48v DC - what switch do I need?

[Dan Easton]

I have a golf buggy powered by 8 x 6v batteries.

I want to power some 12v accessories (which pull no more than 5 amps), so I've got a 48v to 12v step-down which I'm going to wire-in to the batteries. However, I also want an inline switch to be able to disconnect the voltage regulator when no 12v accessories are being used.

What switch can I use? There are a lot of 12v/16amp ones available. As the ampage of my accessories is so low, can I use a 12v switch??

 

[Gryd3]

I have a golf buggy powered by 8 x 6v batteries.

I want to power some 12v accessories (which pull no more than 5 amps), so I've got a 48v to 12v step-down which I'm going to wire-in to the batteries. However, I also want an inline switch to be able to disconnect the voltage regulator when no 12v accessories are being used.

What switch can I use? There are a lot of 12v/16amp ones available. As the ampage of my accessories is so low, can I use a 12v switch??

No.. Voltage must always be matched or Exceeded for 'components'.
The 'Current' must also be matched or Exceeded.

You never want to undersize the voltage or current rating.

 

[Minder]

12v switch no problem
As long as it is on the output side of the voltage regulator, if on the input then you need a 240vac rated one
M.

 

[Dan Easton]

Wow - quick replies. Thank you.

It'll be on the 48v side of the voltage regulator

Ok, this makes sense. I just wasn't sure if getting a 250v/16amp switch would be overkill and cause problems.

Thanks for the advice.

 

[Minder]

If the unit is not in use for some period of time i would tend to switch the input side of the regulator.

M.

 

[BlackMelon]

I think it is crucial to have a switch rated at higher than 12V. Inductor kickbacks tend to cause overvoltage problems on the switch. Putting a diode across a correct component should alleviate this problem, so by doing this, you might be able to use a switch rated at 12V.

BlackMelon

 

[Minder]

The main reason for voltage rating is insulation value, surprisingly automotive relays are made with high voltage insulation, as is most components now. It is not worth making items with low voltage value insulation.
The voltage difference between 12v and 48v is minor, AFA insulation is concerned.
M.

 

[Kiwi]

Make sure you fit a fuse in the positive wire to the 48v-12v reducer. The fuse should be as close to the positive take off point as possible.

 

[davenn]

I think it is crucial to have a switch rated at higher than 12V. Inductor kickbacks tend to cause overvoltage problems on the switch. Putting a diode across a correct component should alleviate this problem, so by doing this, you might be able to use a switch rated at 12V.

BlackMelon

this isn't relevant in this case

Dave

 

[Dan Easton]

If the unit is not in use for some period of time i would tend to switch the input side of the regulator.

M.

Which is what I'm planning on doing. Or am I incorrect?

 

[Dan Easton]

Make sure you fit a fuse in the positive wire to the 48v-12v reducer. The fuse should be as close to the positive take off point as possible.

Ok, will do. Positive take off point?

 

[davenn]

Which is what I'm planning on doing. Or am I incorrect?

great

Ok, will do. Positive take off point?

on the output of the 48V, either side of the switch

 

[Dan Easton]

sp

Make sure you fit a fuse in the positive wire to the 48v-12v reducer. The fuse should be as close to the positive take off point as possible.

Just realised I don't actually know what sort of fuse to put in. Can you get 48v fuses? What amp rating?

 

[davenn]

sp


Just realised I don't actually know what sort of fuse to put in. Can you get 48v fuses? What amp rating?

not that I'm aware of, typically a 240V rated one is used and rated at just a little more than you max current likely to be drawn
with the note ... as long as none of those accessories have huge start up currents ... eg motors