DIY lights - LED project

[mountain_lion]

WH, my observations are based on work bench tests only. I have not constructed a usable housing / mount for my light yet to allow field testing on the bike.

 

I have to admit that by eye it is difficult to see the difference in light output produced by the 1W Luxeons at 600 mA and 900+ mA.

So the point may be moot. Running at 600mA might actually be more efficient producing less heat loss, i.e more  lm/W.

 

I will try to do some comparative light measurements later.

This method looks interesting if you do not have a lux meter.

 

Getting the housing and mounting sorted out is my next priority.

Fine tuning and more experimenting can be done later.

Doubt if my light will look as neat as yours; I am not importing a round heat sink (at least not for now).

 

BTW, What capacity batteries (mAH) are you using?

Have you tested the run time? i.e. how long can you run before the light starts to dim?

 

At 1A load most NiMH batteries seem to maintain their rated voltage for  most of the discharge cycle and then starts to drop quickly near the end.

So voltage drop should not be a major problem.

See battery shootout on candlepower forums (updated recently).

 

1.2V x 8 = 9.6V is close to the limit for driving 3 LEDs in series.

Proof of the pudding is in the eating though; If it works good enough then it is good enough!

 

 

[Older]

and here it is: The setup with 9.6V battery pack' date=' buckpuck controller and 3 x 1W Luxeon LED's and Fraen narrow beam collimator:

 

 

[/quote']

 

With that battery pack and wiring you could have fitted a dynamo!

[markStockton]

 

Mark' date=' got any prices for the Lipos yet?

 

My tests show that 8x AA NiMH can light three 1W LEDs in series, but the 3021 buck puck driver only manages to get the load current up to about 600mA.

With 12 AA's the problem goes away and the buck puck manages a load current of 1000mA.

 

Unfortunately I do not have a lux meter. Without a meter it is

difficult to judge how much extra light you actually get with the

higher current.

 

 

I have 12 AA rechargeables, but it is a whole mix of capacity ratings with some quite old, which is not ideal. I need some of these for other electronics, plus Mrs mountain_lion also wants a light.

Buying another 12 (or more) NiMH AAs is not going to be cheap.

Might be worth it to look at getting Lithium type batteries plus charger.

 

[/quote']

 

I havn't looked further into Lipo's for two reasons:

 

1. The 8 X Sanyo 2,500mah NIMH's that I got are working really well. Lots of light, and the other night after a two hour night ride the cells still had 1,600ma in them.

 

Your finding that they are only operating at 600mah would explain the superb battery life.

 

2. You have to be very, very carefull not to over discharge Lipos, so I need to cobble together some sort of voltage indicator so as not to damage the Lipos.

 

BTW - You also have to balance Lipos periodically when charging them.

 

[Canaris]

correct me on the basics please  Watts = volts x amps.  So a 1 watt LED that has been cuircuited to run at 12 volts will burn 1/12 amp per hour?

 

ergo, the amps is less relavant than the volts.  dimming will only occur when the battery can no longer supply the required amps at the given volts.

[Hog_]

Ok, so I'm going to be ordering my lights and lenses soon. I'm thinking of doing a mix between these 2:

http://www.racedaynutrition.com/features/bikelight.aspx#28

http://www.candlepowerforums.com/vb/showthread.php?t=126276

 

I'm leaning towards 2 x 10deg + 1 x 15 deg lenses, or should I rather go for 2x15 + 1x10?

 

Need to still source the heatsinks, but the rest I'll be getting from Rabtron.

Wish me luck!

 

 

 

[Flemish Lion]

In case someone is desperate for batteries...

 

A friend of mine recently asked me if I would be interested to be an agent for the company he works for, i.e. wholesale of batteries and chargers. But I have a full time job and don't even now how their products are priced in the market - so haven't persued it yet and further thought selling to individuals would be too much of a mission.

 

I bought a Vanson -878 charger (R125), 8 x GP AAA (R46 per 4) - (1000Mah) and 8 x GP AA (R84 per 4) (2500Mah), both rechargeable.

 

I don't have a clue how competitive these prices are. But they have any kind of battery or charger one can think of. E.g. I looked at the 2900Mah, but those were close to R100 per 4 I think - and for my light 2500 is enough.

 

(details for charger see: http://vanson.manufacturer.globalsources.com/si/6008800011523/pdtl/Standard-battery/1001636723/Easy-Charger.htm)

 

Let me know if you really need some batteries and we can perhaps make a plan...

