4
\$\begingroup\$

I'm living off the grid in the bush in a hut I've built since this whole virus drama.

My only issue is I'm not really good with electrical stuff. By this I mean I have a few basic solar set ups that I'm trying my best to get working. One gives me enough power to run a small light in my kitchen which is ok for that purpose but could be better.

The one that I've started working on has eight small 12 volt rechargable batteries. I was able to wire them all together and then wire them to a small solar panel and fully recharge them all today.

My main question is what would be the best lighting system ie LEDs, wire up a standard light fitting???

How much running time would I get off such a set up? I just need some good bright light during the evening to do some craftwork under.

\$\endgroup\$
1
  • 1
    \$\begingroup\$ Craftwork tradition: use candles. \$\endgroup\$
    – Andy aka
    Apr 19 '20 at 11:28
6
\$\begingroup\$

To figure out how much running time you will get from any Solar/LED system, you need to quantify two numbers:

  1. The watt-hours of your battery bank. You said you have eight 12V batteries in your current setup, now you need the capacities (in amp-hours) of these batteries. Your available energy will be 8 (number of batteries) x 12V (battery voltage) x Battery Capacity (Amp-hours) and this result will be in Watt-hours. Sometimes batteries will list this number.

    Let us assume you have 8, 1 amp-hour batteries. So you will have 96 watt-hours of energy available. This means your batteries can provide 96 watts of power for 1 hour. Alternatively, they could provide 1 watt of power for 96 hours. *Note that this is approximately true, there will be some non linear relationship between the load size and the actual results. Since you should be using only a few restively low power LEDs, this should be a decent approximation.

  2. The wattage of your LEDs. When you purchase LED lights intended for consumer use, they will have a power rating, this is the amount of power you can expect them to consume.

    The LEDs in my living room are 5 watts each, and I use 4 to light up the room, so the entire lighting system consumes 20 watts.

So with your 96 watt-hour battery bank, you could provide power to my living room lights for almost 5 hours (96 watt-hours/20 watts).

As far as hooking up your lighting to the battery bank...

They sell LEDs for motor homes/RVs which will operate at 12V. You could also get an inverter to go from 12VDC to 110V AC, and then use normal home lighting, but this will be less efficient as the conversion from AC to DC is an imperfect one.

Good luck!

\$\endgroup\$
3
  • 2
    \$\begingroup\$ You could do with a lot less than 20W of LEDs if you're just illuminating a small space at a low level and other areas only when you're using them (cooking area, reading light). Depending on the size of your hut, 6W might be enough for general illumination and you could add, for example, additional 2W lights for a small cooking area (1m2 / 9 sq ft) and/or a desk or table only when needed. \$\endgroup\$
    – StarCat
    Apr 19 '20 at 11:16
  • 2
    \$\begingroup\$ Also remember that the avalable number of Watt-hours from your batteries is (a lot) less than described above. A lead acid battery should not be regularly discharged by much more than 50%-60% or they will lose capacity quickly. The amount of capacity that's really available is only half the Amp-hours capacity of your batteries. Other types of batteries will be more tolerant of deeper discharge. \$\endgroup\$
    – StarCat
    Apr 19 '20 at 11:16
  • \$\begingroup\$ Thanks Dustin Sackett that is a great help. \$\endgroup\$
    – rawtribe
    Apr 20 '20 at 2:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.