A practical guide for Australian tourers, caravanners, and 4WD owners, with figures taken from manufacturer manuals
Charging a portable power station from a car takes somewhere between 3 and 22 hours of continuous driving, and the deciding factor is almost entirely the capacity of the unit. Distance is the wrong measurement here. Hours behind the wheel is the right one.
A vehicle accessory socket delivers a low, steady current that does not change whether you are crawling through Sydney traffic or sitting at 110 km/h across the Nullarbor. Two hundred kilometres of open highway and two hundred kilometres of stop-start suburban driving refill your battery by roughly the same amount, because what counts is engine running time, not ground covered.
The figures in this article are not estimates. They come from the manuals supplied with three units sold through Outbax, and in one case the manufacturer states the car charging time outright: 18 to 22 hours.
For plenty of Australian tourers the realisation arrives at the worst possible moment. They buy a large unit, plug it into the cigarette lighter socket on the first morning of a trip, and roll into camp that evening with the battery barely half full. Here is what the numbers actually look like, and what to do about them.
» MORE: Compare portable power stations by capacity and car input at Outbax
Why Your Car Caps Charging at Roughly 100W
Most 12V cigarette lighter sockets in Australian passenger vehicles are fused at 10 to 15 amps. That fuse protects the wiring loom behind your dashboard, which was never specified to carry a sustained heavy load.
Manufacturers design around it. The Outbax VoltX E600 lists a car input of 12V to 30V at 100W. The larger VoltX M2400 lists 120W maximum. Both units have AC inputs many times higher, so the ceiling is clearly a deliberate safety decision rather than a limitation of the battery.
Here’s what one of our customers said about the VoltX E600 Power Station:
“Great product , ran my 70ltr 12v fridge for a week using a 100watt solar panel for charging , no issues at all.”
Car Input Watts Are Not Maximum Input Watts
This is where most people go wrong. The M2400 accepts 2000W from mains and reaches full in about 1.5 hours. Through the car socket, it accepts 120W and the manual quotes 18 to 22 hours. Same battery, same unit, a difference of roughly fifteen times.
One more detail to check on the M2400: the car charger and the DC output share a single 120W circuit. Run a camp fridge from the unit while charging from the vehicle, and both are drawing on the same budget.
Does a 24V Socket Really Charge Twice as Fast?
Sometimes, and the manuals show exactly when.
The VoltX Topband V1200 lists a DC input of 12V at 8 amps or 24V at 10 amps. That works out to 96W on a 12V socket against 240W on 24V, which is a genuine two and a half times improvement from the same port. For a 1152Wh battery, that is the difference between roughly 13 hours of driving and roughly 5.
Here’s what one of our customers said about the VoltX Topband V1200 Power Station:
“The item purchased suited my requirements. The ordering, and dealing with the company was easy. The items were delivered quickly and in good condition. Very happy so far.”
Why Some Units Gain Nothing from 24V
Compatibility is not the same as benefit. The VoltX E600 accepts 12V to 30V, so it will happily take a 24V feed, but its input is capped at 100W regardless of voltage. Plug it into a truck socket, and you gain nothing at all.
Read the input line properly. A unit that states an amperage for each voltage will speed up. A unit that states a single wattage across a voltage range will not. It takes thirty seconds to check, and it decides whether a 24V rig is worth wiring a second socket for.
True 24V systems are not rare in Australia. Light trucks, buses, agricultural machinery, and a fair number of serious dual battery touring builds run them. If that is you, the voltage line on the specification sheet is the most valuable number on the page.
