Long time viewer first time poster....one question

[papalas]

i just got 3 fifteen watt panels, and a 12 volt deep cycle battery. I have all the basics with the charge controller and 400 watt inverter. all I really want to do is run lights for the house. I have new 7 watt led lights and my question is how long can I run these lights before I run out of power. just to simplify my question, how long can one 7 watt led lightbulb last on one 12 volt charge. thanks in advance!!

[Naptown]

Well depends on where you live, the capacity of the battery and wether the light is 12 volt or 120 v and how much your inverter consumes in operation
( it is way oversized for the one light and will probably self consume more than the light connected to it)

[inetdog]

Well depends on where you live, the capacity of the battery and wether the light is 12 volt or 120 v and how much your inverter consumes in operation
( it is way oversized for the one light and will probably self consume more than the light connected to it)

It also depends on whether you are asking how long you can run the light before the inverter shuts down or the shorter time for which you can run the light before you risk damaging the battery. Those two can differ by a factor of four or more.

I suspect that the 7 watt LEDs referred to are the 120 volt A20 replacement kind

[papalas]

Well depends on where you live, the capacity of the battery and wether the light is 12 volt or 120 v and how much your inverter consumes in operation
( it is way oversized for the one light and will probably self consume more than the light connected to it)

im running the 7 watts off of a 12 volt socket straight from the charge controller, just wondering how long can I run it so I can vary my other lights. is it better to not use the inverter because it uses a lot more energy?

[inetdog]

im running the 7 watts off of a 12 volt socket straight from the charge controller, just wondering how long can I run it so I can vary my other lights. is it better to not use the inverter because it uses a lot more energy?

You still have not told us how big (in Amp-Hours) your battery is.
With three 15 watt panels, it should not be much bigger than 40AH or you will have other problems (inadequate charging.)

[papalas]

You still have not told us how big (in Amp-Hours) your battery is.
With three 15 watt panels, it should not be much bigger than 40AH or you will have other problems (inadequate charging.)

ummmm 80 amp hours deep cycle

[inetdog]

ummmm 80 amp hours deep cycle

80AH divided by five = 16AH. 16AH times 12 volts is 192 watt-hours. 192 watt-hours divided by 7 watts is ~27 hours.

So, about 27 hours to 80% SOC (20% of capacity discharged), which is as low as you should routinely go for longest battery life.

You should have at least 80 watts of panel to keep that battery happy if it is a flooded lead acid (FLA) battery. For most sealed batteries (AGM) you should have more than that.

[SunEagle]

Your weak link are those 3 15 watt panels. They will take days to charge your battery back up to 100% from 80%.

I would go out and get yourself at least a 100 watt panel and forget about using those 15 watt panels.

[papalas]

Your weak link are those 3 15 watt panels. They will take days to charge your battery back up to 100% from 80%.

I would go out and get yourself at least a 100 watt panel and forget about using those 15 watt panels.

thanks fellas for the advice. baby steps and one day I might just go totally off the grid. but for now just a couple lamps till the wife feels comfortable with all these cords lol

[inetdog]

thanks fellas for the advice. baby steps and one day I might just go totally off the grid. but for now just a couple lamps till the wife feels comfortable with all these cords lol

First comment on baby steps:

Before you go talking about going off grid (unless you mean moving somewhere where there is no grid), read up on why that will cost you two to five times a much for power as what you are paying the electric company.

[Naptown]

Actually change that to 5-10 times if you live in the US.

[inetdog]

Actually change that to 5-10 times if you live in the US.

Two times if you live in Hawaii and take very good care of your batteries.
Maybe more then 10 times if you live in Texas.

[Naptown]

I don't think even Hawaii is that much
Places in the Caribbean perhaps.

[inetdog]

I don't think even Hawaii is that much
Places in the Caribbean perhaps.

High end in Hawaii is over $.50/kWh. Depends on location and usage.

Absolute low end that I have seen for self-reported cost for off grid including battery replacement is ~$1.00 per kWh, although you may not think that is a reliable figure.

[Sunking]

I might just go totally off the grid. but for now just a couple lamps till the wife feels comfortable with all these cords lol

Will not happen. Once yu realize how much battery systems cost you will give up that idea.