"I think it was Carl who mentioned discharging NiCad batteries fully because the conventional wisdom is that if not discharged between charge cycles they develop "memory". All of the NiCads that I completely discharged failed almost immediately. The only memory I see with this is that they lose their memory on how to hold a charge. After this experience I would float charge them and never had a problem since."
Indeed. More accurately termed "zero point". NiCad batteries always had this problem with loosing their zero point. The zero point is as the two words state, the zero voltage, zero current point of the battery.
When one looses it's zero point, it has "shifted" within it's charging capacity, thus the battery tends to not hold a charge as well as when new. Battery restoration machines would basically take the battery and reverse charge it by pulsing the battery over a period of time, slowly returning the zero point to actual zero capacity point returning the battery to it's original state and capable of holding a proper charge.
After a charge and use, the battery will slowly build itself up as it sits. It is this time when the battery is most suspect to developing "memory" or loose it's zero point.
Fast discharging can and often does ruin the battery. It shock discharges it, literally surging the cell to either an open as most had internal protection fuses, or surge the cell enough to damage it to the point of a short or incapable of being charged. Another problem NiCad's had was their bad habit of getting hot, both under charge and under normal use. If the battery is allowed to cool for a bit prior to a slow discharge and recharge cycle, they would last a bit longer and not develop that loss of zero point as often.
For their faults, they sure were expensive, and heavy. Li-Ion is the way to go, emergency use or otherwise.
RFB
All of the NiCads I
ever discharged failed, too.
For my purposes right now,
the NiMHs are doing their job -
I have them powering many
different things.
The Li-Ion batteries - well - I
have several old cell phones
sitting around with perfectly
good Li-ion batteries in them.
I suppose they could be used
to power some of my gear, just
by making some kind of power
adapter, of some kind. I also
have some old phone chargers
sitting around. I am assuming
that all of the Li-Ions and
chargers are about the same,
but I really don't know. The plugs
and adapters are not the same,
but if you are building your
own custom charging set-up, I
guess it doesn't matter.
I can already see one very important
receiver that could be run
using Li-Ions. I am also
assuming that Li-Ions are not
available as AAAs or AAs. I
am also figuring that all
Li-Ions are rechargable, but
I really don't know.
There is so much to know that
i don't know.
Broooooooooooooooooooooooce, DRS2
RFB just posted a really good explanation of the NiCad situation so thanks for that.
By "float charge" I mean that it is always connected to the charger with the equipment off or on and only disconnected when going portable with the device and I suppose this is the same as trickle charging except for having the device turned on. This is what I did with my handheld transceiver and the NiCads lasted for years. If there was a drift in the "zero point" I was not aware of it since the batteries always seemed to give the same operating time when portable.
Bruce, be very careful with LiIons as I have read that they are very sensitive to charging and could explode if this is not done properly. Based on this I would not use any charger not specified for the specific battery. Maybe this is being too cautious but without further information I wouldn't do it.
Neil
Batteries that may explode are very serious devices.
The owner of WBCQ the shortwave station in Monticello, Maine, was talking on his show about having a vehicle battery explode while he was working on it inside his forklift. He was not injured, but could have been.
Thank you Carl and Neil. I'll stay away
from the Li-Ions!
Best Wishes,
Bruce, DRS2
Lithium ion batteries can be very dangerous if something goes wrong. They can even burst into flames. I read in the news a couple years ago about an iPhone that caught on fire on an international flight.
It's pretty scary when you think about it. You could be talking on the phone and next thing you know your hair is on fire.
I try not to think about it. I'm paranoid enough without fears of exploding electronics.
But back to radio. Another good emergency idea would be solar panels. It would be a big investment, but you wouldn't be regretting it if there's a massive blackout and only one gas station in a 20 mile radius with power. That happened here when the reminants of hurricane Ike hit in 2008. There were 750,000+ people without power in the tri state area. That number included gas stations, grocery stores, and other lifelines.
That brings me to another good idea. If you could get donations and an empty parking lot, you could give away meals to hungry citizens, much like a community cookout. You could invite the red cross to talk about where people could find disaster relief. The radio station could become the pulse of a shattered community. A place that people turn to when there's nowhere else to turn.
That would be one great radio station, Channel X 1610 AM
I'd park there for lunch and enjoy the fine programming.
"Lithium ion batteries can be very dangerous if something goes wrong. They can even burst into flames. I read in the news a couple years ago about an iPhone that caught on fire on an international flight."
Usually this is caused by using improper charging devices like those portable battery powered chargers/boosters that do not have the internal microprocessor which talks to the battery via the 3rd terminal. Without this communications link between the charger and battery, your asking for trouble.
Any rechargeable battery can explode in your face if not handled properly. Heck any battery be it rechargeable or not can explode if used improperly.
As the old saying goes...the right tool for the right job.
RFB