Charging while you drive: the touring loops that actually top up your battery

I had a bloke email me last month convinced his DC-DC charger was faulty because his battery was sitting at 40% every evening despite "driving all day." Turned out he was doing the Great Ocean Road, stopping every eight minutes for a lookout. Forty minutes of actual driving spread across six hours. His charger wasn't broken. His itinerary was just never designed to charge anything.

That's the bit nobody talks about when they spruik solar-friendly touring or the best free camps. The shape of a route, not just the region, decides whether your alternator and DC-DC charger are doing real work or barely ticking over. I've pulled apart enough setups now to know the difference between a lap that tops your battery up for free and one that quietly runs it down no matter how good your gear is.

Why driving hours matter more than distance

A DC-DC charger like a Victron Orion-Tr or a REDARC BCDC only does meaningful work once the alternator's actually spinning at decent RPM and the engine's been running long enough to get past the initial bulk phase. Most 20-40A units need roughly 20-30 minutes of continuous driving before they're delivering anywhere near rated output, longer again if you're idling through traffic or crawling a 4WD track in low range.

So distance is the wrong number to plan around. Hours behind the wheel, in reasonably continuous stretches, is what matters. A 300km day on the Birdsville Track with three hours of solid driving does more for a depleted lithium bank than a 150km day on a coastal strip broken into a dozen ten-minute hops between beaches and cafes.

This is why long, straight, remote-feeling routes are secretly good news for your electrics, even though everyone assumes remote means "no charging, better bring more panels." The driving itself is the charging.

Routes that genuinely charge you

The Birdsville Track and Oodnadatta Track are two of the better examples I've measured. Long, largely uninterrupted driving days, often four to six hours between fuel stops at places like Mungerannie or William Creek. If you're running a 40A DC-DC charger off a reasonable alternator, you can comfortably put 100-150Ah back into a depleted lithium bank across one of those days, more if your alternator's a modern smart-charging unit that ramps voltage under load (which, annoyingly, some do inconsistently — worth testing your own rig rather than trusting the spec sheet).

The Savannah Way across the top of the country works similarly well, long driving stints between towns, decent engine load from the terrain, and enough daylight hours in the dry season that solar's doing its share too. If you're linking it into the full Savannah Way itinerary from Cairns to the Kimberley, the driving days genuinely bank you power you can spend on the rest days.

Even a highway crossing like the Eyre Highway, which I've written about before as a trap for solar panels because of the low winter sun angle, is actually fine for DC-DC charging. Long straight driving days at consistent RPM are exactly what a DC-DC charger wants, even if your panels are underperforming on that same stretch. It's a good illustration that solar and alternator charging don't rise and fall together. Assess them separately.

Routes that quietly flatten you

Coastal touring loops with a town every 20-40km are the opposite case, and the East Coast Run from Melbourne to Cairns is the classic offender if you're doing it slowly. Gorgeous, no argument, but the driving pattern is stop-start: fifteen minutes here, a lookout, a coffee, another twenty minutes, a caravan park. Your alternator barely gets out of bulk phase before you've parked again, plugged into 240V or not, and the fridge, lights and any device charging just keep drawing down.

The Victorian High Country around Wonnangatta and Dargo is similar in a different way. Low range crawling for hours, which is hard on the vehicle and genuinely poor for charging, since alternator output at idle-adjacent RPM in low range is a fraction of highway output. Great touring, bad charging day. I always tell people doing that loop to plan a genuinely flat battery going in and a full one at Dargo or Omeo where they can sit on mains power for a night.

Short regional loops close to home, weekend trips to somewhere like the Mid North of South Australia, sit in the same category. Lovely underrated touring, short driving legs, and if you're relying purely on alternator charging without solar backup you'll likely arrive with less charge than you left with, especially in a fridge-and-lights-only setup with no panels at all.

Reading your own itinerary before you leave

The way I actually plan this now, before a lap, is to sketch out each day as driving hours versus stationary hours, not kilometres. If a day's got under two hours of continuous driving, I mentally file it as a "spend" day for the battery, not a "charge" day, and I plan camp accordingly, maybe that's the night we run the generator for an hour, or the night we don't run the fridge on eco mode and expect a top-up from panels instead.

If you're touring with a family and stopping constantly for kids, this matters even more, because family lap patterns are naturally choppy. Worth reading alongside what your kids' devices actually cost you in amp-hours if device charging is stacking on top of an already charge-poor driving pattern.

I'd argue most people plan routes purely on scenery and distance and treat power as something solar or a bigger battery will fix. In my experience the route shape fixes or breaks your power budget before either of those does. A 200Ah lithium bank on a stop-start coastal crawl can end up more stressed than a 100Ah bank on a long desert crossing, purely because of how the charging opportunity is spread across the day.

Matching your DC-DC charger to the pattern

If your touring style is genuinely stop-start, coastal, town-to-town, it's worth sizing your DC-DC charger and solar input assuming the alternator will underdeliver most days. A 25A charger might be plenty on the Birdsville Track and simply inadequate for a Great Ocean Road style lap where you never get 30 minutes of continuous driving. I've seen people oversize the charger and undersize the solar for exactly this reason, when it should be the other way round for that kind of trip.

For readers running the full Big Lap of Australia, this is worth a proper look at your whole route before you leave, not just the remote sections. The desert crossings will look after themselves. It's the pretty coastal detours either side that need the backup plan, whether that's a bigger solar array, a genset for overcast runs, or just accepting you'll top up on mains power more often than the brochure photos suggest.

None of this is really about better gear. My REDARC's the same unit whether I'm on the Oodnadatta or dawdling down the Sapphire Coast. The difference is entirely in how the day's structured, and that's the one variable most people never actually plan around.