do you more power with alkaline batteries(AA) or rechargeable (AA)?

Question

it says on my flashlight u can get 20 hrs with alkaline

Answer 1

The first time you open the rechargeables they should have the same length of time as regular alkalines. But, every subsequent charge of the rechargeables will decrease the amount of life the batteries have. A rechargeable is good for about 10-30 (depending on quality) recharges before they start to lose power more rapdily.

Hope that helps.

Answer 2

Updated:
I just read all the other answers,
NiMh rechargeables really do have more capacity, than alkaline, there is no question about it, go look up the numbers if you want to.
you asked about run time, that has to do with the Ah or mAh rating, and
I am guessing most other answers are assuming you are caring about instantaneous power out or voltage or some other thing that it is apparent that you did not ask.

I love flashlight technology,
some of the new NiMh batteries have much higher capacity than any alkaline, they have 4 times the run time as alkaline in some of my flashlights, but typical is 2 times the run time.
the voltage out from a rechargeable is less,
so some flashlights have way less runtime with rechargeables because they are not designed to run with them at all, a good example is a mini mag light with a krypton bulb.

the flashlights with regulation circuitry (usually in LED flashlights) will run better on any batteries, especially rechargeables.

I would suggest that you try rechargeable, and get the highest Ah rating you can get.
eneloop rechargeables do not internally discharge as much as normal ones, so I would suggest trying them first because you do not need to charge them if you do not use them.
regular rechargeables will self discharge in about 2 months even if unused.

it is possible to get way better performance from a rechargeable than an alkaline, not to mention that they are way cheaper in the long run because you can recharge them in the range of 250 to 500 times.

flashlightreview.com
has actual run times from independent tests, and may tell you more about your light if they have it listed, and if not, its a fun website.

Answer 3

Alkaline batteries are 1.5 Volts, while rechargeables (NiCd, NiMH) are generally 1.2 Volts. The current ratings are about the same (slightly higher in some alkalines), so alkalines give more power.

You asked about power, not energy. If you count recharging the rechargeables multiple times, their total energy is far greater than an alkaline, but for power in a single use, the alkalines are the winner.

.

Answer 4

I haveAA recharge able batteries, it says so on the battery and you can't recharge a normal battery at all. You buy a battery charger they are usually in the same place you buy the batteries. It takes 24 hours to charge them the first time after that it shouldn't be as long. The charger plugs in to regular outlet and you can't charge them through your USB computer port.

Answer 5

20 hrs tells you the total amount of energy, not the power.

Alkaline cells deliver more power than NiCd, because of lower internal resistance. They deliver less power than some Li batteries, because of the higher mobility of the charge carriers.

If you want to know the energy capacity rather than the peak power, look at the "amp-hour" or "milliamp-hour" rating - a bigger number means more energy.

Answer 6

The power is the same, 1.5 volts each. The advantage is that chargeable batteries can be recharged multiple times, which results in a monetary savings.

Answer 7

More with Alkaline. Rechargeable will give you less, but you can recharge it multiple times

Answer 8

for a flashlight alkalines are just fine. power is measured in watts and you are concerned with DC voltage. any correct voltage battery is great for your purposes.

Answer 9

you'll get power longer with rechargeables.

the power "level" is the same