Battery size/type

Dave I'm a big fan of AGM batteries. A bit about them on this link:
www.fridge-and-solar.net/agm.htm

As to size, well bigger is always better. Since you are carrying it on the tray, size and weight should not be big issues. I'd go 120 AH at least. I've got a 120 AH AGM in the back of my Hilux and another in the CT. I doubt that a 75 AH battery would run your 60 lt fridge for 24 hours. Remember you don't get to use all of the batteries capacity and the more often you run it right down, the shorter it's life will be.

The Engle WILL use some where around 1.9 upto 4.5 amps per hr of run time , variables of ambient temp and fridge temp settings , so for a theoretical start point work on 2 amps per hr X 24hrs = 48amps , then for max battery life should never discharge lower than 50% ,, ergo get the biggest AGM battery that you can afford and have room for.

before you go spending heaps of money - how often are you going to have the engel running? if this is for a 'big' multi week/month trip then get a battery which has sufficient amperage to last for 24hrs between starts. if you are going to be stopped for anything more than 36hrs then you need to look at some way of charging other than the vehicle - solar or genset. if however you are only going to be doing day runs every now and then, just put in an el cheapo battery ($100) and this should give you a couple of years of use then just get a new one when it expires. an n70zm is very heavy - try and keep the weight down as much as you can. rgds

Hi Dave,
I run a fridge permanently off a dual battery and on weekends sometimes only drive the vehicle once for a short time. Run an Amptech 105Ah Marine batt, dont have a problem. Sometimes run two fridges from it, a 50 litre and a 25 litre as a freezer. Drive daily then, and no issues. If you wanted to stop for a while could be a problem. Also used to run the 50 litre (waeco) in a Courier dual cab diesel for 2 years with no dual battery. Never had a flat battery until the battery died (2 years and the batt was 3 years old when I bought the vehicle) standard N70Z.
Could park the vehicle on Friday in the summer and run the fridge all weekend and still start the car on Monday morning.
Hope this helps
Ray

I don't know what sort of driving you do, but here's my experience.

1 year ago I put a 110 AH (note - this is Amp hour - not amps - your terminology faux pas has potential to get you into trouble) as an auxiliary battery in my 1HZ 100 Series with one of Derek Bester's ABR dual battery systems. It runs 80l Waeco fridge and 500W inverter usually only having a small load and occasionally, lights.

It was an AGM from a big battery distributor.

1 year later it is not holding charge - maxes out at 12.4V despite being run down to about 9.6V only once and despite frequent LONG alternator recharging.

It was still "under warranty" so I took it back expecting a replacement, but perhaps a discussion about what I wasn' t doing etcetera.

Well, they first tried to tell me that really there was no manufacturing fault with the battery and it had just had a hard life.

They also couldn't really tell me anything that I did particularly wrong with it except use it.

From talking with people who seem authoritative like Derek, it seems that the frequent off-road work; the reasonably frequent extreme heat under the bonnet; coupled with being run down once or twice may well put this battery at the end of it's useful life.

The outcome of the discussion with the retailer is still ongoing 3 days later, but I know for sure:

1. most retailers don't seem to ask enough questions about your use to provide proper advice and the appropriate product (I called 3 big companies/specialists to see what they recommend in terms of technology/product/life expectancy etc.)
2. most retailers can't give any accurate information about their product life in at least my sort of usage
3. it is very hard to know what is the correct information on the subject.

I know it really doesn't give any good advice, but be pedantic, ask a lot of questions, take notes of who you talk to and what they tell you, and then if it doesn't happen you can take them to task.

Cheers,
Andrew.

Why a MARINE battery in a Nissan ??? Just putting a second battery into a Nissan and connecting a large fridge to it , does not mean you can run it forever !! As you are finding out ...if your rig is high up in the Snowys and temps are cold...you will get a couple of days out of your battery...if on the other hand you are up in the Kimberleys ...in the height of the hot season...expect a day /24 hours max...in between you will have to work it out yourself...don't annoy an auto electrician..expecting him to have all the answers...nobody does...then factor in the temperature at which you intend to carry food etc ...freezing , 4C, 8c, or happy with 12c ??... all more to factor in ..Essentially you are fitting a small battery (100AH)...when you really need abou 50 ah per 24 hours as a general guide..factor in a 50% usable level ...and you are bacl to 100ah ..in 24 Hours ( without recharge)...and running your motor for an hour or so will have minimal .(read very little) effect to re-charging your battery !!!

