Difference in Battery Volts

My question...

If I take two 12v Batteries and link them together into a 24v bank...will the output voltage remain at 12v?

If I now have a 24v bank, would I still use a 12v power controller and inverter to run AC from?

There is probably an obvious answer, but just wanted to make sure.

R/Techfields

Comments

  • dsp3930dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: Difference in Battery Volts

    Serial = (negative to positive in a chain)
    Add Volts of each battery together
    Amps stays the same
    Connect inverter red lead wire to positive end of series.
    Connect inverter black lead wire to negative end of series.

    Parallel = (negative to negative / positive to positive)
    Battery Volts stay the same
    Add Amps of each battery together
    Connect inverter red lead wire to positive end of 1st battery.
    Connect inverter black lead wire to the farthest negative terminal in the battery bank from the positive connection. (NOT ON THE SAME BATTERY as the positive connection)

    Two 12v batteries in series equals 24 Volts. (Requires a 24v inverter)
    Two 12v batteries in parallel equals 12 Volts. (Requires a 12v inverter)
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    Also, if you have a 24 volt battery bank, do not "tap off" 12 volts to run some misc. equipment.

    You will end up discharging that battery that is tapped and overcharging the other one.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Great information folks...

    I have three additional questions!

    1 - If I hook the batteries in parallel, I assume in theory that I would be able to hook as many batteries as my wind turbine could support...say three and just continue to go positive to positive to positive and the negitive the same. I understand that the more batteries, the longer to charge so two will most likely be the max for now, I am just asking for future reference. Further, since I don't know what "tap out" is, I most likely will not use any way.

    2 - During the charging process, would each battery be charged equally, to the point that the power controller would prevent an overcharge to any of the batteries...is this correct?

    3 - Is there an advantage to setting the batteries up in serial vice parallel...then using the 24v vice a 12v?

    I am at the baby stages of trying to figure this out and did not want to invest to much cash until I knew exactly what I required. I have already ordered a power controller that will allow 12/24v configuration. I will wait to get the inverter until I am a little clearer on the above questions. Also, just wondering what would be a decent size inverter to say run a few light (LED) and two full size freezers? I intend to add some solar before I'd be concered with the freezer, but wanted to ask so not to purchase an inverter that would be too small.

    Any help is really apprecriated. I have looked through the fourm for the answers, but I am either looking in the wrong place or not understanding what I am looking at.

    R/Guy
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    R/Guy,
    techfields wrote: »
    1 - If I hook the batteries in parallel, I assume in theory that I would be able to hook as many batteries as my wind turbine could support...say three and just continue to go positive to positive to positive and the negitive the same. I understand that the more batteries, the longer to charge so two will most likely be the max for now, I am just asking for future reference.
    The standard Renewable Energy Answer:
    • Yes; you add batteries in parallel, they increase the AH capacity of the bank.
    • Maybe No; as you add batteries in parallel, you have more cabling and--ideally, need to arrange the cabling "on the diagonal" so that the current path from each battery is the same resistance overall. If you connect your inverter/charger to the first battery and parallel from there--the farther the batteries get from the inverter/charger, the more resistance they see, and the less charging/discharging current will support.
    • Maybe No; As you add batteries in parallel--balancing the current gets harder and harder. My two cents--I would avoid placing any more than three batteries in parallel. It also gets expensive because each string should have its own fuse or circuit breaker to protect against shorts. Other issues is a cell can short and start discharging the bank. Also, you need to check once in a while that all strings are still sharing current properly (open cell will kill string).
    Balancing the current through your batteries will really help extend their life...

    Here is a website that show how NOT to connect your batteries in parallel (they do not know this fact). Note that the current from the closest battery goes through less wiring than current from the "bottom" battery of the string (the top battery will supply/absorb more current--the battery at the bottom of the string will supply/absorb the least amount of current because of the extra resistance/voltage drop of the wiring).

    Here is a website that shows how parallel and series-parallel connections should be made (so that the current has to flow through the exact same length of wire--no matter which path is taken).

