Dual Battery Advice Required (and window tinting)

[afryer Lurker Find all posts View Profile Close afryer]

Hi All,

I've just bought a new Prado GXL and have never had one before, so take it easy on me I'm picking it up tomorrow and am glad I found this site because I was going to get the factory tow bar fitted but now am getting the one from Wynnum towbars which doesn't require cutting the rear bumper. I'm also considering getting Wynnum towbars to fit a dual battery system.

My requirements for a dual battery system are essentially for long weekend camping trips, i'd like to be able to use the auxillary battery to power a fridge constantly for at least 3 days with minimal or no running of the engine. I may down the track get a caravan/camper trailer so may also need to recharge the camper trailer battery as well (assuming this is what the andersen plug on the towbar is for).

Wynnum towbars say they fit the following...

* A 105 AH AMP-TECH battery. I'm assuming it's the D70Z (http://www.supercharge.com.au/amp-tech-d70z) since that's the only 105 AH i can find on the AMP-TECH website. This is apparently a sealed wet cell battery, not a dry cell. I'm a novice at this so am not really sure about the difference between a wet cell and dry cell battery or which is a better fit for my requirements.

* A 'solenoid' redarc isolator. Apparently this is not the 'latest' redarc isolator but the guy on the phone was saying it's probably better than the latest ones and a couple hundred dollars cheaper. I'm not sure if the latest ones are DC-DC based. I was reading a few threads here about how some forum members think the 'solenoid' ones are better than the DC-DC ones and I think that might be why the guys at Wynnum towbars were suggesting this isolator.

* A 50Amp fuse from the battery to the andersen plug at the towbar

* A 20Amp fuse from the circuit near the andersen plug to a new cigarette light socket installed in the cargo bay on the passenger side.

* 6 bms(?) wire. I might have misheard that but it's to do with the thickness of the wiring and apparently this is thicker than others would use and therefore better.

* I also asked about the diode that people have mentioned on some threads that increases the voltage for charging the battery but he said it wasn't really necessary.

He was charging $1000 for all parts and labour to install this. I was just wondering what some of the experts (or anyone with experience in dual battery systems) out there think about this setup?

Oh and also if anyone can recommend a place to get the front windows tinted, that would be appreciated.

Thanks,

Anthony

[sunchaser Member Find all posts View Profile Close sunchaser]

Hi Afryer,
Welcome to Prado point!
There doesn't seem to be anyone willing to give this one a go as there is plenty of threads in the archives on this subject if you want to get your head around it all.
If you have a diesel there is just enough room to fit a 100ah battery in the engine bay with the right battery tray. (another thread in archives) If you have a petrol you wont have the room for any more than a 90ah and alot of pipe repositioning. (I have put my battery in the back behind the 2nd row seats)

Any solenoid isolator will do for weekend trips. I think the dc-dc type would be better as it will fully charge your 2nd battery (as your alternator is designed to only charge your starting battery back up to 80% ), and it will float your second battery as well.

A 50 amp fuse seems a little small to me. I use 80 amp as your alternator will put out around that. Resettable fuses (circuit breakers) are good. No need to worry about replacing fuses.
The 20 amp fuse to your load (fridge) seems a little excessive and 10 amp is normal. I would also use an anderson plug there as well. and change the end of your fridge lead to the same as the old cig lighter sockets are crap and heat up and become loose over corrugations etc.

6 B&S or 6 awg ( B&S and awg are the same thing) is the correct size for the length run in your car. make sure they use good solid crimp on lugs.

I picked up the diode from ABR sidewinder which has increased the voltage to my second battery

$1000 seems like rather a lot though. If you have access to a large or hydraulic crimping tool you can do it all yourself. its not hard and can be very rewarding.

link to redarc wire guage sizing http://www.redarc.com.au/images/uplo..._worksheet.pdf

Have fun setting yourself up and get out there camping.
Also for a few hundred dollars you can get a bi-fold solar panel around 120W and will keep your deep cycle battery charged nicely. Remember that while they are designed to be deeply discharged slowly they will lose life span quicker if you discharge it fully. If you only discharge it overnight down to say 75% and can recharge it during the day your battery will last a lot longer. The life span of a battery is something in the order of 1000 cycles if discharged to 80% and only 500 cycles if discharged lower than 50%. I've tried different types of deep cycle batteries like agm etc and found them no to last no longer than an average sealed lead acid battery (sla). Heat and vibration apart from deep discharging are the biggest killers of batteries

I'm no expert just had a bit of experience over the years with it all. Good fun...

