Edit 3/4/06 hosting was lost, images re-added as attachments. due to the limits of attachemnents most of pictures are attached to posts other then where they are written about, I did attach the pictures in order though.
System
Things it can do:
Provide an Auxiliary battery to be abused by accessories while the engine is off, preserving the Main battery for engine starting.
Automatically charge both after engine start, via paralleling, isolate them on shutdown or if the alternator fails,
Bring on the aux battery for starting (paralleled to main) should the main be unable to do so on its own.
A way to disable paralleling.
Draw very little power when in use.
Cause very little voltage drop (.001v at charging current)
Kill power to the starter until commanded by the driver during start, protects from starter contact failure and also a mild theft deterrent.
In cab indication of power to the solenoid,
Provide a consistent source of power for both the OEM electrical and aftermarket loads, no loss of power, memories are maintained such as the clock, stored data in the EFI computer such as long term fuel trim, IAC position etc. The alternator and computers always have a cushion for spikes and sags in the main battery., aftermarket loads have the aux battery for the same thing.
Carry 200A continuous between batteries, 100A to the body, intermittent high amperage to the starter.
Over current protection of all loads through either switching or fuses.
Resist the elements
Things it cannot do:
Cut off power to the entire cruiser.
Start off of the aux battery alone without paralleling to the main.
Indicate state of charge of the batteries (working on this one)
Provide power to a winch (as it sits now, have plans)
Provide short protection for 3 of the 4 main large positive feeds
Close the 9012 solenoid if the Aux battery is %100 dead,
The original plan was a very stripped down version of “Slee’s Dual Battery Setup” just a solenoid and a switch. Wanted to keep the part count down for cost & reliability. If a part is not installed it cannot break.
Original plan
Due to wants and problem stacking it grew some. Though it is still simpler than first glace at the diagram would tell.
As currently installed:
Black, negative/ground
Red, un-fused +
Green, fused +
Blue, switched +
To give a return path (or more accurately source path) for electrical loads. the ground cables are 1/0 gage between the main battery, aux battery, block, and frame , 6 gage between the main battery and body The grounds must always be able to carry the same current as the +.
The main cables from the aux battery + post to the 9012 solenoid, from the solenoid to main battery + post, from main battery + to the starter kill solenoid, and on the starter are also 1/0
The control wiring is built for 10A and is fused at 5 or 7.5 Amps (7.5a charge fuse in under hood fuse box protects the alternator good signal)
The upper half of the rear heat switch controls the 3 mode positions: auto, on, and off,
In the auto position (“LO”) when the engine is started and the alternator starts producing power the alternator good signal goes to ~13.5v, This is ported through the switch to the coil of the mini relay allowing power from the aux battery through a fuse through the relay contacts, choke and then to the solenoid to parallel the batteries, the alternator is already connected to the main battery through the factory fusible links, when the batteries are paralleled the aux battery charges also.
When the solenoid is powered power is also ported back through the switch to light the green “LO” LED,
Inrush of the control circuit is somewhere between 3.8 and 5 amps for 130 milli-seconds, total combined continuous draw of the solenoid, relay and LED is very low at around 0.180 amps.
When the engine is shut down both the relay and solenoid open and the LED goes out, no power is consumed in off, nothing need be done switch is left in LO position
In manual “self jump” power from the second battery through the 5a fuses is ported to close the mini relay rest is similar to the above except the orange “HI” LED is lit, and it will remain closed regardless of engine/alternator operation
In off nothing happens in the control circuit, engine on or off, no power is consumed. The main battery powers OEM loads and is charged if the alternator is working, Aux battery powers aftermarket loads and is not charged.
In the original plan the wire that feeds the mini relay’s coil was suppose to go direct to the solenoid, but there was an electrical noise problem generated by the coil optimizer in the 9012 (PWM circuit) that added noise on AM radio on top of my pre existing engine noise on AM.
Talked to Wane @ Blue Sea I asked about the frequency of the PWM circuit, he did not know, did find out that the peak current of the square wave is 0.4a and average around 0.13a, he first recommended a 330 μF (micro farad) capacitor alone to reduce the electrical noise, I asked about using diodes or resistors to help and he said a choke would help but not really needed, being all about overkill in went the choke along with the capacitor to make a full filter, The choke tends toward leveling the current; the capacitor tends to level the voltage. that was revision 1, noise gone.
But now the alternator good signal would drop to 2v when it tried to close the solenoid and it never closed, I think the added inrush of the capacitor (very short but can be high) pissed off the IC in the alternator, so I had to take the burden off the IC with the mini relay. Revision 2 everything works
I have no idea how much current the alternator good signal can safely provide, after seeing Slee power a solenoid and 3 relay’s on his figured I was safe. Apparently not. Draw on the IC is now only 0.030A just the coil of the mini relay.
In the original plan since auto power came from the alternator the solenoid could be closed even if the Aux battery was completely dead. Manual closure required the aux battery power, this worked out as you would not want to try to self-jump off of a dead aux battery anyway, if the roles were revered and the main was dead the aux can still close the solenoid for self jump
Now the aux battery has to able to come up with ~5A @ 9v for 130 ms to close the solenoid In auto or manual, once closed alternator/main battery power will keep it closed
This should not be a problem in reality. Such a small load could be gotten off of a surface charge of a dead battery.
System
Things it can do:
Provide an Auxiliary battery to be abused by accessories while the engine is off, preserving the Main battery for engine starting.
