✎ battery_technology [the libarynth]

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===== portable power =====

==== reading ====
  * from gatech readings http://www.cc.gatech.edu/classes/AY2001/cs7470_spring/readings/overview.html
  * Mike Johnson. Physical limits of portable power storage. Draft internal tech report. MIT Media Lab.
  * Martin, T. and Siewiorek, D. Non-Ideal Battery Properties and Low Power Operation in Wearable Computing. ISWC 99, October 1999.

sources of power
  * [[Pedal Power]] . .. [[Solar Power]] ,. . [[Fuel Cell]]

(re)charging
  * DIY NiCd/NiMH charger (but doesnt include pic logic) > http://www.angelfire.com/electronic/hayles/charge1.html

==== cerf batteries ====
the [[CerfBoard]] requires a regulated 5v supply, aprox 900mA

we used clones of the Sony NP-F730/750 OR NP-F930/960 infoLithium Battery which could run something like 6hrs. a not so chunky option which lasted around 2hrs is the Sony NP-F550 - 3000mAh, 7.2V. (more details in [[Cerf Notes]])

* A non-isolated 5V regulator (check details w/todor)
  * A detailed design can be found here   http://www.sanpo.t.u-tokyo.ac.jp/~jani/yak/doc/yak-2/regulator/ 
  * With background info here http://wearables.blu.org/wear-hard-02/20027357.html

==== notes ====
from >> http://www.myra-simon.com/bike/charger3.html

NiMH smart charger is to make it from a Maxim 712 chip. Maxim makes two very similar charger chips. The MAX 713 is for NiCad batteries, and the MAX 712 is for NiMH. The 713 turns off when the voltage drops after NiCad battery is fully charged. The 712 turns off when the voltage levels out rather than dropping. They felt that this was a safer approach than trying to detect the small drop that occurs. I think it makes sense, especially as it terminates charging a bit quicker, resulting in less overcharging. The MAX 712 also monitors temperature, and charging can be terminated by maximum temperature. But this requires you to make up battery packs with thermistors in them.

* http://www.maxim-ic.com/
  * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1666
	
trickle charger However, since NiMH batteries are so very sensitive to overcharging, the best approach is to use a very low current in order to minimize overcharge damage. One frequent poster to the bikecurrent mailing list uses a charger that charges at a rate something like C/60 and has had good results with it. C/60 is the capacity of the battery in amp-hours divided by 60. So if you had a battery with capacity 4 amp-hours (4000 mAh), C/60 is 67 mA. At this current rate, the battery would be charged from empty in about 84 hours, i.e. about 3 and a half days.

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Libarynth >  Main Web > BatteryTechnology r5 - 07 Jul 2004 - 13:17
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