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Old February 10th 18, 12:41 PM posted to rec.bicycles.tech
Oculus Lights[_2_]
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Default Battery Replacement on Lights with Internal Li-Ion Batteries

On Saturday, February 10, 2018 at 12:01:17 AM UTC-8, wrote:
On Friday, February 9, 2018 at 10:35:27 PM UTC+1, sms wrote:
On 2/8/2018 12:21 PM, Joerg wrote:
On 2018-02-06 20:48, Jeff Liebermann wrote:
On Tue, 6 Feb 2018 10:52:50 -0800, sms
wrote:


[...]


It's a 2 cell 18650 pack with the batteries in parallel, and a
protection circuit board shared between the two cells. The cells are
allegedly 2800mAH, for a total of 5600mAH.

Seems rather high.


Probably a Chinese spec :-)

Just like with lights where there are lumens and then there are Chilumens.


Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* ... Note that batteries are tested at a 0.2C
discharge, which yields larger numbers than the usual headlight
discharge rate.Â* The Lezyne Deca 1500XXL claims 1500 lumens, which
also seems a bit high.Â* Assuming 120 lumens/watt at a nominal
3.7V/battery, that's:
Â*Â*Â* 1500 / 120 / 3.7 = 3.4A
to run the headlight at full brightness, or 1.7A per cell.
Meanwhile, the cell capacity is tested at:
Â*Â*Â* 0.2 * 2800 = 0.56A


Classic American answer: Then you need a bigger battery. On my road bike
I use eight 18650 cells, four in parallel and two of those packs in
series so the current on the cable to the front light doesn't exceed 1A,
at least not by much.


I decided to do run-time tests on my two Lezyne Decadrive 1500xxl lights.

I think that I have never before experienced a light manufacturer that
significantly under-stated run times.

Running both in "Overdrive Race Mode" the run time was much higher than
the manual stated. mtbr.com measured "Overdrive Race Mode" at 1390
lumens, a little less than the claimed 1500 lumens. The manual says 100
minutes in "Overdrive Race Mode."

On the light with the new 5200mAH battery back, one test gave 157
minutes, one 162 minutes.

On the light with the old 5600mAH battery pack, one test gave 193
minutes, one test gave 216 minutes.

I did not run the battery all the way down. When the "10% remaining"
indicator occurred I stopped the test.

I am going to do a third test as well, as soon as the batteries are
recharged.


Did you also measured the light output over time? Otherwise the numbers mean nothing to me.

Lou


my Oculus lights have a field replaceable battery design. Np changing batteries when drained and replacing with a freshly charged battery, if you aren't able to plug the charger into the charging jack. Your choice of high capacity 5500mAH 26650 or 3500mAH Panasonic 18650.
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