I'm planning on moving my battery to the trunk, but I also want to go with a dual battery setup. Now I remember someone on here saying that they had 2 batteries in the trunk. What all would I have to do to set this up? Would I need any special equipment? I researched this a long time ago, but I forget.
The search yielded the following: http://mmb.maverick.to/showthread.php?t=12557&highlight=dual+batteries Just curious, is there an added benefit to having two batteries? Good luck with the project!
While it is pretty easy to hook up, , just a couple of cables to hook positive to positive and negative to negative, I really dont see any advantage to adding a second battery. You would also need to upgrade your charging system.
The advantage of dual batteries is capacity. You have that extra power when you need it. Under normal circumstances the car will use no more power than it normally does. Your alternator will keep both batteries charged just fine. On the rare occurance of very cold weather when you need the extra capacity your car will start and then the alternator will easily charge the batteries - even from dead - the typical battery has about 50-60 amp hours. That means that from dead it will take a 60 amp alternator about 1 - 2 hours to fully charge the battery. If you have two of them it takes twice the time - remember - this from a dead state of charge. It is not likely to ever happen - especially with two batteries.
While agreed with the following, I also know there is more to it than "hooking positive to positive and negative to negative" I've been wanting to do this to my Sonoma lately and if one battery dies, it can bring the other down in a heartbeat. I'm doing research on it at the moment, but a isolator is best to use
An isolator is used when you don't want the batteries to both operate everything on your car / camper. If you use an isolator both batteries are not available to start the car. Isolators are most often used in motor homes and campers with the second battery running the lights and accesories. The primary battery is only used for the engine and it's accesories. The isolator is a diode setup that allows a charge from the alternator without allowing it to drain power back into the primary system. This is great if you want to run a high wattage amp or light set-up with the engine off but it does nothing to increase the starting power of your battery. In a car it is best to just hook the batteries together positive to positive and negative to negative with the same size cables as you run to the starter. (0 or 00 for trunk mounts)
I'm going to disagree with you. They make setups w/ isolators so that you can use both batteries to start the car, but also keep the separated so if one goes bad, you can still use the other battery. Same thing for using one for lights/amps/etc but also use it to start the car. I will find the link to said mentioned part later, I'm about to head to bed for the day (work at 9PM) The part was very expensive, over $200 but it can be done. Hooking the 2 together isn't the best option in any setup however, as you won't know one is bad until it is too late
Yes that is like you said why you use an Isolator Take a look here it gives a basic schematic on multiple systems with and without an isolator http://www.bcae1.com/battiso.htm
Also... just a suggestion... You could use a knife switch to seperate the batteries, but still run a charging wire to both batteries. Leave the knife switch open, and if the first battery fails, connect the switch and you can start the car. This way if your car fails to start in the staging lanes (for example) you can switch that pretty fast even if you have to have someone pop the trunk and still race w/o getting DQ'd. also, thanks for the link. Gnite folks!
I just cant imagine what you would need 2 batteries for in a car, especially a classic car. Just seems like a lot of extra hassle and expense for a system that would be way more than you would ever or could ever use. Even the most sophisticated, electronic laden cars use one battery. Unless your going the low rider hydraulic suspension type stuff with a thousand watt stereo, just seems like over kill. But hey, if thats what you want, go for it.
I ran dual batteries in my car before, I went to an efficient mini starter, good alternator and an Optima battery. Less hassle less weight. I run dual batteries and dual alternators on my truck but it came from the factory that way.
even weight distribution when you are drag racing.... I am using an auto switching diaode isolator with a toggle so I can also switch from one to another, on my jeep, of course I use it to run onboard air and a winch. Otherwise I don't have a need for it.
Thanks for the thoughts everyone! I'm wanting the extra battery for a backup in cold weather. It regularly gets below zero in winter here. Besides that I listen to the stereo while waiting for my wife outside of stores, when I'm early for an appointment, etc so having a dedicated battery is definitely a plus. Also, with the right inverter I could do a lot of really cool stuff.
If that's all your wanting to do, your best bet would be the knife connector and 2 batteries. Run a chargin wire from the alternator to each battery, but use the knife connector to keep them disconnected unless your first battery fails to start the car. You could wire your radio and other things you'd use while "waiting" from the second battery and it would then recharge once you start the car (which would be from battery number 1)
