12 volt halogen battery system, advice needed

[light77]

Hello,

This is my first post, and I thought it best to come to a place where there are many electrical experts who can give quick pointers, as my profession is not electrical.

I have to set up a lighting system for a small market stall, but there is no access to mains power and the lighting must be halogen not LED.

I was thinking of using 3 low voltage (12 volt 35 watts) halogen lights. The area needed to be covered is only 2 square metre table. The time needed for lighting is around 5 hours per day; there is natural light too, but not a lot.

My question is what is the best type of battery specs to use, as there seems to be endless permutations of 12 volt batteries and I really don’t know which direction to take.

Does a 12v 35 watt, halogen set need very particular batteries and ampere? Would it be easy to also fit a dimmer switch to it if the light was too bright and just wasting power when natural light was pretty good?

Any help from some experts here is very much appreciated,

Regards,

Steve

 

[telectrix]

you would need a battery with a capacity of > 40AH. the best thing would be a leisure battery. say around 80AH> that would give you plenty od battery power. as for dimming, this is usually done when the halogens are fer from 230V via a transformer. the easiest way to dim the lighting if it's too bright is to take one bulb out. watch it, they will be hot.

 

[HandySparks]

the lighting must be halogen not LED.

Why the preference against LED?
I strongly suggest that you investigate LED lighting. It's getting better all the time. Although more expensive, it will need less power than halogen for a given light level and you can therefore use a smaller (and cheaper) battery.

 

[Knobhead]

Power required for 5Hrs is 43.75 AHr. To protect the battery fron cyclic damage add a 50% overhead so thats 65.65 so Tel's 80AHr battery would be fine. Plus it's an off the shelf item.

 

[UKMeterman]

Hi,
Beware any battery of this size can be a fire hazard if the wiring is not carried out correctly, it will melt anything that shorts it out including large spanners. If you do the work do you have public liability insurance? Having got the warning out of the way, you may wish to discuss the project with an automotive electrician. If you want a battery that can't spill sulphuric acid when knocked over try BES120700 - CAMDEN-BOSS - BATTERY, SOLAR GEL 12V 70AH | CPC and you will need a charger like YPC8A12 - YUASA - CHARGER, 12V 8A LEAD ACID BATTERY | CPC Note you will get about 500 cycles out of this battery at 50% discharge, reduce the amount of discharge and the lifetime goes up a lot, have a look at the datasheet.. NB you will need a fuse close to the battery, an automotive electrician will be able to advise. This kit will do your brightness control 12V-40V 10A PWM DC Motor Speed Controller w/ Knob - Free Shipping

 

[light77]

Why the preference against LED?
I strongly suggest that you investigate LED lighting. It's getting better all the time. Although more expensive, it will need less power than halogen for a given light level and you can therefore use a smaller (and cheaper) battery.

Hello, Thank you for replying. The reason is the colour of the light and its effect on the items sold. LEDs are generally too blue, and the warmer ones still give a very different light compared to a halogen. LEDs also seem to show up more dust or slight scratches in items, which is also not wanted. If it were just a Lux problem, then I would go with LEDs, but it has to be a warm light and halogen seems to be the only one I can think of that does the job needed, unless someone knows of others?

 

[ruston]

Just to add, take care when transporting your battery in a vehicle in particular , make sure you use secure terminal caps or if it tips you could easily end up with a fire in your van etc. As UKmeterman said 12v is very unforgiving when let lose.

 

[light77]

Hi, Beware any battery of this size can be a fire hazard if the wiring is not carried out correctly, it will melt anything that shorts it out including large spanners. If you do the work do you have public liability insurance? Having got the warning out of the way, you may wish to discuss the project with an automotive electrician. If you want a battery that can't spill sulphuric acid when knocked over try BES120700 - CAMDEN-BOSS - BATTERY, SOLAR GEL 12V 70AH | CPC and you will need a charger like YPC8A12 - YUASA - CHARGER, 12V 8A LEAD ACID BATTERY | CPC Note you will get about 500 cycles out of this battery at 50% discharge, reduce the amount of discharge and the lifetime goes up a lot, have a look at the datasheet.. NB you will need a fuse close to the battery, an automotive electrician will be able to advise. This kit will do your brightness control 12V-40V 10A PWM DC Motor Speed Controller w/ Knob - Free Shipping

Hello, thank you very much for your reply. It's very helpful to know they could be so potentially dangerous.

Thanks also for the links, I didn't realise they would be so costly, but if it does the job safely, then that's what matters. I'm just wondering now if there is a safer and cheaper way to get the same light cover and quality with lower powered battery and halogens of 6 volt, and without resorting to using LEDs?

I appreciate the time you've taken to find me the information, many thanks.

Regards,

Steve

 

[ruston]

If you take a look at caravan lighting (Google) there is a variety of options for lighting. A lot of caravans have mood lighting these days , worth a look. 12 v though.

 

[UKMeterman]

Hi,
The problem is providing the power, your 35W = 12 volts * 2.96A, halve the voltage and you double the current, and the energy required 35*5*3 watt hours stays the same.. have a chat with these people Spot and Downlighting | LED Lighting | Marl they have been doing LEDs for 40 years so may be able to suggest something.

 

[Richard Burns]

Metal halide lights are much more energy efficient and provide a good colour rendering, but are more fragile to transport. You should be able to get the light intensity you want with 2 x 22W lamps.

You may find your cheapest alternative is to buy a low powered (quiet) generator, you can get these for about £100 with a 750W output, which would be more than enough, you would have the ongoing cost of fuel as opposed to the electricity use of charging the batteries but would be more convenient. so long as you can position the exhaust somewhere unobtrusive.

 

[ruston]

have a look on this site to give you an idea. Spotlights - Internal Lighting for Caravans and Motorhomes