May I run 12 Volt lights from a 24 Volt battery array safely?

[jpcoopee]

I have a 24 volt offgrid power system. After two Cat 5 Hurricanes in September, my AIMS 4K inverter died. With the islands reduced to rubble, I could only find a MAGNUM MS2812, 12 volt inverter to replace it. I made up a set of 'jumper cables', and bridge two 6 volt batteries to feed the inverter. I have 8 ROLLS S-550 428 a/h batteries in two strings, 24 volt solar panels, charge controller, wind turbine, etc.

I try to limit loads on the system, and change the jumper cables to a different pair of batteries everyday, but wonder how much damage I am doing to my batteries. I would appreciate any input anyone might provide.

[bcroe]

I am glad the bad weather missed you. Thanks for letting us know.

I suppose our severe weather is newsworthy, but it is usually quite localized. Most tornados blow thru
affecting an absolute minimum number of buildings; those with basements all survive and rebuild. Nothing
like a hurricane that affects whole states. Flooding throws off the crops, but is only the briefest inconvenience
here. Some of the local powers finally wised up, bought up and condemned a few places way too close to
the river. But the water we send down the rivers can really impact the states south of here. Snow, we never
see anything we can't handle. Thank goodness we see little enduring ice; though that did cost us power for
a couple weeks in Palatine, half a century ago. What is an earthquake? Bruce Roe

[SunEagle]

Yes we had severe weather, nobody hurt. Some outages (not me), a whole row of poles that should
have been replaced long ago just fell over. Some roads flooded. As usual, all my stuff came through
unscathed. Good thing, apparently half a dozen skunks moved in under the skids holding 25 spare
panels. With the lawn saturated, today a big 6 wheeler came in to drop off half a ton of aluminum for
the next project. Bruce Roe

I am glad the bad weather missed you. Thanks for letting us know.

[Mike90250]

I noticed that most off grid devices are designed to run on 12 Volts. .......

Then you have noticed incorrectly. Most 12V devices are for RV/Camper/Automotive use.
I'm off grid, I know other people off grid, and we have Zero 12V devices, except in our vehicles.

[inetdog]

Grid tied systems (no battery cost) can be had installed for less than $5/W of capacity.
Now figure out how many kWh each watt will produce over 365 days. (More in summer, less in winter). Now you can calculate the cost per kWh after amortizing the initial cost over some number of years of expected life.

[bcroe]

Hey Bruce. Good to hear you back on the forum. I saw that some of that severe
tornado weather went over your area the other day. Hope you did not lose any of your panels.

Yes we had severe weather, nobody hurt. Some outages (not me), a whole row of poles that should
have been replaced long ago just fell over. Some roads flooded. As usual, all my stuff came through
unscathed. Good thing, apparently half a dozen skunks moved in under the skids holding 25 spare
panels. With the lawn saturated, today a big 6 wheeler came in to drop off half a ton of aluminum for
the next project. Bruce Roe

[SunEagle]

According to your arithmetic, it would be $17,000/5.04KWH = $3373/KWH. HOWEVER, the company isn't selling
a 5.04 KWH system, they are selling a 5.04 KW sys which might produce around 7000 KWH a year for 20 years,
or more like 12 cents a KWH. Bruce Roe

Hey Bruce. Good to hear you back on the forum. I saw that some of that severe tornado weather went over your area the other day. Hope you did not lose any of your panels.

[Sunking]

Both you and I know that going with a 12volt system is kind of expensive and sometimes dangerous but we have to let it go when people that have made up their mind to stay inside the limits of a 12v box.

It is not worth getting your blood pressure up or calling them names. It won't help them change their mind. Stay happy my friend.

I am always happy, just pointing out ignorance.

1. If you run 12 volt DC means you must use a very expensive Breaker Distribution like a house main breaker panel in a home with a lot of circuits.One beaker for every gizmo with a dedicated run. Use an Inverter just one fuse on the battery to Inverter and your done

2. Want to run a 100 watt gizmo say 50 feet from the battery takes a 10 amp Breaker, 100 feet of #4 AWG copper wire that cost $0.70/ft. Want another circuit, double that. Want 3 you get the picture. Wiring and distribution cost will be outrageous in the thousands of dollars. Use a 1500 watt Inverter and all you need is a single run of #14 AWG wire that cost $0.08/ft orr $8 for 100 feet and you can run 15 of those 100 watt gizmos on a single run of #14 AWG wire. Do the mat $20 vs $everal thousand dollarrs. .

