I mean non rechargeable alkaline batteries like energizer's, some full, some half empty. I know I cannot do that in series, I forgot why, but what about parallel?

I found answers for rechargeable batteries only.


1 Answer 1


The fresh batteries will attempt to 'charge' the older batteries, since there will be a voltage difference.

Depending on the type of battery, and the differences in voltage, the results may be anything from "It works just fine" to bulging and/or leaking and/or overheating batteries. The latter because these are not rechargeable.

With rechargeable batteries, the batteries with the higher voltages will charge the lower voltage batteries until they equalize.

  • \$\begingroup\$ Do we assume fresh batteries in parallel will lose voltage in sync and not produce these problems? \$\endgroup\$
    – Winston
    Aug 21, 2020 at 14:48
  • \$\begingroup\$ Yes, in sync enough anyway. \$\endgroup\$ Aug 21, 2020 at 14:49
  • 1
    \$\begingroup\$ match if voltage is almost same for best performance. But ESR rises with age so less is less so less effect when weak when dead it is like C drops to <5% and ESR is 20x bigger so it acts like a lousy ecap of 1mF with higher ESR in kiloohm range when dead, Voc/Isc=ESR \$\endgroup\$ Aug 21, 2020 at 14:49
  • \$\begingroup\$ @Exocytosis It can only happen once, when you connect them the first time. When they're in parallel the voltages stay in sync automatically. \$\endgroup\$
    – user253751
    Aug 21, 2020 at 17:02

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