In this video, you will learn how to make an easy 12volt off-grid system to run your
fridge.
I won't add solar panels to the system to keep it simple.
This system is ideal for a backup solution when there is a blackout.
We will calculate the fuses and the wire thickness.
I will give some tips about C-rate and then we will calculate the charge and discharge
times.
At the end, I will tell you how much this system will cost you.
We will start with the system overview.
We have a 12V 100Ah AGM lead-acid battery.
We will charge the battery with a 5Amp charger, which equals to 60 watts.
Then we will have a 500W inverter so you can power your AC loads.
Let's start by taking a look at which fuses you will need.
For the charger, you will need a 10Amp fuse.
We choose 10amps because this is the closest to 5Amps.
The charger that we are going to use already has an inline 10A fuse.
So we don't have to add one.
The power of the inverter is 500watts.
If we divide 500watts by 12volts, we become 42Amps.
The closest fuse to 42Amps is 50Amps.
We will use an ANL fuse because it will match the M8 screws on the battery terminals.
We will screw these directly on the battery terminal.
Now we will take a look at the wires sizes.
The charger delivers 5Amps to the battery.
If we use the table we can see that we can use a 16 gauge or 1,5mm squared wire.
The current from the inverter is 42Amps.
The closest we can see in the table is 50Amps.
If we keep the length of the wire under 6ft, we can see that we can use a 6 gauge or 16mm
squared wire.
What about C-rate?
The normal C-rate of a lead-acid battery is .2C.
This means that our 100Ah battery can deliver a nominal charge and discharge current of
20Amps.
We can calculate this is only 240watts.
To make a perfect system, you will need to add another battery in parallel in order to
respect the C-rate of the battery.
If your load is higher than 240Watts, then the capacity of the battery will be reduced.
If you want to learn more about c-rate i recommend watching my video about it.
Let's look at the charge and discharge time.
The 12V 100Ah battery contains 1200watt hours.
But only 50% of that is usable, otherwise, the battery will degrade fast.
This leaves us with 600Wh.
If the fridge or load you are using is 100watts, then you can use the battery for 6 hours.
After you have run the battery to 50%, we need to recharge it.
To recharge 600Watt hours we divide it by the power the charger delivers.
This equates to a 10 hour charging time.
There are no losses mentioned in these calculations.
Running the inverter non-stop will drain the battery.
Only turn on the inverter when you use it.
Here is a list of the components you need to make this system.
I have chosen for a battery from renogy which will cost you 200 dollars.
The inverter has good feedback online and it will cost you 46 dollars.
The 5amp battery charger will cost you 36 dollars, the anl fuse will cost you around
$10.
And the 6 gauge cables with lugs will cost you $16.
The total cost of this system is 308 dollars.
Optionally you can get a battery voltage monitor which will tell you how much power is left
in the battery.
To conclude this video you can see that this system is not that difficult to make.
It will be able to provide you with some emergency power to run lights or even a fridge.
The link to the schematic and parts will be in the description.
If you want to learn more about off-grid solar power, consider reading my bestselling book
about it which is for sale on amazon.