Load Amperage, is this correct?

FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
If I use an inverter, it wants more amps than anything else. Is this the correct way to do this?

LoadAmperageRequirements.png

thank you

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?

    If the 10 amp line coming in is fused/protected--you can connect the nverter directly to that line and skip using the 3x2.5 amp fuses...

    In any case, you want the wire/fuses to be rated 1.25x your maximum expected load anyways (1.25x7amps=8.75amps=>10 amps). You don't want to run your wiring/fuses near 100% of rating--you will get false fuse blows (fuses/breakers are usually rated to "blow" at rated load).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    The 10 amp is coming directly off of the controller. It's fused between the battery & controller.

    If I have the inverter connected directly to the 10 amp with the fuse panel also coming off the 10 amp, wouldn't it split the amperage in 2 giving each about 5 amps? That was my reason for putting the three lines together to get the 7.5 amps. I thought that lines in parallel split the amperage equally.

    I edited the drawing to show, but I reduced the size a little so difficult to read some of the numbers.
    amps out of fuse panel = 2.5 amps
    amps to inverter = 7.5 amps
    amps to lights & fans = 0.1 to 0.5 amps (the 0.5 is just a guess using the higher numbers I found as I couldn't find specs - per my figuring, I'd only get 3.57 amps per line there anyway).
  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?

    Unless the controller load output appears to also have internal protection... From the sell sheet:
    Electronic Protections
    • PV: Overload, Short Circuit, High Voltage
    • Load: Overload, Short Circuit
    • Reverse Polarity: Battery, PV and Load
    • Lightning and Transient Surges
    • High Temperature
    • Reverse Current at Night
    It looks like if you use the appropriate wire gauge--then the controller will limit its maximum output (15 amps?).

    You will need to check the manual for details.

    -Bill

    PS: I would recommend not paralleling fuses/wiring... In many cases, the current does not share all that well and will many times "choose the path of least resistance". For example your 7 amp load, one fuse/wire will take 4 amps, and the others will split the remaining 3 amps--and you will end up blowing one of the 2.5 amp fuses.

    And, assuming your wiring is correct (15 AWG or larger), 7.5 amp vs 10 amp vs 15 amps is not really worth worrying about the differences... Plus, if you sometimes place a heavy load on your inverter (say an electric drill)--the surge won't blow your smaller fuses.

    -BB
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Load Amperage, is this correct?

    Just as a general rule, you should never run anything but the very tiny inverters directly from the LOAD output on a controller. The startup surge on some can blow the controller.
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    I'm using 10 or 12 awg as far as the fuse panel (battery, panels, controller), 16 awg from fuse panel to distribution panel, most of the fans & lights are computer stuff so little tiny wires - no idea of gauge.

    I don't understand the "not paralleling fuses/wiring". Isn't it my only option. If I run serial, I lower voltage.

    My inverter won't power a drill. It's max is 8 amp. It's a APC PNoteAC75 for laptops. I'm only going to use it for a little water pump or maybe a laptop. I could just use it off of the truck battery instead. It's only going to get used for a few minutes / day. I have AC access in my storage unit so I can charge the laptop, toothbrush, screwdriver, etc. there.
  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?

    Paralleling fuses/wiring is just not a good idea if you can avoid it... In your drawing, I would prefer to see the inverter running off of your 15 amp battery fuse (taking into account what WindSun said that high surge currents for inverters and such can ruin solar charge controllers).

    Believe me, taking 3x 2.5 amps fuses and 3x parallel wires is not near as reliable as 1x8-10 amp fuse and a 15 awg wire...

    I cannot tell you how many times I have had to fix/debug my $20-$40,000 test equipment and found that they ran 4 wires in parallel to carry 4x as much current as the rating of 1 wire/connection (through a Molex connector) and see that one or more of the parallel connections is chard.

    Typically, what happens is one wire/connection has a lower resistance than the other parallel connections... So much (or most) of the current flows through the low resistance connection and it overheats and fails... Then the next low resistance connection take the majority of the load, it overheats and fails, and so on--until few months or years down the line, the last connection (way too much current) overheats and fails.

    Remember the fusing is to protect the wiring--not to protect the device... While you would not want to put a 75 watt inverter on the end of 0000 cable connected to your battery--I would not put a 7.5 amp fuse on a 7 amp load... More than likely, you will end up replacing fuses every year or so.

    Placing your 7 amp inverter load on a 15 amp / 14 awg (single cable) is the way to go.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    thank you

    I think as the inverter is optional, I'll just stick with running the little stuff and leave the inverter out. The only thing it was really going to power was the little fountain pump for running water, but that is certainly not a necessity like the fans.

    I can plug the inverter into the truck power for the little time that I might need it.

    I'll more than likely need to add more fans anyway. Can't believe how muggy it's been in the Bay Area for the last few days. Not getting much building done. 3 weeks behind. Not far enough along to order my solar stuff.
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    so this is ok now?
    LoadAmperageRequirements_v3.png
  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?

    That should work fine... Just remember even though, for example, your loads are 0.1 amps on a 2.5 amp fuse--the wires should be sized to support 2.5 amps each.

