# 12v electrics



## jimbod22 (Mar 17, 2016)

I,ve planned a travelling case for my beardie so he can come with me in my motorhome. 240v basking lamp is not a problem if I am on a site and UV is not needed for a few days away. However I often stay offgrid relying on my 12v batteries. Can anyone suggest a way to heat the case using 12v. The only thing I can think of is something like a filament type car headlight bulb.
JIM.


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## paul23 (May 12, 2011)

You'd need an inverter really to convert to 12Vdc from the battery to 240Vac.


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## jimbod22 (Mar 17, 2016)

Cheers Paul, I,ve got one but they tend to use a fair bit of battery running the fan etc. I was looking for something to connect direct to my 12v outputs.
Jim.


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## reptiles-ink (Nov 4, 2006)

If sticking to 12v then use halogen bulbs


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## paul23 (May 12, 2011)

jimbod22 said:


> Cheers Paul, I,ve got one but they tend to use a fair bit of battery running the fan etc. I was looking for something to connect direct to my 12v outputs.
> Jim.


using 12V is going to use almost the same amount of power from the battery as an inverter at 230V. If you want to run a 60W bulb direct from the battery then you are pulling 60W from the battery. If you use a 60W bulb at 230V from an inverter then you are still pulling 60W from the battery , it's exactly the same just the inverter is a much lower current.

You'll lose about 10% for the inverter efficiency (depending how good it is), but with a 12V system you'll lose power in the cable as it's much higher current. How much depends on what size cable you use and length and quality. 

You can't use halogens with DC, you would need an inverter to convert to AC.

You could use peltier coolers in reverse and use them to heat. That's what I use for my worms. They run of a 12Vdc supply and easily maintain 24ºC. to get higher temperatures you would need higher power than what I have. Mine are about 40W I think, so would need somewhere around 120W to get temperatures high enough for a beardie, depending on enclosure size.


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## Lotus Nut (Jan 7, 2008)

Use a 40w to 50w 12v G10 halogen with ceramic lamp holder. They give off more heat than normal incandescent bulbs and are more efficient too so will give same output as 60w standard reflector bulb. Beam angle of GU10'w are normally about 35 degrees so more heat is focussed in this area, reflectors are often about 90-110 degrees depending on bulb size and type.

The GU10 would only draw 4 amps so should be no problem for vehicle electrics though i would use in-line fuse for protection which i expect you would run from leisure battery. Take spare bulb or two (they are quite cheap) just in case as you can be pushing 13.5 to 14 volts or so from your alternator, possibly bit less if you have charge splitter and vlocking diode.

Inverters can be used but cheap ones are really only about 85% effecient and their output A/C sine wave is quite poor too.


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## Lotus Nut (Jan 7, 2008)

Should have asked how big is the viv as if not too large you may be able to use 35w halogen.


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## jimbod22 (Mar 17, 2016)

Lotus Nut said:


> Should have asked how big is the viv as if not too large you may be able to use 35w halogen.


Beardie is in 4x18 at home but when away in the MH I intend to make a 2x15 and allow him access to the MH if warm enough to roam around. I am making the traveling case from a sandwich of thin ply around 25mm expanded polystyrene sheets with a 25mm frame which should retain heat from any source used.
My reluctance to use an inverter is the output is always less than the input due to heat loss and the draw from the internal fan. I would prefer the power drain from the battery to be converted directly to heat in the case.
In my current 4ft viv I use a 42w halogen which gives a basking spot of about 110f.
Jim.


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## Lotus Nut (Jan 7, 2008)

I meant to have said use 12v MR16 halogen as these are quite cheap as are the lamp holders. As its quite a small viv i would fit two bulbs and lamp holders with seperate dc feeds, one with about 16/20w and the other say around 30w. Reason for the two is due to internal MH temps can vary greatly from cool n cloudy skies to very hot clear summer days so just connect bulb according to temp inside MH as its not really easy to make the 12v dimming.

As for the viv i would not bother with sandwich constuction as most heat escapes though ventilation, build basic one with 15 or 18mm, mdf would be fine sealed with exterior varnish and use small vents to lower heat loss. You could always place some polystyrene under viv and on top just to help retain heat a little bit.


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## jimbod22 (Mar 17, 2016)

Lotus nut, thanks for your input. I realised you had given the wrong base when you stated GU 10, a 240v fitment and was going to clarify it with you. I have checked out the MR fitment and it looks spot on for my needs. I have a 35w bulb and will buy some 20w ones and ceramic bulbholders. I thought about a flat reflector between the bulbholder and case to reduce the risk of scorching. I would use spacers to prevent direct contact with the case and promote air flow.
One of my reasons for looking at a sandwich construction for the case is weight saving, as contiboard/MDF units are quite heavy.
Your opinions would be greatly appreciated.
Jim.


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