Question on mah's in different type batteries

I have a question for the battery experts.


My question is in regards to the mah's of an 18650 li-ion compared to an Eneloop AA.

Now, the Eneloop Pro AA NiMh has 2550 mah's. A typical 18650 li-ion has 3400 mah's.

So I'm comparing the run times of a Zebralight sc5 and an sc62. Even on a low output of around 25 lumens, which shouldn't strain the Eneloop at all, the runtime of an 18650 is about 60 hours while the average output of the sc5 on an Eneloop with 2550 mah is only about 17 hrs.

My question is why the disparity with run times with the 18650 having roughly 4 times the run time at the same output of the Eneloop, but only having about 700 more mah's?

Why is this?

The voltage is about 3 times higher in the lithium cell than Nimh cell.

Dave

Does that have an effect on the total mah's?

Not a battery expert but milliamp hour or amp hour (mAh or Ah) is only a useful comparison when comparing batteries of the same configuration and voltage.

18650 batteries are typically around 3.7V while NiMH are 1.2V.

Convert the mAh to Wh (watt hour) by multiplying the Ah x V (voltage) to better compare.

keithy said:

Not a battery expert but milliamp hour or amp hour (mAh or Ah) is only a useful comparison when comparing batteries of the same configuration and voltage.

18650 batteries are typically around 3.7V while NiMH are 1.2V.

Convert the mAh to Wh (watt hour) by multiplying the Ah x V (voltage) to better compare.

Click to expand...

Yep, watt hours (Wh) is what you want to use.

A Eneloop Pro/XX/Duracell Ion Core 2500mAh has about 3 watt hours of energy at 1A according to HKJ.

A typical Sanyo-Panasonic GA hybrid 3500mAh 18650 has about 12Wh, so we're talking four times the energy of a hi-cap AA.

Chris

OK. Thanks guys. I guess I could have googled that but I didn't know what I didn't know, so to speak.

Got it now.

So the Eneloop does have more watt hours than a 14500, but as you said, no where close to an 18650. It's amazing what Zebralight has managed to do with the SC5. A milestone of sorts for the flashlight world.

Thanks.


For anyone reading this, the formula to figure watt hours is: E = ( mah x volts ) / 1000