"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. 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.

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.