Sunligth Cell Power

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?

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" ??? news: snipped-for-privacy@d>> Do anyone know how many cells needed to power one Super Brigth LED for

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

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

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.

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                                    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!

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" ¦b¶l¥ó news: snipped-for-privacy@radagast.org ¤¤¼¶¼g...

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" ??? news: snipped-for-privacy@news.supernews.com ???...

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.

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                                    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!

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

P

"Dave Platt" ¦b¶l¥ó news: snipped-for-privacy@radagast.org ¤¤¼¶¼g...