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I've noticed that many on this forum will hunt for a charger, get one and feel temporary peace. This "hunt" then continues, this time for batteries, and is repeated and again the "peace" is temporary. Witness a sampling of the questions:
- Should I break them in ?
- What sort of numbers (capacity) should I be getting ?
- Should I do a refresh (discharge and charge) ?
- My batteries are hot, should I increaese (or decrease the charge rate) ?
I don't expect these posts and questions to go away but I do have a proposal (Xmas-Project
?) for those with a lot of batteries who do not know which ones "behave well" with their selected charger.
Interested in slaying the battery and charger "birds" with one stone, anyone ? TRY THIS:
- Discharge: Before I go on, lets make a comparison of charging batteries to the task of filling a container with a quart (32 ounces of water). If I drain the whole container by pouring out 1 ounce/sec. The container will be empty after 32 seconds. Let us call this rate (1 ounce/sec) to be equal to a "Wamp"...you'll see why later. The volume is still 32 ounces or "32 Wamp-seconds".
- Charge: Now if I were to pour at double the rate you poured it out (2 ounces/sec), you would be done in half the time (16 seconds).
- SmartCharging: Sounds difficult, but humans do it all the time when they pour themselves a glass of milk without overflowing the cup. Blind people know when to stop by holding a finger inside the top edge and waiting for "the feel".
Bottom Line/The Test Testing the smartness (stopping when full) of your charger depends on "it" and the "batteries". Discharging them completely takes too long and then charging them up takes more time. So do the following:
- Take a battery that has just been fully charged (as indicated by the charger). Skip the trickle portion of the charge process. What we are testing for is the "detect/shut off" capability of charger with a particular battery.
- Discharge them at half the charge rate for 10 minutes
- Charge them a the normal rate (up to a max of 15 minutes). Note the time beyond 5 minutes at which the charger stops. A perfect battery/charger will stop at 5 minutes.
- Use the following rating for each minute beyond 5 minutes:
1 minute over: 20% overcharge
2 minute over: 40% overcharge
3 minute over: 60% overcharge
4 minute over: 80% overcharge
5 minute over: 100% overcharge
Note: The "overcharge" is relative to the small amount of charge that was taken out and not relative to total charge of the battery(i.e. capacity). So if I take a cup out of a gallon container but need to put back in two cups, then the overcharge will 1x (i.e. 100% more) the amount I took out.
For those using a "resistor" to discharge, the value will be:
R_dis ~= 2.9/('Charge Current')So for a 1 amp charge rate, you should use a 2.9 ohm resistor to get about 0.5A disharge.
...tell me what you find,