mAh of batteries question

Quick question:

I know when you hook two batteries in series, you double the voltage but there is no increase in available amperage.  When you hook them in parallel, you double the available amperage, but it's just voltage x1

What about mAh?  If I need to power an 18v thing by wiring two 9v batteries in series, and each battery is 500 mAh, does it follow the same rule as above?

In series, I would still have 500mAh, but in parallel I would have 1Ah?

Yeah.

Ah and mAh and of course MAh are just amp hours.  A rating of how many amps that a a battery can supply for an hour.  1Ah is a battery that can supply one amp for an hour.  Or 2 amps for half an hour.  And 1/2 amp for 2 hours.  Of course there are other things like efficiencies and whatnot that come into play but that is the gist of it.  

So yes - wiring batteries in parallel will increase the available amp hours since you have effectively doubled the size of the battery but the number of cells remain the same so voltage remains the same. 

93gsxturbo said:

 

So yes - wiring batteries in series will increase the available amp hours since you have effectively doubled the size of the battery but the number of cells remain the same so voltage remains the same. 

No.

Dr. Hess said:

93gsxturbo said:

 

So yes - wiring batteries in series will increase the available amp hours since you have effectively doubled the size of the battery but the number of cells remain the same so voltage remains the same. 

No.

Whoopsie - the other one.