    What ever wiring method you choose... The total length of wire (and even number of connections) should be balanced through all of the parallel current paths.
    Further, since I don't know what "tap out" is, I most likely will not use any way.

    Sorry... Say you have two 12 volt batteries in series for 24 volt output... You run your charger/inverter on the 24 volt bank--but you need 12 volts to run a radio.

    It is very tempting to just connect your +12 volt radio to the middle between the 12 volt batteries. The problem is that you discharge only one of the 12 volt batteries. And when recharging--you end up with one battery undercharged (the one running the 12 volt radio), and the other overcharged (the one without the 12 volt load)--because the same charging current is going through both batteries.
    2 - During the charging process, would each battery be charged equally, to the point that the power controller would prevent an overcharge to any of the batteries...is this correct?

    And this is another issue about adding batteries over the years... Batteries in parallel need to really match voltage, resistance, and chemical makeup... It is highly recommended that a bank be installed at the same time so that all batteries are from the same lot and age together.

    Roughly, if you have an old bank and put a new parallel battery in--the new battery will start carrying most of the charging/discharging currents and will quickly cycle age to near that of the rest of the bank. Or--it may be a different lot/brand/model--and it runs a "bit higher or lower voltage" and shares unequally with the rest of the string...

    Can it be done, yes. Will it work, yes. Will it be cost effective, maybe not. Your new battery will probably not last as long as it could.
    3 - Is there an advantage to setting the batteries up in serial vice parallel...then using the 24v vice a 12v?

    There are lots of good reasons to use 24 or 48 volts. Power=Voltage*Current. So, you double the Voltage , then 1/2 the current.

    Note that heating losses in wires is Power=(I^2 * R) -- Note that if you cut the current by 1/2--your wire heating losses are cut to 1/4 as much...

    Also, sending electricity any distance....
    • 12 volt battery - 10.5 volts cutoff= 1.5 volt allowed wiring drop
    • 24 volt battery - 21 volts cutoff = 3 volt allowed wiring drop
    • 48 volt battery - 42 volts cutoff = 6 volt allowed wiring drop
    The advantage of 12 volts--lots of cheap 12 volt appliances and electronics out there.

    The advantage with 120 VAC--Everything works off of 120 VAC, and the new Energy Star appliances are approaching the efficiencies of the 12/24 VDC appliances at 1/3rd the cost (add an inverter and some solar panels--still save money).

    With the newer True Sine Wave inverters and various low power options--the "costs" of operating an inverter a not so high anymore--so many times it is worth the 15% or so extra losses running an inverter to use 120/240 VAC through the rest of the home and leave the DC to the battery bank.
    I am at the baby stages of trying to figure this out and did not want to invest to much cash until I knew exactly what I required. I have already ordered a power controller that will allow 12/24v configuration. I will wait to get the inverter until I am a little clearer on the above questions. Also, just wondering what would be a decent size inverter to say run a few light (LED) and two full size freezers? I intend to add some solar before I'd be concerned with the freezer, but wanted to ask so not to purchase an inverter that would be too small.

    You may end up getting two inverters... One small one to power your lighting loads and can leave on all the time.

    And another, larger one to power your bigger loads. You really need to look at the efficiency of the various options to see what makes sense for you.
    Any help is really appreciated. I have looked through the fourm for the answers, but I am either looking in the wrong place or not understanding what I am looking at.

    Not a problem--feel free to ask questions. We try not to tell people to search for their own answers--it is frustrating--especially if you are not familiar with the terms or what you are looking for.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Thanks so much BB...

    Your guidance is great....a couple more questions.

    I have decided to go with a 24v setup; based on the info you have provided, that seems to be the smartest way. The power controller I purchased will support 12/24v so that works well. I now understand that if I had four batteries, two pair in serial for a total of 24v, then set up the two pairs in parallel to retain the 24v...that would work, is this correct?

