Using batteries properly
Translated from the Spanish original. Read in Spanish
Misunderstandings about this are very common, because over the last 20 years mobile devices have adopted new types of battery technology. So the aim of this note is to give a brief overview of the main types of batteries our devices may be using and how to extend their life in each case.
The three most common types of batteries are:
NiCd
NiMH
Lithium-ion / Lithium-polymer
Nowadays, however, most mobile devices use lithium-ion or lithium-polymer batteries. We can tell what type of battery our device has simply by quickly reading the label on it and looking for one of the terms above.
Probably the most talked-about aspect of battery use is the so-called “memory” effect. Basically, if charge–discharge cycles aren’t complete (for example, the battery is recharged when it’s only at 50% of its capacity), the battery starts behaving as if it only ever had half its charge, because it “forgets” its full capacity. However, this only applies to NiCd batteries and, to a lesser extent, NiMH.
Recommended use
NiCd
– An initial charge of 14 to 16 hours may be needed
– This type of battery is robust and performs better with use
– Interruptions during charge cycles can cause heat to build up
– A full discharge every so often prevents the memory effect. Every 1 to 3 months is recommended.
NiMH
– An initial charge of 14 to 16 hours may be needed
– This type of battery is robust and performs better with use
– Interruptions during charge cycles can cause heat to build up
– The memory effect is smaller than with NiCd. Still, a full discharge every so often is recommended, specifically every 2 to 3 months.
Lithium-ion / Lithium-polymer
– Initially, it doesn’t need to be fully charged or calibrated
– It’s important to keep some charge in it. Otherwise the protection circuit can be damaged.
– It will take longer to charge, but you don’t need to switch the device off.
– A partial charge is better than a full one
– Partial discharges don’t affect the battery
– Full discharges shorten the battery’s life
– It has no memory effect
Some considerations about lithium-ion / lithium-polymer batteries (the ones found in almost every mobile device today)
Why do some people say you need to switch the device off while charging, or that you shouldn’t leave the battery in if the device is plugged into the mains?
– The key issue is temperature. These batteries should be kept below 50 °C while charging, although to maximise their life it’s recommended to charge them between 10 °C and 30 °C. It’s also worth noting that devices generally cut off charging when we’re working plugged into the mains with the battery connected. For that reason, this kind of use isn’t really a problem. Even so, the extreme of always using the device plugged in, like a desktop PC, isn’t recommended either. A reasonable approach could be to run on battery, unplugged from the mains, at least every one or two weeks.
What precautions should you take?
If you’re not careful, these batteries can, in the worst case, heat up to 500 °C and/or explode.
What shouldn’t you do?
– Charge them below 0 °C
– Short-circuit them, tamper with them or damage them physically in any way
– Expose them to temperatures above 130 °C
References:
MIT’s Computer Science and Artificial Intelligence Laboratory
I. Buchmann, Batteries in a Portable World, www.buchmann.ca
T. R. Crompton, Battery Reference Book, Newnes, 2000
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