# 9 volt battery connection **URL:** \ **Category:** Factual Questions\ **Created:** [December 28, 2002, 8:23am UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334 "2002-12-28T08:23:51Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Hayduke\_Lives](https://avatars.discourse-cdn.com/v4/letter/h/e0b2c6/32.png) [@Hayduke\_Lives](https://boards.straightdope.com/u/Hayduke_Lives)\ **Post date:** [December 28, 2002, 8:23am UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/1 "2002-12-28T08:23:51Z")
So, what happens if you connect 2 9volt batteries together? Is there a chance they explode? What if one is dead, the other fresh. Will the fresh on replentish the dead one? ---
**Author:** ![trader\_of\_shots](https://avatars.discourse-cdn.com/v4/letter/t/aeb1de/32.png) [@trader\_of\_shots](https://boards.straightdope.com/u/trader_of_shots)\ **Post date:** [December 28, 2002, 8:36am UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/2 "2002-12-28T08:36:47Z")
If you put them together in say … an oven or a microwave oven or a thermonuclear over … there is a small chance they will explode. Other then that the only danger would be to your tounge. Will the fresh on replentish the dead one … no - if you mean recharge … ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 28, 2002, 8:52am UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/3 "2002-12-28T08:52:02Z")
If you connect them together you will get two very hot batteries and a lot of wasted electricity. ---
**Author:** ![MaryEFoo](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@MaryEFoo](https://boards.straightdope.com/u/MaryEFoo)\ **Post date:** [December 28, 2002, 5:44pm UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/4 "2002-12-28T17:44:08Z")
If you connect them positive-to-positive and neg-to-neg, the weak one will drag down the strong one. If you connect pos-to-neg and neg-to-pos, well, friedo said it. ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [December 28, 2002, 11:06pm UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/5 "2002-12-28T23:06:19Z")
> [@](#): > > \*Originally posted by MaryEFoo \* > \*\*If you connect them positive-to-positive and neg-to-neg, the weak one will drag down the strong one. \*\* Eh? I’m not sure what this means, but with any interpretation I can think of, this is not true. Connecting two batteries in parallel will always result in more available power than either one alone. ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [December 31, 2002, 5:51am UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/6 "2002-12-31T05:51:04Z")
> [@](#): > > \*Originally posted by flex727 \* > \*\*Eh? I’m not sure what this means, but with any interpretation I can think of, this is not true. Connecting two batteries in parallel will always result in more available power than either one alone. \*\* That’s true if they are connected with a load, not true if you connect a dead battery and a charged one in parallel. ---
**Author:** ![raygirvan](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@raygirvan](https://boards.straightdope.com/u/raygirvan)\ **Post date:** [December 31, 2002, 9:00pm UTC](https://boards.straightdope.com/t/9-volt-battery-connection/145334/7 "2002-12-31T21:00:15Z")
_Padeye: not true if you connect a dead battery and a charged one in parallel._ Quite. If we’re talking about just two batteries, plus-to-plus, minus-to-minus, you have a circuit with two opposing voltages: the stronger battery will drive current backwards through the weaker. Depending on the specifics, this can happen even with a load, if the weaker battery provides a lower resistance path than the load.