    The wind generator right now looks to be about 46 feet from where I plan on setting up the battery banks. The web sites you recommended were terrific, but discussed mainly solar which I do not have right now. Is there a web address you can share that based on the output of the wind generator in watts, how large I would need to make the wire coming from the generator to the power controller?

    You mentioned about fuses as well. Do I use a fuse coming into the battery bank or going out or both; and what do I based the amp size of the fuse on?

    I now know that I can purchase a 24v inverter that will permit a 110 output. The cost vary dramatically when doing research. Can you give me a decent brand that would provide a 1500 watt at a reasonable price? If not the same brand, I would like to have the option for both "pure" and "modified" Sine. I probably won't use that much at first, but as I get smarter at this, I hope to increase the output and want to grow the system only as needed.

    Each day I understand more about the process. I am looking forward to actually getting the first light working to tell myself that all the reading and trying to understand something that is new for me, is actually worth what I believe it is.

    Thanks again with all your help...R/Guy
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    R/Guy,

    You are very welcome.
    techfields wrote: »
    I have decided to go with a 24v setup; based on the info you have provided, that seems to be the smartest way. The power controller I purchased will support 12/24v so that works well. I now understand that if I had four batteries, two pair in serial for a total of 24v, then set up the two pairs in parallel to retain the 24v...that would work, is this correct?

    First--In general, I agree with your 24 volt decision... However (yea--you will hate me by the end of this. :roll: ;)), Study your wind turbine's output power characteristics... Many wind turbines require much higher base wind speed before they start charging, the higher up in battery voltage they go. So--a 24 volt bank may not allow you to collect as much energy. Check with your supplier on the details.

    Regarding batteries. Each cell is 2.0 volts nominal. So, 24 volts will require 12 cells... That could be 2x 12 volt batteries or 4x 6 volt batteries all connected in series.

    Personally, I like higher AH rated batteries / cells to avoid making battery banks out of parallel strings (more cabling, fusing, watch for current balance, more cells to water, etc.)--But yes, many people run 2 or three parallel strings without issues.

    Adding batteries in series adds voltage. Adding batteries in parallel adds current/capacity (AmpHours).
    The wind generator right now looks to be about 46 feet from where I plan on setting up the battery banks. The web sites you recommended were terrific, but discussed mainly solar which I do not have right now. Is there a web address you can share that based on the output of the wind generator in watts, how large I would need to make the wire coming from the generator to the power controller?

    Amps is Amps--so solar or wind--you just need to plan for the maximum supported current.

    I do have a question, is the charge controller in the Wind Turbine itself, or will the controller be at the battery bank?

    Assuming the controller is at the battery bank--then the voltage drop from the turbine to the battery bank is less critical. You will just want to minimize voltage drop to minimize power loss.. Typically, 3% maximum drop, most folks aim for 1-2% drop. You can use this voltage drop calculator to estimate the drop. For a 24 volt bank:
    • 24 volts * 3% = 0.72 volts
    • 24 volts * 2% = 0.48 volts
    • 24 volts * 1% = 0.24 volts
    Remember that the calculator link I gave you uses the distance between the turbine and the battery bank which is 1/2 the total wire length there and back for the circuit.
    You mentioned about fuses as well. Do I use a fuse coming into the battery bank or going out or both; and what do I based the amp size of the fuse on?

    Your minimum wire gauge will be based on the maximum current from the turbine * 1.25 safety factor (for NEC in the US). You will probably choose heavier gauge wire to minimize voltage drop.

    The wire needs to be protected from the Battery Bank--which can output 1,000's of amp;s into a short circuit. So, any wire leaving the positive post / bus bar of your battery bank should be protected by a fuse or circuit breaker rated for that particular gauge/type of wire. (fuses/breakers protect wiring from over heating).

    When you run heavier gauge wire--you could use a larger fuse or breaker--Or, just simply the maximum expected current * 1.25 and rounded up.

    For example. say your maximum wind turbine current is 12 amps. Multiply by 1.25 gives 15 amps--NEC says use 14 AWG wire.

