Truck tail-light for daylight

[jawnn]

I want to use a truck tail light for daytime usage, for my bicycle. The small bike lights are not visible to cars moving at 40mph until they are on you. They really need to see you before 1760ft or more. It takes more than 30 seconds for a driver to make a good judgment; and in the dark winter days of the Pacific North West, people’s brains slow down until they are driving in a trance.
This is the taillight that I have: http://www.superbrightleds.com/moreinfo/truck-oval-lamps/ptf-series-truck-light-w-flange-ptf-x56/562/

It has 56 large LEDs. I need to know how much power it uses to figure out what kind of battery pack to buy for it. I do have a flasher, but I want to calculate for full brightness.

Is 415mA about right for each bulb? Or is that for the whole thing? And I should get at least two hours out of the batteries.

 

[Steve K]

The specs aren't very detailed, but it appears that 415mA is the current draw for the taillight as a whole. Figure about 5 watts of power consumed.
I'm not clear as to why it says "55/415mA". I wonder if it has a low level output for normal taillight use, and a high level output for brake light use. It does list some three pin connectors as accessories, so I bet it has a ground, a power wire for taillight use, and a power wire for brake light use (or something like this).

 

[znomit]

I'm not clear as to why it says "55/415mA". I wonder if it has a low level output for normal taillight use, and a high level output for brake light use.

And how well will they handle being used as a brake light all the time?

 

[jawnn]

this is the battery pack I want to use

http://www.batteryjunction.com/tenergy-14-8v-2200.html

 

[find_bruce]

I understand your motivation & concerns, I don't think this light is the way I would go about it - I would be looking at 1 or 2 XP-E red LEDs running at 500 mA each with a decent diffuser to increase the size of the apparent light source. Anyhows that's not what you were asking - so some back of the envelope calcs - if 415mA is in fact the current draw for the taillight as a whole, the 2200mAh battery you linked to should last you more than 5 hours.

I would be astounded if a 5mm led survived the application of 415mA, but in the unlikely event that 415mAh is the current draw per LED, the battery will be dead as a dodo in less than 6 minutes :eek: Even if you used Panasonic 3400 cells you would still need 56 cells to get 2 hours run time. Like I said this is an unlikely scenario & from what I recall of vehicle electrics I do not expect even trucks would be running lights requiring 46A for just 2 stop lights.

In any event given the relative prices I would be getting the light in my hands before splashing the money on the battery. I suspect you would be able to find a cheaper 4S1P pack, if that was what you were after

 

[Alaric Darconville]

I want to use a truck tail light for daytime usage, for my bicycle

This lamp, if it really conforms to FMVSS 108 and the specific SAE standards referenced, is designed for a semi or other vehicle over 80" wide. If it's good enough for that, it's good enough for your use. The dual mAH rating is because it has the tail and stop/turn functions. You probably could have it on the low setting the whole time and be seen OK, but many bicyclists prefer something flashing/strobing. If you flash/strobe at the full intensity, that's probably way too much and may actually put you in more danger.

You could always wire it to your rear brake so it functions like a brake light. It could also be manually flashed that way.

 

[N8N]

Just something to keep in mind, you may want to look for a unit that will work down to 6V in case you ever go with a dynohub setup someday. I did a quick search for one but couldn't find one. You'd still need a rectifier for dynohub use though as the dynohub will be 6VAC.

 

[schizeckinosy]

I use a 44-led Maxxima truck taillight for my tail, and an amber version for the front, both set on the "brake" setting. Mine are rated at 340 ma. I have run them steady at night or with a strobe unit during the day for years, never a problem. They are really bright and you will be seen during the day for sure. No heat issues running at brake, but apparently yours are more powerful so YMMV.

That said, I am really thinking of going with a 1-2w bike light, like a danger zone or similar, and a Vinh P60 5w dropin set to blink for the front. I'm getting tired of lugging the lead battery that I use, and I'm thinking that looking more like a bike is good, and more like a construction zone maybe not as good.

 

[find_bruce]

Just something to keep in mind, you may want to look for a unit that will work down to 6V in case you ever go with a dynohub setup someday. I did a quick search for one but couldn't find one. You'd still need a rectifier for dynohub use though as the dynohub will be 6VAC.

Um you do realise that a dyno hub will happily exceed 6V - just as an example my SP dyno PD-8 churns out the 10.3V to run my light from around 10 km/h

 

[STiFTW]

Well since you are looking at truck lights, and I have done something similar on my MTB, I thought that I would chime in.

I put on a Rigid Industry Duley flood LED light: http://www.rigidindustries.com/Dually-LED-Light-Flood-p/dually-fl.htm

It is powered by an 84Wh LiFEPO battery that is conveniently enclosed in a water bottle: http://www.batteryspace.com/waterbo...trail-techmaleplugforhidhalogenbikelight.aspx

The setup is ... blinding. Well than enough light for me to bomb single track trails in the dark, and it is incredibly visible during the day. Normally I mask it off with some tape on a lens cover until I get to the trails it is that bright.

I wanted something that would be indestructible and have incredible run time since I can go for some very long rides.

 

[schizeckinosy]

^^^ That looks like a great setup!