Dynamo/LED power conditioning

On 2018-05-06 12:19, AMuzi wrote:
On 5/6/2018 12:50 PM, wrote:
On Sunday, May 6, 2018 at 12:01:24 PM UTC-5, Joerg wrote:

For me the only proper way of lighting a bicycle is with a rechargeable
battery. The LEDs get clean DC and the battery can be recharged from any
source, even a pulsating one. That way the lights will not dim to "stand
light" or go out when waiting at a traffic light. Why should bicycle
lighting be inferior to car lighting?

--
Regards, Joerg

What F-ing world do you live in where you recharge the lights on your
car? It must be a pretty F-ed up world. On all the cars I have
driven, you turn the switch and the lights come on. There ain't no
recharging the car lights. Rechargeable lights and batteries. Why
not just duct tape a flashlight to your bars. Then you can stop at
any convenience store and buy some new D batteries and ride forever.


I think Joerg meant that the automobile current from a 12~14VAC
alternator source gets run through a diode bride and then (as switched
by the regulator) through a lead-acid pile.

It's a lot of hardware for a bicycle I agree, but Joerg's seems to work
for Joerg's values of performance and efficiency.


In the old days I had a 6V lead acid battery charged by the dynamo. Not
technically an SLA but it was "tilt-safe". Later I replaced that with a
stack of NiCd. Should have refrained from fixed voltage charging after
that but ... oh well. Regarding switched power conversion I was an early
adopter which made things efficient and allows to run the dynamo (which
is essentially a current source) at a higher voltage, increasing the
power it delivers at a given speed.


... Frank & I prefer a
simple 6VAC tire drive dynamo and others extoll USB-LiIon sets or hub
dynamos. World's a big place and people have their own criteria, which
are often inscrutable.


8V is kind of a de-facto standard for powerful bike lights these days,
meaning two cell packs in series. On the road bike I have a total of
eight 18650 cells and on the MTB four. Works great. Despite being cheap
cells from China they last and last.

A hub dynamo would be nice but the typical bikes and wheel sets sold in
the US do not have one. With Li-Ion it won't matter much. While a hub
dynamo would allow me to reduce the cell count from eight to four or
maybe even down to two the dynamo itself would eat up the weight
savings. So as long as I do not ride more than 4-5h with the lights
fully on I am ok sans dynamo.

The light output from 8W into an LED is really nice. Once I waited at a
red light and a Harley rider pulled up next to me. His big headlight was
about the same brightness as mine except more spectrally pleasant, not
as "hospital-grade" white as mine.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2018-05-07 06:21, David Scheidt wrote:
Theodore Heise wrote:

:Someone noted elsethread the great variation in user requirements,
:and the choice between dynamos and rechargeables is certainly
:affected by them. I need a light only infrequently, so for me a
:dynamo would largely be wasted weight and clutter on the bike. On

Ah, but it would just work. Get on the bike, and ride. a rechargable
light would have to be found, put on the bike, and discover the
batteries are dead.


Not if it's done like on my bikes. The lights and Li-Ion packs are
mounted on the bikes, permanently. When I return from a ride I plug it
in. The charging turns off by itself when full. When I want to ride I
can always be sure to have a fully charged lighting system. The only
thing I have to mount is the MP3 player because that moves between MTB
and road bike. If I forget the MP3 it's no big deal.

--
Regards, Joerg

http://www.analogconsultants.com/

On 2018-05-07 08:31, Jeff Liebermann wrote:
On Mon, 7 May 2018 13:21:02 +0000 (UTC), David Scheidt
wrote:

Theodore Heise wrote:

:Someone noted elsethread the great variation in user requirements,
:and the choice between dynamos and rechargeables is certainly
:affected by them. I need a light only infrequently, so for me a
:dynamo would largely be wasted weight and clutter on the bike. On

Ah, but it would just work. Get on the bike, and ride. a rechargable
light would have to be found, put on the bike, and discover the
batteries are dead.

Assuming you own an automobile, what do you check before you go for a
ride or drive? Got enough gasoline? Fluid levels within limits? Tire
pressure look normal? Engine warning light on? For fanatics, does
the add-on OBD II display panel show anything unusual? Having driven
rolling wrecks during college, walking around the vehicle to see what
has fallen off or was stolen in the night was a regular ritual.


I always make sure that I see the reflection of my brake lights on the
driveway wall when I back out of the garage.


Same with my bicycles. Do you check the air pressure in your tires
before riding?


Ever since switching to thick thorn-resistant tubes that has become a
non-issue for me. They hold pressure for months. I can just hop on and ride.


... I don't, but I give the tires a good squeeze as a
crude pressure check and pump as needed. My favorite mistakes are a
loose quick release, ...


Oh-oh.

A friend had a skewer snap apart mid-ride. Luckily it was the one in the
rear wheel axle.


