Dual battery cost

[guitarnasty]

Just spoke to the auto electrician about a dual battery set up . He quoted me $1000 from start to finish. The cost is higher because of the need for a special red arc battery isolation controller. He says the alternators in the D40 switch off once the main battery is fully charged in order to save fuel costs. Apparently the cheaper red arc isolation switches or similar are incompatible with the alternator and don't work very well leaving the second battery under charged .

Does this sound right? . Coz my Eski is looking real safe at the moment

 

[sparra04]

that's right mate
you need a different isolator
but they aren't much dearer than normall
question him on battery quality
dc/dc is the way to go
a simple isolator wont fully charge ANY second battery
have a read of redarcs website, some great info there

cheers

 

[guitarnasty]

Yep I'll check it out .

They quoted $600 for the redarc isolator ...

 

[siringo]

Find out what the sparky was quoting you for. I've been looking into this over the past few days. Here are some rough costs.

Battery - $300
Quality DC-DC charger and isolator $200 - $300
Quality cabling, lugs, fuses, breakers - say $150.00
Labour - well to get $1000 that will be a charge of $250.00

So it may not be too bad a quote.

Yep, what he said is correct, modern alternators, post 2011 (and this is what I've picked up over the last few days) output a higher voltage on startup and detect when the starting battery is charged. When it is they drop their output voltage. It's this dropping of the voltage that stops the aux battery receiving enough time to charge.

I've just spent some time today looking at DC-DC chargers. I've been looking at 20A chargers, as many brands as I could find. They seem to range from the cheapest I found was an Aussie made one about $160 to Redarc around $350.00.

Cheaper ones are heavier, bigger and may require manual setting up. Expensive ones are smaller, lighter and easier to setup.

If you're starting out and plan on doing any type of camping, I'd get this done correctly first time up, I don't mean get the sparky to do it if you can, but get the right bits and pieces.

$600 for the Redarc isolator is probably the BCDC1240 or larger. That could be overkill.

 

[J13NST]

yep your auto elec is correct.
we need DC to Dc charger to maintain secondary battery to tiptop.
is 1000 including the 2nd battery?

 

[Tappet]

Isn't there some simple mod on cutting a wire on the Alternator Regulator so it outputs 14.2Volts.

Just thinking of how much out lay it was for me. Went the DC-DC charger route.

Charger-was a Jaycar Powertech 40 Amp. $249
Battery- Century 720 Marine 100AH and cheap box about $250
Cable, connectors and fuses probably about $150.

Installed myself. He would do it a lot faster than I would but his quote probably not far off the mark.

 

[guitarnasty]

Yes $1000 including battery. i just didn't realise how much it would actually cost when all I want to do is run a fridge. ....( and I haven't got a fridge yet )

But now I know lots about smart alternators which is a plus

 

[GeoffG]

I bought a CTEK D250S DUAL. It's awesome. The CTEK D250S DUAL is a 5-step charger that automatically adjusts the charging voltage and current according to the battery state of charge and temperature – reducing a battery’s charge time.
A sensor on the CTEK charger senses the battery temperature and adjusts the required charge by increasing the voltage in cold weather ensuring the battery is fully charged, and dropping the voltage in hot weather to avoid the problems of overcharging.

 

[Old.Tony]

I think - as long as the guy is using heavy enough cable, is putting appropriately large fuses (or better still, circuit breakers), is NOT using the chassis for the negative run and is providing a charger that does more than just allow the alternator to charge the aux up - it's not a bad deal. Particularly if the battery is a decent size and build (I'm thinking up towards 100Ah or more, and AGM - definitely NOT gel).

The alternator puts out between 14.1V and 14.7V - usually more likely to be in the 14.2V to 14.5V range. A wet lead acid battery (flooded or AGM) requires about 15V applied to it to reach full charge in a short time. It will eventually reach full charge anyway, but it's like trickle charging the battery with a couple of amps per hour - if you need to replace even just 30Ah (running a fridge at 4A/h on a 25% duty cycle for a day plus lights @ 3 hours for 2A) you need to be driving along for 15 hours to do it! A proper charger will bulk charge at a higher rate, then level it off and bring the battery to 100% much, much faster.

Heavy cabling is crucial for 2 primary reasons: first, it reduces voltage drop ensuring that you don't waste power and that the charger has a better voltage to work with, but more importantly the cable won't heat up under load and potentially cause a fire.

 

[guitarnasty]

Esky!

 

[siringo]

If your D40 is earlier than 2011 or 2010 you may not have a smart alternator and you may be able to get away with just a $100 solenoid. My 40 is a 2010 and i've just been using a solenoid for 3 years (now looking at a DC-DC charger though).

 

[Connaught]

my d40 is an 07 and puts out a pretty constant 13.6-14.2volts, according to the torque app,

i use the sidewinder ABR isolator onto a RITAR 100 a/h battery, and so far so good as they say

 

[BIGCOLL]

Being an auto elec his quote is pretty much on the mark, it isn't cheap no but you do get a warranty on all the work done aswell. Hopefully he is a decent auto sparky and solders everything aswell. I use the redarc bcdc1225lv and i swear by it, have used redarc equipment and it's top notch gear, retail of these units is approx $500 if your paying anywhere north of that then hop on ebay you'll find em for around the $400 mark. Don't go the 1220 it's an older version and only really save $50 plus with the 1225 it can also take a solar panel aswell. Any new car will need this type if unit as the regulator in the alternator is what sences the voltage and adjusts accordingly, if you cut a wire you will simply not get a charge for your battery, the aceptable figures for charging are between 13.2 and 14.5 anything over 14.8 will start to boil your battery and anything under will result in draining the battery. Best thing with the redarc 1225 is the minimum requirement for cable is 6mm resulting in a cheaper prive but i would go atleast 8mm so as to not get as much voltage drop.

 

[batcho]

The dc dc charger is not necessary even with the smart alternator. there is 2 quick fixes. The first is disconnect the green wire from the alternator(few threads on it)
the second is look at the negative battery terminal. there will be a small plug on the engine side of the battery. if you disconnect this you will get a constant charge.

I have been running this setup in my 2013 with projector VSR for 4 months so far and get a constant 14.2v at the aux battery in the very back of the tub.

 

[silvernavman]

Ditto to batcho

 

[BIGCOLL]

This is true but i would just hate to think at what it is doing in the long run to your vehicle, it is all setup there for a reason and is in place and has a designed purpose, so you save $200 here but what's the cost when something goes out because a corner was cut?? Not having a dig just highlighting something some may not have thought about.

 

[batcho]

everything i have read on the smart alternator is that they are only there to save fuel.

Alternators are designed for constant work so i cant see it causing any issues.

 

[batcho]

oh and the plug disconnect method means if the battery isnt in the car or you arent drawing on it for awhile you can simply put the plug back in and you have the factory setup working again.

 

[vandamage]

Take a look at these...
http://arkcorp.com.au/p/3231/arkpak-12v240v-battery-box

 

[Old.Tony]

Those Ark packs look good with a decent size battery, you need heavy cable and fortunately 8Ga cable solders nicely into 50A Anderson plugs so that's the way I'd go (it's the way I did my own). 150W of 240V is enough to power a laptop or recharge a cordless drill battery or several phones (although the USB port should be used for that, great thinking there). It would be safe to use inside a tent particularly with any VRLA battery (AGM/Gel, prefer AGM).

The next one to watch for is LiFePO4-based units. Still far too expensive (different charger required too) but with twice the power in half the weight, it's going to be good to see the prices of that tech drop into the "reachable" zone.