Dyno Hub Question

On Mon, 13 Oct 2014 20:04:08 +1100, James
wrote:

On 13/10/14 17:06, Jeff Liebermann wrote:


Test setup:
http://802.11junk.com/jeffl/LiPo/Ultrafire%2018650%20test.jpg

Hmmm... That's so bad that I'm wondering if I really charged the
battery to full charge. The charger light went from orange to green,
so I assumed that it was done charging. I'll recharge it with my
fancy balance charger and see if that does anything different during a
re-test.

Can you get a few more coulombs out by squeezing the clamp?

Ummm.... no. The clamp is my idea of an improved battery holder. It's
used because the lazy/cheap/inept designer of the West Mountain Radio
CBA II elected to NOT use a 4 wire Kelvin connection to the battery.
Instead, they measure the battery voltage inside the tester. Any
voltage drop in the leads, including the battery terminal contact
resistance, shows up in the curves. It would have been so easy to
measure the battery voltage at the battery with 2 additional small
wires, but they didn't. So, I do my best to minimize additional
voltage drops.

After some experiments with a 5 digit DVM, I found that the typical
18650 and AA battery holders with springs made lousy connections. This
is the way I previously tested batteries, which doesn't work well at
high currents:
http://802.11junk.com/jeffl/NiMH/cba-II.jpg
The plastic clamp is a big improvement on that mess. Incidentally,
soldering doesn't help very much. I partly built a proper battery
holder (with compression screw contacts) out of some scrap Delrin, but
it's not done.

The length of cable between the CBA II and the battery is probably too
long, but necessary for some of my other tests. I guess I should make
a shorter cable.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 13 Oct 2014 06:30:04 -0700, sms
wrote:

I tried it with another charger too. No difference. On protected cells
the protection circuit determines end of charge.

Wrong. EOC (end-o-charge) is determined by the charge controller. All
the protection circuit does is go open circuit if it detects too much
charge current, too much discharge current, too much charging voltage,
and if the battery is drained to too low a voltage. A few have
temperature sensors to disconnect in case of fire. If there was
anything in the battery that is involved in controlling the charging,
it would require the ability of the battery pack or equipment vendor
to set the EOC point, which isn't available.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Monday, October 13, 2014 7:06:12 AM UTC+1, Jeff Liebermann wrote:

Piece of junk battery with barely 750 ma-hr capacity instead of the
rated 3000 ma-hr.

I ran a much looser test of several external batteries for my iPhone and the one I settled on was good for something usefully over 3Ah (say a max of 4Ah if you're generous about wastage) but advertised for 12Ah, so about a quarter to a third of truth is now standard in battery amphour meretrice. Nonetheless a bargain for under EURO 10 delivered, and including a connector kit and a decent enough cable. See "Extended cycling connectivity for credit card tourers and overnight campers" at
http://www.thorncycles.co.uk/forums/...63189#msg63189
where I also describe my rather casual test method. The zipped travelling bag was supplied by me.

Andre Jute
Always lighthearted

On Sun, 12 Oct 2014 23:06:12 -0700, Jeff Liebermann
wrote:

Discharge curve:
http://802.11junk.com/jeffl/LiPo/Ultrafire%20LiPo%203000%20ma-hr%2018650.jpg

Test setup:
http://802.11junk.com/jeffl/LiPo/Ultrafire%2018650%20test.jpg

Hmmm... That's so bad that I'm wondering if I really charged the
battery to full charge. The charger light went from orange to green,
so I assumed that it was done charging. I'll recharge it with my
fancy balance charger and see if that does anything different during a
re-test.

I charged the battery overnight and ran the discharge test again. It
was only slightly better. Maybe an optimistic 900 ma-hr.
http://802.11junk.com/jeffl/LiPo/Ultrafire%20LiPo%203000%20ma-hr%2018650%20test.jpg
Junk battery methinks.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 10/12/2014 2:45 PM, Jeff Liebermann wrote:
On Sun, 12 Oct 2014 12:53:25 -0700 (PDT), Sir Ridesalot
wrote:

Did you notice that the light Steve linked to also has the 18650 battery?
Cheers

Yes. If I were looking for a decent light for bicycle or home, it
would probably have one or more 18650 cells. I much prefer prismatic
cells (such as in a cell phone) than cylindrical, but for the time
being, the 18650 has become the de facto standard power source for
cylindrical flashlights.