    But, you have a 40 foot run of wire... Using the Wire Calculator in the above link:
    • 14 awg @ 12 amps @ 40' = 2.9 volt drop (12.1%)
    • 8 awg @ 12 amps @ 40' = 0.7 volt drop (2.9%)
    • 6 awg @ 12 amps @ 40' = 0.5 volt drop (2.1%)
    • 4 awg @ 12 amps @ 40' = 0.3 volt drop (1.2%)
    I now know that I can purchase a 24v inverter that will permit a 110 output. The cost vary dramatically when doing research. Can you give me a decent brand that would provide a 1500 watt at a reasonable price? If not the same brand, I would like to have the option for both "pure" and "modified" Sine. I probably won't use that much at first, but as I get smarter at this, I hope to increase the output and want to grow the system only as needed.

    You are in Canada (IIRC), so what you can get there may be different than here (cost effective wise). Our host NAWS has been around for 30+ years and stands behind the brands they sell--so I would start there (I am not in the solar biz). They offer both TSW and MSW products.

    "Making your own power" is not cheap--and has serious issues regarding expansion and maintenance... Try to size the system to your needs. "Growing a System" frequently leaves you will lots of "left over parts" to give to friends, keep as spares, or sell on EBay...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Hello again,

    I can't tell your how much I appreciate you assistance...thanks so much!

    I currently reside in Kentucky so you know. On a farm that is basically in a hilly area that has been cleared for cattle so I have wind most of the time throughout the year as it rolls in and up the side towards the house. The solar is for those days when there is no wind...but that will be later of course.

    The Charge Controller will be at the batteries.

    I have a couple of trees closer to the house that I have been for years going to cut down simply because I am concerned that if we ever get a really bad storm, they could topple over and hit the house. I hate cutting them, but I have a wood stove as well so the wood will not got to waste...that would bring the wind turbine nearly 30 feet closer which should reduce the wire and loss due to distance. That may have to happen later this year as the weather is still a tad cool out side for this late in the year.

    On the wire, once I get the actually wire into the house, can the wire be to big? I brought some wire for a buidling I built last year and still have some of the wire that I used to hook up the service. I don't know the gauge of the wire, but it can easily support the service to the 200 amp box I put it. Can this wire be used - I don't believe it is copper, it is aluminium?

    So much to consider, but I will continue so I can understand this. At some point, my wife and I hope to build a smaller place at the back of the property where we can get off the gird, have a well dug for water and go from there....it is funny how the older you get, the less you really do need.

    Once again, thanks for your help...R/Guy
  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: Difference in Battery Volts

    Are you (or more significantly, your turbine) on top of the mountain or down in the "holler" (hollow?)

    Love that country. Spent some time there (almost moved) in the 70's with my church group on Stinking Creek, near Walker KY. I think Pineville was nearest town with > 5000 people.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts
    techfields wrote: »
    On the wire, once I get the actually wire into the house, can the wire be to big? I brought some wire for a buidling I built last year and still have some of the wire that I used to hook up the service. I don't know the gauge of the wire, but it can easily support the service to the 200 amp box I put it. Can this wire be used - I don't believe it is copper, it is aluminium?
    You probably cannot use the Aluminum wire directly. Most connections for solar RE probably assume copper wire.

    Aluminum gets a skin corrosion/oxidation (which is a great insulator) almost immediately and needs a "gas-tight" crimp to copper transition (probably with a grease/sealant) to do it right. You can probably have an electrician splice on copper ends (if it is cost effect). Also, are you going to bury the cable (and need direct burial rated cable) or through below ground conduit or above ground feed?

    Regarding the turbine--Ideally aim for a 60' minimum tower, 30' above any surrounding up wind obstructions, and 500' horizontally away. If you trees grow in the prevailing wind direction ("flagging"), then you have enough wind to consider installing a turbine.

    You might want to save $600 or so and keep an eye out for the Midnite Solar Classic Charge Controller. It is supposed to have a wind version that can do MPPT (Maximum Power Point Tracking) for wind turbines--and can give you several times the power output over a regular turbine to battery to shunt controller setup... It might be ready by spring (or summer, or???).

