From the Survival Blog
Hello HJL and JWR,
I was wondering if you could review
and recommend the latest generation of rechargeable batteries available and a
solar charger as well. I am leaning towards stocking up on rechargeable AA and
AAA and the spacer packs that allow these sizes be used as C and D cell
batteries. The vast array of options is overwhelming, and I am hoping someone
with the expertise required can help. Thanks for all you do. Take care. - J.W.
HJL Replies: I have chosen to
use a modular route so that I have the flexibility to charge whatever I need
charged. Many of my electronics utilize proprietary batteries, but all can be
charged from a vehicle (12-16VDC). I separate my solar setup from the charger
so that I can attache whatever charger the item needs, to the solar module,
which simply acts like a vehicle. I currently use Eneloop batteries by Sanyo.
Most rechargeable batteries have a problem with internal leakage and will only
hold a charge for a couple of months. Disposable batteries generally are easier
to use because they can be used immediately after purchasing them. If you
purchase them, you can throw them in a drawer and pull them out over the course
of several years, and they are ready to go. Now with Eneloop batteries,
rechargeables have the same capability. A normal rechargeable will lose about
75% of its stored charge in six months and come close to having no charge in a
year. Eneloops will hold nearly 75% charge for at least three years. Because of
this slow internal leakage rate, they come pre-charged in the package and are
ready to go when you purchase them. Except for the higher purchase price, they
have overcome practically all of the disadvantages of recheargables. Even the
purchase price is tolerable if you look at the ownership cost spread out over
the life of the instrument you are powering, which is reasonable since these
batteries will take over 1000 charges.
Where you will find issues with your
planned usage scheme is using AA and AAA batteries with adapters for C and D.
Eneloop does not sell a C or D sized battery yet in the U.S., and their AA
batteries are rated at 1900mAh. A decent NiMH rechargable “D” cell battery will
be rated at close 10,000mAh. Eneloop has adapters to use AA in a D size, but
you will loose 80% of the storage capacity in exchange for that long shelf
life. (Sanyo does make them, they just don't sell them in the U.S.)
Alternatively, you can use the higher
power model, but you get fewer charges on it:
You can also get a kit that contains
adaptors from eneloop:
Eneloop adaptors are well made, but
you can get adaptors to use up to 2 AA batteries to make a “D” cell that has
close to 40% of the energy of an actual D cell. (65% of Sanyo's “D” Eneloop
batteries sold in Japan):
Chargers on the other hand are a
little bit more difficult. One of the huge drawbacks to most portable NiMH
chargers is that they must charge batteries in pairs. I have several items that
only use one AAA battery or one AA battery, and it is a real problem keeping
track of dead batteries versus charged ones. I also try to keep batteries
paired for life since they do have a limited number of charges. Pairing a new
battery with an old one can lead to issues with rechargeables. As a result, I
usually mark the batteries on the end cap, identifying the item they power and
the date they went in service. I have found a nice 15-minute quick charger that
will also put a maintenance charge on the batteries, if you forget and leave
them in the charger. It will charge single one, two, three or four AA or AAA
batteries. It is powered by a heavy duty 12V wall wart. The charger states it
takes a power source from 11V to 16V, so you can also power it from your car
battery:
I chose to go this route rather than
a dedicated solar charger to give me more flexibility. I have several other
items, like an Icom IC-T90A, that use 12-16V to charge as well. It then becomes
a simple matter to use a generic solar charger with generic solar panels to
charge all of my electronics. Currently I use a Tycon TP-SC24-10 12/24V 10A
solar charge controller because it is what I had on hand. You will need a
charge controller capable of at least 10A at 12V because that Energizer charger
may be small, but it can really pull the juice when it's in 15-minute charge
mode.
With a setup like this, you can be
semi-portable by using small solar panels. I use two in parallel that I picked
up at a garage sale. They measure 18” x 18”. As an alternative, you can be
completely portable by using a flexible roll-up solar panel.
As always, please check with our
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