Battery
Think of a battery like a fuel tank—but instead of gasoline, it stores energy. The size of the tank (measured in watt-hours) tells you how much energy the battery can hold and deliver. This is called its capacity, and it determines how long you can power your devices before needing to recharge.
Watt-hours (Wh) → how much energy is inside the battery. Think of it as the size of the “fuel tank.”
Charging → depends on your charger or solar panel output (measured in watts). That tells you how fast the tank fills.
Powering devices → depends on how many watts your device needs. That tells you how fast the tank empties.
(Watt hour) Wh = Battery voltage x battery amp hour
What that means...Battery voltage multiplied by the amp hours = the Watt hours
How to use this:
Here are some basic numbers:
12v x 10ah = 120Wh
12v x 20ah = 240Wh
12v x 30ah = 360Wh
12v x 50ah = 600Wh
12v x 100ah = 1200Wh
12v x 200ah = 2400Wh
24v x 10ah = 240Wh
24v x 20ah = 480Wh
24v x 30ah = 720Wh
24v x 50ah = 1200Wh
24v x 100ah = 2400Wh
24v x 200ah = 4800Wh
Did you notice how the watt hours increased when the battery voltage increased?
That's because:
Amp-hours (Ah) measures the amount of charge the battery can store. Think of it as the “size of the tank.”
Voltage (V) measures the electrical “pressure” pushing that charge.
When voltage increases while Ah stays the same, the energy stored in the battery (Wh) goes up because the same amount of charge is being pushed harder, which means more total energy is available.
Think of it like this...imagine water in a tank:
Ah = gallons of water.
Voltage = water pressure.
Wh = total “energy” you get from releasing that water.
If you increase the pressure (voltage) without changing the gallons (Ah), you get more energy out.
So higher voltage batteries store more energy even if their Ah rating is the same.
48v x 10ah = 480Wh
48v x 20ah = 960Wh
48v x 30ah = 1440Wh
48v x 50ah = 2400Wh
48v x 100ah = 4800Wh
48v x 200ah = 9600Wh
1. Higher Voltage (V) delivers more efficient power:
Higher voltage can push more energy with less current, which reduces energy lost as heat in wires and you can use smaller wire.
Some appliances or tools require higher voltage to operate.
Higher voltage batteries lose less energy over long cables.
2. Higher Amp-Hours (Ah)
More Ah means the battery can supply power for a longer time before needing a recharge so you get a longer run time
It supports multiple devices at once without quickly draining the battery.
3. Combined Benefit (Wh = V × Ah)
Higher voltage and higher Ah together mean the battery stores and delivers more energy.
Adds more flexibility giving you the option of choosing a battery that fits your device needs and how long you want it to last.
Real life example:
First, we calculate the total energy (Wh) for each battery:
12V 30Ah → 12 × 30 = 360 Wh
24V 30Ah → 24 × 30 = 720 Wh
48V 30Ah → 48 × 30 = 1,440 Wh
Now let’s compare how long each could power some common devices. I’ll use typical power draws:
Device
Power (Watt)
12V 30Ah (360Wh)
24V 30Ah (720Wh)
48V 30Ah (1,440Wh)
LED Light
Laptop
Mini Fridge
Phone Charger
Small Fan
CPAP Machine
10 W
60W
50W
10W
30W
50W
~36 hours
~6 hours
~7 hours
~36 hours
~12 hours
~7 hours
~72 hours
~12 hours
~14 hours
~72 hours
~24 hours
~14 hours
~144 hours
~24 hours
~28 hours
~144 hours
~48 hours
~28 hours
Things to consider:
Here’s where you might expect me to talk about power needs (Watts), runtime, or voltage capacity—but we already covered that. By now, you should have a pretty good idea of those things.
What I really want to focus on is portability, budget, and expandability.
Let’s be honest—nobody’s going to haul a 50-pound generator on a 100-mile hike. Nobody wants to spend hundreds of dollars on a generator that can’t charge multiple devices overnight. And nobody wants a system that can’t grow with their needs over time. And for me, the most important thing is using batteries that are popular and easy to find, so replacements or expansions are never a hassle.
Choosing a generator that’s easy to carry, affordable, and upgradeable is just as important as the numbers on the spec sheet.
Why it matters:
The Battery:
