Dual Alternator/Battery Anyone done this?

PHATnob · Post by **PHATnob** » Tue Oct 03, 2006 12:23 pm

Hi, I have an ej22 dat I will put into my brumby, and because of the amount of xtra electrical thingos, I was thinking of having a dual alternator setup, with each charging its own battery, and or powering electrical components.

Standard alternator> Battery 1> All regular operations.

2nd 110amp Alternator> Battery 2> Additional operations (Spotlights, ect.)

Any pointers on the best way to do this?

Also post any electrical power savers/increasers in this thread.

PN

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Tue Oct 03, 2006 2:56 pm

Cost wise if you already have a second alternator making a new bracket and pulley would be cheaper but if you are wanting to replace your alternator then go bit and use 1 only.

vincentvega · Post by **vincentvega** » Tue Oct 03, 2006 5:10 pm

what sort of "extra electrical" are you talking here. you would have to be running some serious gear to bother going to a second alternator

easiest would be have the original alternator beefed up, and run a decent battery isolation system

Matt · Post by **Matt** » Tue Oct 03, 2006 5:12 pm

I have set up dual batteries on my brumby. It would be easier to buy a bigger alternator to go in the original position (i.e higher amp rating), unless you have the second alternator and buy a redarc isolator or similar to isolate the 2nd battery. Not us much stuffing around making brackets and gives the same result.

SuBaRiNo · Post by **SuBaRiNo** » Tue Oct 03, 2006 8:26 pm

I have looked into both options and im going to go with the 2nd alternator. Lower AMP alternators seam to charge at lower RPM. As it is with all the toys in my car i seriously can not have everything running at once wven at high RPM and a bigger than HUGE battery.

Also having 2 alternators will distribute the load up more so less tharashing of a single one. AND if one dies... your not stranded.

Mounting is the only real problem but im not sure how u would do the wiring for the set up you are wanting. My one would be a single battery with both Alts charging it.

Idea i was thinking was....(if your keeping the factory air con compressor)... Spin the oil filler spout around.... modify the angle of the dip stick or build around it and bracket it next to the air con compressor using a larger air con belt to run it.

Dave

Outback bloke · Post by **Outback bloke** » Wed Oct 04, 2006 6:03 am

We tried both setups when we were running around with MY's many moons ago. The dual alternator setup works well and keeps the battery booming when running. But after all it is still only the one battery when the car is off.

We also tried high output alternators with one battery. Same thing, battery was fine when running but still only one when not. The high output alternator was the best way to go here as it takes up less room than two, obviously.

Enter the age of twin batteries. We used to run the batteries together with no isolator. Works well when the car is off but still not good enough.

Absolute best set up is
Main battery = high cca = start battery wsith main running components
Dual battery = Deep cycle (big in my case now) to run every thing else.

I run a fair bit of gear off our car including an 80 litre waeco on freeze while we are travelling/away. The start battery makes sure you can do just that. The dual battery is fine for overnight and needs a recharge by morning. This is where high output alternators are good. They can bring a deep cycle battery up to charge very well in limited time.

While we aren't driving the next day we also have an 80amp solar panel that plugs in to the back of the car to charge the second battery.

fredsub · Post by **fredsub** » Wed Oct 04, 2006 8:27 am

as byb01 alluded to, 2nd battery is very usefull where one battery is expected to discharge overnite running a fridge etc,..
Accessories light spot lights etc are really only used while engine is running, and the alternator does most of the work for that.One higher capacity alternator would be an improvement for that.

Also I speculate its more efficient to run one bigger alternator, than 2, because of frictional losses.

As for power saving, the best I've done just recently is HID conversion to 2 flood/work lights, much better output than a 100W halogen, at ~3.5A@12V, thats a huge saving, and means can run off battery much longer without worrying as much about discharge.
Note HID conversion is not legal for main/running lights, however I don't think theres any rules about using them as accessory aux lights or off-road

Hey Bret, which solar panel you ended up choosing?

PHATnob · Post by **PHATnob** » Thu Oct 05, 2006 10:35 am

wow. Lotsa feedback. great.

My setup hopefully will be on an ej22,

Main battery: 1st altenator> Power most normal applications and vehicle operations..

Second battery: 2nd altenator> 7 driving lighs, inverter, logitech z-680s, compressor, many other little things to lol.

So I reckon ill need a lot of grunt, and wit 2 'nators and to batteries, I didnt think that I wood need an isolator solenoid or anything fancy like thhat, just two seperate systems.
Also, I can use the driving lights when the car is off, and even if they drain a lot of power, it wont matter cause I will still have the main battery to start the car and all that jazz.

Cheers all.