Dual Battery set up.

Post by **LEXX** » Thu May 08, 2003 8:18 pm

Hey guys, just need some advice and direction on a dual battery set up for my TJ. Just bought N*A*M's dry cell battery and I've got a Optima Red, any suggestions on how I sould rig this up.
I know there has been a bit of discussion on the topic but hard to get it all in the same thread.

Post by **CJer** » Thu May 08, 2003 10:07 pm

I was looking to do the same but have changed my mind now.

I am going for 1 Optima Yellow and a 120amp alternator. See how that goes for starters.

Website · Post by **murcod** » Thu May 08, 2003 10:23 pm

LEXX, it depends on how much you want to spend and what functions you want the aux battery to perform.

Have a look here for a budget set up I recently finished: http://www.outerlimits4x4.com/PHP_Modul ... php?t=2558

The price was right and the controller does everything I wanted- but it wouldn't suit everyone.

Post by **LEXX** » Thu May 08, 2003 11:13 pm

Well I'm going to be running a winch, a set of Lightforce 240's, a set of fog lights and a "doof doof" sound system. The main reason is for the winch, it a 12,000p megawinch from TJPete. The TJ's run a 117amp (from what I've been told) alternator as standard so I'm not looking at upgrading the alternator "yet". I'm looking for a decent set-up without to much expence, I went into pirana and they won't do a dual set-up for the TJ's, they told me that there isn't enough room to do the job properly, "what the!!!!". And I've heard nothing but bad repots about the pirana set-up, being not very elec minded I need a real simple set-up or for someone to basically "spell it out" for me, I a bit concerend about doing it wrong becasue of the comp n the TJ's.

:wink: :wink:

Website · Post by **murcod** » Fri May 09, 2003 9:16 am

Maybe have a look at 4WD Systems isolators then. They're a "smart" solenoid, but aren't cheap at around the $300 mark. They also make trays, don't know if they'll have anything to suit though?

www.4wdsystems.com.au from memory.

Post by **Andrew_C** » Fri May 09, 2003 9:33 am

Im sorry everyone but the system I use and love after having the dick smith kit, a paranha smart solinoid, and another one that was absolute shiat is the normal solinoid hooked to the ignition. Cheap, reliable and works really well. I had a surge protector on my efi 4runner and that was it. Never had a problem with it. I have a Petrol Mav now and run all my lights, stereo, 8000 high mount, fridge and any other electrical draining device off a deep cycle that is where my normal battery ussually lives. Then I have + cable to a solinoid and then to the + of my other 700cca battery . Obviously both are earthed. The solinoid is connected to the ignition on the car so when its on, the solinoid is closed and power is both batterys. When off, only the deep cycle is connected. To overcome the problem of the deep cycle going flat and not having enough power to click the solinoid, A button is added to the dash to click it from the other battery. As I said, cheap, easy and reliable. Havn't had any problems in 3 years.
I can add a diagram if you want it

Website · Post by **murcod** » Fri May 09, 2003 9:45 am

Andrew, perhaps you could elaborate on what was wrong with all the others? :?:

It could help someone else with their decision on which way to go.

Post by **Andrew_C** » Fri May 09, 2003 10:51 am

Sorry, Ive just had reliability problems with a couple of the smart solinoids. One day they work, the next they dont. The piranah setup was really expensive for what you get but then wasn't anything special and when you had a flat starting battery, you still had to jump start it. Also generally a standard car (not saying many on here are standard) will already have the radio, lights, cig lighter and other bits and pieces setup to run off the main battery supplied with the car. So a smart solinoid which cuts the battery off when the ignition is off that uses the other battery (Ie deep cycle) to run the fridge or anything else you wire to it. You can potentially end up with two flat batteries, The one the fridge flattens and the one the doof doof stereo flattens. Im not saying the solinoid is the be all end all of setups, there is still the problem of if one battery dies you don't know because it starts off the other.
With a solinoid, you have both batterys to winch off, and run everything while the car is running but as soon as you switch it off you only have one to flatten, almost idiot proof.

I suppose the big question to ask anybody that you are buying a duel battery setup off is "Is there a possibility of ending up with two dead batterys". Will you still need to carry jumper leads?
If there is don't bother, just buy a really good single battery from somewhere else and laugh in their face.

Website · Post by **murcod** » Fri May 09, 2003 3:41 pm

Andrew, thanks for the above info. You didn't say what did you found wrong with the Dick Smith kit?

Post by **BundyRumandCoke** » Fri May 09, 2003 9:17 pm

A dead simple, easy to set up, and relatively cheap dual battery charging system is an ordinary relay hooked to activate when your ignition is turned on. Connect this to a heavy duty, continious duty solinoid. Use heavy amp cables all round, and solder all connectors to cables. Ive run this system for the last 6 years with no problems whatsoever. Currently running Optima red top as primary battery, and N70 Exide as second battery. Cost should be well under $100. Nothing to go wrong, nothing to worry about. When ignition is on, both batteries are connected and charging, when ignition is off, both batteries are seperate.

Post by **LEXX** » Fri May 09, 2003 9:42 pm

Thanx guys, just what I was a after. Will be doing it sometime in the next week or so and will let you know how it goes.

