Fuse rating for light system

[Mundo]

Can anyone help with determining fuse rating for a lighting system.

This bike has 2 headlights and two taillights, each light is approx. 3 to 5 watts (?) I think.

All powered by a Ping 48 VDC 20 AH battery.

I tried using a DC amp clamp, no help. Perhaps this meter (Fluke) is not sensitive enough.

 

[to the beach]

Are the lights getting 12 Volts or 48? For a fuse, use the power formula and solve for current in Amps. Use a fuse the next size up from your current consumption.

Power(Watts) = EMF(Volts) * Current(Amps)

so lets say each light needs 5 Watts and you say there are 4 of them:

20 Watts = 12 Volts * Current

Current = 20 Watts/ 12 Volts

Current = 1.7 Amps

So, for a 12 Volts lighting system, a 3 Amp fuse would suffice or a more common 5 Amp fuse would work too.

 

[amberwolf]

Also, if they are incandescent lamps, there will be significantly higher surge currents at power-on (at least several times the operating current), where LED typically won't have that even with big capacitors in a DC-DC. If the fuse is a fast-blow and is rated exactly for the operating current, it may blow when incandescents are first turned on.

 

[dnmun]

fuse should be rated by size of the conductor, not the light. they are 15-20A on a car.

 

[Mundo]

Thanks for the replies.

The front lights (2) are LEDs from Ebay 12 to 72 VDC running off a Ping 48 VDC Battery.


The rear lights (2) are miniature incandescent bulb 0.05 Amp at 55 volts from McMaster also running off the 48 VDC Ping Batery, no convertor.

 

[to the beach]

front lights 2 at 5 Watts each = 10 Watts @ 48 Volts = .21 Amps now add the 2 rears, .1 amp therefore based on what you've stated you are drawing less than .4 amps with the lights on. A 5 Amp fuse should be all you need. You can install a larger fuse but not much smaller.

 

[Mundo]

Thanks to all for the replies...I'll install a fuse holder and fuse this weekend.
It's been a great summer of riding, now it's time to get ready for shorter days coming.

 

[manneokoko]

Hello,
I also need help with choosing fuse for the light.
I purchased this one: http://www.ebay.co.uk/itm/162328945467

I do understand the instructions above for calculating the fuse amp. But I dont know what voltage it runs on since it can take 12-80V input. The bike has a 36v battery that the light will run from.

Please advice.

 

[amberwolf]

But I dont know what voltage it runs on since it can take 12-80V input.

The bike has a 36v battery that the light will run from.

 

[manneokoko]

Thanks Teddy
I was thinking that internally it might convert to another voltage.

So the fuse, I just put it on the positive wire running from directly from battery to light?

Is normal glass fuse ok to use?

In the electronics shop there are 2 variants of glass fuse, 12/24V and 230V. Which should i have?