Bike light - further testing
Aug. 31st, 2009 06:17 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
johnridleyI did a longer term test of the light's runtime, charging it on Wednesday and running it for 40 minutes Thursday, Friday and Monday mornings and Monday afternoon, which totalled 3 hours. Then I brought it inside and it died in about another 10 minutes, so it appears that the light is good for 3 hours regardless of whether you do the 3 hours right after charging or in a few runs over the course of several days.
For this test, I unplugged the lamp from the battery when it was not in use because I did not know the draw of the pilot lamp.
Also, the pilot light on the back switched to "low battery" when the battery was half empty the last few runs, instead of nearly ready to shut off like it did the first time. I'd prefer something in-between; maybe "10 minutes to go" or something.
I have now put the light on an amp meter and come up with these draws from the battery (7.4 volts)
High: 1.46 amps
Low: 0.5 amps
Off (pilot light): 5.6ma (0.0056 amps)
On high, I get 3 hours, 10 minutes. This equates to a pack capacity of about 4.5 amp hours, which is about right for four 18650 cells (2300 mAH nominal each, in series/parallel).
Assuming linear draw, I should get 8 or 9 hours on low. This is FAR more than listed by the manufacturer (they say 4.5 hours). I'm going to have to test this but I don't see how I won't get at least 8 hours. Perhaps the current controller they're using has a lower "low" than the one they originally tested with.
The pilot light for 24 hours is .0056*24 = .13 amp hours drawn. This is close to 6 minutes of runtime. So I'd have to leave it on for 10 days to kill an hour's run time, a full month to deplete the battery. This is about what I originally calculated by sheer guesswork.
I'd still rather that the pilot light wasn't on when the unit was off, but I guess at the cost of 6 minutes per day of pilot light, I'll stop unplugging it every day; I'm concerned that unplugging it an additional couple hundred times a year (every day instead of every 3 days, for me) will significantly reduce the lifespan of the connectors.
For this test, I unplugged the lamp from the battery when it was not in use because I did not know the draw of the pilot lamp.
Also, the pilot light on the back switched to "low battery" when the battery was half empty the last few runs, instead of nearly ready to shut off like it did the first time. I'd prefer something in-between; maybe "10 minutes to go" or something.
I have now put the light on an amp meter and come up with these draws from the battery (7.4 volts)
High: 1.46 amps
Low: 0.5 amps
Off (pilot light): 5.6ma (0.0056 amps)
On high, I get 3 hours, 10 minutes. This equates to a pack capacity of about 4.5 amp hours, which is about right for four 18650 cells (2300 mAH nominal each, in series/parallel).
Assuming linear draw, I should get 8 or 9 hours on low. This is FAR more than listed by the manufacturer (they say 4.5 hours). I'm going to have to test this but I don't see how I won't get at least 8 hours. Perhaps the current controller they're using has a lower "low" than the one they originally tested with.
The pilot light for 24 hours is .0056*24 = .13 amp hours drawn. This is close to 6 minutes of runtime. So I'd have to leave it on for 10 days to kill an hour's run time, a full month to deplete the battery. This is about what I originally calculated by sheer guesswork.
I'd still rather that the pilot light wasn't on when the unit was off, but I guess at the cost of 6 minutes per day of pilot light, I'll stop unplugging it every day; I'm concerned that unplugging it an additional couple hundred times a year (every day instead of every 3 days, for me) will significantly reduce the lifespan of the connectors.