Website · Post by **murcod** » Sat May 10, 2003 1:10 pm

Just be careful if you choose the straight solenoid set up with voltage spikes to your electronics :shock:

I also believe those sorts of setups aren't too good for your alternator.

Do a bit of a search on Google for "dual battery controller 4WD" and you should find lots of info.

Post by **DAZZ** » Sat May 10, 2003 6:01 pm

murcod wrote:Just be careful if you choose the straight solenoid set up with voltage spikes to your electronics I also believe those sorts of setups aren't too good for your alternator.

Do a bit of a search on Google for "dual battery controller 4WD" and you should find lots of info.

I use a diode to protect against voltage spike on a constant duty solenoid. This dissapates the collapsing magnetic field into itself so there is no voltage spike. I have used this on my '99 Frontera V6 for about 2.5 yrs with no problems. Also I have fitted them to many vehicle at work.
Complicated dual battery isolators can give too many problems.....

Just my2c!!!!!

Website · Post by **murcod** » Mon May 12, 2003 8:52 am

The only problem with diode isolators is the voltage that is dropped across them. Most diodes drop at least 0.6V when forward biased (sorry about all the jargon, I'm an Electronics Tech by trade!). This means the second battery may never charge fully as you need the higher voltage feeding into it for the current to flow and completely charge it.

Just my thoughts.....

Post by **ausyota** » Mon May 12, 2003 9:26 am

Im thinking of putting dual batteries on my diesel lux and the second bat will be mounted under the tray.
I have heard that because it is mounted further away I may get a voltage drop.
What is the best dual battery system for mounting this way?
I was thinking maybe going ultra simple with one of those big marine switchs (off, 1, 2, 1+2) but will the second battery get fully charged when in parralel?
Also if I go with this system will both batterys need to be the same type?
Thanks.
Paul.

Website · Post by **murcod** » Mon May 12, 2003 9:58 am

ausyota wrote:Im thinking of putting dual batteries on my diesel lux and the second bat will be mounted under the tray.
I have heard that because it is mounted further away I may get a voltage drop.

Paul, the Dick Smith/ Jaycar kit would be perfect for your situation as it actually requires between 0.2 to 0.05 Ohms resistance in the cable going to the second battery. For most installs this means running a long cable around the engine bay- but for you that wouldn't be a problem! :lol:

I don't see why you couldn't use any type of controller you wanted, just make sure you get heavy duty cable (like the stuff they use in 600Amp jumper leads) to go to the aux battery and get it crimped by an auto elec place to get a good connection. The cable will cost you a bit, but there's no reason I can think of why it wouldn't work. People often move their batteries into the boot of cars and run the cables all the way back to their engine bay with no problems.

Post by **Rainbow Warrior** » Sat Jan 17, 2004 9:11 pm

Andrew_C wrote:Sorry, Ive just had reliability problems with a couple of the smart solinoids. One day they work, the next they dont. The piranah setup was really expensive for what you get but then wasn't anything special and when you had a flat starting battery, you still had to jump start it. Also generally a standard car (not saying many on here are standard) will already have the radio, lights, cig lighter and other bits and pieces setup to run off the main battery supplied with the car. So a smart solinoid which cuts the battery off when the ignition is off that uses the other battery (Ie deep cycle) to run the fridge or anything else you wire to it. You can potentially end up with two flat batteries, The one the fridge flattens and the one the doof doof stereo flattens. Im not saying the solinoid is the be all end all of setups, there is still the problem of if one battery dies you don't know because it starts off the other.
With a solinoid, you have both batterys to winch off, and run everything while the car is running but as soon as you switch it off you only have one to flatten, almost idiot proof.

I suppose the big question to ask anybody that you are buying a duel battery setup off is "Is there a possibility of ending up with two dead batterys". Will you still need to carry jumper leads?
If there is don't bother, just buy a really good single battery from somewhere else and laugh in their face.

The smart way to get around a lot of this is to do the opposite of a normal dual battery system, when you install the second battery, only wire the starter motor, alternator & ignition to it, then you can leave whatever you like on all day.

I'm on my second car with the solenoid set up and never had a problem, I do however try to run identical batteries, rotate them occassionally and replace them together. I left my headlights on from 6.30am till 6pm all day and started fine, because I run 2 batteries for my auxillary and one start battery, the 55w headlights were still even lit at normal brightness.

Post by **Rainbow Warrior** » Sat Jan 17, 2004 9:14 pm

ausyota wrote:Im thinking of putting dual batteries on my diesel lux and the second bat will be mounted under the tray.
I have heard that because it is mounted further away I may get a voltage drop.
What is the best dual battery system for mounting this way?
I was thinking maybe going ultra simple with one of those big marine switchs (off, 1, 2, 1+2) but will the second battery get fully charged when in parralel?
Also if I go with this system will both batterys need to be the same type?
Thanks.
Paul.

I have 2 auxillary batteries under my tray connected by a 35mm welding cable to a ignition switched solenoid, I've had no problems charging them or starting off them alone.

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Dual Battery set up.

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