    Always look "upstream" of your wiring and make sure it is appropriate for the fusing/breakers you are using (don't for get the ground wires too--if not using "chassis" ground).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Load Amperage, is this correct?

    that's not ok for it appears you are recombining them again. why? eliminate the 2nd connection buss on the far right. i'm also assuming that you are going to use the lvd feature on the controller for all of those little loads.
  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?

    I assumed the second terminal block on right was the ground return... Is that what you were looking at Niel?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Load Amperage, is this correct?

    yes, but i should make sure that is what he intended for it with the loads inbetween the differing connecting busses. if that is the case then all is fine, but if he is just running wires to the other buss without a load then that's not good. he didn't show loads inbetween the busses and no - at the far right wire to indicate a ground buss. one has to be sure of intent.
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    The smallest fuses I've seen are 1 amp. These wires are pretty small. The fuses I've got are 3 amp, which looks like it should be good for 24 awg wires. I can try some of the 1 amp fuses. That should be good for 29 awg. At least there all it would toast would be the little wire to the fan or light. I've never seen fuses in computers for any of this stuff.

    thanks again
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    The second buss is the ground one, I just didn't take it out of the picture when I edited it. I put them in full size to figure out how much room it all needed. I'm trying to figure how things can be made to take up the smallest space. Sorry for the confusion.

    I know better than to run power directly to ground :D It's been a bit, but I've installed AC for the telephone company and done lots of DC powerwork, also for telephone company. Also building computers and doing automotive repairs.

    ps. I'm a girl. Should be able to tell by the motorcycle. All the hardly riders tell me that it's a girl's bike;)
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Load Amperage, is this correct?

    glad you clarified that as you're good to go with it.
    btw, it doesn't matter to me what sex you are, but in any case you have good experience.:D
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    gee, amazing how much you can miss reading something. I've been thru the SunSaver manual several time, highlighting stuff. This time is the first that I noticed the "! CAUTION: Do not wire an AC inverter of any size to the
    load terminals of the SunSaver MPPT. Damage to the load control circuit may result. Wire inverters directly to the battery or battery bank."
    Maybe not having TV will help since I'll be reading more and that improves comprehension:D

    I'm always one of the guys. It's just when I'm called 'he', I had to correct. - carpenter, mechanic, computer tech, motorcyclist, etc.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Load Amperage, is this correct?

    that caution is because loads and surges can easilly exceed the capacity available going through the lvd with some devices. if just an inverter operating a small tv, you might get away with it and the new lcd screens don't seem to save anything imho. a kill-a-watt meter will tell you what the tv's requirement will be from an ac point of view(i believe it to be higher on a black screen). the inverter itself draws extra over and above your ac loads to operate so even if you would have a tv that may be say 90w and you have say a 10a lvd (10a x 12v = 120w) (with this meaning up to 10a), with inverter efficiency sometimes around 80% (better inverter efficiencies will be had on many quality inverters, but even then that is at their rated power and this can be much worse when operating far below its rated watts) or less with some inverters, this could translate to 112.5w. add to that any inrush currents and you now see the problem and the reason for the caution. fans and other electrical motors will draw a great deal on startup too so you must know what the application going to the lvd will draw worst case.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Load Amperage, is this correct?

    Other fuse blocks to consider:

    http://bluesea.com/category/5/21/productline/125
    http://bluesea.com/category/5/21/productline/126

    Available from www.westmarine.com

    HTH,
    Jim / crewzer
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    Thank you. I've already got the fuse panel and two distribution panels. Also I need to go with as compact as possible. Only 28 square feet total area x about 4 feet high. I'm trying to figure out where a weeks worth of bluejeans will fit. ;) Walls only 1.5" with insulation inside. Probably end up putting distribution panels in battery area. These are nice though.

    I was in WestMarine a few months ago when I needed some rubber boots for concrete work. My employer generally supplies them, but I have much smaller feet than the average carpenter so I got my own. I just discovered another WestMarine near my new storage unit so will have to go explore.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Load Amperage, is this correct?
    FreeBrrd wrote: »
    Probably end up putting distribution panels in battery area. .

    Even with using a AGM battery, try to keep all the parts low in the area and the battery as high as possible. This is in case the battery lets of some hydrogen gas.
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    Thank you

    The area is only 10"x14"x12" - about an inch higher than the battery box. There will be some sort of vent to outside, maybe the conduit with a vent hole before it goes thru the roof. Air will be flowing inside the roof above the insulation, below the roof.

    I think the distribution & fuse panels will have to go on the ceiling. Either in a plastic box or with a plexiglass piece over them. Lots of design will happen as things get built.

    This is fun! I've got a page on my site for this. When I post pictures, etc. I'll put a link. I want to take pictures as the project progresses. Also comment on how the computer mods work for lighting & cooling. I'm going to feel like the guy in the movie that got trapped in the computer, can't think of the name of the movie. Long time ago, 20 - 30 years.
  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: Load Amperage, is this correct?
    FreeBrrd wrote: »
    Also comment on how the computer mods work for lighting & cooling. I'm going to feel like the guy in the movie that got trapped in the computer, can't think of the name of the movie. Long time ago, 20 - 30 years.

    Tron, 1982?....(more characters)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • FreeBrrdFreeBrrd Solar Expert Posts: 116 ✭✭✭✭
    Re: Load Amperage, is this correct?

    that's the one! Have to see if they have it at the library. They don't have Soylent Green.
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