Dual Battery TD 150 GXL

[Boris Lurker Find all posts View Profile Close Boris]

I would also like to add my thanks to everyone. Vigorously defended opinions aside, there is a wealth of knowledge out there that we would never have access to without this forum.
I have now decided that is going to be simple enough to fit my own battery setup, and also that my local ARB may have a vested interest in overstating the importance of a DC/DC charger when they quoted $1400 to fit a complete system (without running any cable th the rear of the vehicle or fitting any additional outlets...)

Cheers

[cbm8880 Senior Member Find all posts View Profile Close cbm8880]

So without wanting to incite violence again... Now that people have had these systems for a while, is there really any need for the "voltage booster" devices that leighw and abrsidewinder are selling?

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

Hi Boris, and I’m at a bit of a lose to the amount ARB quoted if this is without cabling to the rear ect.

Furthermore, LeighW’s voltage booster is $35 and a decent quality dual battery kit will give an isolator and cabling for the engine bay for under $200 all up, NOT fitted.

This would not only allow you to fully charge both batteries under the bonnet, and any other battery in your set up in a reasonable drive time, but it would also brighten your headlights.

As I have raised before, these DC/DC converters actually have more of a disadvantage when you look at other options available.

[steve167 Lurker Find all posts View Profile Close steve167]

Hi Brains. Can you please tell me how to get the wires from the battery back to the 12V socket in the rear?

Cheers

[Brains Find all posts View Profile Close Brains]

Hi Brains. Can you please tell me how to get the wires from the battery back to the 12V socket in the rear?

Cheers

Steve,

I ran the cabling through the large grommet in the firewall and down the side of the vehicle into the rear. All the cabling is behind the plastic trim and under the scuff plates inside the doors. I run all cables as twin sheathed so red and black insulated cable sheathed in black insulation layer.

[Tauras Junior Member Find all posts View Profile Close Tauras]

Gents, all this information has given me the confidence to DIY install my dual battery system.

After visiting ARB to pickup a redarc SBI12, I was informed that unit is not ideal as my alternator will not provide adequate power for the job. I mentioned installing a diode in place of my alt fuse, they raised a valid point that the current fuse and design are there for a reason and that I should not mess around with it. They then suggested I install a battery charger instead, BCDC1220.

I had a look at that unit and noticed that the wires were very thin, a fraction of the 3 B&S I was going to use for the job, are these really adequate to charge a car battery? In addition there is a blue starter wire that is to be wired to the vehicle ignition, I understand what the wire is for however have no idea where to connect it, other than perhaps the cigarette outlet in the centre console?

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

Tauras, the fuse has worked fine on my Prado for over 2 years.

Suggest that you do a search and have a read as this has been extensively discussed and debated. Both methods diode and charger work, it's just a case of if you want to spend the extra for no particular gain.

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

I think both types of dual batery systems have benefits. It's no so much cost (not a lot of diference) but what suits your needs. From listening to many threads on this from people like LeighW, drivesafe etc , here is my high level summary.

1. Traditional Isolater ( ie Redarc, Surepower , others etc)
Pros
Well understood
Works well with non D4D prados
Fast rechage -IF your battery supports it . Lots of people talk about 1 hour recharge time IF you have the right AGM like an Optima. Great but they are Expensive batteries. Close to $400ish . Couple of those add up real quick.
Wet cells also work fine but are slower to recharge. I have a traditional isolater with wet cells and it will not recharge my wet cell deepcycle in 1 hour.

Cons
D4D prado seem to need the voltage booster diodes. Lots of them are only in the mid - highish 13 volt range. (including mine)
No included solar regulator ( if you need this ie not running your car every few days if you are camping)
You might have to drive longer with the low voltage D4d's to charge the non AGM batterys

2. BCDC (Redarc BCDC 1225 etc)
Pros
Many have a Solar MPPT. Saves you a couple of hundred dollars if you are buying solar later as you dont need to buy a MPPT regulator. Yes a non MPPT regulators are cheaper but you stil need to buy one in an isolator setup and MPPT are better.
Higher voltage but lower amps to the Auxilary battery. ( pro and con)
Can be customised to the type of battery you have and you can use lower spec batterys as well

Cons
Expensive compared to a isolator option above.

So I think both have a place and it just depends what you want and your specific usage
Cheers
Robert

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

I think both types of dual batery systems have benefits. It's no so much cost (not a lot of diference) but what suits your needs. From listening to many threads on this from people like LeighW, drivesafe etc , here is my high level summary.

1. Traditional Isolater ( ie Redarc, Surepower , others etc)
Pros
Well understood
Works well with non D4D prados
Fast rechage -IF your battery supports it . Lots of people talk about 1 hour recharge time IF you have the right AGM like an Optima. Great but they are Expensive batteries. Close to $400ish . Couple of those add up real quick

Cons
D4D prado seem to need the voltage booster diodes. Lots of them are only in the mid - highish 13 volt range. (including mine)
No included solar regulator ( if you need this ie not running your car every few days if you are camping)
You might have to drive longer with the low voltage D4d's to charge the non AGM batterys

You don't need a special battery if you use a traditional isolator but it won't work well unless you boost the voltage.

