Would it be possible to use a changeover switch in this example?

HappyHippyDad · Oct 29, 2018

I am having a play in my shed

.

It has a 12v supply fed from a solar panel

I have 3 gang light switch which switches the following

1. 4 x 7w LED MR16 downlights.
2. 1 x 12v LED striplight (12w)(the tapelight thingy that just sticks on)
3. 1 x 20W 12v floodlight

I basically want to have a 230V backup light in there in case the battery packs up. The shed has a 230V supply to it and I originally thought I would just add a new 230V light to use when needed. However, and this is my question, would a single LED driver be ok to power all the above? If so, which one would I need with regards max wattage and constant voltage/current?

Below is a drawing of what I want.. cheers

(ps.. the drawing should say '4' x LED MR16's)

[ElectriciansForums.net] Would it be possible to use a changeover switch in this example?

Darkwood · Oct 29, 2018

The concept is fine, the issue is your LED lamps, they will either have integral drivers or need an external driver, this is fine for your 230v mains powered option but your 12v option has no drivers in line.

You need to decide what voltage rating your LED's are going to be IE you tend to get integral drivers inside 230v AC LED lamps, your typical 12v lamp will need a driver spec'd for the supply voltage as well as the lamp rating.
I will also add that LED drivers tend to have a minimum load threshold so you also need to take that into account, the higher the maximum wattage rating may mean a higher minimum threshold meaning the driver may refuse to work if say you just had 1 lamp on it through the switching options.

PS - this is as I understand it but don't have too much to do with this stuff so happy to stand corrected on the matter. Also I will add the supplies would be on the changeover switch output lines, the load would be on the common input, kind of a reverse setup to standard, you don't want to blow up your solar set-up or short out your supply, also get a 3 position to allow a central 'off ' option you can safely lock off.

GeorgeCooke · Oct 29, 2018

happyhippydad said:
I am having a play in my shed .

It has a 12v supply fed from a solar panel

I have 3 gang light switch which switches the following

1. 4 x 7w LED MR16 downlights.
2. 1 x 12v LED striplight (12w)(the tapelight thingy that just sticks on)
3. 1 x 20W 12v floodlight

I basically want to have a 230V backup light in there in case the battery packs up. The shed has a 230V supply to it and I originally thought I would just add a new 230V light to use when needed. However, and this is my question, would a single LED driver be ok to power all the above? If so, which one would I need with regards max wattage and constant voltage/current?

Below is a drawing of what I want.. cheers
(ps.. the drawing should say '4' x LED MR16's)

View attachment 45307

So total load 60watts. At 12v that is 5 amps. To allow for switch on surge get a 12v 8 amp ( or more) DC power supply ( not a LED driver).

Lucien Nunes · Oct 29, 2018

If all the lighting operates at 12V, i.e. it has its own resistors built in to operate from a constant voltage, then a constant 12V is what you need. But as mentioned above, LED drivers are not necessarily the best choice and may be awkward with switchable loads. A 12V regulated DC power supply would serve the purpose, in which case, yes, you can use a changeover switch to select that or the battery as source. There is no switch-on surge with LEDs themselves (only on the mains side of drivers and power supplies) so you don't specifically need to allow extra for that, but all power supplies last longer if you don't push them to their limit.

If you want lighting with the battery removed, that would be the solution. But if what you want to allow for is the battery being low due to lack of sun, surely you want to recharge it ASAP? If it is lead-acid, it will suffer from being left discharged while you happily work under your power-supply-derived 12v lighting. A regulated multi-step charger might be a more useful solution, that could be used to top up the battery and supply the lighting at the same time, without risk of damaging either. However, most chargers will not operate the lights without a battery being connected.

HappyHippyDad · Oct 29, 2018

darkwood said:
The concept is fine, the issue is your LED lamps, they will either have integral drivers or need an external driver, this is fine for your 230v mains powered option but your 12v option has no drivers in line.

You need to decide what voltage rating your LED's are going to be IE you tend to get integral drivers inside 230v AC LED lamps, your typical 12v lamp will need a driver spec'd for the supply voltage as well as the lamp rating.
I will also add that LED drivers tend to have a minimum load threshold so you also need to take that into account, the higher the maximum wattage rating may mean a higher minimum threshold meaning the driver may refuse to work if say you just had 1 lamp on it through the switching options.

PS - this is as I understand it but don't have too much to do with this stuff so happy to stand corrected on the matter. Also I will add the supplies would be on the changeover switch output lines, the load would be on the common input, kind of a reverse setup to standard, you don't want to blow up your solar set-up or short out your supply, also get a 3 position to allow a central 'off ' option you can safely lock off.

Thanks Darkwood,

Your first paragraph says I'll have problems with the 12V supply. My shed is already running on 12V with all the lights listed.

I have a solar panel connected to a charge controller which is connected to both the battery and lights. It all works fine as is connected as it should be.

The LED driver below states 'Load 0-100W' so that wouold hopefully take care of the other problem you suggested.