3. So If you are ignorant foolish enough to spend that kind of money, then you really do not care if you burn your house down because low voltage is extremely dangerous and prone to fire.

4.. 12 volt gizmos are expensive, inefficient, and poor quality that will not last.

But you are right SE. Let them go for it. I will be more than happy to take their money away from them by helping. At least I can try to make it safe so they can live long enough to learn how foolish it is.

[Sunking]

I may get 8 batteries almost for free, but I want to start with 2x 6volt batteries to create a 12V system to use 12 volts devices.

I have some used condoms for sale cheap.At least they will still work.

[Sunking]

You are very confused about things. You need an education in the basics of electricity. After that, download (for free) and read "Solar Power Your Home for Dummies". After the basics and the read, you will be better informed and better able to answer your own questions.

Ditto, you do not know what you are talking about.

[J.P.M.]

I spend as high as 822 kWh a month in the summer and the other months about 600 kWh a month. I spend about $1,000 a year in electricity. A Solar company quoted me $17K for a 5.04 kWh system 18x 280 Watt panels. That's $3.50 a kWh. One has to be crazy to pay $3.50 a kWh when I'm paying now only $0.22 a kWh.

You are very confused about things. You need an education in the basics of electricity. After that, download (for free) and read "Solar Power Your Home for Dummies". After the basics and the read, you will be better informed and better able to answer your own questions.

[bcroe]

I spend as high as 822 kWh a month in the summer and the other months about 600 kWh a month. I spend about $1,000 a year in electricity. A Solar company quoted me $17K for a 5.04 kWh system 18x 280 Watt panels. That's $3.50 a kWh. One has to be crazy to pay $3.50 a kWh when I'm paying now only $0.22 a kWh.

According to your arithmetic, it would be $17,000/5.04KWH = $3373/KWH. HOWEVER, the company isn't selling
a 5.04 KWH system, they are selling a 5.04 KW sys which might produce around 7000 KWH a year for 20 years,
or more like 12 cents a KWH. Bruce Roe

[john95]

I spend as high as 822 kWh a month in the summer and the other months about 600 kWh a month. I spend about $1,000 a year in electricity. A Solar company quoted me $17K for a 5.04 kWh system 18x 280 Watt panels. That's $3.50 a kWh. One has to be crazy to pay $3.50 a kWh when I'm paying now only $0.22 a kWh.

[SunEagle]

Don't feel that way SunEagle! I'm going to build one 12V system for my off grid small cabin and one 24V or 48V system for my home in Los Angeles. Your advice is very well appreciated. I just hate to be tied to the grid and having to spend $20K for a grid tied system.

There are a lot of people that do not like to be tied to the grid but when you do the math an off grid low voltage system can result in cost of over $1/kwh. That for some is 7 times what the grid cost for the same kWh and you don't have to have a hobby of keeping the batteries happy as long as possible before you have to replace them.

The choice to live off grid depends on where and who you are. I and others just try to provide the cost details comparing a 12volt system to a better 48volt system. Of course if you plan on burning less than 1kWh per day you might get away with that 12volt but most people want to use 5 times that amount which will cost you a small fortune.

The choice is yours to make. I just don't like people making their choice without knowing the facts.

[john95]

Both you and I know that going with a 12volt system is kind of expensive and sometimes dangerous but we have to let it go when people that have made up their mind to stay inside the limits of a 12v box.

It is not worth getting your blood pressure up or calling them names. It won't help them change their mind. Stay happy my friend.

Don't feel that way SunEagle! I'm going to build one 12V system for my off grid small cabin and one 24V or 48V system for my home in Los Angeles. Your advice is very well appreciated. I just hate to be tied to the grid and having to spend $20K for a grid tied system.