Battery Longevity? Watch Battery vs. AA's in series

[Captain Amateur]

Hey everyone,
I'm really new to electronics in general, so any input would be very much appreciated.

In terms of a 3V power source in a low drain scenario, which of these options will last longer?

1. 3V Lithium CR3032 - Capacity of 240mAh
2. Two Alkaline AA's in series (3V) - Capacity of 1700 - 2500mAh (who really knows?)

Here's the real scenario:
I'm replacing the battery in an old Gameboy Color game that required a CR2025 to hold saved games and run the clock - which means a small discharge is required at all times. I was thinking of just using a CR2032, because it will give me more capacity than the CR2025 and still fit in the casing.

However, wanting to get fancy and really increase the capacity, I bought a AA battery holder at radio shack (wired in series to meet the 3V requirement), and cut a hole in the side of the game cartridge. I attached the leads from the AA holder to the terminals inside the game cartridge, and everything works just fine.

However, from a longevity standpoint, was this the right move?

My main concerns are thus:
1. Since a CR3032 has direct connections with the terminals inside the cartridge, there is very little power lost, but with the AA holder, I'm using the full length of the wires attached (around 3" - 4"). How much voltage do I lose over that length of 22 gauge wire?

2. How well do Alkaline AA's perform in a low drain scenario? Will they actually last for 7x longer than the CR3032, as their capacity would lead you to believe, or will they fizzle out even sooner?

Sorry for the long first post! Thanks so much for your time and input.

Tyler

 

[(*steve*)]

Assuming that they have a long enough shelf life, a higher capacity (larger mAh) battery will almost always outlast one with a lower capacity in a given application.

shelf life and self discharge mean that a cell will discharge by itself. In some applications where the current drain is very low, the battery life is determined by this alone.

Most high quality AA cells have a shelf life (conservatively) of 5 years. However the same is not true od rechargeable cells, which might self-discharge in 1 to 3 months in the worst case.

How long did the original 2025 last? If less than 5 years then an AA cell will last longer.

The button cells are designed for long life and are very well sealed. I've never had one leak. In contrast, you may find that an AA cell used for a long time starts to leak before it is discharged.

If you do replace the battery with AA cells, use high quality batteries as this will generally result in longer life in this application and reduce the chance of leakage.

Direct answers to direct questions:

1) Too little to measure, although you could calculate it. this length of wire might reduce a projected 5 year life by a couple of minutes (maybe)

2) Maybe. If 7x > 5 years then probably not, if less then probably yes.

 

[ElectricMaster]

I would go with Lithium