LED 12v DC downlights

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Re: LED 12v DC downlights

Postby Gordon-Loomberah » Fri Aug 30, 2013 7:33 pm

I'm home all the time and I've used an average of 10kWh/day (AC) over the past 2 months (a 2 person household) with a 21kWh LiFePO4 battery, and 4kW of PV, with zero use of the generator. I have solar HW, no gas or electric boost, and do most of my cooking on an induction cooktop or electric oven/microwave. Canberra does get more cloud than here in winter, but not hugely more.
$20000 saved on batteries can buy an awful lot of generator fuel, plus extra PV to get you through cloudy periods.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
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Re: LED 12v DC downlights

Postby davidg » Fri Aug 30, 2013 7:48 pm

Hobie1 wrote:but will probably need 4 AWG as "backbone" wire.

We use mm2 in Australia. AWG is "American Wire Gauge" ;)

Fire risk if the wire is undersize for distance and or the amount of current, it will have a higher resistance to the power being conducted which in turn increases the wire temp which in turn increases the heat which in turn ......... you get the picture. This is the result not the exact reason however all wire has a resistance and the lower the voltage the faster the resistance becomes an issue, which is one the reasons why as the run becomes longer so the wire size must be increased. (You may beware of this, however I must point it out anyway.)

4AWG (We don't use AWG in Aus) = approx 21mm2 the nearest in Aus is 25mm2 that will be somewhat more expensive compared to 1.5 mm2 typically or maybe 2.5mm2 in "TPS" (Red, Black & Earth). If you intended to run the wire in low voltage rated wire then it must be seperated from the LV wiring (regular mains wiring) the specific requirements are in AS3000:2012. 400+ page doco that must be complied with for all wiring installations unless you are going to all ELV (Extra Low Voltage) less than 50Vac, 120VDC ripple free is the defination of ELV.

I seen people go down this rabbit hole before, with all due respect it will almost certainly not save you money which means of course it will ............................
Last edited by davidg on Fri Aug 30, 2013 8:31 pm, edited 1 time in total.
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Re: LED 12v DC downlights

Postby davidg » Fri Aug 30, 2013 8:15 pm

LEDMAD wrote:More accurately, they don't require an external transformer. They have a small transformer (driver) included in the globe itself.

OK, I was staying on the simple side of things, thats all. Not a transformer in them though last one I pulled apart the base circuit was a tiny high frequency PWM IC, tiny resistor & zener to regulate the voltage. Very simple.

LEDMAD wrote:You can't test overall light output with a Lux meter. Many of these LED lights have a very narrow beam (you can't believe the packaging). So directly under the light might be as bright as a halogen. But at an angle of say 30 degrees, they might only be a third as bright.

Watt Test was not a light test it was measured on bench test for power consumption. Lux test was on the kitchen bench with them installed in the ceiling moving the meter around the benches in the kitchen was an average and they do actually have a reasonable spread on the bench or I would have pulled them out right then.

Good heat-sink on the light and after a couple of hours running still only slightly warm to the touch no I did not measure the actual temp I should have. I have a temp probe for the multimeter I was doing the testing with. I simply forgot, they have been in now for about 12 months and they are dimmable although they are never dimmed at all, neither were any halogens when they were there either. As for the cost they were about $12.00 each so not OTT for the actual globes.
Last edited by davidg on Fri Aug 30, 2013 8:39 pm, edited 2 times in total.
Off-grid/Hybrid System Specialist - Store Sun to use later- I Do!
SELECTRONIC SPMC-482 7.5kW, 8.2kW's of Arrays
AC-Coupled Grid-Connect Inverters,
2100Ah 48V Bank

Auto Backup Genset
PVOutput Stats

Sparkys light up your life :)
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Re: LED 12v DC downlights

Postby Hobie1 » Fri Aug 30, 2013 8:22 pm

Mmm. Seems another idea crashes and burns. Oh well. Back to the "lighting board"!
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Re: LED 12v DC downlights

Postby andysox » Thu Jan 22, 2015 12:31 am

Personally, I would stick with AC bulbs. Arent they cheaper too?
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