There's a particular kind of frustration that comes with waking up to a flat battery at camp. The fridge has gone warm overnight, the phone's dead, and suddenly that remote stretch of coastline feels a lot less idyllic.
Solar charging handles most situations brilliantly, but it has limitations. Overcast skies, dense tree cover, and overnight energy demands create gaps that panels simply cannot fill. This is where a portable generator like the Gentrax GTX6600 inverter generator earns its place in your setup, delivering fast, reliable power regardless of conditions.
These tips for charging deep cycle batteries with a portable generator will help you select the right equipment, charge safely, and get the most from every litre of fuel.
Why a Portable Generator is Your Battery's Best Mate
Generators offer three distinct advantages over other charging methods that make them worth the investment for serious off-grid travellers.
Speed and Consistent Power Delivery
Solar panels like the VoltX 12V 100W Fixed Solar Panel produce variable output depending on angle, cloud cover, and time of day. A generator delivers consistent, high-amperage power from the moment you start it. For larger battery banks or LiFePO4 systems requiring substantial energy input, this consistency translates to significantly faster charging times.
Where solar might trickle charge over an entire day, a generator paired with a quality charger can restore a depleted 100Ah battery in four to five hours.
All-Weather Reliability
Rain, heavy clouds, or simply being parked under trees—none of these affect generator output. This reliability matters most during extended trips when you cannot afford to wait for ideal conditions. Whether you're running a campsite fridge, powering medical equipment, or maintaining home backup systems during outages, the generator delivers regardless of the weather.
Multi-Purpose Versatility
Unlike dedicated solar setups, a generator can simultaneously run 240V appliances while charging your batteries. Get your morning coffee, power tools at a remote worksite, or charge multiple devices—all while the battery charger does its work in the background.
Compare this to the common practice of idling a vehicle engine to charge batteries. That approach consumes far more fuel, creates unnecessary engine wear, and delivers inferior charging current through most vehicle alternators.
Choosing the Best Generator for Battery Charging
Not all generators suit battery charging equally. Modern lithium batteries, in particular, require specific power characteristics that only certain generators provide.
Why Inverter Technology Matters for Modern Batteries
Inverter generators like the Gentrax GT3500 inverter generator produce what's called a pure sine wave—clean, stable electrical output nearly identical to mains power. This matters because LiFePO4 batteries contain sophisticated Battery Management Systems (BMS) that monitor and protect the cells. Rough or unstable power from conventional generators can confuse these systems or cause charging irregularities.
Conventional generators work fine for power tools and rough applications, but for anything with sensitive electronics—laptops, smart chargers, lithium batteries—an inverter generator is the appropriate choice.
Here’s what one of our customers said about the Gentrax GT3500:
"Generator arrived within days of ordering. Oil and fuel added and just 2 pulls on the rope it fired up flawlessly. Easy to use and understand unit seems robust and good quality . Will be using it to keep my house batteries on caravan charged as there is no 240v power where it’s stored. Very happy with this purchase."
The Quiet Operation Advantage
Modern inverter generators operate between 50 and 65 decibels at typical loads. That's roughly equivalent to normal conversation—a dramatic improvement over older conventional units that could exceed 80 decibels.
This quiet operation makes inverter generators practical for campgrounds with noise restrictions and residential areas during power outages. The Gentrax 4.2kW Camping Generator, available through Outbax, exemplifies this balance of power output and neighbour-friendly noise levels, running at only 58dB.
Fuel Efficiency and Eco-Mode Benefits
Inverter generators feature eco-mode technology that automatically adjusts engine speed to match electrical load. When you're running a battery charger drawing 500 watts from a 2kW generator like the Gentrax GT2000 inverter generator, eco-mode throttles the engine down rather than running at full speed.
The practical result: fuel consumption can drop by half during battery charging compared to running at full throttle. Quieter operation is a bonus.
Getting the Right Size Generator for the Job
A common mistake is sizing the generator to the battery rather than the charger. Your 200Ah battery doesn't determine power requirements—your charger does.
The formula is straightforward: Check your charger's input power rating in watts (usually printed on the label or calculated as Volts × Amps). Select a generator with continuous wattage comfortably above this figure to account for inefficiency and allow headroom for other small loads.
For example, a smart charger drawing 500 watts runs comfortably on a 1.2kW generator like the Gentrax GT1200. This compact unit offers excellent portability without sacrificing the power needed for effective charging.
Step-by-Step Guide to Charging Your Battery Safely
Generators produce carbon monoxide—an odourless gas that kills. Every safety step below exists for good reason.
Positioning Your Generator Correctly
Place the generator on flat, stable ground outdoors with the exhaust pointing away from any occupied spaces. Maintain a minimum five-metre distance from tents, caravans, annexes, and dwellings. This distance is non-negotiable regardless of wind direction or perceived ventilation. Never operate a generator inside a garage, under an awning, or in any partially enclosed space.
Connecting Your Smart Charger
Use a quality multi-stage smart charger designed for deep cycle batteries. These chargers automatically adjust output through bulk, absorption, and float stages to fully charge without overcharging.
Note: Connection sequence matters. Attach the charger clamps to battery terminals first (positive to positive, negative to negative), then plug the charger into the generator. This order prevents sparking at the battery terminals when power is applied.
Starting Up and Monitoring the Charge
Start the generator and allow it to run for approximately one minute before connecting loads. Keep eco-mode disabled initially to ensure stable startup power.
Once the generator runs smoothly, plug your charger into the 240V AC outlet. After charging begins, engage eco-mode to conserve fuel. Most Outbax smart chargers display clear indicator lights showing bulk, absorption, and float stages—glance at these periodically to track progress.
Must-Know Tips for Better Battery Charging
These refinements separate efficient charging from wasted fuel and shortened battery life.
Why the 12V DC Outlet Falls Short
That 12V "cigarette lighter" style outlet on your generator looks convenient, but it's designed for small accessories—phone chargers, LED lights, perhaps an air compressor. The outlet typically delivers 8-10 amps maximum and provides unregulated voltage.
For deep cycle battery charging, this translates to painfully slow charge rates and potential battery stress from voltage fluctuations. Always use a proper 240V smart charger for meaningful bulk charging.
Matching Chargers to Battery Chemistry
AGM and LiFePO4 batteries require different charging profiles. Lithium batteries accept higher charge rates and need specific voltage cutoffs to protect their BMS. AGM batteries require gentler absorption phases to prevent damage.
Quality smart chargers like the Victron 12V 30A SLA/LiFePO4 Charger offer selectable modes for different chemistries. Outbax stocks LiFePO4 batteries across popular capacities—12V 100Ah and 12V 200Ah options—alongside compatible chargers designed specifically for lithium chemistry.
Creating a Hybrid Solar-Generator System
The most practical approach for extended travel combines solar and generator charging. Solar handles daily maintenance charging during good weather, while the generator provides rapid top-ups during overcast periods or high-demand situations.
This hybrid strategy maximises fuel efficiency while ensuring you're never caught short when conditions turn against you. Outbax solar blankets and portable panels integrate seamlessly into this approach.
Final Thoughts on Powering Your Adventures
A quiet, fuel-efficient inverter generator provides the fastest and most reliable method for charging deep cycle batteries during off-grid travel or home backup situations.
Three things matter most:
- Choose an inverter generator for clean, electronics-safe power output.
- Always use a quality 240V smart charger matched to your battery chemistry.
- Prioritise safety through proper ventilation and generator placement away from occupied spaces.
Ready to secure reliable off-grid power? Explore the Outbax range of Gentrax inverter generators and VoltX lithium batteries to build a system that keeps your adventures powered—regardless of weather or location.
