"Robert Green" wrote in
:
"ransley" wrote in message
.
.. On Mar 31, 6:22 pm, Anthona wrote:
I just purchased online from home depot an edger/trimmer...In the
specifications it said electric, nothing mentioned about batteries.
and i thought that was what i getting. It turned out it was cordless
with 18v ni-cad battery. Now from past experience, i have had bad
luck with those batteries...mostly through my ignorance of different
type of batteries..Recently i learned that Lithium batteries were the
better choice, if i was going for cordless. I went back to the site
and sure enough, the heading of the sale did say cordless. Now can
someone tell me how to maintain these batteries when not in use?
Obviously here in the new england area i won't be using it all year.
The manual says nothing about that.
Who made the trimmer, HD Ridgid brand has a lifetime warranty on even
batteries, but if its maybe B&D dont count on much the second year,
with HD I think you have 30 day return, for an edge trimmer I would
only use gas or 120v corded. Nicads are considered discharged just
when the unit slows, running a battery dead can ruin it, they also
need to be charged to their peak then charging must stop or you cook
the battery to a shorter life, so you need to know how to determine
your charger does it right.
Agree. B&D cordless tools have had the worst performing batteries
I've ever run into. The only exception was their cordless lawn mower
and those batteries lasted only because I completely disregarded their
instructions and did NOT leave it plugged in all the time.
The mower uses lead acid cells, which may be why it lasted, but the
trimmers, edgers, drills, vacuums and every other B&D nicad based
cordless device I have ever owned did not survive longer than one
season.
The drill packs always suffered the same failure mode. The centermost
battery in the back failed first because it overheated when charging
because it was in the center of a ring of other ni-cads and could not
dissipate the heat from charging as well as the outer batteries.
Any tool you buy today should either be NiMH or LiOn.
NiCad is old,
bad technology, subject to memory issues and premature death.
IF misused. Otherwise,they are fine."memory issues" has been debunked.
you can screw up NiMH just as easily as NiCd,if you don't charge them
right.
Also,
with LiOn cells, manufacturers HAVE to build in overcharging
protection. In the B&D devices I took apart, they charged as long as
they were kept plugged in and overcharged very easily. There was no
autoshutoff when charged circuitry.
probably due to cheapo slow chargers,that aren't regulated in any way.
Fast charger systems have sensors or smart ICs to monitor charge and shut
down when the pack is fully chargerd.
LiOn packs will explode if overcharged, so manufacturers put
temperature and other sensors in their charging circuits to prevent
overcharging. Sometimes, other things go wrong, though:
http://en.wikipedia.org/wiki/Lithium-ion_battery says:
"For example, approximately 10 million Sony batteries used in Dell,
Sony, Apple, Lenovo/IBM, Panasonic, Toshiba, Hitachi, Fujitsu and
Sharp laptops were recalled in 2006. The batteries were found to be
susceptible to internal contamination by metal particles. Under some
circumstances, these particles can pierce the separator, causing the
cell to short. The cell will begin to rapidly convert all of its
energy into heat. This creates an exothermic oxidizing reaction,
causing the temperature to a few hundred degrees Celsius in a fraction
of a second.[81] A chain reaction occurs when neighboring cells heat
up, and in some cases, causes the battery to ignite."
So, not ALL the kinks have been worked out with LiOn batteries, but
I'd still prefer them for the power-to-weight ration in any hand
powered tool with one exception.
All that said, I often still prefer to use devices that accept
standard battery sizes so I can buy and charge my own NiMH cells. Not
as convenient as built-in lithium ion batteries, but a certain class
of items, like cameras, MP3 players, etc. it's nice to be able to buy
batteries when away from a charger or carry ready spares.
--
Bobby G.
Ok,the guy wanted to know how to maintain the NiCd pack he ALREADY HAS.
It's best if you recharge before putting the item away;don't store NiCds if
they are depleted.
Also,chargers that fast charge (1 hr or less)give better NiCd life.
IF you happen to have a slow (trickle) charger,use a timer to charge to the
recommended full charge time and no more.it's probably best to remove the
pack from the charger when it's finished charging;some chargers will
discharge a pack left in it.
One nice thing about Lithiums is that they keep a charge much longer in
storage. (but they cost more)
both NiCds and NiMH self-discharge in storage.
There are a couple of brands of loose NiMH cells that have very low self-
discharge,like Kodak,but you don't find them built into packs.
They're called "precharged NiMH". I don't know if they are offered in other
than AA,AAA sizes yet.
--
Jim Yanik
jyanik
at
localnet
dot com