dual battery installation NT Pajero.

ozi2 · Guru

dual battery installation NT Pajero.

Nichol · Member

Hi Ozi2,

I will try to address each point seperatly.

-Battery Selection
AGM batteries typically do not like hot environments. While I think they are the best battery to use make sure the one you choose is able to work under the engine bay. I use Lifeline batteries, expensive but reliable and backed up with a good warranty.

-Isolator
I know there is a lot of debate on the forums about this but I prefer using DC-DC chargers as in my experience they typically provide a much better charge to the second battery.

-Fridge cabling
The Waco CF50 will use more than 2 amps when running, however as it does not run 100 percent of the time averaged out it may draw 2 amps an hour. I assume a load of 10-15 amps on compressor fridge circuits (this allows for start-up current etc). I also try to keep each fridge on its own circuit, this means that if fr some reason any other accessory blows the fuse you will not loose power to your fridge as well.

I would look at using 6mm2 or 8mm2 cable for your run.

Cheers,
Nichol

jimricho · Guru

I endorse the above comment re selecting a battery that's ok to mount in the engine bay. Also if considering a DC - DC charger such as Ctek M205 (or similar) check if there are any problems mounting this in the engine bay too if that's what you intend.

In my installation I have a Rotronics (solid state) isolator (had it for nearly 12 years) and the connections from the main battery to the Rotronics and from the Rotronics to the aux are maxi-blade in-line fuses (60 amp). The tails on the fuse holders appear to be about 8 B&S and are long enough (in my installation) not to need additional wire lengths spliced into the line. I have found this arrangement to be most satisfactory.

I also have a Ctek 7 amp charger mounted in the rear of the wagon and when on a powered site this takes over the job of supplying the fridge as well as topping up the battery. The Ctek can be set to work as a stand-alone (without battery connected) 13.6 v power supply if needed.

(edit to add PS)

PS: I also have Baintech model LVC low voltage cut-out fitted to ensure that the battery is not totally discharged.

-- Edited by jimricho on Monday 9th of January 2012 08:03:29 PM

ozi2 · Guru

G'day Jim & Nichol,

thanks for your comments........yep, forgot to mention that I have the Ctek and very happy with it too! (my son in law has eyes on it)

It amuses me when I approach sales staff and outline my requirements, ie 6B&S and they want to sell me something else (lighter).

In my last installation I had the battery in the back in battery box with the usual 12v outlets, solar etc and this did work very well. With the heat problems in the engine bay that problem can be solved with the AGM dislike of heat.

Jim, with your Pajero, do you have a battery mounted in the engine bay? (and off topic, do you have the load rating for your roof rack rails)

Nichol, what sort of prices are we talking about for 100+ lifeline AGM?(Optima $400)

Thanks again, I appreciate your comments and suggestions,

cheers,

ozi2

jimricho · Guru

yes mate, the battery is in the engine bay but it is only about 50ah capacity as in my set up that's all there is room for. The tray is a TJM job specially for the diesel (NP model) but I have an idea that ARB may do a unit that can accommodate a 100 ah (N70) size battery. I have seen an aux battery installation in a petrol NM/NP but it entailed some extensive mods to the air intake system. I'm not familiar with the NT so I don't know how relevant this is.

My battery is an Optima "Red Top" which is a cranking battery rather than a deep cycle but it does the deep cycle job very well and is almost 10 years old (will be in May). Being designed as a cranking battery it is quite happy to live in the engine bay. If the battery is discharged to around 11.5 volts or so it will accept an initial charge of 50 - 60amps (I've measured it) with the engine idling. I've also been able to get an extra day's running on my Bushman (not in deep freeze mode however) with an hour's idling of the engine.

Sorry can't help with the load rating for the racks, I presume you mean the channel that the racks fit into.

I'm not familiar with the Lifeline but I note Nichol's positive comments, especially in regard to the temperature and warranty issues. Maybe a little extra expense now could save a lot of aggravation in the long term.

cheers,

Jim

Nichol · Member

ozi2,

The RRP if an N70ZZ 100AH lifeline battery is $595. As I mentioned they are expensive, but work in the high heat bonnet conditions and have a 5 year pro-rata warranty. The equivalent range in the optima is the Yellow Top, which I think has a similar RRP, however has a smaller power to size ratio (you need a bigger physical size for the same power)

I agree with jimricho about watching the heat with DC-DC chargers.As with all solid state electronics they do not like heat and start to loose performance the hotter they get.

I have seen some dc-dc chargers under the bonnet that had stopped charging as it was to hot. I recommend trying to install the DC to DC chargers inside the Cab if possible.

I also agree using a low battery disconnect is a good idea as flattening your battery to low is a sure fire way to kill it.

Cheers,
Nichol

jimricho · Guru

The Red Top was originally used as a starting battery in a previous vehicle I owned, the reason for purchasing it. When I sold it I wasn't going to let the Optima go too. It was then installed in a boat and worked very well in this task too. It stood for lengthy periods without being used or connected to a charger (naughty boy!).

It has since then been used as a deep cycle, firstly in a tent trailer, then for a short while as a house battery for the Goldstream and for the last couple of years as the aux battery for the tug. It has outlasted a Yellow Top I owned but it would be unfair to draw any conclusions from that as there were probably external factors involved. Unfortunately Optima is out of the question for you as you require the higher amphour capacity.

A little bit of lateral thinking should find a way around where to mount a DC - DC charger, perhaps forward of the radiator somewhere if there's space??? Or maybe inside the cabin with cables feeding through the firewall????

Another thought is how important is it to have all the smarts of a DC-DC if a standard dual battery setup will do the bulk of the work, supplemented from time to time with solar and/or charging from ground power via a smart charger?

DC-DC chargers are a very recent innovation whereas dual battery setups have been around for yonks. Don't know what the alternator voltage is in the case of the NT but in my NP it's 14.4 volts which is fine for charging an aux AGM battery if steps are taken to minimise voltage drop. For house batteries in caravans or if mounted in the rear of the vehicle it's a different story.

ozi2 · Guru

G'day Jim & Nichol,

sorry, I have been laid low with a bug. I will get back to you once over the damn thing. Thanks for your comments to date.

Cheers,

ozi2

jimricho · Guru

Hi Ozi, hope you're back on deck soon,

I just checked the Lifeline and noticed that the specs call for a charge rate of 14.2 - 14.4 (absorption phase) and 13.2 - 13.3 (float). You may need the DC - DC charger to meet these parameters. Also you'll need to select a (240v) smart charger that fits these requirements if fitting one of these too.

PM me your email and I'll email you a handy chart from Federal Batteries that lists their line of batteries and the suitability of various chargers.

cheers,

Jim

Smokeydk · Guru

As Jim said....not much room in a Pajero for big batterys.....

I have Rhino roof racks...Heavy duty

http://www.rhinorack.com.au/Vehicle_MITSUBISHI_Pajero_4011.aspx