Sunligth Cell Power

[townt.com]

Do anyone know how many cells needed to power one Super Brigth LED for 6
hours?

Thx!

P

 

[Eric Smith]

townt.com wrote:

Do anyone know how many cells needed to power one Super Brigth LED for
6 hours?

What kind of cells? Alkaline AA? Lithium coin? Silver oxide button?
NiCd? NiMH? Lithium polymer?

How much current are you going to pass through the "Super Brigth LED"?

What are you using to limit/regulate the current? A fixed
resistor? A linear regulator? A switching regulator?

What is the air-speed velocity of an unladen swallow?

 

[townt.com]

Hi,

I just doing an project.

I wanna to use Solar Cell to ligth the 8.0 x 8.0 mm LED, 1.8 to 2.5V,
1200mA.

No idea for the regulator yet. I just want to put in my bicycle. If the LED
can work over 6 hours per day is wonderful.

Do you think I should use the Lithium cell to store the energy?

Thanks!

P

"Eric Smith" <eric@brouhaha.com> ???
news:m37ibc5f4u.fsf@donnybrook.brouhaha.com ???...

townt.com wrote:
Do anyone know how many cells needed to power one Super Brigth LED for
6 hours?

What kind of cells? Alkaline AA? Lithium coin? Silver oxide button?
NiCd? NiMH? Lithium polymer?

How much current are you going to pass through the "Super Brigth LED"?

What are you using to limit/regulate the current? A fixed
resistor? A linear regulator? A switching regulator?

What is the air-speed velocity of an unladen swallow?

 

[Peter Bennett]

On Fri, 25 Jul 2008 22:43:07 +0800, "townt.com" <info@townt.com>
wrote:

Hi,

I just doing an project.

I wanna to use Solar Cell to ligth the 8.0 x 8.0 mm LED, 1.8 to 2.5V,
1200mA.

No idea for the regulator yet. I just want to put in my bicycle. If the LED
can work over 6 hours per day is wonderful.

Do you think I should use the Lithium cell to store the energy?

Thanks!

If you want to use 1200 mA for 6 hours, your battery capacity has to
be at least 7200 mA-H - but you should never fully discharge a
rechargeable battery, so you need at least a 10 A-H battery - I'd
probably use a small sealed Lead-acid battery. (but I haven't looked
at the capacity/price of the current Lithium batteries.)


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[townt.com]

Yes. Thank you very much for your idea. I think the split arrangement is
wonderful.

Do you think I can use the rechargable-battery for this project ?

But I have no idea to use the Solar Panel to recharged the battery ? In the
market, I think there is some solution. Isn't it ?

"Dave Platt" <dplatt@radagast.org> ŚbślĽó news:vropl5-scd.ln1@radagast.org
¤¤źśźg...

I just doing an project.

I wanna to use Solar Cell to ligth the 8.0 x 8.0 mm LED, 1.8 to 2.5V,
1200mA.

Whoof. That's a flashlight-grade high-power LED!

No idea for the regulator yet. I just want to put in my bicycle. If the
LED
can work over 6 hours per day is wonderful.

Well, the LED certainly can work for that long (if you have a good
enough heatsink on it). The battery and solar panel, on the other
hand... well, getting as much power as you need is going to be
nontrivial.

You're looking at around 5 watts of power just for the LED... that's
30 watt-hours per day.

Given that the battery-charging process isn't 100% efficient, and the
regulation of current for driving the LED isn't 100% efficient, you
should probably budget 50 watt-hours per day from the solar panels if
you want to be able what you want.

These days, a typical consumer-type solar panel capable of delivering
4-5 watts of power (e.g. 400 mA at 12 volts) costs anywhere from $40
(flea-market bargain price) to over $100, and has close to 2 square
feet of panel area. These panels are fairly well suited to charging
12-volt lead-acid cells.

That's probably about the largest panel that it would make sense to
place on the back of a bike (e.g. above the rear mud-guard). And, in
order to get 6 working hours of light out of a monster LED like the
one you're considering, you're going to have to have that panel in
direct sun for the full day.

Do you think I should use the Lithium cell to store the energy?

You're going to need something reasonably sophisticated to handle this
arrangement, I think.

If you're going to need more than an ampere at 2 volts (nominal), the
issue of choosing the proper battery type and regulator are quite
significant. I'd expect that some form of switching buck regulator
will probably be most efficient, as you can draw power from a
higher-voltage battery (such as a LiION or a lead-acid gel cell) and
transform it down to a higher current at a lower voltage.

Lithium batteries are tricky to charge... they *require* a charge
control IC circuit which is correctly configured for the battery
chemistry and size. Doing it wrongly can and will damage the battery,
with consequences up to and including a catastrophic fire.

Although they're heavier, a good modern NiMH battery pack might be a
bettery choice - they're less tricky to charge.

Lead-acid are the heaviest, and (I believe) have the lowest amount of
energy storage per pound, and many types won't live very long if you
deep-discharge them regularly... but they're probably the easiest to
charge-control.

You might find that you need to use a split arrangement... have a
solar panel and charge controller at home, the LED on the bike, and
two battery packs - one installed on the bike (for use) and one
connected to the charger at home.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[townt.com]

Hi,

Yes. I think use the sealed Lead-acid battery is also OK. Maybe I can add
some other LED for brake ligth, left sign and rigth sign.

Wowow. Wonderful.

P



"Peter Bennett" <peterbb@somewhere.invalid> ???
news:f61k84lfd8a8qcv7u8mtg8uga5mo0q3jjb@news.supernews.com ???...

On Fri, 25 Jul 2008 22:43:07 +0800, "townt.com" <info@townt.com
wrote:

Hi,

I just doing an project.

I wanna to use Solar Cell to ligth the 8.0 x 8.0 mm LED, 1.8 to 2.5V,
1200mA.

No idea for the regulator yet. I just want to put in my bicycle. If the
LED
can work over 6 hours per day is wonderful.

Do you think I should use the Lithium cell to store the energy?

Thanks!


If you want to use 1200 mA for 6 hours, your battery capacity has to
be at least 7200 mA-H - but you should never fully discharge a
rechargeable battery, so you need at least a 10 A-H battery - I'd
probably use a small sealed Lead-acid battery. (but I haven't looked
at the capacity/price of the current Lithium batteries.)


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[townt.com]

Yes. You are rigth. I will try this when I am in holiday.

P

"Dave Platt" <dplatt@radagast.org> ŚbślĽó news:cqgsl5-il.ln1@radagast.org ¤¤źśźg...

Yes. Thank you very much for your idea. I think the split arrangement is
wonderful.

Do you think I can use the rechargable-battery for this project ?

Depending on what type of rechargeable battery you select... yes, you
can probably use one. As I mentioned, there are tradoffs between the
different types (weight, energy storage capacity, ease of charging)
and you'll have to evaluate them based on your needs.

But I have no idea to use the Solar Panel to recharged the battery ? In
the
market, I think there is some solution. Isn't it ?

Most companies which sell solar panels, will also sell "charge
controllers" intended for charging 12-volt lead-acid batteries.

There are also solar panel / charger systems designed for charging
NiMH cells. Google for "solar battery charger". There's probably an
off-the-shelf solution which will meet your needs.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!