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Recharge Batteries in 30 Secs
An anonymous reader writes "NEC has developed organic radical batteries
which are recharged in 30 seconds. Good news, they won't (probably) cost more than the current NIMH batteries." Why is it that I'm not holding my breath to have this technology in a laptop?
I saw no mention of the level of heat generated when charging a battery this fast. I haven't worked out any equations, but I was under the impression that there was a certain amount of heat generated per unit of time when charging / discharging batteries.
In a break from /. style I actually RTFA - it says 80 hours of MiniDisc use.
If that's accurate I want one for my iPod, I guess with less drive spinning than an MD it'd last even longer?
One of the nice things about current batteries is that you can't get them to discharge very quickly. Shorting these out might cause excessive heat issues.
NEC is ... working on a way to prevent excessive discharge of power from the cell.
So, it can be used to discharge a great amount of power, but the trick is keeping it from doing so when you don't want it to!
The article states it is good for Hibrid cars what about electrical ones. I thought a Major problem with electric cars is the time it takes to recharge thus making them impractical in long drives.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
If we assume that these batteries have a capacity of 1000 mah, which seems like a reasonable figure since they say they can power an MP3 player for 80 hours, then charging it in 30 seconds implies that during the charging process it is accepting 120 watts.
a) That's not going to be any tiny little wall transformer doing the charging.
b)I sure hope they have the safety and quality assurance issues worked out, because if it doesn't shut off at the exact instant when the battery is fully charged, that 120 watts is going to go somewhere.
It might not be much more dangerous than a firecracker but I suspect it could be pretty dramatic.
"How to Do Nothing," kids activities, back in print!
If you've ever had the misfortune of keeping a server up and running while there is major construction going on nearby, you know you can get multiple blackouts of varying duration.
I like to use a UPS to support a server to the last safe second with enough time for an orderly shutdown... but I can't, because I need to know the UPS will last through at least two consecutive blackouts without time to recharge.
Now, with a 30 second recharge, servers under my care could survive twice the blackout duration without increasing the risk of a sudden shutdown.
liquid helium isn't a good coolant, becuase it's heat capacity is very low. Liquid nitrogen is a much better coolant, and it's also much cheaper. Besides, that battery might not even work at 77k, much less at 4k.
what sig?
Thus the battery holds about 1.2 * 3600 * 1.2 = about 5KJoules.
90% charge efficient means 500Joules as heat.
E = c * m * delta_T
where c = specific heat capacity, m = mass, delta_T = temperature change.
According to Sony, a AA battery is 30g. I don't know what the specific heat capacity of a battery is, but metals are between 0.1 and 0.9, and water is 4. Lets assume it's 1.0 J/gK.
delta_T = E/c*m = 500/(1.0 * 30) = 16 celcius.
That's about 30F for those of you who like odd units. Not such a big deal.
Of course the 90% number is drawn out of the air.
The concept is great, but this is a potential problem with widespread use. They say their first market is Uninterruptible Power Supplies. The short recharge time is great, except the load during that short time will be tremendous.
Your servers draw 100 amps max? When the power comes back on and all your batteries need to recharge at once, expect a serious spike. I'm not an EE, but if it takes 30 seconds compared to 8 hours, that's 960 times faster, which means 960 times the load per unit of time.
Accountants as hosting companies will cry every time the power flickers, as the demand charges shoot up 800%
That what was all this school was for... to teach us how to solve our own problems. -- janeowit