I regularly do week long trips where my system works fine. My mate who has one of the BCDC unit actually seems to spend a lot of time idling his car charging the battery, which I don't ever do. But ultimately both systems work fine.

The solar is a useful function especially if it is a good MPPT unit. I have mine mounted direct to the solar panel which allows me to move it around, and it gets borrowed occaisionally to charge other peoples batteries.

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

I've been using an AGM Aux battery with an SBI12 isolator and diode/fuse voltage booster for over a year now with no problems. The fuse is still in series with the diode so can't cause any warranty problems. I get approx 14.1-14.4 volts on normal cruise and the aux battery still gives me plenty of power.

I don't see the benefits of the DC-DC charger for the money outlaid.

VXWesty

[Brains Find all posts View Profile Close Brains]

I have been using an Allrounder 80AH with Redarc SBi12 and ABR Sidewinder ABD (diode booster). I get 14.1-14.4V on charge for the first hour to hour ABD a half.
I chose this setup over a DC DC charger as the majority of my driving when running a fridge is day trips and on holidays where the car gets driven a few hours a day. Unless you go for a Redarc 1240 you would have to drive for in excess of 3-4 hours to get that elusive fully charged battery. I see the DC DC chargers as a great setup in a caravan or camper where the 2nd of 3rd battery is a long way from the alternator and you are driving for long periods of time, but in the two and a half years I've been running my system I have never had any issues with running a fridge when the vehicle was being driven everyday for short trips like from Cathedral Beach to Eli Creek at Fraser Island.

Technically if these DC DC chargers are that fantastic then you should be able to connect them from a battery and charging that same battery without having to start your car at all. Has this been tested?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Technically if these DC DC chargers are that fantastic then you should be able to connect them from a battery and charging that same battery without having to start your car at all. Has this been tested?

That would be cteating power from nothing at all, using a battery to charge itself is impossible. If anyone works out how to do this then you will be a very rich person in a very short space of time............. free power, who wouldn't pay for that

The real question in this debate is whether the smart isolators are even worth the expense, they are convenient and neat but I reckon 99% of the time a $20 solenoid activated of the oil pressure switch would achieve just as good a result.

I have never understood why the DC DC chargers are needed, and no one has yet posted anything that I have read to convince me they are needed, or for that matter even useful in comparrison to an isolator.

Cheers Andrew

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

My experience running an AGM and a conventional battery with a conventional (Piranha) isolator was that the lead acid battery is always trickle charged even when the isolator is charging the auxiliary. As a result of how fast an AGM will charge I kept boiling the lead acid battery dry. That was on the 90 when I had it. Before fitting the AGM I had the usual deep cycle lead acid battery and had no issues. So when I built the 120 up I went for a Rotronics smart system that completely isolates the two batteries when charging. Still prioritises the starting battery but when the AGM is sucking serious current the starter battery isn't being bombarded too. But I wouldn't do it again. Cost a damn fortune for a start and it isn't wonderful though it hasn't killed the starter battery as before. My biggest concern is the D4D stepping up with enough voltage to charge the AGM properly. I haven't fitted the magic diode but I do top up the AGM with an AC smart charger from time to time because we leave the fridge in the 120 full time running and if there are no decent trips the AGM runs down. Pretty simple and I charge the thing to 100% before we go camping and then have the solar panel to augment the charge while away. The car battery keeps the fridge cool and the 2nd auxiliary charges the 'phones, iThings and provides some LED lighting.

Not really sure what I would do next time. I am really happy with the AGM batteries regardless of some of the opinions being bandied around. I have two when we camp, one in the trailer and the other under the bonnet of the 120. Both fully charged before leaving and both topped up while camping. I like the idea of the DC-DC system and compared to the Rotronics unit I fitted they are a fair price. I think the Rotronics unit was more hype than performance though and I wont bother taking it out of the 120 when I sell it.

Good luck and well done to all those who manage to keep a lead acid and AGM or calcium battery happy with a simple isolator and standard (or Pamela Anderson style silicon enhanced) alternator. Didn't work for me. I will do more research when the time comes but the DC-DC system gives me more volts and total isolation which is what I want.

[Tauras Junior Member Find all posts View Profile Close Tauras]

Can anyone tell me where I could connect the ignition wire from the DC-DC unit inside the engine bay?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Andrew, it just boost the charge rate and conditions the battery in the process as well. That's where the difference is.

John (##########).

Conditions the battery? WTF doees that mean? Sorry but this all just comes across as sales BS to me.

having run various combinations of batteries, including OE crank battery with AGM for second battery and sealed deep cycle lead acid in the camper, now running Optima for crank, AGM for second battery, OE prado battery in camper trailer and no fancy charging system. All seems to charge OK, the fridge is always cold, the Prado always starts, the water pump and light in the CT can run for as long as I have ever camped in 1 spot without charge...............

Sorry still don't get the DC DC concept, I wish someone could explain to me why they are so good but for all I read i simply don't get it.

Cheers Andrew