檢測普通鋅錳(meng)干電(dian)(dian)(dian)(dian)池的電(dian)(dian)(dian)(dian)量(liang)(liang)是(shi)否充(chong)足(zu)，通常有兩種(zhong)方(fang)法(fa)。第(di)一種(zhong)方(fang)法(fa)是(shi)通過測量(liang)(liang)電(dian)(dian)(dian)(dian)池瞬時(shi)短路電(dian)(dian)(dian)(dian)流來估(gu)算電(dian)(dian)(dian)(dian)池的內阻，進而判斷電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)量(liang)(liang)是(shi)否充(chong)足(zu)；第(di)二種(zhong)方(fang)法(fa)是(shi)用電(dian)(dian)(dian)(dian)流表(biao)串聯一只阻值適當的電(dian)(dian)(dian)(dian)阻，通過測量(liang)(liang)電(dian)(dian)(dian)(dian)池的放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流計(ji)算出電(dian)(dian)(dian)(dian)池內阻，從而判斷電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)量(liang)(liang)是(shi)否充(chong)足(zu)。

第一種方法的最大優點是簡便，用萬用表的大電流檔就可直接判斷出干電池的電量，缺點是測試電流很大，遠遠超過干電池允許放電電流的極限值，在一定程度上影響干電池使用壽命。第二種方法的優點是測試電流小，安全性好，一般不會對干電池的使用壽命產生不良影響，缺點是較為麻煩。
筆者用MF47型萬(wan)用表對(dui)一(yi)節新2號干電池和一(yi)節舊2號干電池分(fen)別用上述兩種(zhong)方(fang)法(fa)進(jin)行測試對(dui)比。假設(she)ro是(shi)干電池內(nei)阻(zu)(zu)，RO是(shi)電流(liu)表內(nei)阻(zu)(zu)，用第二種(zhong)測試方(fang)法(fa)時，RF是(shi)附加的串聯電阻(zu)(zu)，阻(zu)(zu)值3Ω，功率2W。

      實(shi)測結果(guo)如下。新(xin)2號(hao)電(dian)(dian)池E=1.58V（用(yong)2.5V直(zhi)流(liu)電(dian)(dian)壓(ya)檔(dang)測量(liang)），電(dian)(dian)壓(ya)表(biao)(biao)內阻為(wei)(wei)(wei)50kΩ，遠大于(yu)ro，故可近似認為(wei)(wei)(wei)1.58V是(shi)電(dian)(dian)池的電(dian)(dian)動勢，或(huo)稱開路電(dian)(dian)壓(ya)。用(yong)第一種方(fang)法時，萬用(yong)表(biao)(biao)置5A直(zhi)流(liu)電(dian)(dian)流(liu)檔(dang)，電(dian)(dian)表(biao)(biao)內阻RO=0.06Ω，測得電(dian)(dian)流(liu)為(wei)(wei)(wei)3.3A。所以 ro+RO=1.58V÷3.3A≈0.48Ω，ro=0.48-0.06=0.42Ω。用(yong)第二種方(fang)法時，測得電(dian)(dian)流(liu)為(wei)(wei)(wei) 0.395A，RF+ro+RO=1.58V÷0.395A=4Ω，電(dian)(dian)流(liu)500mA檔(dang)內阻為(wei)(wei)(wei)0.6Ω，所以ro=4-3-0.6=0.4Ω。

舊2號電池用第一種方法測量時，先測得開路電壓E=1.2V，電表內阻RO=6Ω，讀數為6.5mA，萬用表置50mA直流電流檔，ro+RO=1.2V÷0.0065A≈184.6Ω，ro=184.6-6=178.6Ω。用第二種方法，測得電流為 6.3mA，ro+RO+RF=1.2V÷0.0063A=190.5Ω，ro=190.5-6-3=181.5Ω。
顯然兩種(zhong)測(ce)試(shi)方法的結(jie)果基本一(yi)致。最終計算(suan)結(jie)果的微小(xiao)(xiao)差別是由于讀數誤差、電(dian)阻RF的誤差以及接觸電(dian)阻等多方面因素(su)造成的，這種(zhong)微小(xiao)(xiao)誤差不致影響(xiang)對電(dian)池(chi)電(dian)量的判斷。如(ru)果被測(ce)電(dian)池(chi)的容(rong)量小(xiao)(xiao)、電(dian)壓高（例如(ru)15V、9V疊層電(dian)池(chi)），則應將RF的阻值適應增(zeng)大。