Something I’m quite often asked about the Cube is – can the battery be replaced, and if not, how long will it last?
The first part is easy to answer: no, the whole thing is sealed in and can’t be replaced. If you want a device where you can replace the battery, you would need a battery compartment and that would mean a visible seam, so it would not pass inspection.
As for the battery life, I could give you a glib, made-up answer – say, 10 years – but that would just be a guess, and who knows where anyone will be in 10 years?
So let me give you some information and you can draw your own conclusions.
The Cube is powered by a lithium polymer battery. Similar to what you have in your cellphone. Lithium polymer batteries can generally be charged and discharged about 400 times. A cellphone is usually charged and discharged fully every 24 hours – sometimes more often – and usually they last about 2 years before performance deteriorates.
But the Cube is very different. First of all, you are very unlikely to put it through a full charge/discharge cycle. You are more likely to be topping it up regularly, rather than waiting for it to go flat (which it won’t actually do – it goes into sleep mode when the voltage drops below a certain level). So you can charge it a lot more than 400 times.
Second, unlike a phone, the Cube only draws significant power when it is transmitting. Even between transmitting each number it puts itself into sleep mode for a few seconds.
Now to get into some figures, for those who like them. The battery has a capacity of 30 milli-amp hours, which is to say it can deliver a milli-amp for 30 hours. The Cube, in sleep mode, takes about 5 micro amps which translates into 6000 hours, which is 250 days. Now it’s not going to stay fully charged in sleep mode for 250 days because the battery has its own self discharge rate, but it’s certainly possible for it to remain useable and charged for several weeks.
When you are using it, the Cube transmits constantly. On a single charge, it will transmit for 36-48 hours. So if you used it for an hour every day, you could in theory get about a month’s use out of it. Again that’s an over-estimate because of the self-discharge factor, so let’s be very conservative and say you could use it for an hour every day for a week before it needed recharging.
So being ultra-conservative, if you performed with it for an hour every day, it ought to last 400 weeks, i.e. 7 years.