    There have been a few posts about the Beta testing here in the last few months.

    Start in this thread around post #26...

    Good Luck!

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Hello BB,

    More great help, thanks.

    I do plan to place the line underground inside PVC, and seal with silicon when necessary at the ends. Underground wire is rather expensive so I will try to use what I already have and if need be, I will purchase the underground line at a later date. This initial project is more to make sure I know what I am doing...eventually, it will be on a larger scale when we put a small cabin up at the back of the property in a year or so.

    I believe with the help you have provided, I should be on my way to get something set up. I am gone off and on so have to take breaks inbetween working to do this. So far, I am having a blast. The battery volt issue for some reason I was not able to get my head around, you cleared that up....again thanks.

    I will let you know as I progress where I failed and if and when I have success generating electric power!

    R/Guy
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: Difference in Battery Volts

    Another thing to note that B.B. touched on: aluminum wire will corrode much quicker with DC current than it does with AC current.
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    On the corrison for aluminum wire, even if it was in the original coating that you would hang from telephone pole to pole?

    R/Guy
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    I am not sure--Using the proper transition fitting (Al to Cu) then using the copper wire in the final connection to the equipment is part of the answer.

    Aluminum is very reactive to oxygen... But pure aluminum (as opposed to high alloy/strength aluminum) quickly forms a very hard surface corrosion that is pretty impervious to water/air.

    The problem is aluminum wants to form that layer even at connection points that are not hermetically sealed connections.

    And alumimum tends to cold form/creep... It moves away from the pressure point, gets a little corrosion, the point get a little hot, alumimum expands and cold flows away more, more corrosion--cycle continous until an insulative skin fully forms in the contact area. Then either cutting of power (even at 120 VAC) or there is such high resistance, the connection overheats and can cause a fire.

    There are som Al/Cu rated outlets and switches (not sure I would trust Al wire in them)--but the standard solar RE equipment is probably not so rated.

    Presumably, a Listed Au-Cu transition connector properly lubed and crimped (with the correct tool) will be OK.

    The other issue with corrosion--if you get water (plus salts) next to an AC connection/wiring--the "plating" or electrolosys goes back and forth--and not much damage happens.

    With DC, if there is any current flow, the more negative terminal will lose material to the more positive terminal (why phones and other industrial DC equipment tends to be positive ground to prevent corrosion on water mains and such)... cathodic protection...
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Another questions for the experts....

    If I hooked two 12v batteries in series to make a 24v system, will the batteries charge at a 12v rate, or would the wind/solar output have to meet a 24v output?

    Thanks a ton once again....

    R/techfields
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Difference in Battery Volts
    techfields wrote: »
    Another questions for the experts....

    If I hooked two 12v batteries in series to make a 24v system, will the batteries charge at a 12v rate, or would the wind/solar output have to meet a 24v output?

    Thanks a ton once again....

    R/techfields

    In order to charge a battery you must apply more Voltage than the battery has in it. If your power source is fixed and you increase the Voltage you will lose current.

    100 Amp/hrs of battery 'wants' to be charged at 5-13 Amps, regardless of the Voltage. Convert to Watts to see the difference:

    10 Amps @ 12 Volts = 120 Watts
    10 Amps @ 24 Volts = 240 Watts

    If the charger is only capable of the 120 Watts, upping the Voltage to 24 will result in the current rate dropping to 5.

    These are rough, 'demonstration only' calculations using nominal numbers. I have not including actual charge Voltages (usually 14.2 for a 12 V system or 28.4 for 24 V) nor factored in efficiency losses (upping the Voltage through any means will cost you some power).
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Great scoop, so the reason I see folks going to a 6v system is based more on the charge/discharge of the lower volt battery itself if I understand your comment below. Using four, 6v batteries in series, producing a 24v system would still require 28v to charge, is that correct?