Cheers Gaz

[sunchaser Member Find all posts View Profile Close sunchaser]

oh and if you type " pradopoint.com/showthread dual battery set up " into google it will come up with one result from pradopoint but if you click on "show more results from www.pradopoint.com" at the bottom it will bring up every thread on the subject. well over 20 pages!
And there's heaps of wiring diagrams on the net for dual battery set ups too

Cheers Gaz

[Nova Member Find all posts View Profile Close Nova]

Actually try the following in google to search only pradopoint.

siteradopoint.com dual battery (or any search terms)

Sometimes google search is easier that the forum one.

Cheers Nova

[Nova Member Find all posts View Profile Close Nova]

Did the $1000 include the towbar? Makes a big difference.

There is a heap of discussion re dc-dc chargers and solenoid systems, never seen a really clear answer. Dc-dc charges slower but may get a few percent more charge in, solenoid and alternator charges way faster but not quite as much. I would assume if you want to run the engine to charge the battery then using the alternator would be better. If you are driving all day, maybe dc-dc is better.

Cheers Nova

[afryer Lurker Find all posts View Profile Close afryer]

The $1000 quote was just for the dual battery all parts and installation.

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

In terms of gear required, have a look here (swap auto reset Circuit breakers for fuses or manual reset ones):
http://www.pradopoint.com/showthread...l=1#post505232

Ive just purchased all my dual battery gear - including a Voltage Sensitive Relay, 50A Circuit Braker, 50A Fuse and 7m of 6B&S cable for $270 - See HERE. Plus my battery ($200). Giving me a total of $470 for parts. The labour will come from me - because its free. My 2nd battery is at the rear of my Prado, hence so many metres of cable.

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

A standard isolator setup and a booster diode if required (for use with high compensation alternators) will fully charge your in car battery much faster then a 20A DCDC charger can.

With regards to the trailer the above setup will put the bulk charge back in much quicker, so if you intend to heavily discharge your batteries ie 50% SOC or lower then the above would be better than a 20A DCDC charger, the deeper the discharge the more it swings in favor of the VSR setup. If your only going to lightly discharge your battery ie not under 70% SOC then a 20 DCDC charger would be a little faster.

A 40A DCDC charger in the trailer would give better results than a VSR setup but you have to weigh up if the added expense is worth the gain and some batteries may not be happy with the charge rate.

The VSR setup on a standard alternator or a boosted high compensation type will fully charge your batteries, as both will provide around the same maximum charge voltage as a DCDC can ie around 14.2V-4.4V@24C.

The above assumes adequate cabling is installed ie at least 13.5mm2 and your using batteries that will except a high charge rate.

Cheers
Leigh

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

I bought
- my redarc dcdc charger for $390 of ebay.
- $150 odd for a TJM battery tray (10 inch) which allows for an 80 amp hour battery
- ACDelco deep cycle battery maintenance free 82 amp for $170
- 6b&s wiring from ebay - cant remember pricing
- redarc fuses for around $40 per pack of two
- bought my own crimping tool for $40
- bought my own buntane soldering torch and gas bottle for $29 from bunnings
- a number of 50 amp Anderson plugs (genuine) for a few bucks each

There are a few other incidentals I need like a fuse box for the engine bay and a nice baintech fuse box for the rear.

Doing the install myself. In all honesty it wont be too difficult. just need to make sure my connections are nice, neat and tidy and good quality. Use that split cable hiding material etc... ill put a post up when I get time to do it.

[AussieAndy Find all posts View Profile Close AussieAndy]

Where abouts in Brisbane are you? If you are the western side or travel out this way I have a great window tinter. He did all windows on my Prado for less than the dealer wanted to just do the fronts.

Also agree on the DIY battery if you feel up to it, can't be too expensive. $1000 isn't as excessive as some are saying when you include labour. They will also be charging retail on parts etc. $150 for solenoid, $150 for tray, $220 for battery, $150 for wire, fuses, plugs etc. and 4hrs to install at $80/hr adds up to $990 so think about that (try finding a tradesperson at under $80/hr).

