How to Stop Your Car Battery Going Flat While Parked
There’s nothing quite like coming home from a holiday, getting back to the car, turning the key and hearing… absolutely nothing.
A flat battery is one of those small problems that can quickly become a very annoying one. Whether your car has been sitting on the drive for two weeks, parked in a garage over summer, or left in an airport car park while you’ve been away, the battery can slowly lose charge even when the car isn’t being driven.
Modern cars are especially good at quietly using power in the background. Alarms, keyless entry systems, trackers, clocks, onboard computers and dashcams can all place a small drain on the battery. Leave the car long enough, particularly if the battery was already low, and you may return to a vehicle that simply will not start.
Why car batteries go flat when parked
A car battery does not need to be faulty to go flat. If the car is not being used, the battery is still powering small systems in the background. This is often called parasitic drain.
The problem is worse if:
• The car only did short journeys before being parked
• The battery is more than a few years old
• The car has lots of modern electronics
• A dashcam or tracker is still active
• The vehicle is parked for a week or more
• The battery was not fully charged before you left
Short trips are a common cause. A quick run to the shops, school or work may start the car, but it often does not give the alternator enough time to properly recharge the battery. So when you then leave the car parked, it may already be starting from a low state of charge.
Before you leave the car at home
If your car is staying at home while you go away, the best thing you can do is connect it to a smart battery maintainer.
For a healthy battery that simply needs to be kept topped up, the OptiMate 2 Duo is a simple and effective choice. It is designed to charge and maintain 12V batteries automatically, then switch into safe long-term maintenance once the battery is full.
That means you can leave the car parked on the drive or in the garage knowing the battery is being looked after, rather than slowly draining day by day.
If your battery has already gone flat before, is slow to start, or you suspect it is not in great condition, the OptiMate 5 is the better option. It can maintain a healthy battery, but also has the ability to recover many deeply discharged batteries. That makes it a stronger choice if you want both prevention and recovery in one charger.
Can you leave a smart charger connected while you’re away?
With a proper smart charger, yes. That is exactly what a battery maintainer is designed for.
Older trickle chargers could keep pushing power into the battery, which was not ideal for long periods. A smart charger is different. It monitors the battery, charges it correctly, then switches into maintenance mode. It only tops up the battery when needed.
This makes it ideal for:
• Cars left at home during holidays
• Second cars
• Classic cars
• Vehicles stored in garages
• Cars that only do short journeys
For easy use, it is worth fitting a permanent connection lead to the battery. Once fitted, you simply plug the charger in when the car is parked. No messing around with clips every time.
What if you’re parking at the airport?
Airport parking is different because you usually will not have access to a mains socket. In that situation, the best option is the OptiMate Solar 20W Car Kit.
The solar kit uses daylight to help maintain the battery while the car is parked. It is particularly useful if your car is going to be left for several days or weeks in an open car park. Instead of relying on the battery to cope on its own, the solar panel helps offset the background drain from the vehicle’s electronics.
It is a much better option than hoping for the best, especially if your car has shown any signs of a weak battery before.
Quick checklist before you go away
Before leaving your car parked, run through this simple checklist:
1. Give the battery a full charge before you leave.
2. Unplug unnecessary accessories such as USB devices or dashcams if safe to do so.
3. Make sure all lights and interior lamps are switched off.
4. Lock the car properly so the systems can go to sleep.
5. If the car is at home, connect an OptiMate 2 Duo or OptiMate 5.
6. If the car is at the airport, use the OptiMate Solar 20W Car Kit.
A flat battery after a holiday is frustrating, avoidable and often expensive. The good news is that a little preparation goes a long way.
If the car is staying at home, a smart maintainer like the OptiMate 2 Duo is the simple solution for keeping a healthy battery topped up. If you want extra reassurance and recovery capability, the OptiMate 5 is the stronger choice.
And if the car is being left at the airport, where mains power is not available, the OptiMate Solar 20W Car Kit gives your battery support while you are away.
Look after the battery before you leave, and there is a much better chance your car will be ready to start when you get back.