www.batteryuniversity.com
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ph2t
- bitPimp
- Posts: 1979
- Joined: Tue Mar 25, 2003 6:33 am
- Location: taco city
www.batteryuniversity.com
http://www.batteryuniversity.com/
A handy site for all you nerds.... Care of Trash from ausmicro.
cheers pimps,
ph2t.
A handy site for all you nerds.... Care of Trash from ausmicro.
cheers pimps,
ph2t.
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SPORTCAR
- Posts: 14
- Joined: Sat Dec 20, 2003 10:31 am
- Location: Canada
Thanks Ph2t!
If wanting ultimate "impossible-looking" performance is nerdy, then count me in!
A couple of thing I learned that interested me:
1) nicads drop the most current on demand.
2) my big plans for LiPo may be overenthusiastic: Lithium Polymer is suggested for 2C output maximum. I've read they can do 5 C, hopefully this will be enough for the trorque I need.
I have no idea what the short current draw is of my favourite motor is (cause its so cheap: the Toy East King 4.2), but nicad will do up to 20 C.
3) the way to get Lithium polymer to give peak current is to get them to 60 Celcius. I'm already envisioning a built-in thinsulate battery cover with a thermister in there and a gentle heating element... I'm hooked on the Lithium polymer for its 100-160 wh/kg "gravimetric energy density" instead of NiCad's 45-80. I just learned this gravimetric energy density measure at your link: if I've go it right, the 145 mAh, 3.7 V, 3.5g kokam battery I've ordered (Bishop Power Products) will be 153 Wh/kg (153 = .145 x 3.7 / .0035)
A stock nicad is 100 mAh at 1.2V and 4 g (know a precise weight? my scale I got at a head shop isn't good at fractional grams but this should be close by my eye) only gets 30 Wh/kg. If you buy a perfection 200 mAh NiMh one, still you only get 60 Wh/kg (twice capacity, same weight to my eye).
http://www.b-p-p.com/kokam145.htm
I just got an email from them, they have 600 LiPo's (145mAh) in stock right now...
Brett
If wanting ultimate "impossible-looking" performance is nerdy, then count me in!
A couple of thing I learned that interested me:
1) nicads drop the most current on demand.
2) my big plans for LiPo may be overenthusiastic: Lithium Polymer is suggested for 2C output maximum. I've read they can do 5 C, hopefully this will be enough for the trorque I need.
I have no idea what the short current draw is of my favourite motor is (cause its so cheap: the Toy East King 4.2), but nicad will do up to 20 C.3) the way to get Lithium polymer to give peak current is to get them to 60 Celcius. I'm already envisioning a built-in thinsulate battery cover with a thermister in there and a gentle heating element... I'm hooked on the Lithium polymer for its 100-160 wh/kg "gravimetric energy density" instead of NiCad's 45-80. I just learned this gravimetric energy density measure at your link: if I've go it right, the 145 mAh, 3.7 V, 3.5g kokam battery I've ordered (Bishop Power Products) will be 153 Wh/kg (153 = .145 x 3.7 / .0035)
A stock nicad is 100 mAh at 1.2V and 4 g (know a precise weight? my scale I got at a head shop isn't good at fractional grams but this should be close by my eye) only gets 30 Wh/kg. If you buy a perfection 200 mAh NiMh one, still you only get 60 Wh/kg (twice capacity, same weight to my eye).
http://www.b-p-p.com/kokam145.htm
I just got an email from them, they have 600 LiPo's (145mAh) in stock right now...
Brett
Yeah. Like that.