Sorry for the low quality camphone pics.
The second battery has 3 purposes:
1. An auxiliary battery which I can use while parked in remote areas to power my vehicle electronics, lights, refrigerator and so on without discharging the starting battery.
2. An emergency starting battery if I do run down the main starting battery or if it goes dead.
3. To power a future winch and other future heavy auxiliary loads.
The battery tray was designed in collaboration with Landcruiser Northwest, and was fabricated by Landcruiser Northwest. The bling rack is from ebay (seller "ppbillet").
I also designed and had LCNW fabricate a bracket to hold a marine grade 325 ampere battery switch and a bypass relay. This bracket is also 1/8" powdercoated steel, and is mounted to the 4 existing six millimeter threaded holes on top of the left fender apron.
The battery switch allows the entire vehicle electrical system (except the starter) to be powered from the main battery, the auxiliary battery, or ALL. The intermediate ALL switch setting connects both batteries in parallel, and allows a "make before break" action which ensures continuous power to the vehicle during battery switchover, avoiding having to reset the compass, etc.
During driving operation, the switch is set to in Position 1 to connect only the main battery to the vehicle electrical system.
During camping activites, the switch is set to Position 2 to connect only the aux battery to the vehicle electrical system. The starter battery is isolated in this setting.
This switch does not require relay current to operate. So, no relay coil current penalty is associated with activating the auxiliary battery. This may seem small but the coil current of a 200 amp relay will run down a big battery in just a few days
The ALL position allows the 2nd battery to jumpstart the first battery, or vice versa. It also allows charging of both batteries simultaneously.
I have provided a 200 amp bypass relay also mounted on the switch bracket, to allow the auxiliary battery to be charged during engine operation, without having open the hood, and switch to "ALL".
This bypass relay will be activated by pressing a momentary action button on the dash. This will activate a small latching relay to apply power to coil of the 200 amp bypass relay. The large relay will then connect the auxiliary battery to the vehicle electrical system, allowing the auxiliary battery to charge while the engine is running. This latching relay will disengage when the key is turned off, ensuring the bypass relay coil current does not drain either battery when the vehicle is parked. As a second benefit, this bypass relay can be used to apply power to the vehicle from the auxiliary battery if the battery switch fails.
The original starter battery remains connected to the starter. The deep discharge auxiliary battery will never be used to start the vehicle except in the case of a failure of the starter battery.
The bypass relay is not shown in the circuit, but it provides a bypass connection between the fuesbox and the optima, allowing a path for the alternator to charge the optima if the switch is in the "1" position, and also allowing the optima to power the vehicle if the switch fails.
The bypass relay coil circuit is not completed. And I have to shorten some battery cables... But I do finally have auxiliary battery power.
"You have the right to remain silent."
Linear Mode
