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Tanker01

Lets talk LEDs and LiPos

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Wanting to hook up a lightweight rechargeable LiPo battery to power LEDs on my bike that I may be getting street legal eventually. How long should I expect a LiPo (lets say 2200MAh) to run my headlight, taillight, and signals for? I would run 2 LED small pods in the front for headlights, one flood and one spot (to simulate high beam and low beam) LED turn signals all around, and LED taillight and brake light. I am trying to keep this as simple as possible. I plan to keep my AC stator powered headlight as well as a backup. I am aware I will have to charge the LiPo separate from the vehicle. Has anyone done this or have any insight on doing this?

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Posted (edited)

Figure out the draw of the led lights you want to power with the battery.  This information should be easy to find when you buy the lights. 2200 mA is 2.2 amps.  So a 2.2 amp load will discharge that battery in an hour. A 1.1 amp load will discharge that batter in 2 hours. A .55 amp load will discharge that battery in 4 hours, and so on. 

 

First figure out what lights you want and find out how much your total load will be. Then figure out how long you want to be able to power these before having to recharge your battery. Then size your battery accordingly. 

Edited by MixinGasKickinAss
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1 minute ago, MixinGasKickinAss said:

Figure out the draw of the led lights you want to power with the battery.  This information should be easy to find when you buy the lights. 2200 mA is 2.2 amps.  So a 2.2 amp load will discharge that battery in an hour. A 1.1 amp load will discharge that batter in 2 hours. A .55 amp load will discharge that battery in 4 hours, and so on. 

Ah math. I forgot this portion of Circuits class... That class is the reason why I became a ME not an EE... 

Best way to handle the turn signal flashing? same flasher relay for front and rear? or can I do the same flasher relay for all 4 lights even? Trying to keep this as simple as possible, its already a 300lb bike and it will be very seldom used on the road. 

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one flasher for all four, flasher between battery and turn signal switch, turn signal switch directs +12v to left or right pair of turn signals.... seems that would be the easiest.

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Ok heres the math

Front lights (assuming both on): 2(5W/12V)=0.82A

Rear lights (assuming both on): 2(2W/12V)=0.33A

Turn Signals (pulsing on hazard): 4(3W/12V)=1A

Total amp draw with all lights on =2.15A

So that 2200mAh light will last me an hour assuming my W values were correct. 

The battery in question (RC helicopter LiPo has a 50C rating) so 50c*2200v=110000mA it will have a 110A max discharge rate

An hour of the street legal lighting should be more than enough for what I am planning to use it for. and at only 2.15A draw I am well within the max discharge rate.

Any recommendations for a good flasher relay or handlebar light control?

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I would not recommend using a lipo in this application since over discharging it will basically destroy it after a couple times, and there is zero need for their massive discharge rates.

why not just use a rectifier? 

Edited by Wild Alaskan
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You can get 6000mAh rechargeables cheap and where I put mine to power a 36W LED light.

Mock up before actual WP connections.

1199076431_20171021_1647501.jpg.9b66ca3b0aaecf38c97db98426dfe40d.jpg2030932161_20171021_1648231.jpg.9f0daf006658c68fe179df739a8a0199.jpg

If you know the watt hours of the mAh battery and calc from where I bought my batteries

Our 3500 mAh and 6000 mAh batteries have a 42 and a 72 Watt Hour capacity respectively. Divide these numbers by your total Wattage to determine how long your battery will last. Our Luma 5 Standard Density LED Light Strips, for example, require 24 Watts per roll. One roll, therefore, will run for (42 / 24) 1.75 hours with the 3500 mAh Battery or (72 / 24) 3 hours with the 6000 mAh battery.

I tested my 36W light and got 1.5 hours (72W/36W=2 hours) of full run time and I stopped it before the battery was fully discharged.

EDIT - Sorry just noticed the bike has a battery.

I'm assuming its 12V so why not run directly off the battery , add a LED relay for indicators and fuses/on/off switch as needed?

 

Edited by filterx

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14 hours ago, Wild Alaskan said:

I would not recommend using a lipo in this application since over discharging it will basically destroy it after a couple times, and there is zero need for their massive discharge rates.

why not just use a rectifier? 

do you mean a rectifier and a battery charging circuit? or just a rectifier? If I just use a rectifier the lights will not work when the engine is off. To be street legal in Indiana, headlights and taillights need to be able to operate up to a minute after turning the engine off. I suppose a capacitor and rectifier together may accomplish this but I would rather just use a battery that I can replace or upgrade if I need to. 

