Cordless Drill Advice
#16
Just to verify times to charge any type of battery... Use this calculator. You input the mah (Milliamp Hours) of the battery then the output of the charger mA (Milliamps) and then click on Calculate. The resulting time will be displayed.
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It works for any type charger/battery combination. I use it for my AA Lithium and NiCad batteries, and yeah - they work great!!!!
~~ Mikey KB3VBR (Admin)
~~ NARA Member # 75    
~~ Baldwin Eddystone Unofficial Website

~~ I wonder what that would look like in 1:20.3???
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#17
I built my own replacement pack using batteries from Newark Electronics for a fraction of the price of a replacement pack.

It's not likely that you can "overcharge" a battery, as their internal resistance increases with charge to the point where it won't take any additional charge once it is fully charged.
Do NOT use a charger that is rated higher than the battery pack...Bad things can (will) happen....
Gus (LC&P).
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#18
Steamtrains Wrote:I built my own replacement pack using batteries from Newark Electronics for a fraction of the price of a replacement pack.

It's not likely that you can "overcharge" a battery, as their internal resistance increases with charge to the point where it won't take any additional charge once it is fully charged.
Do NOT use a charger that is rated higher than the battery pack...Bad things can (will) happen....

Some chargers, like a few of the "quick charge" ones that I have, will use a higher charge voltage than the battery's rating. An 18 volt battery has a nominal rating of 20.7 volts, but I've had charges that start off at over 22 volts. That, as you say, will kill a ni-cad battery if you leave it on too long. The better chargers will sense the voltage and not allow it to get overcharged. I've heard that it's best to fully discharge a ni-cad battery before charging it because it has memory and may never fully take a charge. I've tried that with little success.

We made small one-amp and five-amp power supplies for the security industry, and we'd put a series resistor in the charging circuit to keep a float charge in the backup battery, but they used sealed lead-acid batteries which act differently than ni-cads. Besides, the output was set to match the battery voltage, and that goes to what you are saying, overcharging means too high a voltage, not too much current.
Don (ezdays) Day
Board administrator and
founder of the CANYON STATE RAILROAD
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#19
ezdays Wrote:Some chargers, like a few of the "quick charge" ones that I have, will use a higher charge voltage than the battery's rating. An 18 volt battery has a nominal rating of 20.7 volts, but I've had charges that start off at over 22 volts. That, as you say, will kill a ni-cad battery if you leave it on too long. The better chargers will sense the voltage and not allow it to get overcharged. I've heard that it's best to fully discharge a ni-cad battery before charging it because it has memory and may never fully take a charge. I've tried that with little success.

We made small one-amp and five-amp power supplies for the security industry, and we'd put a series resistor in the charging circuit to keep a float charge in the backup battery, but they used sealed lead-acid batteries which act differently than ni-cads. Besides, the output was set to match the battery voltage, and that goes to what you are saying, overcharging means too high a voltage, not too much current.

You're right regarding Ni-Cads...It's good practice to drain them to almost zero every now and then, and then re-charge them.

Looonngg time ago I flew competition R/C planes which could cost several hundred $$'s a pop, so tender loving care of the batteries was my #1 priority. Didn't like it when they wound up in a pile of rubble... Nope
Gus (LC&P).
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