Batteries Batteries Batteries AHHH!

Who told you that?

AGMs are well suited as an aux battery to run fridges etc as long as you don't flatten them below about 50%. That is why they are used in caravans. If you have a so called 'smart' alternator fitted to your Hilux you may have problems charging.

You should have no reason to switch to 2 batteries for starting other than in an emergency when the start battery is flat.

The solar panel can be connected to the battery to assist with charging.

Not sure who has told you not to use an AGM as an auxilliary, but as far as I'm concerned they are the best one for the job (aside from the new Lithiums which I don't know enough about to comment).

However, in my experience, the BIG over-rider to my previous comment is the LOCATION of said AGM battery.

I have been using AGM batteries for about 14 years now but I NEVER mount them under the bonnet.

I have always located them in the back, close to the "job" they have to do.....(eg: fridge etc). That way they are away from the heat of the engine; and it is heat (as well as improper maintenance/charging) that kills the AGMs.

I bought my first AGM in 2002; a 120a/h Fullriver. That battery was still going strong in my Landcruiser when I sold it a few months ago. It had always been located in the rear of my (3) vehicles during all that time.

It is my understanding that AGMs in general, will accept charge from an alternator, solar, DC-DC charger or a 240 volt charger. Over those last 14 years, my Fullriver had seen charging from all of those sources at various times.

The other factor is: Never let them get too discharged. I had a "rule" that I wouldn't allow my battery/ies get below about 12.4 volts if possible.

I agree that ideally a DC-DC charger (eg: Redarc BC-DC type) is a great idea, but not essential. It just means that if you mount the aux battery in the rear, as I suggested, you really need to also use heavier gauge cable to charge it, whereas if you mounted a DC-DC charger close to the battery in the back (as I did), then you can get away with smaller gauge cable (say 6mm sq, which is still a decent size cable, but easier to run to the back than the heavy gauge stuff like you'd use in an Anderson plug).

Roachie

What Roachie said is good advice. If you have to mount your deep cycle under the bonnet use a wet cell, I believe they can handle the heat a lot better..............Jeff

Intersting if the system is already there and working ok forget what others are telling you and see how it performs.

The AGM may be rated for heat, if not as you already have it leave it till it dies and then maybe look at a Marine battery or other AGM.

As the setup was already here check to see if the previous owner fitted a booster diode, if he has you shouldn'thave any issues with charge voltage.

hi
stick with the 2x marine batteries .
Century marine pro 620 75ah
Century marine pro 720 100ah
As u have said the 100ahr is the way to go
There are some whats called hybrid batteries AGM that do both duties [crank/deep cycle ] and have an underbonnet warranty . This may be an alternate choice .
100ahr is a good size to start .
100watts of solar is not giving a lot of wiggle room . A little light on for cloudy days /high demand periods .
Going the way u r suggesting, expansion is just to duplicate what u already have to allow for bigger fridges etc etc

Run your electrical loads via a low voltage disconnect . ABR sidewinder sells a couple of different units at a good price . These will save your batteries/wallet by not overdischarging batt therefore shortening its life .

swamp

For years we ran two identical Allrounder 105 ah batteries with a 200 amp Redarc isolator between them. One was wired for cranking and the second for 4WD accessories such as the fridge, a 40 lt Engel, and anything that we wanted to charge, mainly just the satellite phone that would hold a charge for a week. We never used it. No mobiles etc, just a laptop on the odd occasion we took it.

This was okay for two night stops.

We then got a 21 lt as a second fridge, used only as a freezer, for longer overnight stops up to three nights. So we got another matching Allrounder and installed it in parallel with the accessory battery. All three under the bonnet of the 100 series.

The only problem we have had with this setup was that the crank broke inside on the CSR. Luckily all were identical so all I had to do was take the broken one out of circuit and insert one of the two accessory ones in it's place until we got the broken one replaced.

Just to confuse you, along comes another option. The car is a Toyota 4.2td 100 series.

All three can be switched into circuit for tasks such as winching.

Phil

Haven't read all the replies but batteries aside you are better off charging the laptop with a 12v laptop adapter rather than an inverter. 12v charging is much more efficient. Inverters should only be used when this no other solution. AGM battery is fine and you might want to suppliment the charging with a solar panel.