Sorry..been there done that ...you could add a solar panel etc for stationary charging but that's another matter..it's good and works..but could be a hassle in a Nissan..

I'm running an Engel 40L + Two Zone off a Remco 100A/H AGM charged through a Pirahna isolator.
I found the previous Optima 55A/H didn't last long enough.

Interesting topic........and I will have a look at the forum archives when I get time.

I have been thinking about getting a small portable (temp) solar panel to quickly attach to the rhino bars on top to charge the cruiser deep cycle battery for the Engel 39 litre, at times when vehicle is not being run. Would be interested to hear what others use as have little knowledge on the solar subject ie .........size/brand/type of panel/and what other parts are needed to be able to do this as a temporary charging arrangement. I have a Piranah charging system on the cruiser.

Andrew has posted a very valid point re running batteries too low.

I have knackered two batteries allowing them to totally discharge a couple of times.
The first one was a 77Ah Deep Cycle wet cell battery.
The second one was an expensive 55Ah AGM (Orbital) battery.

I now use a low voltage cutout device which will disconnect the battery supply when it has dropped to 11.6 volts. This is just above the 30% threshold, below which you shouldn't go.
The Orbital will not charge above 12.2 volts and will not maintain that for long.
(It's stuffed.)

I have gone back to a deep cycle wet cell battery as an auxiliary as this is the largest capacity battery (in Amp hours) that will physically fit in the engine bay. At least this wet cell is "maintenance free".

I still use the 75Ah+ Thumper AGM portable system when I remove the fridge from the car and coupled with a 40 watt solar panel I believe I have the best solution at a "modest" cost. The only improvement I could make is to increase the solar cell capacity, or add an Inverter type Gennie, but I have not found the need for these extremes yet.

Gday Dave

I've had pretty good success so far with a fairly std exide extreme - 85 AH from memory. I've only done 2 trips where the vehicle was parked for very long since buying the fridge (80l waeco), but both trips I got 48 and 50 odd hours from memory, both with the voltage not going below 12.2v. The contents of the fridge was very cold when starting, as while the car was travelling to the destination I crank the temp down, and get everything almost frozen, then set the temp to about 2 deg on the fridge, which keeps the inside temp from 2 at the cold end to about 6 at the warm end. This was in 34 degree temps, but only opened the fridge about 10 times per day (had a beer esky).

I think the dual purpose batteries such as the century you mention and the extreme I have can take charge pretty quickly from an alternator, at least until they are about 80 odd % charged, so a short trip etc can give you a handy top up, and while doing so crank the temp down while using the alternator's power so It wont cycle for a while once stopped (and setting the temp back up to normal)

Although from what I have read, the AGM's are better and last longer, for the price and a 2 yr warranty the exide will do me and my circumstances, I now have a 3rd exide which I transfer from the car to the boat as required, it is in a batterybox with external terminals and a ciggie lighter (whitworths $50.00), so I can have a 3 mattery set up in the car, charge the 3rd battery in the boat, and have a dual battery in the boat as well.

Everyone's needs are different, the hard thin is working out what you really need!

Cheers Andrrew

Itsdave

As usual you get a host of different replies when it comes to batteries and fridges.

My experience is as follows:

I run two Century Overlander 700cca cranking batteries in parallel through an ordinary solenoid with a dasboard switch as a cut out.

I have a 32lt Engel with a Two Zone. The Engel is run on Freeze all the time. Normally we drive most days but if sitting still for up to 5 days I idle the Nissan engine for 20 minutes in the evening and 20 minutes in the morning and if it is a warm day, 20 minutes after lunch. This seems to keep the batteries charged at 12.6volts plus. Both my batteries are now 2 years old.

It works for me.

Cheers