Hand Held Radios (Com + Nav)and GPS...Help?

Morgans wrote:

NiMH have a self-discharge rate of 3-5% per day. If you are going on
extended trips, purchase an alkaline battery pack.


You need to google about that to see for yourself. They self discharge at
slightly over 1% per day.

Agreed, but the self-discharge rate can increase as the cells age.

Given the fact that they have a higher capacity
than alkaline, they will still have more capacity left over, even
considering self discharge, than alkalines for at least two or three weeks.

The relative capacity of alkalines and NiMH cells depends on how large the
current draw is. For AA cells, alkalines are typically rated to have a
capacity of about 2800 mA-hr which is higher than the rating for today's
NiMH of about 2200 mA-hr. However, the 2800 rating for alkalines is tested
at a very low discharge rate of 20 mA and at higher current draws the
effective capacity drops substantially. At a current draw of 1 A (1000
mA), the capacity of alkalines drops to about 750 mA-hr while NiMH cells
are much less affected and still deliver almost their rated capacity. So
for low-power devices the alkaline cells still outlive a single charge of
the NiMH cells, but for higher-power devices the NiMH cells last much longer.

In the case of a communications radio it depends on how it's used - if only
used to receive I'd expect the alkalines to do better but if frequently
used to transmit (i.e. higher power) then the NiMH cells will last longer.

Even if the alkalines might last longer than a single charge of the NiMH,
I'd usually still use the rechargeable NiMH for the lower long-term cost.
But a spare set of alkalines (or even better Li) cells is good for backup
since they have such good storage characteristics.