I was wondering if I could get by with wiring one brand new optima red top with another relatively same age red top using parallel wiring? I went ahead and bought a stinger 200 amp relay just in case though.

Thanks Jason

 

I am not sure if your vehicle has a dual battery setup or what but, dual battery setups are a pain. The problem is the internal resistance of the batteries are not the same so they will fail faster than a single battery setup, if there were some way to make the internal resistance of batteries exactly the same this would work perfectly. Some vehicles require 2 batteries setup this way to start well though so your kind of stuck if this is the case.

If you have a single battery setup and want dual batteries the best way I have found to do this is add a battery isolater. It is a small unit that takes the output from the alternator and re-directs it to 2 batteries. It will charge the battery that needs it. I have used this type of setup in my pickup for over 10 years. I was able to fit both batteries under the hood, it looks pretty cool and works great. I have all accesories connected to the spare battery, if my alarm, stereo or anything else gets left on it discharges the spare battery and my main engine battery is still full of charge to start the vehicle. I didn't move over the dome light to that circuit but you should to be totally protected from a dead battery and your lights if you are really looking for total protection.

If you do this try to get a battery isolater with twice the current capacity of your alternator. So if you have a 45amp alternator get a 90 amp battery isolator. This just assures you will never over power it and have something fail. I also got some very nice circuit breakers that you can reset with the push of a button, if you have driving lights, big stereo ect... or if you have a wiring problem these will pop and cut all power. You can find the problem and fix it and just reset the circuit breaker and your up and going again. Circuit breakers are a must for this setup, you don't have to buy the ones you can reset with a button but they are nice. I have 2 pairs of KC driving lights, when they are both on my circuit breaker will pop after about 15 minutes. There is not a heavy duty alternator available for my pickup do to the factory wiring so it is just a little to much for it to run both sets of lights. The wiring is very easy and it works really well when you are all done. Good luck.

 

Can't you isolate the batteries with a solenoid? I just bought a camper and want another battery. I was just going to use the solenoid to isolate my camper battery

 

In theory yes, but solenoids take power and would require some additional support circuitry. The isolator uses two diodes and has three wires to connect, it doesn't get much easier or more reliable. IMHO