There are a few helpful guys in SE Qld, if you need some advice or assistance shoot me a PM.

[afryer Lurker Find all posts View Profile Close afryer]

Hi All,

Thanks for the replies so far. I do understand that this topic has been discussed before in other threads, but this kind of technology can change and so it's good to get the latest information.

I picked up my Prado and one thing that has thrown me slightly is the 220V 100W 3 pin plug in the back. Why would they go with 220V 3pin instead of a 12V? I thought 12V was pretty standard. Also with that 220V plug being attached to the crank battery, it would be risky to run a fridge off that plug if the engine wasn't running right? Is there an isolator that will cut off the power to that plug if the crank battery voltage drops below a certain threshold?

For the dual battery setup, I'm still undecided between using a traxide SC80 or USI-160 isolator in combination with a diode to increase the alternator voltage, or the recard bcdc 1220. One thing swaying me towards the traxide is the ability to charge both the auxillary and crank batteries using a solar panel plugged into the anderson plug near the towbar. That sounds like a convenient way to recharge with solar.

How do you use solar panels with the redarc bcdc 1220? From the circuit diagrams, it looks like you need a relay and that the solar would be plugged into that. Is the relay part of a standard installation when using the redarc bcdc 1220? Also is it located under the bonnet? And in that setup, does the solar panel charge both the crank and auxillary batteries?

Thanks,

Anthony

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

The inverter may or may not run your fridge. The inverter is small so check the output compared to your fridge input. The inverter doesn't run when the engine isn't on so no risk of flattening the main battery. With the Redarc BCDC only the 1225 and 1240 have inbuilt MPPT solar controllers. If you go to Redarcs site there are a few standard wiring setups. I use a BCDC1225 with an AGM battery in the back. Wired up using a changeover relay as per Redarc wiring suggestions. Have a look if you are interested, link is in my signature. If you have trouble finding the pages on the Redarc site post here and I will post links. My solar infeed is via an Anderson plug on the factory roof rails. Again pics of that and the panel in my build. The solar set up this way only charges the auxiliary. If you only take power from the auxiliary when the engine is off then you shouldn't need to charge the main too.

When you by the BCDC you only get the device and a short length of wire. You need to make the rest up. Wire, joiners, cable ties, heat shrink, relay etc. if you go this way get the Britax relay I bought. It has the larger pins and you can easily crimp 10mm2 cable into the terminals. A standard relay is designed for maximum 6mm2 and some people just cut out 4mm2 of cable which seems pointless to me when you can easily get the right relay.

I was concerned about under bonnet temps and weight so that is why I put my auxiliary in the back. I don't need 7 seats often and my setup is easy to remove. Anyway I put the air compressor behind the drivers headlight...

[rags Advanced Member Find all posts View Profile Close rags]

One thing to be aware of with the Wynnum Towbars is that for the trailer plug wiring they make up their own harness but use scotch lock type connectors much to my disappointment. If I was aware of this I would of got a Toyota harness.
Not sure what they do with the dual battery wiring

[afryer Lurker Find all posts View Profile Close afryer]

Hi Rags, thanks for the heads up about the scotch lock connectors. I haven't owned a caravan before so am interested to hear your opinion. If you could start again, what type of connectors would you want? I might chat with the guys at Wynnum towbars to see if that could be upgraded. I still am liking the fact that their towbar doesn't cut into the rear bumper and is about $250 cheaper than the toyota one.

[AussieAndy Find all posts View Profile Close AussieAndy]

Part of the cost deduction, if they are just using tails, is the wiring loom. The factory loom has a control module (just really a box with relays in it) to prevent overloading the tail light wiring and protect it from shorts and spikes from the trailer. It also has the correctly fitting grommets for the floor to stop the dust and stuff getting up in there. I have a spare genuine loom kit sitting here as I bought it to use with my rear bar, turns out kaymar also use lumen to make their loom and module so it is almost identical. Its a $60k+ car, don't save $100 and fry the electrics with some dodgy hire trailer.....

Edit- Plus the body loom has a plug sitting there for the trailer wiring to plug into, no cutting, no hacking, just plug and play