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

[john95]

I noticed that most off grid devices are designed to run on 12 Volts. If I have wired 4x 6V batteries to make a 24 volt battery array and 24 volt solar panel array, how can I run 12 Volt devices without disconnecting the 24 volt battery array to have a 12 volt battery?

I also noticed that building a 24v system is cheaper. A 160 watts @12v panel costs $165.00 while a 320 watts @ 24v panel costs only $144.00 so, 2 of these get me 640 watts for $288 while 4x 160 watts get me 640 watts for $660.00, really big difference!

[littleharbor]

This sounds like a theoretical question. Do you have any equipment yet? What you can do is use a MPPT charge controller to charge a 12 volt battery bank. If you have the 4 - 6 volt batteries you would wire them in series/parallel for 12 volts.

[organic farmer]

One of our off-grid neighbors has a completely 12vdc house. He built it in the 1980s. Every appliance in his house is 12vdc. You can do it. And it is a lot cheaper. I almost went 12vdc with our house. I was pricing out each appliance, but when I got to our well pump, that one stumped me.

[john95]

This sounds like a theoretical question. Do you have any equipment yet? What you can do is use a MPPT charge controller to charge a 12 volt battery bank. If you have the 4 - 6 volt batteries you would wire them in series/parallel for 12 volts.

I'm planning on picking up 4x 6 volt new batteries next week. I have not got them yet because there is a chance that a friend of mine can get me 8 used (working fine) of these batteries from his company for like $200.

I though about making a big 12 volt battery of the 4x 6v batteries, but don't you guys advice not to wire batteries in parallel under any circumstances?

[SunEagle]

One of our off-grid neighbors has a completely 12vdc house. He built it in the 1980s. Every appliance in his house is 12vdc. You can do it. And it is a lot cheaper. I almost went 12vdc with our house. I was pricing out each appliance, but when I got to our well pump, that one stumped me.

I know it can be done but you must have a small house or used very large wire for the 12v distribution system. The problem with most 12v pumps is that the amp rating on one that will do the job is pretty high.

[john95]

One of our off-grid neighbors has a completely 12vdc house. He built it in the 1980s. Every appliance in his house is 12vdc. You can do it. And it is a lot cheaper. I almost went 12vdc with our house. I was pricing out each appliance, but when I got to our well pump, that one stumped me.

Exactly! This was my first idea. It makes a lot of sense, 12 volt it is universal. Computers, cars, fans, lights, refrigerators, you name it, works on 12 volts. I don't like the idea of converting 12, 24, 48 or even 96 volts into 120 AC and then have to convert the 120 AC to 12 volts again for every darn device to work. If the wire gets to hot or voltage is lost due to distance, we can place the battery next to the device to work and problem solved.

[NEOH]

I noticed that most off grid devices are designed to run on 12 Volts. If I have wired 4x 6V batteries to make a 24 volt battery array and 24 volt solar panel array, how can I run 12 Volt devices without disconnecting the 24 volt battery array to have a 12 volt battery?

I also noticed that building a 24v system is cheaper. A 160 watts @12v panel costs $165.00 while a 320 watts @ 24v panel costs only $144.00 so, 2 of these get me 640 watts for $288 while 4x 160 watts get me 640 watts for $660.00, really big difference!

There are devices that can help equalize the 12 volt load over the entire 24 volt battery bank.

https://www.allbatterysalesandservice.com/browse.cfm/4,3147.html

A dual voltage system allows for 24 Volt (high wattage devices) and 12 Volt (low wattage devices)

Some balancing devices transfer the energy from the bank with the higher voltage to the bank with the lower voltage = efficient
Some balancing devices just make heat from the higher voltage bank = wasteful

[PNPmacnab]

My entire camp is 12V, just because I don't want to buy a battery. I use the one out of a vehicle I don't take. There are little buck converters you can buy under $4 that will do the 12V conversion. I actually use boost converters for lighting, upping the voltage to 35V. I buy these 18W 120V led ceiling lights that are cheap and rip out their converter. The LED actually operates on that voltage at reduced power of about 9W, more than bright enough.

[littleharbor]

When you parallel two strings of batteries you don't have the problems you get with 3 or more strings. You connect your CC and loads to opposite diagonal corners and still have even balance. Now when you mention being able to get 8 batteries (6 volt?) is when you run into even charging problems. Do you need 8 batteries for this project?

[Sunking]

One of our off-grid neighbors has a completely 12vdc house. He built it in the 1980s. Every appliance in his house is 12vdc. You can do it. And it is a lot cheaper. I almost went 12vdc with our house. I was pricing out each appliance, but when I got to our well pump, that one stumped me.

Then your neighbor is an idiot.

[Sunking]

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

Where the hell did you come up with that fairytale? 12 volts is for Toys, RV's, and morons. Off grid homes use the exact same appliances anyone uses made for 120 and 240 VAC. The crap junk you see for 12 volts is made for RV's and truckers. It is low quality over priced junk. Then you have to spend a freakin fortune and own a copper mine to run power.

[john95]

When you parallel two strings of batteries you don't have the problems you get with 3 or more strings. You connect your CC and loads to opposite diagonal corners and still have even balance. Now when you mention being able to get 8 batteries (6 volt?) is when you run into even charging problems. Do you need 8 batteries for this project?

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.

[littleharbor]

You originally mentioned 4-6 volt batteries which I said was fine. If you need more power you can use larger batteries. L-16 batteries are common.

[SunEagle]

Where the hell did you come up with that fairytale? 12 volts is for Toys, RV's, and morons. Off grid homes use the exact same appliances anyone uses made for 120 and 240 VAC. The crap junk you see for 12 volts is made for RV's and truckers. It is low quality over priced junk. Then you have to spend a freakin fortune and own a copper mine to run power.

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.

[john95]

You originally mentioned 4-6 volt batteries which I said was fine. If you need more power you can use larger batteries. L-16 batteries are common.

Ok. Thank you.