SUN-600G directly to battery bank?

Discussion in 'Connecting to the Grid' started by windbag, Feb 9, 2011.

  1. windbag

    windbag WindyNation Engineer

    Has anyone tried to run one of these SUN-600G (30-60VDC) inverters directly to a battery bank?

    I believe I read on here that someone asked SUN if there inverters can be hooked to batteries, and they replied back NO. I just wanted to confirm this with you guys in case someone knows something more about it and/or has tried it.


  2. dlmcbm

    dlmcbm WindyNation Engineer

    I am not sure about the 600 but I would think they are the same. I have a 300w wind grid tie (10.8-30v) made by masspower. I am pretty sure thats who makes the sun models. I hooked mine to a 24v battery bank and it was putting out 295 watts. All of these chinese grid ties are so limited on information its hard to tell whats what and who's it what. LOL

    Mine is the LT-300g and I have a LT-600g on the way.
  3. Minnesota

    Minnesota WindyNation Engineer

    I have several SUN and Power Jack GTIs. Some have low-end startup/cutoff at 10.8, 12, and 14V, and around 28-30V on the top end.

    Connecting battery(s) in this range and the GTI will max-out trying to transfer the stored power to the grid until they cut-off at their respective low ends. A 24V Battery bank on a any of these "12V" GTIs is a good way to put your battery bank to death.

    I see very little rationale to use a GTI with a battery of any size, though a small one can be used in parallel with a wind turbine to smooth out the power flow and voltage range, but everything has to be selected just right.

    The world still lacks an affordable wind GTI under 1000w and $500. That would sell.
  4. windbag

    windbag WindyNation Engineer

    Thanks for the replies. I agree that it would not be wise to leave one of these inverters hooked up to a battery bank all of the time if it would pull down the battery bank voltage too low. I was just wondering if these SUN inverters were designed to be able to handle a constant flow of max power (like if it was hooked up to a battery bank) without burning up the inverter itself.
  5. Minnesota

    Minnesota WindyNation Engineer

    I think it will handle the power, just like as if it was connected up to solar panels that were able to put out more than the GTI could handle .... no problem.

    The only issue is heat. At max current the MOSFETs get really hot and if they are not mounted well to the heatsink inside (poor factory workmanship) then they will fail and have to be replaced.

    I personally opened all my GTIs up and check this early on. I even added thermal grease to each MOSFET as I do run them at about 1/2 the sticker rating pretty much all the time. Have not fried one yet and I have 8 now (250 SUNs and 300 PJs). They work well for the money and near 90% efficiency at the level I run them at. They are less efficient at lower wattage.

    Speaking of heat, I looked for a thermistor of some evidence of a thermal sensor inside but there is none. These things have a little programmed microcontroller in them and they can sense/measure the current flow in order to control it so I think they use software that flips the fan on and off based on the power it senses is being moved through. I have some where the fan comes on and stays on, others the fan goes on and off, and others the fan never comes on ... so there are different version of the software involved and you really never know what you are getting exactly. So far they have all worked well.

    As an engineer, I know that running well below the max rating on things that they tend to last almost forever. Push it and things can die very fast and at unpredictable times. I stay under 150W "IN" on these GTIs.

    Welcome, btw.
  6. windbag

    windbag WindyNation Engineer

    Thanks Minnesota. I think I might experiment with a SUN-600G. Good idea to remove the cover and put some thermal paste on the MOSFETs and make sure they are attached to the heat sink (case) properly. Too bad they don't have a thermistor in there. Seems like one of those things where they could have spent a little more money and had a much better product. Unfortunately, it seems that Chinese manufacturing is somewhat famous for cutting corners to save a little and end up loosing a lot!
  7. murray2paddles

    murray2paddles WindyNation Engineer

    Mn. It is so refreshing to have someone tell it like it is about some of the snake oil sales men in the micro wind world. Jeff may you rest in peace !
  8. windbag

    windbag WindyNation Engineer

    I ordered a SUN-600G to experiment with... should be fun. The Chinese can do a very good job if they are motivated to do so.
  9. murray2paddles

    murray2paddles WindyNation Engineer

    Don't worry, they are motivated and probably leading the world in wind or at least micro wind technology.
    Some of us on the forum might also be of Chinese origin !
  10. dlmcbm

    dlmcbm WindyNation Engineer

    I got mine today. I stated before that it was a lt-600g but came in as a sun-600g. It take a little bit to get it warmed up (low watts out at first then it kicks up). I tested with 24v batteries to make sure it worked. I also found that my kill-a-watt meter is incorrect. I have another and it was saying 120W and kill was reading 70W. I looked at amps and it was about 1.3 amps wich tells me the 120 is a lot closer then the 70.
  11. windbag

    windbag WindyNation Engineer

    I got mine today too. I hooked it up to my 48V battery bank to test it out. My battery bank is not fully charged and voltage was around 49.4V under load. At that voltage, I used my clamp on DC ammeter to check DC current into the inverter. I used the Kill-A-Watt meter to check AC power output. The wattage varied a little over time, but it hovered around 520-550W. I took 3 readings and calculated efficiency. Right at 82%.