    R/Techfields
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    You need to charge the entire bank at the bank voltage... You could charge each "battery" individually (say 4x 6 volt batteries--and 4x battery chargers or even wind turbines)... The issue with wind turbines is they are not a very consistent/matched set of charging devices... You will probably end up with batteries not evenly charged.

    The reasons that "most" solar RE guys use 6 volt, 4 volt, or even 2 volt batteries is that they want the largest Amp*Hour cell that they can physically move...

    Say you have a 150 lb limit for your battery (two people, no lift/crane). You can get 6x 12 volt 150 lb batteries and put them in parallel, or you can get 6x 2 volt 150 lb cells and put them all in series. My personal opinion is that I would prefer the 2 volt cells in the above configuration. There are fewer cells to check, there is less wiring/fuses/breakers, and no problem with balancing current flow through 6 different strings.

    The other issue with Wind turbines is many of them only output reasonable amounts of power when connected to a 12 volt battery bank. Connect the same turbine to a 48 volt battery bank--and you are looking at no power unless it is blowing 25 MPH or more...

    If you have a low voltage turbine (12 volt) and need a 24 volt battery bank--Take a look at the Solar Converter option... Very cute way of charging (and discharging) a 12 volt battery in a 24 volt string.

    EQ 12/24-50

    I have not tried the setup--But it does look feasible. I would check out standby losses--you may end up with 1% of 50 amps (0.5 amps) of standby losses--which could add up when there is no wind available. It is probably not that bad. However, I have never tried them, so I don't know what other issues you may run into.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Thanks so much...

    I am picking up batteries tomorrow so just wanted to know the options I should look at. I intend to get solar as well, just the cost is a bit right now. I don't expect to much from the wind, more trying to get past the learning curve before I tackle the house. I hope to be able to run my security lights in the shop are with the wind/battery bank. I get a pretty steady wind most of the time. From you words, I may have to scale back to a 12v vice a 24v but sill should be enough to work with the light outside. Currently, the lights are CF flood lights, but I hope to find some LED that will serve my purposes...I thank you again for your help.

    R/Techfields
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    If you can use motion detection lights--that will even save you a bunch more power... Lights turning on due to motion usually attract more attention than lights that are on all night--A possible double win.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Good scoop...R/Techfields
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Difference in Battery Volts
    techfields wrote: »
    Great scoop, so the reason I see folks going to a 6v system is based more on the charge/discharge of the lower volt battery itself if I understand your comment below. Using four, 6v batteries in series, producing a 24v system would still require 28v to charge, is that correct?

    R/Techfields

    Yes. Unless you do the ridiculous route and disconnect all batteries, then recombine them in parallel to charge at 6V (but much higher Amperage). Forget I even mentioned that; it's totally impractical.

    Most people go with the 6V batteries because they are an inexpensive way to get a manageable size package of power. Good value in terms of $/Amp/hr and configurable for any standard system Voltage.

    Then we get in to the discussion of why choose a particular system Voltage over another. The usual rule-of-thumb is the higher your consistent Wattage needs the higher system Voltage you use to keep the DC Amperage as low as possible for the equivalent AC output. Many will point out that an inverter such as the Xantrex XW6048 is a better buy per output Watt than others, but sometimes there are advantages to using lower Voltage systems. This would include the readily available 12 Volt DC accessories/equipment and the ability to obtain charge-level Voltage under lower light conditions with a given array size.

    Confused enough yet? :p
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Howdy,

    I am back to hopefully get a fix on why my batteries are not charging...

    Today, we have lots of wind...I have put up self made turbine with a treadmill 21a motor, get consistently, 8-10 volts output from the generator. I put a blocking diode in the correct direction on the positive side of the output (turbine) to the battery. At present, I am using two 12v deep cylce batteries as my storage source.

    The wind has been blowing pretty consistent for the past 4 to 5 hours without any increase in voltage to the battery charge...I am pretty confident that the wiring is correct from the turbine to the batteries. I am using a Coleman Air 160 amp controller which has me put the pos/neg of the turbine directly to the batteries...still no charge. The blocking diode is going in the correct direction as the volt meter is showing 8 volts before the diode and 23.91 after the diode.

