Dual battery for dummies

[Graz Senior Member Find all posts View Profile Close Graz]

I have put an arkpak in the rear of my car to run the fridge and anything else i need

http://www.arkcorp.com.au/p/3231/ark...0v-battery-box

i am using this dual battery kit from enerdrive

http://www.enerdrive.com.au/battery-...al-battery-kit

Now i know nothing about electrics on a car so i am trying to get my head around how this works
my alternator regulator will charge my main battery till it gets to around 14.5 volts or so.
How does it then charge my arkpak if it is suppose to turn shut its gate and not charge my main battery.
The enerdrive system just runs the red lead to the positive on the main battery.
So to me, if my main battery is at full charge and it then try's to charge the arkpak. it is also still running a charge into my main battery ?
That can not be good for the main battery if i drive all day charging my auxiliary battery.
Any help with this would be very much appreciated

[Guest Close Guest]

It'll be fine. Current flows from high potential to low potential. When the main battery is at the same potential as the alternator, charging stops.

[Richoson Avid PP Poster! Find all posts View Profile Close Richoson]

I just looked at the site and after the car has been started it state that the VSR charges both batteries, and also if one battery is being charged by an external source it will also charge the other battery, pretty tricky stuff sounds like a good unit.

See ya on the tracks. Richo.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

In a normal car setup the alternator puts out a float voltage in your example
14.5V The main battery floats across this voltage and is is always being charged
to some degree by the alternator. The battery accepts what charge (current) it
requires depending on its SOC (State Of Charge) ie a flat will accept a large current
40 Amps or so and this current will gradually reduce to a trickle as the battery charges.

When you connect another battery to the alternator, ie connect it to the terminals
of the cranking battery it will take whatever charge it requires and the alternator will
happily supply it.

A popular misconception going around that is being pushed by certain after market suppliers
is that once the cranking battery is charged the alternator stops charging the battery and therefore you have to install a DCDC charger to charge a second battery. This is only the case in a couple or so of the latest models ie the BT50.

The vast majority rely on the float method and the battery or batteries simply take what
charge they need.

A VSR is simply a voltage controlled switch that isolates the two batteries when the alternator stops charging, ie motor turned off. It is used to prevent any loads that maybe connected to the auxillary battery flattening the cranking battery.

Cheers
Leigh

[Graz Senior Member Find all posts View Profile Close Graz]

Thanks for the reply guys, You sorted out this dummy :-)

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Do you mind Graz me asking how much you paid for it ?? I just put one on layby for $399 obviously without battery that's another roughly $300/350 havnt decided on which one yet.....There is an optional charger pack I'm going to get as well which will charge from ciggi/12V outlet or did you already have your duel charger in place ?? I was going to get duel battery but this is so much more versatile and I like the fact I can hook up my cpap machine inside van or tent. I believe it will charge from the Anderson plug ?? I may have that part wrong........Cheers Steve

[Graz Senior Member Find all posts View Profile Close Graz]

Hey Steve
Yeah i paid $399 from BCF.
And i also got it because it becomes a portable power source
Yes it does charge from the anderson plug, But it does not go through the boxes smart charger.
the dual battery system from enerdrive cost me $180 but i now see them on ebay for $150
Only thing i found bad about it is.
Its a pain in the butt to mount anywhere in the car safe.They sell a mounting kit for $20 but its ok for an empty box, as soon as you put a battery in it the first bumpy hill you come across will rip it off its mount. ( see photo of mount ) its just 2 3mm x 20mm slides that go in about 10mm
so i had to make a holder for it with a swing away bracket at the back so i could remove it

[Graz Senior Member Find all posts View Profile Close Graz]

This is my bracket

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Good set up Graz, I havnt worked out how/where I'm going to do mine yet. Might have to either modify my draw set up or maybe go on top. Waiting to mount cargo barrier so I can set it out. Just waiting on some brackets getting made up for barrier......Cheers steve

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Another question Graz, would the battery charge quicker your way or via the ciggi outlet or no difference.....Im imagining the duel battery controller !! I also checked out a dc to dc charger it was $300 for memory, apparently this will charge in approx. 3 to 4 hours while engine is running......Cheers Steve

[Pete t pops Junior Member Find all posts View Profile Close Pete t pops]

The arc battery packs look good, friend of mine just put one in his camper.

[Graz Senior Member Find all posts View Profile Close Graz]

Could not tell you Steve .
But i would say it would be quicker through the andersom plug just by going through the way larger cable being able to put through a lot more current ?
I did run the battery down to 80% when i first connected it all up and did a 35min drive and it said it was back to 100% charged when i got home.
I also spoke to arkpak last night and they said they have tested the mount in off road conditions and it held up fine.
Still i would not trust my $400 to a $20 mount ?