... a loose nut from an unfinished repair, and my
folding pedals in the folded position. I take a quick look at the
frame and gears for any sign of damage. I check for my seat bag of
tricks, which contains tools, parts, munchies, and a few dollars.


That is one of the few things I make sure after each ride, that I
replenish the beer money in the bike wallet.


Batteries do not provide a visual or mechanical indication of SoC
(state of charge), but you can add something like this:
https://www.ebay.com/itm/Lithium-ion-Charging-Battery-Voltage-Capacity-Percent-Level-LED-Indicator-18650/181692946263
Some headlights have a similar indicator built in. I use a DVM
(digital voltmeter) instead.


For about the same money you can get a DVM module that shows the voltage
to two digits behind the decimal point.


More problematic is the tail light, which usually runs on alkaline AA
or AAA cells. I haven't seen one with a SoC indicator and would not
expect to see one as the added circuitry and display would probably
cost more than the tail light. So, I run the alkalines until they
die, and carry a few spare NiMH cells which I rotate as needed. With
LSD (low self discharge) NiMH cells, they remain mostly charged for
months.

While just jumping onto the bicycle and going for a ride is a nice
thought, the reality is that we all do some manner of pre-flight check
before riding. So, why is it so painful to add a headlight battery
test to the checklist?


Just use a bike mounted pack and that issue goes away.

--
Regards, Joerg

http://www.analogconsultants.com/

On 5/6/2018 10:01 AM, Joerg wrote:

snip

For me the only proper way of lighting a bicycle is with a rechargeable
battery. The LEDs get clean DC and the battery can be recharged from any
source, even a pulsating one. That way the lights will not dim to "stand
light" or go out when waiting at a traffic light. Why should bicycle
lighting be inferior to car lighting?

I have dynamo wheels on several bicycles and it's nice to just go. Not
worry about charging lights off the bike.

OTOH the dynamo lights are not suitable for all situations. The
multi-use paths around here are generally alongside creeks and are
unlit, with a lot of twists and turns as they go over and under roads,
waterways, and railroad tracks. You need a higher-power light,
especially if you want to proceed at an expeditious pace.

It would be possible to have a hub dynamo capable of powering higher
power lights but there seems to be little demand for it now that there
are so many Li-Ion powered high-power lights available for relatively
low prices.

On 2018-05-08 03:21, John B. wrote:
On Mon, 7 May 2018 20:23:54 -0700 (PDT), "
wrote:

On Sunday, May 6, 2018 at 5:15:51 PM UTC-5, James wrote:
On 07/05/18 03:01, Joerg wrote:


Note the three big 470uF capacitor in the schematic. That's the "flicker
reduction trick" :-)

Problem is, electrolytic capacitors do not live long in harsh climate
conditions such as the black light enclosure baking in the glistening
Arizona desert sun for hours every week or riding around the Klondike in
a harsh winter.

For me the only proper way of lighting a bicycle is with a rechargeable
battery.

Bull**** alert!

We all know how reliable rechargeable batteries are, especially in harsh
environments, right?

OTOH, here is an electrolytic cap from Vishay, that has a "useful life"
of 1,000,000 hours at 40C, and 8000 hours at 125C.

If I remember my metric system correctly from elementary school or wheneverr I learned about it. 100C is boiling, 212Fahrenheit. So 125C would be about 250F? At 250F, I'm not sure I'd be worrying about whether my electric cap light was working or not.


257C actually :-) But with electronic stuff it is quite possible for
internal temperatures inside the various electronic devices to be at
much higher temperatures then ambient temperature inside the
enclosure.

Jeff can probably describe LED (for example) temperatures versus
ambient at greater length then the life of the LED at these
temperatures :-)


Old rule in vehicle design and even more so aerospace: Avoid the use of
electrolytic cap in designs like the plague. Without electrolytic
capacitors, electronics can last almost forever. If you must use them
(though I can't see why) then derate the heck out of their capacitance
so they last at least close to "forever".

Good quality electrolytics are possible. Some not too smart engineer had
placed the big capacitor right next to the always hot rectifier tube on
the amp of our Hammond organ. We just sold it but that capacitor was
still ok after 57 years, some of which under heavy use.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

On Tuesday, May 8, 2018 at 2:10:43 PM UTC-4, Joerg wrote:
Once I waited at a
red light and a Harley rider pulled up next to me. His big headlight was
about the same brightness as mine except more spectrally pleasant, not
as "hospital-grade" white as mine.

I remain absolutely astonished that people think the headlight on a bicycle has
to have the same brightness as the headlight on a motorcycle capable of 100+ mph.

- Frank Krygowski

On 2018-05-08 12:01, Frank Krygowski wrote:
On Tuesday, May 8, 2018 at 2:10:43 PM UTC-4, Joerg wrote:
Once I waited at a
red light and a Harley rider pulled up next to me. His big headlight was
about the same brightness as mine except more spectrally pleasant, not
as "hospital-grade" white as mine.