    Any clues of what I need to do?

    R/Techfields
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Difference in Battery Volts

    How do you expect to charge a 12 Volt battery with a "charging source" that puts out only 8-10 Volts?
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: Difference in Battery Volts

    It appears that the voltage input is not high enough, 8-10 volts will not charge a 12 volt battery! A fully charged 12 volt battery is really ~ 14.4 volts.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Difference in Battery Volts

    Have you tried running the generator/alternator on an electric drill to see what voltage it is capable of outputting?

    If it is capable of > 30 VDC (with useful current), then your blade set may not be capable of turning the generator fast enough... It could require a new set of blades with a different pitch. Or even a small transmission of some sort to double (or more) the generator RPM.

    These two forums may have more information for you too. They both are more geared to DYI wind turbine systems than this forum is.

    www.otherpower.com
    www.builditsolar.com

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    Everyone, thanks...I mistakenly thought it was the amps the charged the battery, even if I had 4 amp charging, it would still add to the storage of power, did not understand that I needed a full 14 volts to charge a 12 volt battery.

    I have three motors set up right now, going to the battery, but only one hooked up. Can I hook the three together and combine to get the volts I need? If so, can I just wire them together with a diode on each, then to the battery?

    Thanks again for all the hlep folks.

    R/Techfields
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Difference in Battery Volts

    Voltage is like electrical "pressure"; if it isn't higher at the source than the destination, you get no flow. Not the best analogy, but it gives you an idea.

    Can you connect two (or more) turbines together to up the Voltage? Sort of. To increase Volts you need to connect them in series: a negative to positive connection on the outputs between the two. This isn't a great idea, as their output will vary quite a bit. Not as simple an equation as hooking multiple PV's or batteries together. Usually turbines are paralleled to up Amperage, but if the Volts aren't there you can't get any increase.

    If the output is in AC at some point, there's a trick with diodes and capacitors called a "Voltage doubling circuit" - but it's complicated.

    This is why we say wind turbines are a learning experience; you usually learn they're not very good.
  • techfieldstechfields Registered Users Posts: 13
    Re: Difference in Battery Volts

    I like the response Cariboocoot, you're correct that in the end, I should have went with solar, but this was a interesting journey to say the least. What I found to work or not work with wind it seems I can take and use with sola...which I will when I start getting solar together.

    If my controller works with both wind and solar, does that mean that the combination of both could generate the necessary volts to maybe charge my batteries? I can now clearly see that just wind is not going to work with my current setup. No worries, this was a learning curve for me and I am not discouraged in the least to continue with this.

    In hindsight, I now believe I should have spent the extra money on 6v batteries vice the two deep cycle 12v I did purchase and stay away from the 24v systems to begin with. I am going to scale back to a 12v charging system for now and start looking for some solar panels I can afford.

    Life is good, so I will work with what I have and move forward.

    Thanks again for the words of help.

    R/Techfields
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Difference in Battery Volts

    One thing you really can't do is a series connection of solar & wind.

    You might want to do as Bill suggests and investigate those turbines; find out what they're capable of and see if there's some reason why they won't put out enough. Maybe there just isn't enough wind; that is often the case.
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: Difference in Battery Volts
    techfields wrote: »
    I like the response Cariboocoot, you're correct that in the end, I should have went with solar, but this was a interesting journey to say the least. What I found to work or not work with wind it seems I can take and use with sola...which I will when I start getting solar together.



    In hindsight, I now believe I should have spent the extra money on 6v batteries vice the two deep cycle 12v I did purchase and stay away from the 24v systems to begin with. I am going to scale back to a 12v charging system for now and start looking for some solar panels I can afford.

    Life is good, so I will work with what I have and move forward.

    Thanks again for the words of help.

    R/Techfields
    Actually if you got true 12v deep cycle batterys, you could still go a 12 v system. 24v makes for saving money on wire and amount of controlers you will need. S:Dlarvic
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