Shot down in flames: Mobile phones batteries and fires

The picture of the culprit: Samsung s4 phone that caught fire

The picture of the culprit: Samsung s4 phone that caught fire. Courtesy of Steve Noviello facebook page.

FoxDFW reports a story of a Samsung Galaxy s4 phone placed under a pillow getting so hot it melted the plastic and scorched the bed clothes.

“The whole phone melted” said her dad, Thomas. “The plastic, the glass. You can’t even really tell that it was a phone.” Tolfree says her phone slipped under her pillow as she fell asleep, and the smell of something burning woke her up in the night.

“I didn’t think much of it, so I went back to sleep, and then I woke up again and it was more prominent,” said Tolfree. Her dad suspects the phone overheated, causing the battery to swell and start a fire.

Samsung added something perhaps important

A spokesperson for Samsung says their products are safe, and pointed out that the battery inside the phone was a replacement unit and not an original Samsung part.

Nevertheless, the company does agree there is a need for consumer education when it comes to rechargeable batteries. That’s exactly why they post a warning in their user guide, which specifically states covering one of their devices with bedding or other material could restrict airflow and cause a fire.

To their credit, Samsung agreed to replace the bedding even if they will blame it on the non-Samsung battery.

Some of the commentators on the site as simply asinine especially the ones moaning about why a 13 years old has a nice smart phone. Why does that even matter? If she had been 22 year old, would that make it ok? There are some interesting comments in there about Galaxy getting hot which makes putting it in a case impractical. A simple internet search shows many people saying the same thing about the Galaxy.

Knowing something about the industry, the temperature of the phone is going to be a function of how much you are asking it do to. When using the phone to process High definition video for example, it  may put itself into an overdrive mode where it ups the voltage to get more frequency performance out of it. Both increasing voltage and frequency directly influence how much power is produced which gets converted to heat. Add in to that background tasks like continous telephone transmission to check for phone calls and messages, GPS, program updates and  running multiple programs simultaneously, and the electronics is being asked to do a lot.  Unfortunately, there is nowhere for the heat to go but be radiated out through the case.

Now add the battery. This uses Lithium ion battery which has properties of packing in a lot of battery power in dense space. It also has an advantage of being charged quickly and can be charged multiple times. However, in the wrong circumstances, if it has a defect inside it, it can result in internal short circuit which go into thermal runaway. Lithium ion batteries are the same technology that is used in the dream liner 787 which unfortunately had at least two instances of catching fire while in the airport. Tesla electric cars also can be affected by similar problem. So have laptop computers. The Economist does a good job explaining this and why we are stuck with them.

So are there some things you can do to help yourself? You bet your bottom dinari there is. Ranjit has a great you tube which illustrates how to do this with the S4. An easy one is disabling air gestures where it should also extend battery life. He specifically discusses heating under charging where there is an obvious explain to this: the charger has more current output : 2A instead of prior generation of 1A. It is there to charge the battery faster but side effect is more heat.

How to fix some heat problems with the S4

What was missing from the fox story is how Ms Tolfree was using her phone. If she was charging it at the same time as well as running the phone full out and the battery is defective, then this would be a perfect storm. The bedding acted as a thermal insulator and trapped the heat.

People are blaming Samsung but this is something potentially impacting all phones. Even iphones can suffer from problems during charging – see Daily mail.

A common observation though is impact of charging it. Many of these are rapid chargers which give out higher currents. Get a short in the cable and you can be in trouble. You may not realise it but it is not the voltage that kills you when you are electrocuted but the current. An electrostatic discharge by walking on  carpet say is many thousands of voltages but current is tiny. Even if you are hooking up a rapid charger via USB be way of the higher current. There are different standard of USB where higher USB, the more current it is capable of supporting.

While discussing fire form charging, not looked at here is the quality of the cable. I owned an iphone 4 and was forever having to buy new cables due to it breaking at the interface to the connector. In addition to it breaking, it has the potential to short wires inside – the classic cause of electrical fire.

The problem situation is where it catches fire when NOT on charge. There was one case of  a 14 years old student in Maine getting second degree burns which her iphone 5 caught fire in her pocket. There is speculation that the phone broke when she had it in her back pocket and sat on it. Thankfully, this does appear to be a very rare case where a prior instance of an iphone 4 catching fire was attributable to a botched screen replacement where it had punctured the battery pack. Thus, it seems these are not random events but had attributable causes.

The walk away is be aware of portables are sources of danger. If your handheld is running hot and your battery is always running low, look at what your phone is actually doing. Close down programs and shut down unnecessary things like location finders. Take a look at how you have email settings : The more frequently it checks, the more power it is consuming.

If you are using a rapid chargers, be especially aware of this. Be cautious of its interaction with non-supplier batteries where you may have a false saving. Pay attention to you plugs and cables as well and make sure they are compatible.

Think “Hot and Bothered”: If running hot, you need to be bothered.

Claude.

Claudius