Evakool esky and power supply

[liltuffy]

Fellow Ausfishers, I seek your advice, knowledge and experience- PLEASE, I know this might be a bit long winded but I need to explain my situation.

Firstly I have a 3 litre diesel 4x4 2000 model hilux with an N70ZZ battery.

I use a 500 watt inverter for powering all sorts of things including lights and a TV/DVD player and take 3 little kids (4-6 years old) and a missus. For the past 20 years I have been using a 40 litre Chescold 3 way fridge and for the lat 10 years an 85 litre evakool esky to keep food and fish cold for periods up to a week whilst away.

Since we need more cold room space I am contemplating buying either an 85 litre or 110 litre Evakool fridge/freezer and probably a 100 amp hour absorbed glass matt deep cycle battery rigged up in to a box so you can take it out of the car.

In years past (and even now) I have taken the fridge out of the car and hooked up the gas for when we are out fishing or driving around and can be confident that everything will continue to run nicely while I am out and about.

I like that arrangement and would like to set things up and leave them in the camp for a couple of days before having to recharge the deep cycle by probably bunging the battery back in the car for a tour and recharging the battery.

I can't afford and don't really want solar power and all the associated stuff but would appreciate peoples opinions on the implicatios of a removable battery and where it could be mounted to power a new fridge.

Appreciate your thoughts

Craig in the V-Sea

[shano]

what we do is use 2 trojan 105, 6volt batteries hooked up in series these are 220 amp hours ! we have the evacool 70ltr fridge/freezer as a freezer ,and also a gas fridge! im in the same situation as you with missus and kids so have to have all the luxeries! anyway we run the generator at night for lights ect, and what i do is hook the battery charger up to the batteries each night to give them a top up! we lso run the gas fridge 24/7 for non frozen foods!

[chisel]

I'd suggest reading the info on these sites and perhaps contacting the shop owners:
http://www.fridge-and-solar.net/
http://www.sidewinder.com.au/

If the AGM is mainly for the fridge then I think it should survive a couple of days - but I'm not really sure how much power the big Evakool eskies use. If they average 2 amps then you won't get 2 days out of 100 AH battery.
I'm looking at getting a 47-litre evakool, a power-pack (portable dual-battery box with isolator - see sidewinder link) and a 120AH AGM ... I figure that will give me 3 days before needing any recharging.

[NormC]

I carry 2 fridges. A 70 litre Reefer (with freezer compartment) and a 40 litre Engle. We sometimes run the Engle as a freezer.
When camping in one spot for long periods, I unload both fridges. They are then run from two 120 AH AGM batteries in the CT.

Time between 'essential' charges is very dependant on ambient temp. At mid 20s, two days is not a problem. In mid 30s and higher (as on recent trip to NT) daily charging is necessary. We don't have the room to carry solar, so I carry a generator and run it for 3 or 4 hours a day through a 25 Amp multi stage charger.

Although your plan of only charging every 3 days or so will work, it has a couple of downsides:

Running batteries down a long way dramatically shortens their life.

Because the battery will be low when you charge, it will take a fairly long run to get it back to full charge. Not charging fully will just shorten the time you have till the next charge and in the end you will be doing it every day anyway.

A 110 litre fridge freezer will use a fair bit of power. Running your battery flat will cause three problems. The food will go off, the beer will get hot and if you do it too often you will stuff the battery.

Since you don't want solar, and (as with most of us) money is an issue, I'd be looking at one of the cheap GMC generators from Bunnings. I normally wouldn't recommend them, but in your case I think it might be the go. I think you can get a 1 KVA for under $200. Get a reasonable battery charger (at least 20 Amp) and run it for about 3 hours a day and you should be fine.

Just make sure you do the charging in the middle of the day as those cheap gennies are pretty noisy.

[Brett1907]

You can get a 12 volt generator specifically designed for fast charging of batteries. Effectively they are an alternator connected to a small petrol motor and can give out up to 70 - 80 Amps, plenty for deep fast charging of AGM batteries. They also have a safety feature that prevents over-charging. They aren't cheap (approx. $900 I think) but they are MUCH lighter & smaller than a 240V generator, and will charge the batteries a hell of a lot quicker too. A mate of mine has one and he is able to go weeks away running purely on 12V.

Don't remember the name or where to get them but will ask him and then post.

Brett

[chisel]

Battery charger: http://www.fridge-and-solar.net/genset.htm
At 55amps I guess it could take an hour or so to charge the battery unless it has been run down. Great if you have the money and the space.
Trouble is I guess they are banned in many places just like generators are (??)

[Brett1907]

Just checked out the specs, they are noisy aren't they. You would only need to run it for an hour or so a day, even on a 120amp battery. I think they ban gennies because there are people who run them all day. Went to a camp ground last easter and this one guy ran his about 18hrs a day, people were really getting the s#$ts.
I wouldn't mind it if some ran one of these for an hour or so each day or two, but then I would do it myself.
As for space, they are smaller than a Honda EU10i, and lighter.

Brett

[Ian1]

The problem with deep cycle batteries is getting the charge into them. They are designed for low current output over a long period. Unfortunatly the same goes for charging. Just because a charger is capable of 55 amps doesn't mean it will put 55 amps into a deep cycles battery. Deep cycle batteries have a higher internal resitance then starting batteries, hence the higher CCA off starting batteries. A starting battery with low internal resistance will charge a lot quicker then a deep cycle.
One way around this is shano's idea of using 2 6 volt batteries in series as you then have to batteries to take the charge and can get more amps in during the charge period.
At 14 volts most deep cycle batteries will only take about 10 to 15 amps at most. That means if you charge for one hour at 15 amps you are only putting 15 amp hours back into the battery. If the fridge averages 2 amps, which would be the minimum, you will only get 7.5 hrs running.
Sometimes its better to use a dual purpose battery and replace it more regularly.

Cheers

Ian

[chisel]

I think the AGM type deep cycle batteries can take charge a LOT faster than the other deep cycles. That's what I've heard anyway. The fridge&solar site suggests a full charge in 2.5-3 hours although it's not specific about how deeply they've been discharged and how big they are.

[Brett1907]

chisel is right, here is the link for AGM batteries.

http://www.fridge-and-solar.net/agm.htm

Brett