Automatically charge both after engine start, via paralleling, isolate them on shutdown or if the alternator fails,
Bring on the aux battery for starting (paralleled to main) should the main be unable to do so on its own.
A way to disable paralleling.
Draw very little power when in use.
Cause very little voltage drop (.001v at charging current)
Kill power to the starter until commanded by the driver during start, protects from starter contact failure and also a mild theft deterrent.
In cab indication of power to the solenoid,
Provide a consistent source of power for both the OEM electrical and aftermarket loads, no loss of power, memories are maintained such as the clock, stored data in the EFI computer such as long term fuel trim, IAC position etc. The alternator and computers always have a cushion for spikes and sags in the main battery., aftermarket loads have the aux battery for the same thing.
Carry 200A continuous between batteries, 100A to the body, intermittent high amperage to the starter.
Over current protection of all loads through either switching or fuses.
Resist the elements
Things it cannot do:
Cut off power to the entire cruiser.
Start off of the aux battery alone without paralleling to the main.
Indicate state of charge of the batteries (working on this one)
Provide power to a winch (as it sits now, have plans)
Provide short protection for 3 of the 4 main large positive feeds
Close the 9012 solenoid if the Aux battery is %100 dead,
The original plan was a very stripped down version of “Slee’s Dual Battery Setup” just a solenoid and a switch. Wanted to keep the part count down for cost & reliability. If a part is not installed it cannot break.
Original plan
Due to wants and problem stacking it grew some. Though it is still simpler than first glace at the diagram would tell.
As currently installed:
Black, negative/ground
Red, un-fused +
Green, fused +
Blue, switched +
To give a return path (or more accurately source path) for electrical loads. the ground cables are 1/0 gage between the main battery, aux battery, block, and frame , 6 gage between the main battery and body The grounds must always be able to carry the same current as the +.
The main cables from the aux battery + post to the 9012 solenoid, from the solenoid to main battery + post, from main battery + to the starter kill solenoid, and on the starter are also 1/0
The control wiring is built for 10A and is fused at 5 or 7.5 Amps (7.5a charge fuse in under hood fuse box protects the alternator good signal)
The upper half of the rear heat switch controls the 3 mode positions: auto, on, and off,
In the auto position (“LO”) when the engine is started and the alternator starts producing power the alternator good signal goes to ~13.5v, This is ported through the switch to the coil of the mini relay allowing power from the aux battery through a fuse through the relay contacts, choke and then to the solenoid to parallel the batteries, the alternator is already connected to the main battery through the factory fusible links, when the batteries are paralleled the aux battery charges also.
When the solenoid is powered power is also ported back through the switch to light the green “LO” LED,
Inrush of the control circuit is somewhere between 3.8 and 5 amps for 130 milli-seconds, total combined continuous draw of the solenoid, relay and LED is very low at around 0.180 amps.
When the engine is shut down both the relay and solenoid open and the LED goes out, no power is consumed in off, nothing need be done switch is left in LO position
In manual “self jump” power from the second battery through the 5a fuses is ported to close the mini relay rest is similar to the above except the orange “HI” LED is lit, and it will remain closed regardless of engine/alternator operation
In off nothing happens in the control circuit, engine on or off, no power is consumed. The main battery powers OEM loads and is charged if the alternator is working, Aux battery powers aftermarket loads and is not charged.
In the original plan the wire that feeds the mini relay’s coil was suppose to go direct to the solenoid, but there was an electrical noise problem generated by the coil optimizer in the 9012 (PWM circuit) that added noise on AM radio on top of my pre existing engine noise on AM.
Talked to Wane @ Blue Sea I asked about the frequency of the PWM circuit, he did not know, did find out that the peak current of the square wave is 0.4a and average around 0.13a, he first recommended a 330 μF (micro farad) capacitor alone to reduce the electrical noise, I asked about using diodes or resistors to help and he said a choke would help but not really needed, being all about overkill in went the choke along with the capacitor to make a full filter, The choke tends toward leveling the current; the capacitor tends to level the voltage. that was revision 1, noise gone.
But now the alternator good signal would drop to 2v when it tried to close the solenoid and it never closed, I think the added inrush of the capacitor (very short but can be high) pissed off the IC in the alternator, so I had to take the burden off the IC with the mini relay. Revision 2 everything works
I have no idea how much current the alternator good signal can safely provide, after seeing Slee power a solenoid and 3 relay’s on his figured I was safe. Apparently not. Draw on the IC is now only 0.030A just the coil of the mini relay.
In the original plan since auto power came from the alternator the solenoid could be closed even if the Aux battery was completely dead. Manual closure required the aux battery power, this worked out as you would not want to try to self-jump off of a dead aux battery anyway, if the roles were revered and the main was dead the aux can still close the solenoid for self jump
Now the aux battery has to able to come up with ~5A @ 9v for 130 ms to close the solenoid In auto or manual, once closed alternator/main battery power will keep it closed
This should not be a problem in reality. Such a small load could be gotten off of a surface charge of a dead battery.
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) routed along the fender protected in spiral wrap and zip-tied into place
and get yourself a real LC...!
I have been looking for those around town, could not find any, Toyota did a good job with that with the OEM wiring. Those are a got to have, I have a bad habit of setting tools on the battery (nice flat convenient spot) been waiting to drop a wrench of the solenoid and see a fireworks show, it is only a matter of time. 