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do you mean a rectifier and a battery charging circuit? or just a rectifier? If I just use a rectifier the lights will not work when the engine is off. To be street legal in Indiana, headlights and taillights need to be able to operate up to a minute after turning the engine off. I suppose a capacitor and rectifier together may accomplish this but I would rather just use a battery that I can replace or upgrade if I need to. 
Yes if you need it work for a bit with the engine off you will need a very small battery. If you use a capacitor it's going to have to be yuge. With proper type of battery nothing special is needed to charge it, it will charge direct off the rectifier
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1 hour ago, Wild Alaskan said:
7 hours ago, Tanker01 said:
do you mean a rectifier and a battery charging circuit? or just a rectifier? If I just use a rectifier the lights will not work when the engine is off. To be street legal in Indiana, headlights and taillights need to be able to operate up to a minute after turning the engine off. I suppose a capacitor and rectifier together may accomplish this but I would rather just use a battery that I can replace or upgrade if I need to. 

Yes if you need it work for a bit with the engine off you will need a very small battery. If you use a capacitor it's going to have to be yuge. With proper type of battery nothing special is needed to charge it, it will charge direct off the rectifier

The bike in question is a '87 XR600R. It already has a voltage rectifier in the wiring harness. Would I be able to use that rectifier and run wires parallel from the output from it to a battery and then have a DC circuit?

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The bike in question is a '87 XR600R. It already has a voltage rectifier in the wiring harness. Would I be able to use that rectifier and run wires parallel from the output from it to a battery and then have a DC circuit?
Yep as long as the it is outputing DC and not AC. Also check the voltage, I think Honda switched from 6v to 12v sometime around then. You will need to put the battery or all the lights on a switch so the battery doesn't just discharge powering the lights upon turning off the bike

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11 minutes ago, Wild Alaskan said:

Yep as long as the it is outputing DC and not AC. Also check the voltage, I think Honda switched from 6v to 12v sometime around then. You will need to put the battery or all the lights on a switch so the battery doesn't just discharge powering the lights upon turning off the bike

What is the best way to tell if it is outputting AC or DC? I have a multimeter but I have never used it to determine whether the reading was AC or DC, just simple voltage readings and ohm readings of circuits I already knew which they were. 

EDIT: Is there a chance of messing up the pulse generator signal or CDI/coil by hooking a battery into the circuit?

Edited by Tanker01

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Posted (edited)
6 hours ago, Tanker01 said:

What is the best way to tell if it is outputting AC or DC? I have a multimeter but I have never used it to determine whether the reading was AC or DC, just simple voltage readings and ohm readings of circuits I already knew which they were. 

EDIT: Is there a chance of messing up the pulse generator signal or CDI/coil by hooking a battery into the circuit?

Not as long as the battery is within the nominal voltage of the system, and you hook it to the correct wires.

You can use your tongue to test for ac/dc, or you could use your meter, test it on both and note the results.

Edited by crypto666
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23 hours ago, Tanker01 said:

What is the best way to tell if it is outputting AC or DC? I have a multimeter but I have never used it to determine whether the reading was AC or DC, just simple voltage readings and ohm readings of circuits I already knew which they were. 

EDIT: Is there a chance of messing up the pulse generator signal or CDI/coil by hooking a battery into the circuit?

If the LED's you're adding are 12V DC and the battery is 12V DC, as I previously mentioned in my EDIT, make a wiring harness with a fuse/on/off switch straight off the battery. I wired my harness into the 12V DC controlled the on/off switch on my DRZ400e "if i remember correctly the head light wiring"

20170503_183129.1.thumb.jpg.4553f0a281be51155e7cb20b34e0a816.jpg

Above comes on as soon as I turn the ignition on/off on, then works as a brake/indicators when switched

20181121_163627.thumb.jpg.542206b0f5c8a848e3b01c5192f85661.jpg

Above only come on when I turn the indicator switch left/right

AC vs DC cus I am by no means and expert on that.

https://www.google.ca/search?source=hp&ei=CDiNXKGhH5X_-gTkzpXYBA&q=measuring+12v+ac+vs+dc&oq=measuring+12v+AC+vs+&gs_l=psy-ab.1.0.33i22i29i30l2.402.10162..12987...0.0..0.718.3651.14j2j1j1j1j1j1....2..0....1..gws-wiz.....0..35i39j0i67j0i131i67j0j0i131j0i22i30.WH3zn1Ns5bQ

Good luck :)

Edited by filterx

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17 hours ago, crypto666 said:

Not as long as the battery is within the nominal voltage of the system, and you hook it to the correct wires.

You can use your tongue to test for ac/dc, or you could use your meter, test it on both and note the results.

Like touching your tongue to a 9v battery :)

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