I remain absolutely astonished that people think the headlight on a bicycle has
to have the same brightness as the headlight on a motorcycle capable of 100+ mph.


You as an engineer should know this:

https://policedriver.com/over-driving-your-headlights/

So your 100mph statement is quite ridiculous.

Also, as I've said many times before I like to be seen. Since I have
these bright lights I have noticed a substantial drop in cases where car
drivers pull out in front of me. Objective accomplished, and at a very
modest cost.

--
Regards, Joerg

http://www.analogconsultants.com/

On Tuesday, May 8, 2018 at 12:43:00 PM UTC-7, Joerg wrote:
On 2018-05-08 12:01, Frank Krygowski wrote:
On Tuesday, May 8, 2018 at 2:10:43 PM UTC-4, Joerg wrote:
Once I waited at a
red light and a Harley rider pulled up next to me. His big headlight was
about the same brightness as mine except more spectrally pleasant, not
as "hospital-grade" white as mine.

I remain absolutely astonished that people think the headlight on a bicycle has
to have the same brightness as the headlight on a motorcycle capable of 100+ mph.


You as an engineer should know this:

https://policedriver.com/over-driving-your-headlights/

So your 100mph statement is quite ridiculous.

Also, as I've said many times before I like to be seen. Since I have
these bright lights I have noticed a substantial drop in cases where car
drivers pull out in front of me. Objective accomplished, and at a very
modest cost.

You should see some of the dyno light DRLs -- no charging, ride forever and plenty bright. Perfect for people who feel the need for bright lights on sunny days. I was practically blinded by a guy with a Supernova E3 triple during the day. Totally unnecessary on a cycletrack. In fact, the cycletrack through south waterfront has turned into such a dope parade that I am now avoiding it until the weather turns to **** and the cyclists go away.

-- Jay Beattie.

On 2018-05-08 13:13, jbeattie wrote:
On Tuesday, May 8, 2018 at 12:43:00 PM UTC-7, Joerg wrote:
On 2018-05-08 12:01, Frank Krygowski wrote:
On Tuesday, May 8, 2018 at 2:10:43 PM UTC-4, Joerg wrote:
Once I waited at a red light and a Harley rider pulled up next
to me. His big headlight was about the same brightness as mine
except more spectrally pleasant, not as "hospital-grade" white
as mine.

I remain absolutely astonished that people think the headlight on
a bicycle has to have the same brightness as the headlight on a
motorcycle capable of 100+ mph.


You as an engineer should know this:

https://policedriver.com/over-driving-your-headlights/

So your 100mph statement is quite ridiculous.

Also, as I've said many times before I like to be seen. Since I
have these bright lights I have noticed a substantial drop in cases
where car drivers pull out in front of me. Objective accomplished,
and at a very modest cost.

You should see some of the dyno light DRLs -- no charging, ride
forever and plenty bright. Perfect for people who feel the need for
bright lights on sunny days. I was practically blinded by a guy with
a Supernova E3 triple during the day. Totally unnecessary on a
cycletrack. In fact, the cycletrack through south waterfront has
turned into such a dope parade that I am now avoiding it until the
weather turns to **** and the cyclists go away.


They sure are much better than those sorry 2.4W bulbs from the not so
good old days. However.

1. Hardly any bike or wheel set in America has a hub dynamo. So you have
to buy new spokes and spoke it in.

2. When you get to an intersection, traffic light or whetever where you
need to stop many of these lights eitehr go out or they enter a "stand
light" mode which is rather dim.

3. They still can't hold a candle to MagicShine and clones of it. 8W
into a Cree XM-L is a different caliber than 3W.

4. The StVZO lights for dynamos that I have seen have a much too sharp
cut-off line which is uncomfortable on an uneven road or on the MTB.

5. The prices of many of those lights are outrageous. Often fat
three-digits. I don't want a $200 headlight on my bike only to have it
ripped off by a hobo a few months later.

As for blinding, this can easily be avoided. I did not ride one lone
mile on either the road bike or the MTB before installing an
after-market diffusor lens. Aside from no longer blinding other traffic
participants it also resulted in a nice broad beam.

--
Regards, Joerg

http://www.analogconsultants.com/

On 08/05/18 13:23, wrote:
On Sunday, May 6, 2018 at 5:15:51 PM UTC-5, James wrote:


OTOH, here is an electrolytic cap from Vishay, that has a "useful
life" of 1,000,000 hours at 40C, and 8000 hours at 125C.

If I remember my metric system correctly from elementary school or
whenever I learned about it. 100C is boiling, 212Fahrenheit. So
125C would be about 250F? At 250F, I'm not sure I'd be worrying
about whether my electric cap light was working or not.


Expect the temperature inside an electronics enclosure to be higher than
the ambient air temperature.

--
JS