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標題: 自製放電架生 [打印本頁]

作者: stanley_wwy 時間: 2008-5-19 13:50
標題: 自製放電架生
我想自已買料整件架生可以十零廿amp 放7.2v 直電.

想問條數點計同買咩料?

簡簡單單就得, 唔駛cut-off.

插加粗線加電阻/放電石? 有冇sample 睇?

thanks

作者: 恆.com 時間: 2008-5-19 15:45
我用12v 石英膽放電,火數唔識計

作者: lowtech 時間: 2008-5-19 15:57
The formula is V/I=Resistor value.
That means 7.2V/10A=0.72 ohm.
If you buy a 0.5 ohm resistor for discharge a 7.2V battery,the discharge current is 7.2V/0.5 ohm = 14.4A
But the power of the resistor is W=(7.2x7.2)/0.5 ohm =around 100W!
I am not a expert on RC electronics,I suggest you can go to samshuipo Wah Fai to buy two 1 ohm 50 W resistors and parallel it(be careful the discharge resistor is very hot).Just a experimental suggestion.
hope this can help!

作者: stanley_wwy 時間: 2008-5-19 16:12
標題: 回復 3# 的帖子
i guess the problem may not be as simple as just considering the Ohm's Law?

by simply connecting to resistors, the heat generated would be quite dangerous.....

thanks anyway.

any brothers can share experience?

作者: stanley_wwy 時間: 2008-5-19 16:15
標題: 回復 2# 的帖子
試個parallel 兩個....得大約5a....

可以parallel 多幾個, 不過好似好笨

作者: MrSH 時間: 2008-5-19 22:35
我諗都要parallel 多幾個當20A放電 7.2V 都成百幾W 能量差唔多全部轉化做熱能買10個10W水泥電阻應該會放到你要求(又唔會熱得好勁,電阻就自己慢慢計) 做埋有cut off 都唔算好難啊整粒op.amp 上網有資料 (我都打算自己整個不過當balancer用) 不過做唔到constant A數放,因為電壓一直下降 I=V/R

作者: stanley_wwy 時間: 2008-5-19 23:00
標題: 回復 6# 的帖子
唔....唔該先.....諗諗下你又講得啱......百幾w heat dissipation.....真係好似係屋企放火咁

op. amp........我係electronics 有限公司.....得AL 程度, 仲要俾番晒阿sir.......唔識攪

冇...因為見倒有部ko 舊款charger 有 20a 放電......想自已又整個啫

[ 本帖最後由 stanley_wwy 於 2008-5-19 23:03 編輯 ]

作者: SnackEater 時間: 2008-5-20 01:50
去百佳買Philips 50W 12V halogen 燈膽，紙盒四個裝，平均唔洗十蚊個，parallel駁，估計每個都扯到4-5A，唔夠再加。

作者: stanley_wwy 時間: 2008-5-20 09:13
標題: 回復 8# 的帖子
依, 睇睇先, 唔該.

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