檢測普通鋅錳干電池的電量是否充足，通常有兩種方法。第一種方法是通過測量電池瞬時短路電流來估算電池的內阻，進而判斷電池電(dian)(dian)量是(shi)否充足；第二種方法(fa)是(shi)用(yong)電(dian)(dian)流(liu)表串聯一只(zhi)阻(zu)值適當的(de)電(dian)(dian)阻(zu)，通過測量電(dian)(dian)池(chi)的(de)放(fang)電(dian)(dian)電(dian)(dian)流(liu)計(ji)算(suan)出(chu)電(dian)(dian)池(chi)內(nei)阻(zu)，從而(er)判斷(duan)電(dian)(dian)池(chi)電(dian)(dian)量是(shi)否充足。

    第(di)一種方(fang)法(fa)的(de)最大(da)(da)優點(dian)(dian)是(shi)簡便，用(yong)萬用(yong)表的(de)大(da)(da)電(dian)(dian)(dian)(dian)流(liu)檔就可直接判斷出干(gan)電(dian)(dian)(dian)(dian)池(chi)的(de)電(dian)(dian)(dian)(dian)量，缺(que)點(dian)(dian)是(shi)測試電(dian)(dian)(dian)(dian)流(liu)很大(da)(da)，遠(yuan)遠(yuan)超過(guo)干(gan)電(dian)(dian)(dian)(dian)池(chi)允許放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)的(de)極(ji)限值(zhi)，在一定(ding)程度上影(ying)響(xiang)干(gan)電(dian)(dian)(dian)(dian)池(chi)使(shi)用(yong)壽命(ming)。第(di)二(er)種方(fang)法(fa)的(de)優點(dian)(dian)是(shi)測試電(dian)(dian)(dian)(dian)流(liu)小，安(an)全性好，一般不會對干(gan)電(dian)(dian)(dian)(dian)池(chi)的(de)使(shi)用(yong)壽命(ming)產生不良影(ying)響(xiang)，缺(que)點(dian)(dian)是(shi)較為(wei)麻煩。

    筆者用(yong)(yong)MF47型萬(wan)用(yong)(yong)表(biao)對(dui)一(yi)節(jie)新(xin)2號干(gan)電池和一(yi)節(jie)舊(jiu)2號干(gan)電池分(fen)別用(yong)(yong)上述兩(liang)種(zhong)方(fang)法(fa)進行測試對(dui)比。假設(she)ro是(shi)干(gan)電池內阻，RO是(shi)電流(liu)表(biao)內阻，用(yong)(yong)第二種(zhong)測試方(fang)法(fa)時，RF是(shi)附加的串聯電阻，阻值3Ω，功率2W。

    實(shi)測結果如下。新2號電(dian)(dian)(dian)池E=1.58V（用2.5V直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)壓檔(dang)(dang)測量），電(dian)(dian)(dian)壓表(biao)內阻為(wei)(wei)(wei)50kΩ，遠大于ro，故(gu)可近似認為(wei)(wei)(wei)1.58V是電(dian)(dian)(dian)池的電(dian)(dian)(dian)動(dong)勢，或稱開路(lu)電(dian)(dian)(dian)壓。用第一種方法時(shi)，萬用表(biao)置5A直(zhi)(zhi)流(liu)(liu)電(dian)(dian)(dian)流(liu)(liu)檔(dang)(dang)，電(dian)(dian)(dian)表(biao)內阻RO=0.06Ω，測得電(dian)(dian)(dian)流(liu)(liu)為(wei)(wei)(wei)3.3A。所(suo)以ro+RO=1.58V÷3.3A≈0.48Ω，ro=0.48-0.06=0.42Ω。用第二種方法時(shi)，測得電(dian)(dian)(dian)流(liu)(liu)為(wei)(wei)(wei)0.395A，RF+ro+RO=1.58V÷0.395A=4Ω，電(dian)(dian)(dian)流(liu)(liu)500mA檔(dang)(dang)內阻為(wei)(wei)(wei)0.6Ω，所(suo)以ro=4-3-0.6=0.4Ω。

    舊2號電池用第(di)(di)一種方法測(ce)量時，先(xian)測(ce)得開路電壓E=1.2V，電表(biao)內阻RO=6Ω，讀數為6.5mA，萬用表(biao)置50mA直流(liu)電流(liu)檔，ro+RO=1.2V÷0.0065A≈184.6Ω，ro=184.6-6=178.6Ω。用第(di)(di)二種方法，測(ce)得電流(liu)為6.3mA，ro+RO+RF=1.2V÷0.0063A=190.5Ω，ro=190.5-6-3=181.5Ω。

    顯然兩種測試方法的結果基本一致。最終計算結果的微小差別是由于讀數誤差、電阻RF的誤差以及接觸電阻等多方面因素造成的，這種微小誤差不致影響對電池電量的判斷。如果被測電池的容量小(xiao)、電(dian)壓(ya)高（例如15V、9V疊層電(dian)池），則應將RF的阻值適應增(zeng)大。