30 replies to this topic

[Captn_Awesome]

One option:

http://www.arrid.com...sub=twin_charge
or
http://redarc.com.au/products-and-services...mart-start-bcdc

Probably not enough current to properly charge the rear battery. As far as a dual battery reg/isolator/charger though - one of the best!

Option 2:
http://redarc.com.au/products-and-services...smart-start-sbi

Smart solinoid. Love these solenoids - but for the problems you are presenting its not gunna solve anything unless you use it to charge a "jumper" battery which would mean that you would leave everything as it currently is and you would have a button on your dash to latch the solenoid when your trying to start your car - and you're hoping that your batteries haven't equalised to a point so low that you still cant start the car any way.

Option 3:
http://redarc.com.au/products-and-services...smart-start-bms
One of the coolest battery management systems I've seen in a LONG time! 240V input to charge your batteries when your home, PWM charging, voltage regulation, solar input etc.

All these are "reasonable" options. BUT unless your alternator can output enough current (which going by your earlier information its not) your going to struggle. I would still be looking at upgrading the alternator becasue at this stage I cant see you getting out of this for under $3-400 by the time you buy a second battery and an isolator and set it up correctly.

Things I would be checking - Check your alternator is grounded well. Check the voltage at the exciter and if you can what sort of current is going field windings and if this fluctuates with load (ie demands from your stereo) might be worth even just upping the size of the feed cable to the exciter - heck could possibly just use a relay and take a feed from the alternators (+) output to get the voltage at the exciters as high as possible. This could possibly be enough to get your alternator working to its full potential and help alleviate the issues your having.
Also how old is your current battery? CCA? RC20AH? How many plates and what condition are they in (id suggest f**ked if this issue has been going on for a while)
What size feed to your battery are you getting from your alternator - many early cars use pissant 10ga cable. 8 or even 4ga will see massive improvements here - clean up all the terminals also.

Personally I'd be installing a big marine battery as suggested. They are cheap, they cycle well, generally have thicker plates than even a standard starting battery and most are 13plate minimum design.
How hot does it get under your bonnet? heat reduces the ability of the battery to take charge and will make a battery expire prematurely - if you know it gets hot under there might be time to look at a heat shield set up around your battery.
Get your hands on a clamp meter - check what you alternator it putting out. Check what your stereo is drawing (may need some form of data logger to get a mean average), check what your whole car is drawing with lights on, wipers, fan etc - and how's that alternator coping?
Is it a possibility to reduce current draw at all? how many amps are you running? - do you need them all? are there any more efficient options? is it possible to sit in your car with every thing off but the motor running for 2 -5 minutes when you arrive at your destination - this may be enough to get the charge required to turn over your car.

At the end of the day batteries store energy, they dont produce it, your alternator does that.
Much like our dams where we are consuming more than is coming in - eventually without more input or less output its going to dry up.