12 Volt load with 24 volt system

[Seekscore]

I have a 24VDC wind turbine that is hooked to 2 - 12 VDC batteries. I want to use a standard 12VDC inverter but want to spread the load out between two batteries evenly so I don't just discharge one battery. I was thinking I could use some blocking diodes to run the 12VDC inverter in parallel with both batteries while using them in series with the turbine to charge them. Will this work or am I missing something?

[ghurd]

It will not work.

Simple explanation.

Look at the wire between the batteries.

Which way is the current traveling in that wire?  Both ways???

Meaning it is not traveling in that wire, and that wire does not count, so remove it.

Remove that wire and the 12V inverter is being fed 24V.

G-

[Seekscore]

Ghurd,

Thanks for replying. Forgive me for being hard head'd. I drew it a different way but electrically the same. The load will only see a difference of potential of 12 volts since the blocking diodes will prevent the load sensing the full 24. Do you still see the same result? I might be having a brain fart but I think this will work.

Thanks, Mike

[Flux]

Still wont work. Both your supposed 12v loads will see 24v - 2 diode drops.

Flux

[Seekscore]

Okay. Thanks for the help guys! Back to the drawing board.

[ghurd]

Save your gray matter and chalk...

It can not be done.

That exact problem is why I am anti-24V small systems in North America.

There are no small or medium sized, 24VDCin, 110VACout, 60Hz, known-name-brand, reasonable quality, reasonably priced, inverters currently available.

There were for a short while.  There was an insufficient demand.

Nearly impossible to find 24V CFLs.  Etc.

Just a 2 cent rant.

G-

[Seekscore]

I understand. How do people use a 24VDC wind turbine in a practical application? I use one inverter hooked to just one battery but it seems that the batteries get discharged at different rates? Do people use 2 - 12VDC inverters? What about 48VDC systems? 12 volt systems seem impractical due to the size of the wire that you must use to prevent loss in the line from the turbine.

Please educate me wise ones

Thanks for the info!

Mike

[tanner0441]

Hi

I use a 1KW inverter in my camper but it is not practical to run it for more than a few minutes 10 max. My wind and solar setup is 12V but that is only 600W pure sine wave.

On one of the earlier posts on here it was recomended to use a 24 to 12V inverter to keep the battery load balanced. I looked on EBay and there are 24V inverters at sensible prices as long as you don't mind modified sine wave. I would be inclined to sell your 12V inverter and use the money to fund a 24V one.

Brian

[Rover]

You will need to give more info...

• What do you intend to power with the inverter?
  
  
• What wattage inverter are you thinking about?
  
  
• What kind of batteries? amp/hrs?
  
  
• What is your charging source, and how reliable is it... amp/hr day etc (rough ok)

  
  
  

My opinion, but when I see just 2 batteries in series for 24 volts,  I'm thinking this may have been better served as a 12 volt system runing 12 volt stuff without an inverter. I assume that the batteries are ~ 100 amp/hr each which is not a lot of capacity for an inverter situation unless it is a very light load for short periods.

[ghurd]

A couple questions,

a 24 to 12V inverter?

eBay 24V inverters at sensible prices?

G-

[Tinbendr]

Would something like this work?  While the link is talking about higher pack voltages, it might offer one solution; if you're handy with a soldering iron.

[Flux]

Not sure what the situation is in N America but here in the UK, there are a fair number of 24v MSW available for our 230v supply.

If you want a better product then there are plenty of sine wave 24v devices from Studer, Victron Energie , Mastervolt etc.

If you only want light then 12v can be ok especially with the new range of led lamps coming on line, when the price drops this looks to be an excellent way to go. I never bothered with those 12v cfl things I have never found one bigger than 11W and they cost the earth here, a cheap msw inverter and mains cfl works out better and cheaper.

Unless you have a really big system, 24v seems a good way to go here and I would only consider 12v for very small systems but the situation could be very different elsewhere.That is one problem with this board, we have people from all over the world and a solution that suits one area may not be viable in another.

Flux

[Seekscore]

Thanks for the replies.

I personally don't have a good reason or use for a wind turbine other than I just want to play with it and learn. I live on the grid and my utility bills are reasonable. Originally I bought into all the marketing hype on the web and thought I could power my home and sell electricity back to the power company. That fantasy is over. I am just fascinated by wind power now. I got into hydroponics last year and grew a bunch of tomatoes and peppers using CFL's in a "grow box" as an experiment. I have so many stinking rabbits where I live, you can grow anything outside. I think it would be really cool to grow them only using power from the wind. It takes around 150 watts to power the CFL bulbs. I would use them for about 12 hours a day. I am getting a green house this summer as well. There is nothing better than home grown veggies!

I guess I am just going to use 2 12VDC inverters now to generate my power and try to draw down the batteries at the same rate.

My question now is how do most people in the USA utilize a 24 volt wind turbine or a 48 volt for that matter. The vast majority of commercial turbines I see are 12, 24 or 48v. There are a lot of 12 volt accessories out there. Are you biting the bullet and purchasing 24 or 48 volt accessories? Do you use 12 volt accessories? Do you convert it to 110AC? My feeling is that a 12 volt machine is impractical due to the size of wire you have to use if your batteries are not close to the turbine.

Mike

[Rover]

I really can't answer the 24/48 volt question... since mine is 12 volt and I run 12 volt stuff (based of 6 batteries ~ 700 amp/hrs) .. hopefully someone else will chime in.

But if your purpose is grow lamps... might want to look at DC solutions... such as LED based grow lights (google.. you'll get a ton) . This removes the inverter and the losses from the conversion to AC. (you could also just remove some of the grid powered  CFLs and use some DC powered LEDs in their place)

The next bit is based on the 150 W CFL drawing 150W (if the 150 mark is just a comparison to incandescent or floods, subsitute the actual draw for th CFL's)

150 W CFL for 12 hrs is a pretty big draw on a 2 battery bank (based on your drawing I assume 2 batteries) 150w/24v = 6.25 A , * 12 = 75A/hr.  You'd need to make roughly 85 to 100 A/hr (every day) from your source to keep things on even keel (or supplement with a battery charger)

[ghurd]

With 24 or 48V, big name brand inverters.

There are some 24V Aims or Samlex inverters available new, but still kind of steep prices compared to other brands equivalent 12V versions.

Anything 48V should be a fairly large system where a 48V inverter is not such a large percentage of the total system cost.  A 48V system is generally a large power system for more serious use.

If you can go with a 12V LED grow light solution, could probably use one of those ebay 24V to 12V DC-DC converters.

G-

[bob g]

there are literally tons of ups inverters out there awaiting repurposing that are 24volt buss units

APC has several models up to about 2kva that are 24volts

they make several that are pure sine wave, or at least very clean sine wave

efficiency is about 85% or so, which isn't fantastic, but the price is right as

they can be had for little or nothing.

downside is the pull  10s of watts idleing so you probably would want to shut them off when not needed.

for experimental purposes, there is a lot to be said for the use of one or more such units.

replace the batteries with higher amp/hr units and the surge capacity becomes respectable as well.

bob g