[Canaris]

interesting thing to note.  THe traditional AAA and AA batteries are 1.5V but the RECHArGEABLES are 1.2V.  THE diference is very little if you stack 2 or 3 batteries together, and few appliances will notice the votage drop.  However, if you stack eight batteries in series the diffence is .3 x8 = 2.4 volts.  THis difference is significant for lights and appliances rated at 12 volts and you will see a diference in performance.  Ergo, if you are building battery packs with AAA batteris that are rechargeble you will have to use 5 for 6 volts and 10 for 12 volts.

 

Additional note:  I have only seen grandcell 1.5v AA rechargeable batteries

[Hog_]

 

In case someone is desperate for batteries...

 

A friend of mine recently asked me if I would be interested to be an agent for the company he works for' date=' i.e. wholesale of batteries and chargers. But I have a full time job and don't even now how their products are priced in the market - so haven't persued it yet and further thought selling to individuals would be too much of a mission.

 

I bought a Vanson -878 charger (R125), 8 x GP AAA (R46 per 4) - (1000Mah) and 8 x GP AA (R84 per 4) (2500Mah), both rechargeable.

 

I don't have a clue how competitive these prices are. But they have any kind of battery or charger one can think of. E.g. I looked at the 2900Mah, but those were close to R100 per 4 I think - and for my light 2500 is enough.

 

(details for charger see: http://vanson.manufacturer.globalsources.com/si/6008800011523/pdtl/Standard-battery/1001636723/Easy-Charger.htm)

 

Let me know if you really need some batteries and we can perhaps make a plan...

[/quote']

 

That actually sounds pretty good. Maybe if there's enough interest we can do a biggish order to make it worth your while.

 

 

[Willehond]

I bought some Duracell 2650mAh AA's for R55 per four at Dischem last year!  I think they made a pricing error, so I bought loads.... Willehond2008-04-17 06:59:42

[mountain_lion]

 

correct me on the basics please  Watts = volts x amps.  So a 1 watt LED that has been cuircuited to run at 12 volts will burn 1/12 amp per hour?

 

ergo' date=' the amps is less relavant than the volts.  dimming will only occur when the battery can no longer supply the required amps at the given volts.

[/quote']

 

In general you are correct, IF you are using a constant voltage source.

 

For power LEDs, you normally use a constant current source, e.g. the buckpuck driver.

The buck puck essentially regulates the voltage across the LED to keep the current constant. However the buck puck cannot increase the voltage above the supply voltage of the battery.

 

Also note that for a LED to emit light the supply voltage needs to be higher than the "forward voltage" of the diode. Typically forward voltage for power LEDs is between 3.5V and 4V for power LEDs.

 

See the Luxeon site and data sheet for more info.

 

 

 

 

[mountain_lion]

 

I bought some Duracell 2650mAh AA's for R55 per four at Dischem last year!  I think they made a pricing error' date=' so I bought loads.... [/quote']

 

Lucky bugger! They sure got the price wrong; should have been R55 per battery not per four pack!

 

[Willehond]

I bought some Duracell 2650mAh AA's for R55 per four at Dischem last year!  I think they made a pricing error' date=' so I bought loads.... [/quote']

Lucky bugger! They sure got the price wrong; should have been R55 per battery not per four pack!

 

Indeed, we cleaned them out!

[Hog_]

 

I bought some Duracell 2650mAh AA's for R55 per four at Dischem last year!  I think they made a pricing error' date=' so I bought loads.... [/quote']

 

Seeing as they're second-hand, I'll offer you R50 per pack - If it's still unopened

 

 

 

[Willehond]

I bought some Duracell 2650mAh AA's for R55 per four at Dischem last year!  I think they made a pricing error' date=' so I bought loads.... [/quote']

Seeing as they're second-hand, I'll offer you R50 per pack - If it's still unopened

 

Sorry, but as you can see, they have already been put to very good use!  R110 for a 9,6V battery pack, not bad hey? (I have since found an 8 piece battery holder)

 

[Hog_]

FINE! You could've made a nice profit, but NO, you want to keep them for yourself!

 

I'll just have to go to Dischem myself! I'm sure they haven't noticed by now.

 

 

 

 

 

[markStockton]

For those who are Jhb based, I got my 2500mah Sanyo's for R 25.00 per cell from a small battery supplier called SJ Andrews in Marlboro.