Pure Energy Rechargeable Alkaline

[Michael Louie]

Has anyone used the Pure Energy rechargable alkaline batteries before?
How good are they and what other sizes of cells are sold besides the AA
variety?

Has anyone used the special charger to recharge other types of alkaline
batteries? (ie Duracell, Energizer....)

Any help would be appreciated.

Thanks.

[Dave Martindale]

mil...@unixg.ubc.ca (Michael Louie) writes:
>Has anyone used the Pure Energy rechargable alkaline batteries before?
>How good are they and what other sizes of cells are sold besides the AA
>variety?

I've used them, though not enough yet to tell whether they live up to
their claims. You can find lots of technical info on rechargeable
alkalines at http://www.bti.ca.

The basic thing you need to know is: The cells initially have about 80%
of the capacity of a throwaway alkaline. If you use them till they are
exhausted then recharge, you will notice each cycle getting considerably
shorter, and you will only get a small number of cycles (perhaps 10)
before you decide they aren't lasting long enough and throw them out.
(Though even 10 cycles is a savings over throwaway cells, in the long
run).

However, if you use only a small fraction of their capacity before recharging,
you will get many more cycles, up in the hundreds, before they become
unusable. You get much larger savings this way.

For example, if you have a device that normally runs 10 hours on throwaway
cells, you might expect 8 hours from the first cycle of Pure Energy cells,
then less and less from each subsequent cycle if you wait until the cells
are discharged before recharging. However, if you really only use the
device for 2 hours per day, and you recharge the batteries every night,
then you are using only 25% of the initial capacity before recharge.
Under these conditions, you should get hundreds of cycles from one set
of cells.

Of course, if you only needed to operate the device 2-3 hours per day,
you could use AA nicad cells (they have about 1/3 the capacity per cell
of the rechargeable alkalines). And the Nicads should last several times
as long as the alkalines. So if you really do use something every day,
nicads are probably the better choice.

But nicads self-discharge about 1% per day, so if the device sits a couple
of weeks between uses, the nicads won't be fully charged unless you recharge
them just before use, rather than just after. And with months between uses,
nicads will retain little charge. But alkalines have a shelf life of years,
so they are much better for "occasional" use.

In addition, most nicad chargers are slow trickle chargers that take overnight
to recharge a set of cells. Fast nicad chargers are available but are
expensive. Because of the cell chemistry, all alkaline chargers are
regulated chargers, and most of them are fast chargers as well.

As for what's available: The Pure Energy brand, made in Canada, seems to
have only AA and AAA cells and two chargers available. The "Rapidcharger"
takes AAs only but charges rapidly. The "EnviroCharger" takes both AA
and AAA, but takes about twice as long to recharge cells from a given state
of discharge.

Rayovac Renewals are the same chemistry, but slightly different physically
than the Pure Energy cells. There are two chargers; one handles AA and AAA
only, while the other also does C and D cells. Both are fast chargers.
The Rayovac cells seem to charge fine in the Pure Energy charger. The
Rayovac chargers have a funny positive terminal design that is supposed to
prevent you from charging normal alkaline cells, and it also interferes
with charging Pure Energy cells. But if you use a knife to cut off the
little strip of plastic jacket that wraps around to the positive end of
the Pure Energy cells, they can be used in the Rayovac charger too.

>Has anyone used the special charger to recharge other types of alkaline
>batteries? (ie Duracell, Energizer....)

I've experimented with it, and it does seem to return some charge to the
"throwaway" cells. However, there are some problems with this:

- If something goes wrong with the charger and it overcharges the cells,
gas pressure builds up inside. The Pure Energy and Renewal cells have
a safety vent to release this pressure. Throwaway cells don't, since
discharging doesn't release gas and they aren't designed to be charged.
So throwaway cells could explode under overcharge conditions.

- Apparently alkaline cells tend to grow zinc dendrites or "whiskers" inside
the cells during charge. In throwaway cells, these can short out the cell.
Rechargeable cells use stronger separator materials to prevent this from
happening.

So it may work, but you probably won't get as long a life as cells designed
for recharging, and there is some risk.

By the way, the cheapest place I've found for Pure Energy cells and chargers
is The Real Canadian Superstore. The Renewal cells seem to be about $8.00
per pack of 4 AA everywhere I've seen them, about double what the Superstore
charges for Pure Energy.

Dave