» MORE: Caravan and 4WD power setups: matching your unit to your vehicle
Driving Hours by Capacity: What Each Size Actually Needs
The table below translates capacity into the only unit that matters on tour, which is engine running time from empty to full.
| Battery capacity | 12V socket (100W to 120W) | 24V socket (200W to 240W) | Practical verdict |
|---|---|---|---|
| 250Wh to 300Wh | 3 to 4 hours | 3 to 4 hours if input is capped | Full refill in a morning of driving |
| 500Wh to 700Wh | 5 to 7 hours | 2.5 to 3.5 hours | Full refill on a long driving day |
| 1,000Wh to 1,200Wh | 12 to 14 hours | 5 to 6 hours | Roughly half a tank per driving day |
| 1,800Wh to 2,000Wh | 16 to 20 hours | 8 to 10 hours | Top up only. Plan a second source |
| 2,200Wh and above | 18 to 22 hours | 9 to 11 hours | A trickle rather than a charge |
Table 1: Driving hours to charge from empty. Bands of 300Wh, 1,152Wh, and 2,240Wh are confirmed against VoltX manuals. Others are calculated and include roughly 15 per cent for conversion losses.
You can run the sum yourself in ten seconds. Divide capacity in watt-hours by the car input wattage, then add about 15 per cent for conversion losses and heat.
The M2400 is the proof. Its 2240Wh divided by 120W gives 18.7 hours, and the manual quotes 18 to 22. The E600 gives 3.1 hours against a quoted 3 to 4. The arithmetic holds across the range.
The pattern is consistent. Below about 700Wh, vehicle charging is a genuine refill method. Above about 1,200Wh, it becomes a top-up that slows depletion rather than reversing it. That is not a criticism of the larger units. A 1,920Wh battery such as the Outbax ACE 2000W 1920Wh runs a fridge, lighting, and device charging for days. It simply cannot be refilled through a 10-amp fuse in one day of driving.
What Three Manufacturer Manuals Actually State
Specification sheets are more useful than most buyers realise, provided you know which lines to read. These figures are taken directly from the supplied documentation.
| Model | Capacity | Car input | Car charge time | Solar input | AC input |
|---|---|---|---|---|---|
| VoltX E600 (PB-20E) | 307.2Wh | 12V to 30V, 100W | 3 to 4 hours | 100W (DC 12-30V, Max) | 60W charger, 5 to 6 hours |
| VoltX Topband V1200 | 1152Wh (25.6V/45Ah) | 12V/8A or 24V/10A | About 13 hours at 12V | XT60, 11.5V to 53V, 550W max | 200 to 240VAC, 700W max |
| VoltX M2400 (S2200Pro) | 2240Wh (44.8V) | 120W max | 18 to 22 hours | XT60, 12V to 59V, 1200W, 2 to 6 hours | 2000W max, 1.5 hours |
Table 2: Charging specifications as published in the VoltX E600, Topband V1200, and M2400 manuals. All three use LiFePO4 cells. The M2400 is rated for 4,000 cycles and carries a 24-month warranty.
What the manuals do not do is translate any of this into driving hours for the mid-range units. That translation is left to the buyer, which is precisely why so many people get it wrong on their first trip.
What You Actually Need to Put Back Each Day
Charge time only matters in relation to what you are drawing out. The M2400 manual publishes runtime figures for common loads, and they are a useful sanity check before you commit to a capacity.
| Appliance | Rated draw | Runtime on a 2,240Wh unit |
|---|---|---|
| Car refrigerator | 65W | About 29 hours |
| Television | 110W | About 17 hours |
| Laptop | 60Wh per charge | About 31 charges |
| 12V LED camp light | 5W | About 380 hours |
| Electric cooker | 800W | About 2.2 hours |
| Smartphone | 3,095mAh | About 165 charges |
Table 3: Published runtime figures from the VoltX M2400 manual. Real results vary with appliance duty cycle and ambient temperature.
Run the comparison and the picture sharpens. A fridge rated at 65W draws roughly 77W of continuous equivalent power to reach that 29-hour figure, which is close to 1,850Wh across a full day. Eight hours of driving at 120W returns about 960Wh.
In other words, a day of driving will not keep a fridge running indefinitely on car charging alone. Real fridges cycle rather than run flat out, so a moderate driving day usually covers a fridge and very little else. Add lighting, device charging, and a television, and you are drawing down faster than the socket can refill.
That is the calculation most buyers never make, and it is the one that determines whether a trip ends with a working fridge or a warm one.
