Electronics > Beginners

Help selecting correct fuse.

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Terry01:
I am going to wire a spot light up to my wheelchair for some extra light at night.

It's a cheap 60w 9-32v LED light that I will run off my chairs 24v supply. I would like some help with what size of in line fuse to use and confirmation that I join it in the positive line before the on/off switch? I am only using 1 of the spot lights.

Thanks in advance for the help.

Wimberleytech:

--- Quote from: Terry01 on February 03, 2020, 11:53:11 am ---I am going to wire a spot light up to my wheelchair for some extra light at night.

It's a cheap 60w 9-32v LED light that I will run off my chairs 24v supply. I would like some help with what size of in line fuse to use and confirmation that I join it in the positive line before the on/off switch? I am only using 1 of the spot lights.

Thanks in advance for the help.

--- End quote ---
Your pictures are not a lot of help, so I looked around on the internet to find similar.  My guess is that these draw 5 amps at 12 volts (thus 60 W).  Most likely LED constant current regulators on board so the 5 amps would be a little more at 24 volts due to efficiency.

I would probably start with 10 amp fuses.  If they blow under normal operation, try something bigger.  You could just measure the current with a DMM and then size up the fuse a little bit.

BTW, I 100% test any fuse I install in a system.   :-DD

I would put the switch in the positive line for no other reason than habit.  There is unlikely a common ground in your chair, so it probably does not matter.

Comments above are mostly guesses, but if I were doing this myself, what I have described is exactly what I would do.

LateLesley:
At 60W, 24V, its going to draw around 2.5A. That will increase a little as the voltage drops (since I think these use an internal converter for the wide voltage range input), So I personally think you'd be good with a 5A fuse. I think 3A would be a bit close to the wind, and 10A a bit much.

Concerns I have - You say you are running these of your chair batteries. What's the capacity (AH) of the batteries? (I assume 2 x 12V in series? )

Why such a high power light? 12000 Lumens is a LOT of light. I've seen these ones - http://www.ledworklight.net/20W-Cree-LED-Work-Lamp-Spot-Light-Bars-OffRoad-12V-24V-for-Car-Trailer-DRL

they are only 20W, 1500 Lumens, which while not as bright, is still a lot of light at a 1/3 of the power, which would mean less drain on precious battery life.

Its just I'm thinking if this is running off the wheelchair's batteries, efficiency might be a concern.

Edit, I forgot to say, as to where to put the fuse, try and fit it as close to the battery as possible, then run cable from there to the switch, then switch to light. The reason being, you want the fuse to protect the cabling, so if it gets damaged before the switch, and shorts to the frame, which I assume would be grounded, it would pop the fuse, and not cause a cable/battery fire. So always try and locate fuses as close to the source of power as possible.

Terry01:

--- Quote from: LateLesley on February 03, 2020, 03:23:47 pm ---At 60W, 24V, its going to draw around 2.5A. That will increase a little as the voltage drops (since I think these use an internal converter for the wide voltage range input), So I personally think you'd be good with a 5A fuse. I think 3A would be a bit close to the wind, and 10A a bit much.

Concerns I have - You say you are running these of your chair batteries. What's the capacity (AH) of the batteries? (I assume 2 x 12V in series? )

Why such a high power light? 12000 Lumens is a LOT of light. I've seen these ones - http://www.ledworklight.net/20W-Cree-LED-Work-Lamp-Spot-Light-Bars-OffRoad-12V-24V-for-Car-Trailer-DRL

they are only 20W, 1500 Lumens, which while not as bright, is still a lot of light at a 1/3 of the power, which would mean less drain on precious battery life.

Its just I'm thinking if this is running off the wheelchair's batteries, efficiency might be a concern.

Edit, I forgot to say, as to where to put the fuse, try and fit it as close to the battery as possible, then run cable from there to the switch, then switch to light. The reason being, you want the fuse to protect the cabling, so if it gets damaged before the switch, and shorts to the frame, which I assume would be grounded, it would pop the fuse, and not cause a cable/battery fire. So always try and locate fuses as close to the source of power as possible.

--- End quote ---

Awesome, that's the info I was looking for! Thanks!

My batteries are either 85 or 87Ah, I can't remember exactly but defo 1 or the other. They are also 2 x 12v in series to get the 24v like you guessed.
I need the light mostly for walking the dog at night and the few times I get caught out in the dark. My chair has already got factory fitted lights and indicators which are fine for pavement use at night but the lights are just not strong enough for the park  as there are no street lights or anything like that.

I think the battery consumption will be fine as i'm not in the chair 24/7, I use it 4-10 hrs a day. I only have MS so just use the chair when I go out, I use rails, walking poles and the walls to help me get about in the house. If I find it is draining the battery too much I will buy a smaller light to adjust like you say.
I am using the one have as it is what I have laying around.

Thanks again i'll post a photo when i'm done  :)

Terry01:

--- Quote from: Wimberleytech on February 03, 2020, 02:33:40 pm ---
--- Quote from: Terry01 on February 03, 2020, 11:53:11 am ---I am going to wire a spot light up to my wheelchair for some extra light at night.

It's a cheap 60w 9-32v LED light that I will run off my chairs 24v supply. I would like some help with what size of in line fuse to use and confirmation that I join it in the positive line before the on/off switch? I am only using 1 of the spot lights.

Thanks in advance for the help.

--- End quote ---
Your pictures are not a lot of help, so I looked around on the internet to find similar.  My guess is that these draw 5 amps at 12 volts (thus 60 W).  Most likely LED constant current regulators on board so the 5 amps would be a little more at 24 volts due to efficiency.

I would probably start with 10 amp fuses.  If they blow under normal operation, try something bigger.  You could just measure the current with a DMM and then size up the fuse a little bit.

BTW, I 100% test any fuse I install in a system.   :-DD

I would put the switch in the positive line for no other reason than habit.  There is unlikely a common ground in your chair, so it probably does not matter.

Comments above are mostly guesses, but if I were doing this myself, what I have described is exactly what I would do.

--- End quote ---

Your guesses are not a lot of help so I looked elsewhere  :-DD

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