HappyHippyDad · Oct 29, 2018

Lucien Nunes said:
If all the lighting operates at 12V, i.e. it has its own resistors built in to operate from a constant voltage, then a constant 12V is what you need. But as mentioned above, LED drivers are not necessarily the best choice and may be awkward with switchable loads. A 12V regulated DC power supply would serve the purpose, in which case, yes, you can use a changeover switch to select that or the battery as source. There is no switch-on surge with LEDs themselves (only on the mains side of drivers and power supplies) so you don't specifically need to allow extra for that, but all power supplies last longer if you don't push them to their limit.

If you want lighting with the battery removed, that would be the solution. But if what you want to allow for is the battery being low due to lack of sun, surely you want to recharge it ASAP? If it is lead-acid, it will suffer from being left discharged while you happily work under your power-supply-derived 12v lighting. A regulated multi-step charger might be a more useful solution, that could be used to top up the battery and supply the lighting at the same time, without risk of damaging either. However, most chargers will not operate the lights without a battery being connected.

Thankyou Lucien,

It looks like the DC power supply is the way forward then.

I'm not sure I get what you mean about the battery being left discharged whilst I use the 230V supply. As in my above post, the solar panel would still be charging the battery.

This whole scenario is really just to have a bit of a play. It has come about as i did not look after the last battery properly and had to change it. During the few weeks it took me to decide to change the battery I had no lights and that is problem I wish to avoid (whilst having a bit of a play as well).

plugsandsparks · Oct 29, 2018

If you go down the driver route, would recommend you go for 75W, 12V constant voltage. You could knock up a simple DC power supply, or rob one from an old appliance. There are plenty of diagrams on internet for a 12V psu using simple components, but if it was me i would just get a CV DRIVER as you can pick them up cheap as chips

Wilko · Oct 29, 2018

Hi - did you intend to keep the 230V to 12V supply on at all times?

HappyHippyDad · Oct 29, 2018

Wilko said:
Hi - did you intend to keep the 230V to 12V supply on at all times?

I intend to mainly use the 12V supply from the battery. The 230V supply will only be used if the battery becomes faulty, or if the charge controller kicks in when the battery voltage becomes too low and stops me from using the lights. Thats when I will use the changeover switch.

HappyHippyDad · Oct 29, 2018

Could I ask why the consensus is to use a 12 DC power supply rather than an LED driver? I realise you've already explained to an extent Lucien, but MR16's always have an LED driver so why the change in this case ?

HappyHippyDad · Oct 29, 2018

Lucien Nunes said:
If all the lighting operates at 12V, i.e. it has its own resistors built in to operate from a constant voltage, then a constant 12V is what you need. But as mentioned above, LED drivers are not necessarily the best choice and may be awkward with switchable loads. A 12V regulated DC power supply would serve the purpose, in which case, yes, you can use a changeover switch to select that or the battery as source. There is no switch-on surge with LEDs themselves (only on the mains side of drivers and power supplies) so you don't specifically need to allow extra for that, but all power supplies last longer if you don't push them to their limit.

If you want lighting with the battery removed, that would be the solution. But if what you want to allow for is the battery being low due to lack of sun, surely you want to recharge it ASAP? If it is lead-acid, it will suffer from being left discharged while you happily work under your power-supply-derived 12v lighting. A regulated multi-step charger might be a more useful solution, that could be used to top up the battery and supply the lighting at the same time, without risk of damaging either. However, most chargers will not operate the lights without a battery being connected.

Would this be suitable Lucien? https://uk.farnell.com/xp-power/vcs...604796549:pla-300288194765&CAAGID=14406255429
If not, could you link to a more suitable power supply if possible, thanks

plugsandsparks · Oct 29, 2018

A constant voltage (12V) led driver is in effect a 12 V DC power supply. The one you have linked is cheap as chips and has good regulation but as you can see the packaging is not ideal is it. It needs cooling and to be put in a box, ....

telectrix · Oct 30, 2018

why not leave the 12V installation as it is, and add a 230V light totally separate from the existing lighting, just to switch on as and when needed?

HappyHippyDad · Oct 30, 2018

telectrix said:
why not leave the 12V installation as it is, and add a 230V light totally separate from the existing lighting, just to switch on as and when needed?

As soon as I saw that you'd replied I thought that's what you would be writing about

.

Where's the fun in that Tel? Would it be cheaper.... yes! Would it be easier to install..... yes! Would it be less likely to break down.... yes!

Actually, I've decided that you're right. No change over switch, no DC power supply, just a standard, cheap switch start batten that I've got left over from a job!

I have however just put a changeover switch in for my sockets... very exciting for a purely Domestic installer to mess around with something different. Bear in mind this is 'my' shed not a customers, hence not as neat!

GeorgeCooke · Oct 30, 2018

happyhippydad said:
but MR16's always have an LED driver

No they don't. MR16 means multifaceted reflector 16 eights of an inch diameter. Nothing else. MR16 are available in 12v. 24, 120v, or 240v and with various types of base.

Would it be possible to use a changeover switch in this example?

HappyHippyDad

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Darkwood

GeorgeCooke

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Lucien Nunes

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HappyHippyDad

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