Car Fridge & Battery Setup Explained
In this article I am simply telling some stories about experiences we have had with our fridge and battery setup. I will tell you some of the gear we have used in the past and some of the lessons we have learnt along the way. Hopefully amongst my ramblings, you will find the bits of useful information you came here for. I can also answer any questions if you would like to post them in the comments section at the bottom.
The battery
We used to have an ABR Sidewinder. Capacity unknown. It’s a box that contained 8 x motorcycle batteries in it connected in parrellel. It had several connections on it including standard positive + negative terminals, 2 different 12 volt outlets, plus 2 Anderson Plug Connections. One as an output, and one as an input that we connected to the battery for charging.
Our current setup consists of the same box (the ABR Sidewinder) but the 8 x motorcycle batteries we have replaced with a single 120AH battery.
There are several bits of information I can give you about batteries.
Firstly, is storage. We learnt this one the hard way. When we took our battery box to a battery shop to be tested, we popped it open and all of the 8 batteries inside had swelled up and were ruined. We asked the guy what might have caused that to happen and he said if you leave it sitting in your shed for a year, then try charging it up fully it can happen. Bingo. This is exactly what we did. We didn’t use the battery for a solid 10 months while we were in King Ash Bay, Northern Territory working. We then charged the battery up ready for our next trip and found it only lasted an hour before the alarm went off.
Next I can tell you what type of battery you need. You need a “deep cycle” battery. This type of battery is different to a normal car starter battery. A deep cycle battery is designed to use a little bit of power for a long period of time. A starter battery is designed to use a lot of power for a short period of time (starting a car). If you were to swap the batteries over, you would probably find that they would still work. However they would not last very long at all.
Also there are different types of deep cycle batteries. You want an AGM deep cycle battery. An AGM battery comes in a sealed box, which means you could even tip it on its side and it wouldn’t leak. It also doesn’t emit poisonous gasses. If you are using the battery inside the cabin if the car (which we do) it is actually a legal requirement to use an AGM battery.
The fridge
Our fridge is a mid 1990’s model 40 litre Engel. It still runs beautifully and all the seals are perfect. The only down side is the juice it chews through. It uses 2 to 3 times the power of a modern Engel Fridge. But if we stay on top of charging, we are usually all good.
With that being said, at some point we need to bite the bullet and buy a new fridge. To buy the current model of the 40 litre Engel is about $1,200. That’s going to hurt, but it will give us a lot more freedom purely because it’s power consumption is so much lower than our old one.
Advice
You should try and avoid taking the battery’s power to below 50% of its capacity. You can do permanent damage to the battery by doing so. The juice or power usage is measured in AMPS(A). And your battery’s capacity is measured in AMP HOURS(AH). Our fridge uses about 5amps per hour. And our battery is 120AH. So I would prefer to only use 60AH of the battery (50%). This gives me 12 hours of solid running time before I need to charge it.
You should have your battery hooked up in a way that it charges while you are driving. If you are camped somewhere for a few days, then you will need to charge the battery each day, and I don’t mean by turning the car on. Our method of charging is our little Ryobi Generator that we connect to a 20AH charger. Charging of the battery while driving will only be effective after a big drive.
The battery also needs to be hooked up in a way that it will never drain the power from the starter battery of your car. For example, your batteries are connected to each other because you want them both to charge while the car is running. But after a couple of days camping, your battery that is connected directly to your fridge will be empty. At that point, you don’t want the fridge to bleed the cars starter battery dry too. That will give you all kinds of hassles trying to get the car started.
With our ABR Sidewinder box, it has a built in solenoid in it that will never allow this to happen. A very primitive method would be to simply have a switch in the line that connects the batteries. When you stop the car, you will need to remember to turn the switch off. You probably wouldn’t forget more than once or twice!
