running 2 batteries Options

[yellowchinaman]

I've seen people having an extra car battery in the boot for the extra ICE they have.
I am thinking of installing a small extra battery in the arm rest to boost the power of my existing racing battery.
Question is, what is the proper way or doubling a battery and is there a problem with mixing different battery types and size? For instance, can I add a small 12v motorcycle battery with the 12V car battery?

[Hanyo]

Let me chime in about this topic:

It's not the best idea to run batteries in parallel. ( maintain 12 volts but doubles the amp)

The reason is if there is a difference between internal resistance between the batteries one acts like a resistor and drains the lower resistance battery.

This is the same reason why golf carts use big 6 volt batteries in series. You get double the amps and maintain the same volts with out internal resistance issue.

The proper way to install a parallel battery would to install a glow plug solenoid between the booster battery that only is connected to your vehicle battery when the ignition is on. The theory is the booster is only connected when starting and charging. And completely disconnected while the car is off. This is to avoid internal resistance draining mention earlier.

But once you factor in all that crazy extra wiring and extra battery. Your better off buying a li ion battery in the first place.

http://www.jegs.com/p/Lithium-Pros/Lithium...770167/10002/-1


I hope that helps. Yellowchinaman, what symptoms are you having to want an extra battery?

This post has been edited by Hanyo: Mar 19, 2014 - 1:18 AM

[czwalga]

Let me chime in about this topic:

It's not the best idea to run batteries in parallel. ( maintain 12 volts but doubles the amp)

The reason is if there is a difference between internal resistance between the batteries one acts like a resistor and drains the lower resistance battery.

This is the same reason why golf carts use big 6 volt batteries in series. You get double the amps and maintain the same volts with out internal resistance issue.

The proper way to install a parallel battery would to install a glow plug solenoid between the booster battery that only is connected to your vehicle battery when the ignition is on. The theory is the booster is only connected when starting and charging. And completely disconnected while the car is off. This is to avoid internal resistance draining mention earlier.

But once you factor in all that crazy extra wiring and extra battery. Your better off buying a li ion battery in the first place.

http://www.jegs.com/p/Lithium-Pros/Lithium...770167/10002/-1


I hope that helps. Yellowchinaman, what symptoms are you having to want an extra battery?

Not true. Golf carts are put in series to up the voltage. You put 3 12volt batteries and series and you have 36 volts with the same amount of amp hours as a single battery.