Dave Plowman (News) wrote:

In article ,
The Natural Philosopher wrote:

I'd guess you mean PP3? AA cells to make up 9 volts would take up a
lot of space. You could have an internal invertor to give 9 volts or
so from 3, and indeed many pro devices use this. Not sure about the
costs, though.


I replaced the PP9 in my roberts radio with a spare 8.4v Nicad pack from
a toy plane. Its been great. Runing now for 2 years at zero cost of
battery replacement, and my R/C charger recharges it in 20 minutes...


PP3 sized rechargeables are available as well.


The problem with pro gear that uses something like a PP3 - radio mics etc
- is that they are designed to be as small as possible given a reasonable
battery life. And no rechargeable comes close to an alkaline in this
respect.

Many churches etc will get away with using a NiCad PP3, given that they
only need a couple of hours life. TV etc requires at least 6 hours so they
can be changed during a break.

I wonder if they cold handle 2 cell lithium packs? I'd say you could
getr up to an ampere hour at 7v or so, which wold equate to several days
of use at the sort of 10-15mA thata PP3 normally is cpaable of.

I'd agree that 7 Nicads in a PP3 sized box is likley to be about 80mA/h...