Adding second battery to the 4x4 for battery capacity

[oowess]

Just checking I have this right...

If I add a second battery to the 4x4 wired in parallel, that doubles the battery capacity, right?

Same input/output voltate, no change to alternator needed, just the life increases?

edit: used the wrong term before, corrected now.

[1290]

Wont double battery life, but reserve capacity, so it will have double the reserve of one battery
May also double charging time for 2 big batteries as opposed to one!
Do you have equipment you need running while moving and or stationary ?

Wire in parallel = same voltage, twice current (for same batteries)
Wire in series = twice the voltage, same current (dont do it 24v will tend to kinda kill your electronics)

[Guliver]

Found a few things.

https://www.google.com/search?q=second+ ... ar+battery

[oowess]

Wont double battery life, but reserve capacity, so it will have double the reserve of one battery
May also double charging time for 2 big batteries as opposed to one!
Do you have equipment you need running while moving and or stationary ?

'battery life' wasn't the term I meant.

Mean't capacity as you said, updated post now.

It's just for leaving things on for the day while out with the car off like the radio, or lights for a few hours at night, that kind of thing.

No special equipment while moving or not.

[sbd3927]

Just wiring a second battery in parallel isn't a very good way to do it. It would also likely require two new batteries, same life and age. Otherwise charging current could do funny things, eg. more charge to the older (lower voltage) battery. Also, if you flatten the two batteries, you are still in trouble.

Simple version is second battery, wired in with positive through a high amperage solenoid. Various ways to engage that, manual override switch, wired to ignition etc, different benefits/problems with each.
Stepping up further, alternate battery charging systems that make sure the primary is charged first, then the secondary. Some have solar input as well. You run your accessories off the secondary and never risk your ride home.

My 4wd had the solenoid system, which I left in place when I upgraded to charging system. A few times the primary has ended up flat, engage solenoid, start car and off I went. Also good for getting a high initial charge current for the alternate batt, which is best for glass mat batteries (AGM).

[oowess]

Sounds like I'm best taking it to the mechanic for this.

More complicated than I realised from the sounds of it.

Thank you anyway for the replies people

edit: to an auto-electrician.

[1290]

Sounds like I'm best taking it to the mechanic for this.

More complicated than I realised from the sounds of it.

Thank you anyway for the replies people

Auto-elec......

[Chronos]

Sounds like I'm best taking it to the mechanic for this.

don't waste your time with a mechanic IMHO

what are you trying to achieve? i set up a deep cycle, charge solenois, solar charger and panel in my ute for fridge and lighting around camp. i could post some details if you like

Chronos

[Westy]

I've been threatening to do this for years myself, might take you up on this offer Mr C .

[KWhorenet]

For information/example only. I'm in no way affiliated with Redarc.

This manual has diagrams and explanations. May help to understand what people are talking about with regard to solenoid isolator units and dual battery set up.

Also shows using a solar panel set up.

http://www.redarc.com.au/images/uploads ... Manual.pdf

[oowess]

what are you trying to achieve? i set up a deep cycle, charge solenois, solar charger and panel in my ute for fridge and lighting around camp. i could post some details if you like

Details would be good.

I just want more battery usage time, so I can use the stereo, lights etc. with the car off for a few hours while out and not have to worry about finding I killed the battery and I've stranded myself in the middle of nowhere with a flat battery.

[Chronos]

what are you trying to achieve? i set up a deep cycle, charge solenois, solar charger and panel in my ute for fridge and lighting around camp. i could post some details if you like

Details would be good.

I just want more battery usage time, so I can use the stereo, lights etc. with the car off for a few hours while out and not have to worry about finding I killed the battery and I've stranded myself in the middle of nowhere with a flat battery.

might be better with a deep cycle for that stuff and preserve your starting battery

i'll what i can put together

Chronos

[1290]

I'm sure you can route the charging circuit (ie. low current) to the main and spare battery, but starting load just to the main battery (high current)....
as previously; auto-elec.

[on_one_wheel]

http://www.redarc.com.au/products/categ ... -isolator/ one of these will suit your needs. Iv got the dual sence smart start.
My second battery powers my uhf, fridge socket aux power sockets and camp lights. The redarc I have charges the main battery untill fully charged then closes the switch joining the two batteries together, when the charge in the main battery drops bellow 12.7 v it opens up the circut between the two saving the starting battery from being run down too far.

with a setup like this you can use a deep cycle battery as your aux power supply and crank tunes till it goes dead flat and still be able to start your car... the redarc switch will, look after the rest.

[oowess]

might be better with a deep cycle for that stuff and preserve your starting battery

i'll what i can put together

Thanks Chronos.

Also 1290 and on_one_wheel for the additional info.