You've charged the battery, packed the fridge, loaded the car and headed away for the weekend.
Then somewhere around the second night, you start wondering how much power you've actually got left.
The fridge is still running. The lights are on. A couple of phones have been charged. Maybe you've used an inverter for a coffee machine or laptop. But is a 100Ah lithium battery going to make it through another night?
That's the part battery specifications rarely explain.
Knowing that a battery is rated at 100Ah is useful, but what most people really want to know is much simpler:
How long will it actually run my gear?
Start With What 100Ah Actually Means
A 100Ah lithium battery stores a certain amount of electrical energy, but amp hours alone don't tell the whole story.
For a typical 12.8V LiFePO4 battery, 100Ah represents roughly 1,280 watt-hours of stored energy.
That gives us a much more useful number because most appliances are rated in watts.
In simple terms, if an appliance continuously used 100 watts, a 1,280Wh battery could theoretically power it for around 12.8 hours.
Real-world systems aren't quite that neat. Inverter losses, cable losses, appliance cycling and battery protection all affect runtime, but watt-hours give us a very good starting point.
Your Fridge Probably Uses Less Power Than You Think
A portable fridge doesn't normally run its compressor continuously.
It switches on, cools down, switches off and repeats that cycle throughout the day.
That means a fridge that might draw 40 or 50 watts while the compressor is running can average considerably less over 24 hours.
Ambient temperature makes a big difference too. A fridge sitting in direct sunlight in the Pilbara will work much harder than the same fridge under an awning on a cool autumn weekend.
As a rough example, if your fridge used around 30Ah over 24 hours, a 100Ah lithium battery could potentially keep it operating for several days before charging was required.
Add lighting, phone charging and other accessories, though, and that runtime begins to change.
The Little Loads Add Up
It's rarely one appliance that catches people out.
It's everything happening at once.
A phone charger doesn't use much power. Neither does an LED light. A water pump may only run for a few minutes at a time.
But add them all together over a couple of days and they become meaningful.
A Typical Weekend Setup
Imagine a setup running:
- A 12V fridge
- LED camp lighting
- Two phones
- A water pump
- A laptop for an hour or two
- Occasional inverter use
For many travellers, a 100Ah lithium battery can comfortably support that sort of setup across a weekend, particularly if there's some solar input during the day.
The important word there is particularly.
How often you recharge matters just as much as how much capacity you start with.
High-Power Appliances Change the Equation Quickly
This is where people sometimes get caught out.
A fridge might quietly sip power all day, while a coffee machine can demand a huge amount for a very short period.
Induction cooktops, kettles, hair dryers, microwaves and larger coffee machines generally operate through an inverter and can draw hundreds or even thousands of watts.
Run them for only a few minutes and the total energy consumption may still be manageable, but use them repeatedly and your battery percentage can fall surprisingly quickly.
It's Not Just About Energy
You also need to consider how much current the battery can deliver at once.
A 100Ah battery with a 100A maximum continuous discharge rating, for example, has limits on the size of inverter load it can support continuously.
That's why battery capacity and discharge capability need to be considered together when designing a power system.
Starlink Can Be a Bigger Load Than People Expect
Remote internet has become part of the camping setup for plenty of travellers, especially people working from the road.
Starlink isn't necessarily a massive load at any one moment, but it may operate for hours.
That's what makes it different from something like a coffee machine.
Small loads running continuously can consume more energy over a day than large appliances that only operate for a few minutes.
If Starlink, a laptop and a fridge are all running for much of the day, a 100Ah battery can still work well, but solar or alternator charging becomes increasingly important.
Why Lithium Gives You More Usable Capacity Than AGM
This is one of the reasons a 100Ah lithium battery can feel considerably larger than the 100Ah AGM battery it replaces.
Traditionally, AGM users have been encouraged to avoid repeatedly discharging their batteries too deeply if they want reasonable service life.
LiFePO4 batteries are designed to tolerate much deeper cycling.
So even though both batteries might say 100Ah on the case, substantially more of that capacity can usually be used from the lithium battery.
If you're considering making the switch, we've gone into this difference in more detail in AGM vs Lithium: Is It Finally Time to Upgrade?.
Solar Completely Changes the Conversation
Without any charging, your battery is essentially a bucket of stored energy that gradually empties.
Add solar and you're topping that bucket back up throughout the day.
If your solar panels replace roughly the same amount of power you're using each day, a 100Ah battery can support an off-grid setup for much longer than its capacity alone would suggest.
That's why asking, "How long will a 100Ah battery last?" sometimes isn't the right question.
A better question is:
How much power do I use each day, and how much of it can I put back?
Once those two numbers are reasonably close, battery capacity becomes more about getting through overnight periods, cloudy days and heavier-than-normal usage.
Bluetooth Makes This Much Easier
Older battery setups often required a bit of guesswork.
You'd look at voltage, make an estimate and hope there was enough capacity left for the night.
With a Bluetooth-enabled lithium battery, you can open an app and see exactly what's happening.
You can monitor state of charge, current draw, charging performance and battery temperature without pulling panels apart or reaching for a multimeter.
That makes it much easier to learn what your own setup actually consumes.
After a few trips, you'll know whether your fridge typically uses 20Ah or 35Ah per day, how much your inverter really costs you, and whether your solar is keeping up.
It's one of several features we cover in Five Features That Separate Premium Lithium Batteries from Cheap Imports.
So, Is 100Ah Enough?
For many weekend campers, caravans and 4WD touring setups, yes.
A quality 100Ah lithium battery can provide a very capable foundation for running a fridge, lighting, electronics and occasional inverter loads.
If your setup includes larger appliances, long periods of Starlink use or extended stays away from charging, you may need either more battery capacity or more charging capability.
The advantage of starting with a well-designed lithium system is that you can plan around what you genuinely use rather than guessing.
The VoltGo VLRV1280A 12.8V 100Ah Bluetooth LiFePO4 Deep Cycle Battery provides 1,280Wh of stored energy, Bluetooth monitoring and a 100A continuous discharge capability, making it a strong starting point for caravan, RV and off-grid installations.
If you're still working out what type of lithium battery best suits your setup, start with Choosing a Lithium Battery Doesn't Have to Be Confusing. It covers the bigger picture, including battery capacity, charging, Bluetooth, heating and the features that actually matter when you're travelling.