Take a look at the CAT range of batteries.
a 175-4390 product number, 1000 CCA And at a price of $145 you just cant be beat..
Dont get all charged up over batteries.
A Pussy battery will solve all your troubles he he he he
plenty of starting grunt and extra spare in times of need like winching or running the stereo to your dolly parton songs ;-)

And spare cash to burn, that will keep the other CAT happy :-)

Stephen, there is never any right answer - too many variables.
My preference with 2 batteries in the heat under the bonnet is to use identical cranking wet cell batteries. I buy a new one every 2 years so I'm always cranking from a fresh battery. The 2 year old cranking battery gets relegated to duties as the aux battery to run the engel which it does just fine. I drive the vehicle most days or top the battery up with a solar panel if staying put. When its 4 years old, it gets pensioned off - usually to one of my son's cars or his shed.
I use AGM batteries in the traytop we had, in the Tvan and also the caravan. I killed an AGM once by charging it off the alternator - I had great wiring so the battery would easily get 45A going into it but the fineprint on the battery case said max initial charge current of 27A. Lots of AGMs have current restrictions and will lose capacity if charged too fast. Optimas are a notable exception, with no restriction on charging current. I also killed a wet cell battery by upsizing the voltage in the heat of an Adelaide summer - boiled the battery and it never recovered.

So in your situation, 2 marine batteries is a great choice and with the aid of 100W solar you will have no trouble running the engel and laptop.

hi Stephen F2
The SSB battery u are looking at is a calcium/calcium battery. Your vehicle may not be suitable unless it came with calcium type from new . The charging voltage is higher and the algorithium may be different . I would enquire with SSB about suitability . There may be some dc to dc that do calcium .

I am in the same position the second battery holder in my Pk Ranger suits mostly the smaller units agh agh .

There may be others that can offer advise on a mixed battery system .

swamp

hi
An idea that may help u out to run
1x marine cranker 100ah in the engine bay
1x marine cranker 100ah in the rear tray or in factory style side

Fit the equal size battery of your choice is the best way [All batteries probably last longer when not in the engine bay]
existing isolater
Run longer cables to battery mounted in tray
You could make your own battery box or buy one
U could get an auto electrician to wire if u r not handy
All costs would be affordable
Use AT LEAST 3 b&s cable if not the larger 2b&s

swamp

PS now I understand why people do this . Some people also mount there battery under the tray either infront of the rear wheel or behind . As I said I am in the same predicament U will notice plenty of these mounting styles just have a good look around when driving .

hi
Stephen F2
You cannot charge a tray mount battery of the cig lighter wires
cig lighter wires should be [some use even smaller ] 6mm auto wire which = 4.5mm2 cable
charge would be very slow ,cable might run hot /melt . Don't due it . Good results are as below .

cables from main via isolater to second battery
good 6 b&s= 13mm2
better 3 b&s = 25mm2
best 2b&s = 35mm2

Hard wire to second battery
Run your cables thru amain fuse then low voltage disconnect then fused to individual circuts
fridge
led lights

An incoming connector for solar etc
incoming for a 240volt battery charger
swamp

Thank you to everyone who answered my questions.Did my head in but good way to learn.I contacted a few battery places ,some wanted to sell me extra charges etc .In the end got a bit frustrated so went to local battery shop where my dad the Mechanic used to get stuff sorted.People may think why I not like my dad and understand cars.He was bad teacher but he understood cars better than people.The 2 guys in shop very helpful one had Hilux like me and explained what he had in it.In the end with discussion with both guys with different views on what to do.Ended up with 1 810cca cranking battery and other 105ah Allrounder .They will test it all out today and see how well solar panel charges the Allrounder.Very cheap $365 cash for the 2. 3 year warranty on cranking bat.See how we go can only try.Found out they import most batteries for around $30 each .So some retailers have huge mark ups on batteries.One of the guys in shop where I bought batteries used to work for the importer.Made in Philipines brand I bought.So if you see a broken down SA Silver Hilux blame me for buying cheapos ha ha ha