 10 foot cable, AWG #8 cable will handle 75 amps sustained, but with a 2-3% voltage drop. AWG #4 cable will handle the same 75 amps for less than 1% voltage drop. AWG #1/0 or #2/0 cable will handle it with virtually zero voltage drop, less than 0.1 volt.
Don't go get a $7 voltmeter and expect to read amps of more than a few milliamps unless you also have a shunt in the circuit. You need a ammeter (amp meter) to read amps greater than 10 amp in most cases. A battery monitor, like a Xantrex, will monitor volts, amps and lots of other things. But it's not cheap.
A 100 amp alternator will not put out 100 amps to an aux bank. The vehicle's electrical system will take what it needs first, and then whatever is left over goes to the house bank.
Do not try try to charge a house bank with a charger plugged into an inverter. When the isolator is closed (current running through it) all of the batteries in the vehicle are connected to together. When you plug a charger into an inverter and connect the inverter to the system, you are literally using amps from the battery to charge the battery. The alternator must charge the battery, and at the same time you are drawing those amps right back out to power the inverter and the charger. The inverter draws 1-2 amps, and the charger will draw 8-10. You're going backwards when you do that. You're also just murdering your batteries.
The cranking battery will recharge very quickly, because you draw out very few amps when you use it to start the engine. A few hundred amps, but for only a second or two. The cranking battery will recharge in a matter of minutes.
If you have a 150 amp alternator, then the vehicle is probably using close to 90 amps of that, so no matter what you'll never get more than 50 or 60 amps from the alternator to the house bank. You've got 190 amp hours worth of batteries. If you've discharged them to the point where the inverter won't work, then it'll take a 30 amp charger about 6 hours to get them back to 50%, and then another 12 hours or so for them to become fully charged. As they get closer and closer to becoming fully charged, less and less amps will flow into the batteries. The last 10 or 15 amps alone could take 5 or 6 hours.
The Espar heater will draw an average of 1.5 to 2 amps per hour, depending on how cold it is and whether your van is insulated or not. If all you run is the Espar and nothing else, you could run the Espar on a fully charged 190 amp hour battery bank for 48 hours before you got down to 50% DoD, and another 30 or so hours before the voltage dropped too low to run the Espar.
If you draw 50 amps out of your house bank, expect 8-12 of charging time to fully recharge the batteries. If you regularly draw the batteries down below 50%, or don't fully charge them (at least once a week), then the life of the battery bank will be 12-18 months, at most.
It appears that everything is connected properly, except for the isolator. A regular battery isolator (like a Sure Power Isolator) will not work with some alternators, Bosch in particular. If I knew exactly (brand and model) what kind of isolator you have, I can tell you if it'll work or not. More than likely you need a battery separator. Both an isolator and a separator are simple relays, but they work differently in how the pass current through the relay.
It's also better to connect the isolator/separator to the same terminal that the alternator connects to, or that fuse block where the alternator and the battery (and everything else) connects, rather than to the cranking battery's positive terminal. When you connect it to the positive terminal on the cranking battery, the house bank will draw it's charging current from the stored electricity of the cranking battery first, so it must be charged and then discharged in one brutal step to get current to the house bank. It'll work, but it'll reduce the life (and starting capacity) of the cranking battery significantly.
With the engine at idle, measure the voltage just before, and just after the isolator. The voltages should be the same coming out of it (going to the house bank) as it is coming into it (from the alternator). There might be a .1 or .2 voltage drop coming out of it, depending on the diode type that the isolator has within it. But no more than .2 volt difference. It should also be at least 13.2 volts going into the isolator. If it's not, there is a connection problem at the cranking battery.
"When I check if there is voltage coming from the isolator to the aux batteries, I don't know if I am reading a residual charge on the aux batteries or power through the isolator. I don't seem to know how to use the darn thing."
If the voltage shows in the lower 12.x range, or lower, that's the voltage of the batteries themselves. If it's higher than 13 volts, then it's the charging voltage.
On the voltmeter look for DCV (DC Voltage, instead of ACV). Turn the dial to 20. Plug the black lead into the COM hole, and the red lead into the V/Ohm/ma hole (not the 10 ADC hole). That should tell you the voltage.