Dual Battery Setup

[Polara]

So, I'm trying to find a wiring diagram and instructions on how to add a secondary battery to a car. The car is an '85 Toyota Tercel Station Wagon. I thought on doing this because its going to become a stormchase vehicle, meaning radios of the HAM nature, laptops, possible small televisions, ect ect ect. Anyway, I want to set a single battery aside for starting that car and have the other for the chasing tools. I also need them both to charge while the engine is running. Anyway, thanks for any help, suggestions and tips are welcomed!

[Knailgun]

well, to do this, you'l need a battery isolator...to break the power between them, and secondly, you'll need a non wetcell battery for the interior...optima would work good for this. Personally, I would make it a point to put a bigger alternator on it first....kudos on the old school tercel choice

[Polara]

Well, I've looked around for a good amount of time for a better alternator, but its impossible to find a performance alt for an 85 tercel.

[Fever]

Ya there's probably not an off the shelf ho alt for that engine, but if you have the room some people fab up new brackets to hold a larger gm style alts. Do you think you have the room under the hood?

[Polara]

I have tons of room in the alt area, problem is I don't have the tools or skills to make brackets. My other question is, how big of wire should I use when coming off the battery? I have been told its best to go straight off the battery when powering my power inverter. My other problem would be finding a place in the firewall to route the wire...

[Knailgun]

Originally Posted by Polara

I have tons of room in the alt area, problem is I don't have the tools or skills to make brackets. My other question is, how big of wire should I use when coming off the battery? I have been told its best to go straight off the battery when powering my power inverter. My other problem would be finding a place in the firewall to route the wire...

you probably will have to drill a hole, just remeber to put a grommet on it. Use 8-4 awg...depending on the size of your inverter

[Polara]

Just out of curiousity, All I have to do is run a cable from the positive terminal of the battery, and just bolt a cable to the floor of the car, and then connect that to the negative terminal of the inverter, I know I could on others, but I'm just wondering if this stays the same on a Toyota.

[hilux5084]

I have done many of these mods the best method I have seen is to parallel the second battery with a voltage sensitive relay in series with the positive cable. The relay only connects the second batt while the alternator is charging. An added feature I fit for off roaders is a inline solinoid wired with starter sized cable to a push button switch in case the vehicle batt goes flat. I hope this helps you a bit .
Joe