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General => The garage => Topic started by: jonnypolish on 01 September 2010, 21:37

Title: Additional Battery
Post by: jonnypolish on 01 September 2010, 21:37
Haven't covered this before in all my time, Have seen them here and there in other cars but am at a bit of a loss when it comes to sorting one out for myself!
I am looking into this avenue of installing an additional battery in the boot to power my sound system so there is less clutter going through the car and the engine then has its own dedicated power supply!
I'm running 6k+ Watts on the subs and a variation through the components that the lights dim GREATLY at night, so i have resorted to leaving the stereo off at night!

My Questions is:
1) Do i need another alternator? or can i use the existing one to run both batteries?

I look forward to your replies,
Many thanks, Jon
Title: Re: Additional Battery
Post by: Ben Lessani on 01 September 2010, 21:42
You'll need a split charging system.

Better off buying a bigger alternator and KISS.
Title: Re: Additional Battery
Post by: Ben Lessani on 01 September 2010, 21:46
Here's some info on split charging though ...

http://www.talkaudio.co.uk/vbb/showthread.php?s=&threadid=50222

http://www.m-99.co.uk/Electrical/12v_Car_Split_Charging_Kit_-_C/12v_car_split_charging_kit_-_c.html

(http://www.m-99.co.uk/Electrical/12v_Car_Split_Charging_Kit_-_C/split_charger_relay.jpg)
(http://www.m-99.co.uk/Electrical/12v_Car_Split_Charging_Kit_-_C/split4.gif)
Title: Re: Additional Battery
Post by: jonnypolish on 02 September 2010, 19:51
That EASY! Cheers mate!
May Look into the Larger alternator route,
I take it that both batteries will be receiving the same charge? or a slightly lower one going to each?
Title: Re: Additional Battery
Post by: emery1990 on 03 September 2010, 17:52
Looks like its just running the battery in parallel  so would receive the same voltage
Title: Re: Additional Battery
Post by: Ben Lessani on 03 September 2010, 18:00
Looks like its just running the battery in parallel  so would receive the same voltage

It is, but it regulates charge level independently.
Title: Re: Additional Battery
Post by: jonnypolish on 03 September 2010, 18:42
Cheers lads! The info is much appreciated!
Title: Re: Additional Battery
Post by: Diamond Hell on 03 September 2010, 21:05
Buy a marine split charge system - much better quality.
Title: Re: Additional Battery
Post by: jonnypolish on 04 September 2010, 08:25
Cheers DH, Will get onto it today!
Title: Re: Additional Battery
Post by: Sazbard on 04 September 2010, 09:29
Haven't covered this before in all my time, Have seen them here and there in other cars but am at a bit of a loss when it comes to sorting one out for myself!
I am looking into this avenue of installing an additional battery in the boot to power my sound system so there is less clutter going through the car and the engine then has its own dedicated power supply!
I'm running 6k+ Watts on the subs and a variation through the components that the lights dim GREATLY at night, so i have resorted to leaving the stereo off at night!

My Questions is:
1) Do i need another alternator? or can i use the existing one to run both batteries?

I look forward to your replies,
Many thanks, Jon


Firstly, is this 6k rms power? or MAX power? If it is a geniuine 6k then you should be looking at an upgraded alt and battery in the boot.
You don't really need a split charge system, this is more for if you play the car with the engine off, it splits the batterys so you only drain the rear battery and can start the car again without worry about flattening the front one.

What amp, or amps are you running??

I presume you have run 0 guage from the front to the back and used a fused distro block with 4 guage coming out?

Dimming lights usually mean you haven't done:

1. Battery to ground (In your case  use 0 guage for this)
2. Alt to battery (you should be ok with 4guage for this)
3. Check that alt ground is all cleaned up.

Make sure your earth point in the boot for the amps is all cleaned up nicely.

Title: Re: Additional Battery
Post by: danny_p on 04 September 2010, 18:23
6KW will be PMPO that'll roughly equate to 3KW rms or  1500 W ACTUAL POWER CONSUMPTION.

so your ICE will be wanting 105 AMPS @ 14.4 volts the car will need 30-50 AMPS

my sugestion would be to go and buy a battery from a diesel version of your car as it'll proably fit in the std battery location but it extra capcity and power delivering ablity will help keep voltages more stable, and then get a bigger alternator idealy somethign in the 150A+ range

multipul batterys won't help if your alternator isn't big enough because all the power has to come from the alternator at the end of the day.  also that split charging system thats linked to is NASTY    it looks like it just isolates 1 battery from the other when the car isn't runniing so you can flatten the battery your useing to run stuff and still start the car but when the car is started and that battery is completly flat its gping to try and pull onw hell of a current trying to charge itself back up, at best thats really bad for the batterys service life and it's not exactly safe, uncontrolled charging can result in batterys getting very hot and going bang
Title: Re: Additional Battery
Post by: Diamond Hell on 04 September 2010, 19:38
Listen to this man.
Title: Re: Additional Battery
Post by: jonnypolish on 04 September 2010, 23:15
danny_p
Noted. Am Following your instructions! Was going to get a bigger alternator to start with, but funds got in the way :( Although did get a bigger battery  :huh:
Will upgrade my alternator before running anymore equipment :) (and will check the battery is capable!
Thanks again guys!