Charging Safely on Tour: Four Rules That Protect Your Vehicle
The risk with vehicle charging is rarely the power station. It is the starter battery under your bonnet.
- Only charge while the engine is running. Most vehicles cut power to the accessory socket at ignition off, which is the behaviour you want. The alternator does the work, not your starter battery.
- Find out whether your socket stays live. Some older models and certain utes keep the socket powered with the keys out. A power station left plugged in overnight will flatten a starter battery quietly.
- Watch cabin temperature. The M2400 manual specifies a charging window of 0°C to 40°C, and the E600 allows 0°C to 55°C. Australian summer cabin temperatures routinely exceed the lower of those. Keep the unit out of direct sun and clear of the cooling vents.
- Do not store it flat. VoltX advises recharging a stored unit periodically rather than leaving it empty between trips. A battery left at zero for months loses capacity permanently.
Cold matters less often here, but if you are charging on an alpine or inland winter morning, the manuals direct you to bring the unit up to temperature in a warm space before connecting anything.
When to Stop Using the Cigarette Socket and Upgrade
There is a clear threshold. Above roughly 1,200Wh, the accessory socket is no longer a serious charging method, and the sensible move is to bypass it.
DC-DC Alternator Chargers
A dedicated 12V to 12V alternator charger wires into the engine bay and draws 500W to 800W, well beyond anything a fused socket can deliver. That brings a large unit from empty to full in one to two hours of driving rather than twenty.
These units are standard fitment in well-sorted Australian touring builds for good reason. They also protect the vehicle, since a proper installation manages the draw on the alternator rather than leaning on a dashboard circuit that was never designed for sustained current. Installation is a job for an auto electrician unless you are genuinely confident with vehicle wiring.
Anderson Leads and the XT60 Port
Both the M2400 and the Topband V1200 ship with an Anderson to XT60 cable in the box, which tells you how the manufacturer expects serious users to charge. The XT60 solar port on the M2400 accepts 12V to 59V at up to 1200W, and the V1200 accepts up to 550W on the same port. An Anderson lead from a properly fused point feeds that input instead of the dashboard socket, and it stays connected on corrugated roads where a cigarette plug rattles loose.
Solar as the Companion, Not the Competitor
Solar and vehicle charging solve different problems. The alternator works while you drive and does nothing at camp. Solar does the reverse. The M2400 reaches full from solar in 2 to 6 hours using MPPT tracking, against 18 to 22 from the car socket. For trips longer than three days, most experienced tourers run both.
| Charging method | Typical power | Time to add 1,000Wh | Key consideration |
|---|---|---|---|
| 12V accessory socket | 96W to 120W | About 11 to 13 hours | Limited by a 10 to 15-amp fuse |
| 24V accessory socket | 200W to 240W | About 5 to 6 hours | Only helps if the unit rates amps per voltage |
| DC to DC alternator charger | 500W to 800W | About 1.5 to 2 hours | Wired direct to the engine, bypasses the socket |
| Solar through XT60 | 550W to 1200W rated | 2 to 6 hours in good light | MPPT units perform better in poor light |
| 240V mains at 50Hz | 700W to 2000W | Under 1.5 hours | Powered sites only, or before you leave |
Table 4: Charging inputs compared. Wattage figures reflect the rated inputs published for the VoltX E600, Topband V1200 and M2400.
» MORE: Portable power station buying guide- matching capacity to how you travel
The Bottom Line
Vehicle charging is measured in hours of engine running time, not kilometres. It is a genuine refill method below about 700Wh, a useful top-up to around 1,200Wh, and a trickle above that. A 24V socket halves the time only if the unit rates a separate amperage for 24V, and a DC-DC charger removes the constraint altogether.
Size the battery against your realistic charging setup rather than the headline wattage on the box. A smaller unit you can actually refill will serve you better on a long trip than a large one you cannot. Units including the VoltX E600, the Topband V1200, the VoltX V1800, the ACE 2000W 1920Wh, the VoltX M2400, and the DJI Power 1000 Mini are listed at Outbax with their input specifications alongside capacity for exactly that comparison.
