<span class="highlight">Power</span> <span class="highlight">packs</span>

Nevermind the 1200amp that is cranking amps if you want to use it as a backup check its Amp hour rating for how long it will run your fridge. You can generaly buy an N70Z batery for that price & would run your fridge longer than any portable batery pack @ jump start your vehicle. Some power packs strugle to crank dead flat baterys especialy diesels.

I think they're a good option if you're sure you'll be running the car every day, and have a fairly big capacity starter battery (eg. 100AH). Certainly a lot cheaper than the full dual battery setup.
However, if you have a big fridge, will probably be staying in one spot for more than a day, or just want to be sure the fridge will always work and the car will always start ... cough up and pay for a proper dual-battery setup.

Lachie,

My brother has used and abused one of these for about 4 years now and it has been great! They have an 18 amp hour AGM battery in them 1000 cranking amps.
Super crap have some pretty dodgy packs, but for around $240.00 this one has been great and worth every cent.

http://www.batteriesdirect.com.au/shop/store.php?crn=256Image Could Not Be Found

Other wise Derek Bester from ABR has some pretty good power packs, I use one of his 90amp battery packs as a dual battery setup in my rig. Runs my engel and camp lights for 3 days without charge.... highly recommend his gear.

Hope this helps

They are really designed to be an emergency supply of power for jump starting rather than a power source for fridges etc because the batteries are too small, 18AH battery wont power much for very long. So it gets down to your real need.? For longer power supply to fridges etc you are better off with a 80-100AH battery in a battery box, heavy and slightly portable but more suited to running 12v devices for extended periods of time.

I have had dual battery systems for a long time & seem to learn something extra every time I have a discussion with fellow four wheel driver's. Firstly I am not a mechanic or auto electrician. I have learnt from many mistakes in life. I have had a Super cheap battery pack for about 7 years (the one you mentioned) I take it camping & never use it to run a fridge. I run my shower pump & at times (2 X 12v outlets) 2 fluro lights. The secret in using these items is DO NOT follow the instructions that come with it. Simply monitor the battery condition gauge & once it gets into the yellow then & only then do you charge it. I charge mine via a CTEK or Smart charger which puts the required 14.2 volts into it. The recharging items that come with the battery pack are basically useless. Recharging after every use stuffs the battery memory. I was taking these items back to Super cheap every 12 months for a refund until a very young girl in the store told me how her mother recharges it. Hence I have had the present one for all this time. Now, dual battery systems you need to do a lot of home work & basically go to a reputable 4WD shop like ARB or TJM. If you run a second battery run all your accessories off it like your fridge. IF, you run your accessories & run 2nd battery down to say 11 volts & by mistake you have flattened your start battery you won't be able to start your car (you will need at least 12v to start your diesel) Your deep cycle (2nd battery I use an AC Delco 600 CCA) should have 14.2 or 13.8 in it. I use an ARB dual battery system with a Piranha battery monitor. I have a cut off on the 2nd battery at 12 volts so it cannot be flattened. I had a TJM system for 20years however I believe the new ARB system is just as good & a lot cheaper. The best people to get advice from are people on this forum & people who work in off road shops that are doing what we do...go camping & touring they know by experience. Hope this long reply helps in some way.

Thank you all for your replies
I was thinking of using it manly as a jump starter if the prado battery went flat.
Heading off without out another vehicle these holidays and was thinking of a cheap back up. The fridge seems pretty good at turning itself off when the battery gets low but I just don't trust it with no one else about.

But as said these power packs may not start a diesel motor anyway.
I suppose if I did have a power pack I would be using the light or something on it and it would be even worse as a jump starter.

I will just have to get my act together and put a duel battery in.
Even if I just get say a TJM battery tray and put a battery in it until I get time to wire everything up ?
Lachie

Lauchie,

You risk buggering your starting battery if you let it run down until the fridge cuts out.

Depending on the cutout setting of your Waeco, you may be draining the battery down significantly and this is not good for a starting battery. They are just not designed for it. Therefore, your cheap solution may turn out to be a new starting battery in a relatively short period, or a stranding, if it poops itself when you are in a remote location.

I don't believe there is any compromise. I use my main battery to run the vehicle, period.

I have a 75Ah Thumper power pack which I use as a portable battery pack when camping, as my auxiliary battery was fixed.

Now that I have upgraded my vehicle to a dual cab ute, I have installed one of ABR's "Flyer" dual battery systems as my auxiliary and now have the advantage of both being removable and both capable of being charged by the vehicle alternator while running the fridge at the same time.
Both of these auxiliary systems are of AGM deep cycle batteries which are specifically designed for deeper current drain than a starting battery.

Both can also support jump start capability if I need it, but I don't envisage the need as the starting battery is only used for normal vehicle operation.

Think carefully on what your requirements are and select a solution that suits that purpose.

Bill.

Some years ago I had a RR 2 door. The local mechanic fitted a second battery and a three way switch. Battery one on, battery 2 on, both on. I used to start on the fully charged battery, then switch to the flat battery, then to both. At night I used to alternate the batteries each night so that the same battery was not flattened twice in a row.
I was running a small fridge and lights. I ran on the same two batteries for over 12 months.
Things have improved since then so the damage should be less.
Regards
Brian

Lachlan,
I'm guessing you have a diesel.
From your description, you would get by fine with just a bit more battery capacity.

Since the dawn of time, this was easily done by wiring two identical batteries in parallel. Even Toyota do it these days on the 100 and 200 series LandCruisers. No fancy isolators etc.

Both my daughter's vehicle and mine have twin Exide Extreme N70 batteries wired this way and you can easily run an engel for 2 nights and a day and still start the vehicle easily. The advantages are that its a cheap setup, no fancy bits to fail, both batteries charge up easily, and the batteries last a long time because they are joined for cranking, and are not discharged down as far as a single battery.

Keeping it simple works fine for this application. If you are the type of camper who stays put for a week, then do something different, but 90% of the people I know would be fine with this setup.

Some astronomical numbers floating around in an otherwise down to
earth forum, may well confuse the unsuspecting battery user.
It's about things called 'starter packs' offering 1200CCA and such.

Exorbitant claims like these may raise doubts in some people
intending to use a second battery which in many cases, is of a
deep cycle design, thus not rated in CCA.

Back to the 1200CCA....

For the interested, here's some numbers and a bit of physics.
Typical starter motors have an internal resistance of 30 to 40
milliOhm.
This means the initial maximum current spike the battery has to
deliver for a split second (while the starter motor spins up) can
only be 300 to 400A. Due to additional resistances in this circuit
(solenoid contact res, wire res, battery internal res, battery
clamp contact res, you can subtract another 50A from this
theoretical peak current.
Once the starter motor has spun up, it'll generate a voltage which
acts against the battery voltage, say around 6 Volts.
So, once the starter motor spins, the current consumption will drop
back to around 150 to 200A.

Don't be fooled by silly adds.
You can't bend the laws of physics even if you are a sales rep.

I'm frequently being asked if my deep cycle 100Ah AGM batteries can
be used for starting, and the answer is yes you can. These
batteries are not rated in CCA, but are specced to deliver 370A for
a duration of 5 minutes.
You could crank for 15 minutes before you run this batt flat (flat

means the terminal voltage has reached 9.5V).

So why settle for a 'starter pack' with a small battery in it, when
you can, for a little extra, have a 100Ah deep cycle AGM battery
with six times the Ah rating, plus starting capability?

Hope this makes things a bit easier for you.

Best, mr.batteryvalue