This system is a medium sized backup system used as a backup power source.
When the grid goes down, you can power your fridge from the battery. You can also run a microwave.
With the recent hurricanes in the US, this would be a great system to use as a backup to power your fridge(s).
This system can also be used in a van. When you are in a campground, you can recharge the batteries from shore power and when you are on the road, you can run the loads from the battery.
Parts used
| Part | Price |
|---|---|
| 24V 2000W Giandel Inverter | $349 |
| 24V 20A charger | $169 |
| 24V 200Ah battery | $1199 |
| MRBF fuse block | $31 |
| 30A MRBF fuse | $16 |
| 100A MRBF fuse | $17 |
| 6AWG cable | $32 |
| 6AWG M8 lugs | $10 |
| Total | $1,823 |
Optional:
Description
I have chosen a 24V 200Ah battery for a total storage capacity of 5,120Wh. You can add more batteries in parallel if you want the battery to last longer. However, as you will see later, you can add a generator to it to recharge the batteries on gasoline or propane.
Let’s calculate the estimated runtime for some common appliances:
- 300W fridge with 30% duty cycle: 1.8 days
- 50W laptop on AC: 78 hours
Curious how i calculate battery runtime with a fridge? here is how i do it:
300W* 8 hours = 2,400Wh daily power consumption
inverter idle power consumption is 15W for 24h = 360Wh
2,400Wh + 360Wh = 2,760Wh of power consumption per day
battery capacity is 5,120Wh/2,760Wh = 1.8 days of runtime.
Why do i use 8hours? A fridge is not running all the time. Depending on the environment temperature. 8hours is a duty cycle of 30% which is typical. I have tested this with my own fridge (check the video here).
The fuse we will be using for the charger is 30A because the maximum current the charger can deliver is 20A with a 12AWG or 4mm² wire.
The fuse to the inverter will be 100A with a 6AWG or 16mm² wire.
I have used an MRBF fuse because it bolts down on the battery terminals so you need less lug crimping.
You can also get pre-crimped battery cables here (6AWG with M8 or 5/16″ lugs).
Adding a Generator
I have added a generator to the system. The running power of the generator is 1,850W on gasoline and 1,665W on propane. The 29.2V 20A charger has a power rating of: 29.2V*20A=584W.
I recommend running the generator at 50-70% of its max power output (1,850W*0.7=1,300W max). So you can add another battery charger to the system, you will have a total charging power of 1,168W. It will take: 5,120Wh/1,168W=4.5 hours to recharge the battery.
Questions? Send me an email here.