How to make your tech devices' batteries last longer

Travelling from Auckland to Wellington, you may notice your phone battery going flat despite fully charging it before you set off - this is just one of the ways the power is being drained without you realising.

Dr Ulrich Speidel, senior lecturer at University of Auckland's School of Computer Science, says the further you are away from a cell phone base station, the "louder your phone has to shout to be heard", and the more battery power it needs to do this.

"It uses vastly more power when it needs to talk to cell sites that are a couple of kilometres away as opposed to a couple of hundred metres."

And of course, if you add on downloading or uploading, more power will be used, he says. So it's best to switch your phone off when you're passing through those rural areas or take your SIM card out, if you can.

Charging responsibly

If you're using the cigarette lighter port with a tiny charge or cable that can't pump through enough current, whilst also keeping the kids entertained on your device, then you may still well find you're battery draining, Speidel says.

So it's key to get the right tools.

Consumer NZ product test writer Nick Gelling says your device battery can suffer long-term damage if you're consistently careless about how much you're charging or not charging.

"When the charge drops to low, below 20 percent, it can cause long-term damage [if it's always happening] but also if your laptop is sitting at 100 percent all the time, that can also put a strain on the battery so try and keep it in that middle range of close to 50 percent as you can."

A 10,000 mAh (milliamp hours) power bank can recharge a typical phone twice, a 20,000 mAh one about four times but these ones are also the largest you're allowed to take on planes.

"Then you can go for several days without having to plug into a wall," Speidel says.

Navigation

Gelling says wireless functions like Bluetooth and location services are more battery efficient than they used to be about five years ago.

Go with a simple map navigation map (e.g. ones without changing views or satellite view) or preload it when you're still at home - this way you're not only conserving data but also won't have the extra load on your battery with it needing to communicate with a faraway cell site, Speidel says.

App usage

When's the last time you had a look at how many tabs you had open in your browser? Practising browser 'hygiene' will stop those tabs from loading in the background, Speidel says.

Most of the "bigger" apps have been programmed to optimise power use but ones that you use once in a blue moon can turn into power hogs in the background, Speidel says. Android and Apple phones will often have a setting which will tell you how much battery is being used by apps.

Gelling suggests limiting ways your screen is used, including lowering brightness, turning off app notifications, setting your screen to automatically sleep after being idle for a minute, and go into battery saving mode from the start of your trip.

"[Battery saving mode will] automatically dim your brightness and make a few other little savings in the background and you can enjoy that benefit for the whole day rather than it just kicking in when you get desperate."

If your kids are staying entertained on their tablet, turn on flight mode to automatically switch off WiFi and other apps that use data. You can still turn Bluetooth back on if you need them for their headphones.

Camping without losing charge

Carry a torch instead of switching on your phone's powerful LED light, Speidel says.

Outdoor enthusiast Jono Collins of NZ Fun Adventures says small power banks are affordable and will suit most campers, with higher spec options able to be charged using a plug-in solar panel and can power pretty much anything.

Power stations are a bit more pricey but helpful if, say, you want to take your kitchen mixer camping, Speidel says.

"Have a look at the wattage (that tells you whether it'll power a laptop or perhaps something gruntier) and the amp-hour rating of the battery in the power station. Don't buy one that doesn't declare these."

How do I know when it's time for a new battery?

"The industry standard for tech devices seems to be when the device has 80 percent of its original capacity - if your laptop lasted for 10 hours when you got it new but now it only lasts for eight then maybe that's a sign of the battery degrading and it's time to consider replacement," Gelling says.

However, Gelling says Consumer NZ thinks that's a bit extreme and you can probably keep using it - it's a personal preference.

To give it a long life, avoid the extremes of battery capacity and maintain it between 20 percent and 80 percent whenever you can, Gelling says.

If you can use your laptop plugged in, it's better for long term health too, he says.

"The other thing with laptops is that when they are plugged into the wall, and you're using them, that tends to bypass the battery. So the battery isn't actually being used in that case, the computer is running off of mains power. So that is ideal for keeping the battery in a good way because it's not getting charged and discharged all the time."