Re: Tigerlight doesn\'t seem as bright
You know, the plague/challenge of the computer age is to educate/convince people not to open unknown/unexpected attachments/etc.
The same challenge of the rechargeable light/tool industry is to get people to not:
1) over discharge the batteries
2) leave these things on the charger (even a smart charger)
I hate to sound like a know-it-all (someone's got to end this madness), but the way to get the absolute LONGEST life from your batteries is to charge them fully, take them OFF the charger, and only put them back on when they start to "dump" or noticably begin to "dim" or "slow down (drill/etc)".
This has nothing to do with memory, but it has EVERYTHING to do with voltage depression and cell stress/heat from repeated/prolonged overcharging. Even a smart charger will raise the temp of the battery significantly. This will accelerate cell failure, period.
The voltage of your tigerlight/magcharger/etc is easy to figure. Take the # of cells, 6 in the case of the tigerlight, and multiply by 1.2 volts per cell (7.2 volts total). This should be pretty darn close to MOST any rechargeable tool/light's voltage measured under a typical load (this voltage will remain pretty constant except when right off the charger and right at the end of the run).
Typical load in a tigerlight would be using a stock bulb. Granted, a drill/saw is harder to measure and is harder to define a "standard" load situation. I would guess that in the case of a motorized tool, a simple no-load full speed condition would be close enough. There are other variables present in the drill though, maybe I should not have opened that can of worms.
If the voltage is under this value (7.2) by some rough multiple of 1.2 then one or more cells have prematurely discharged or are shorted.
Take the following example:
tigerlight pack is 6 cells
typical runtime is 60 minutes (arbitrary #)
should be approx 7.2 volts under standard load
voltage right off charger under load = 7.8
voltage after 5 minutes = 7.2
voltage after 20 minutes = 7.0
voltage after 30 minutes = 6
You can see that somewhere between 20 and 30 minutes, 1 cell (1.2 volts of power) discharged before the others. This lowered pack voltage to 6 volts (7.2-1.2=6). If this had been around 4.8 then 2 cells would have discharged. This was his original measurement.... right?
These cells will usually recharge to 1.2 volts per cell, so final voltage, or voltage right off the charger, or voltage RIGHT after turning the light on means...... nothing. Unless (always an exception) the cells are REALLY bad, but most packs fail from 1 or more cells being weak, not failing completely.
Take the following data. I collected this from a light I own. It has a 25 watt mr-16 bulb and 5 4500mAh cells. Runtime is approx 90 minutes. The initial reading is right off the charger. Column 1 is the time, column 2 is the pack voltage.
time voltage
0.01 6.56 (instantaneous reading when light was fired up)
4 6.32
9 6.15
15 6.04
21 6.012
27 6.012
43 5.99 (nominal voltage achieved, 1.2 volts per cell)
51 5.96
60 5.91
68 5.87
76 5.8
86 5.72
89 5.67
94 5.59
95 5.56 (see note below)
96 5.53
97 5.49
99 5.39
100 5.32
101 5.26
102 5.14
103 4.79
104 4.57 (nasty yellow color)
105 3.94 (test ended)
At 95 minutes, pack voltage was 5.56 volts. 5 cells in the pack means that each cell was still providing 1.112 volts. This was right about the time when your naked eye would notice that the brightness was falling off. So, when you think the pack is dead (which it pretty much is), you should still measure practically 1.2 volts per cell.
At 104 minutes (nasty yellow), the cells are still at .914 volts each.
Hope you guys all got something from this, and that I didn't make too many typos or wander too much.