The default decent light now has a Cree XM-L T6 (100 lumens/watt),
capable of 1000 lumens with a proper thermal solution and sufficient
power, and an 18650 battery or battery pack. Higher cost lights have the
latest LEDs that are more efficient. 200 lumens/watt LEDs is probably
what the SuperNove E3 Pro is using.

You just have to be sure that it's actually a XM-L T6 LED, and you have
to acquire quality 18650 cells.

For a self-contained light I don't think many cyclists want more than
single cell light. For lights with a separate battery pack multiple cell
packs are fine. I'd rather have a shorter duration light without a
separate battery, and change batteries if I am doing a night ride longer
than a couple of hours.

You need to watch out for crappy lights no matter what the power source
and no matter what the country of manufacture. The schtick about "cheap
Chinese flashlights" should really be "crappy lights regardless of
origin or brand."

On 10/13/2014 11:30 AM, sms wrote:

snip

You need to watch out for crappy lights no matter what the power source
and no matter what the country of manufacture. The schtick about "cheap
Chinese flashlights" should really be "crappy lights regardless of
origin or brand."

It's interesting to look at the specs from different companies marketing
the same unit:

160 lumens:
http://www.dhgate.com/store/product/genuine-assassin-yzu01-flashlight-cree-t6/193832992.html
480 lumens:
http://www.dx.com/p/assassin-yzu01-cree-xm-l-t6-480lm-white-5-mode-zooming-flashlight-black-1-x-18650-3-x-aaa-231912
2000 lumens: http://www.ebay.com/itm/161398547525 (they never really
say 2000 lumens, the heading says 2000lm but they never claim that that
means 2000 lumens)

The reality: assuming 100 lumens per watt, based on the current
consumption, the battery voltage, and a generous estimate of the
efficiency of the converter circuit, 366 lumens. This is reasonable
considering the variable conversion factor between lumens and chilumens.

Whatever it is, I used this on Saturday for many hours and I got a lot
of comments like, "where the hell is that light coming from?!"

On 10/12/2014 10:28 AM, Jeff Liebermann wrote:

Now you tell me. I'll probably give it away as a gift.

Strange beam pattern.

No kidding. When focused to the smallest size, it provides perfect
image of the LED geometry on the wall. I could probably use it as a
microdot projector.

Incidentally, the lens comes out quite easily, which then produces a
nice wide pattern that might be useful for the "be seen" aspect of
bicycle lighting.

I got it because it's easy to power it from a dynamo. It would make a
good "being seen" flasher for those with dynamo lights that want
something for daytime use. It doesn't rattle, it has a good switch, and
it doesn't require removing the battery to charge it. It's still better
than probably 95% of the bicycle lights you see on the road.`

On 10/13/2014 9:46 AM, Jeff Liebermann wrote:
On Mon, 13 Oct 2014 06:30:04 -0700, sms
wrote:

I tried it with another charger too. No difference. On protected cells
the protection circuit determines end of charge.

Wrong. EOC (end-o-charge) is determined by the charge controller. All
the protection circuit does is go open circuit if it detects too much
charge current, too much discharge current, too much charging voltage,
and if the battery is drained to too low a voltage.

The protection circuit opens if the battery voltage gets too high, not
if the charging voltage is too high. The open circuit charging voltage
is always higher than the 4.26V of the protection circuit on any Li-Ion
charger.

The protection circuit enables the use of a dumb charger because it will
open circuit when the battery voltage rises above 4.26V. So if you use a
4.3V dumb charger the battery will charge to 4.26V then the protection
circuit will open and charging will stop.

Look at the car charger that came with the light from Amazon. It has
nothing inside other than a current limiting resistor (and the LED and
series resistor). The theory is that even at 12-14V open circuit the
Li-Ion cell can be charged because a discharged cell will be around 2.5V
and will pull down the charging voltage to the battery voltage because
the series resistance of the battery is very low. The voltage will
slowly rise and the protection circuit will stop the battery from being
charged to over 4.26V. That's the theory, anyway. But the series
resistor inside that car charger is too low of wattage (looks like 1/4W)
to dissipate the heat so it began to heat up and smell after a short time.