    Most important was the fact that this inverter does not like to be run at max output. After around 10 minutes, is shuts down. Even with a external cooling fan blowing on the inverter case to help cooling, it still shuts down after a short time. When it cooled off for a while, I'd hook it up again and it would work for about 5-10 minutes before shutting down. Obviously, the is not meant to be run on a 48V battery bank all the time. It would probably be great for a lower voltage and a lower power output.
  12. dlmcbm

    dlmcbm WindyNation Engineer

    I would say the higher the voltage the better. Higher it is the lower the amps to reach the output. The amps is what makes the heat. They just wont run at full power all the time. I have heard from a lot of people that you only want to run them at about half the rated power for long periods.
  13. windbag

    windbag WindyNation Engineer

    Yes, I can see that this SUN-600G is definitely not designed to run at it's rated max output (540W). So, this inverter will not work with a battery bank. There are some grid tie inverters that specifically state they can be hooked up to a battery bank. This is obviously not one of them unless perhpas it is run with a lower voltage battery bank that results in lower power output. In my case, it won't work with my 48v battery bank, because I don't have a good way to throttle back the amount of current going into the inverter. It's "pedal to the metal" with a 48V battery bank.
  14. Minnesota

    Minnesota WindyNation Engineer

    Windbag ... would it come back on its own after a cooling period or did you have to disconnect/reconnect it to get it to reinitialize? It's a disaster for wind if it just quits and then then sits there.

    I was not able to find a thermistor in my SUN250Gs or PJ300s so I suspect the software controls the fan on/off based on what it sees for current flow. I have 6 of these units and the fan operation is not consistant across the units even though the look "identical." One runs the fan almost right away and keep it on. One cycles it. Another it never comes one. We don't know what we are getting when we buy these things. Version control is a mystery. Cross your fingers and give the Chinese your money. :(
  15. windbag

    windbag WindyNation Engineer

    True, Minnesota. With some Chinese made products, you never know what you are going to get! On this unit, the fan turned on after maybe 1 minute and then ran continuously.

    I also didn't see any thermistors inside, so I'm not sure how the inverter even knew to shut down. Must not have been based on temperature. MIght have been based on high current flow for a period of time. When it first shut down, I waited for a little while but it didn't start back up. I was afraid to keep it plugged in because I thought it might damage something. Actually, when it first stopped working, I thought it fried completely. Oh great, a 10 minute life span! Perhaps if I waited longer, then it would have restarted on it's own. I ended up unplugging it for maybe 5 minutes and then plugging back in. Then it started working again for about 5 more minutes. I repeated this about 3 times before calling it quits. It obviously will not work (for more than about 5 minutes) when hooked to a 48V battery bank.
  16. murray2paddles

    murray2paddles WindyNation Engineer

    :cry: :cry: ouch ! That cement wall hurts my head each time I hit it !

    Ah, I have a solution, buy American then maybe the fan will turn off, OR on. :lol:
  17. leamywind1

    leamywind1 WindyNation Engineer

    I applogize if I have missed any information. What Sun G 600w inverter is being spoken about?
    The one for wind or the one for solar? :?
  18. windbag

    windbag WindyNation Engineer

    I have a SUN-600G for solar. This is what I wanted because I am simply using it to hook up to my existing 48V battery bank. I don't need something that will track the rapidly changing voltage of a batteryless grid tied wind set up.
  19. minermike

    minermike WindyNation Engineer

    I've read all there is to read on this forum about Grid tie invertors and am still without a definate answer.It seems like there still isn't a reasonably priced one that you can hook straight to a battery bank and not have to worry about it shutting off and not coming back on or smoking it,seems like it's still is just a guessing game of trial and error.I decided to just buy a cheap grid tie that states it's good for solar,wind and battery,300 watts $91.00 delivered.I just run a 12 volt system and while working in the shop with my lights and radio running on the average i can maintain 12 volts in the bank,now i live in a low wind area and might go days without any wind but my deep cycles do a good job of storing juice.i'v never had my invertor shut down due to low voltage.what i'm wondering is how fast a grid tie will suck my bank dry if i hook it straight to the bank,i want to still charge batteries at the same time.?? If it would just pay for my phantom loads from clocks and t.v.s i'd be happy.I just read that grid ties work best at half power but how do you regulate that??? I'm confused.Thanks guys realy enjoy this forum and those that pertisapate.
  20. murray2paddles

    murray2paddles WindyNation Engineer

    Hi mike, welcome
    You bet it can be confusing at times !
    Well for starters how I understand the grid ties, they wre not meant to feed a battery bank , they are designed receive power from your turbine or solar panel and plug directly into your home grid service .
    When you hear us talking about using a battery bank that is a trick used to control the volt input from your turbine. Those batteries are not wired directly to the inverter, they are wired to the turbine with a blocking diode in between so current can only flow into the batteries. Depending on the volt size of your battery bank will determine what voltage you wish to hold your turbine input too, we are calling this clamping !

    Your question on how fast will a grid tie take voltage from your battery bank, it is immediately .
    But if your grid tie inverter is for example a 14-28 volt range your input power will ave to reach that 14 volts before your inverter will become active and create grid power.

    There are some inverters available that are reasonably priced and work white well. The ones we have been testing and getting very good results from are called Sun grid tie "for wind only " we ave stayed very strong on staying with the directions using wind rated for wind ! Our favorite one right now as been the Sun 500 DC wind rated.

    There will be more info for you but I will let some of the others talk with you also .

    Keep posting, good to hear from you.

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