bad inverter or bad me...?

audiodave1audiodave1 Registered Users Posts: 10
Hello Group,
I have built a small 12v off grid system connected to the house thru a 6 circuit transfer switch.
Midnite kid+WBJR, Prowatt2000 (GFI removed), (2) energizer 230Ah 6v, (3)245w panels parallel 36v.

40' of 10awg from the panels to the CC
5' #8 from the CC to the batteries
3' of (pair) parallel #1 from the inverter to the batteries.
20' of 12AWG to the Reliance transfer switch. (works fine with a Honda EU2000 connected to it @ 14a)

No charging issues or operational issues. no blown breakers. no hot wires.

BUT...

If I am drawing 70a of current @ 13v (according to the KID) , the Prowatt says it is @ 42% capacity on it's screen and a digital AC current meter on the input to the transfer switch is showing 4.3a (It's within 300ma of the Fluke) which is the draw of the HVAC fan on high speed.

This does not add up to me. Should I not be seeing higher current like about 7a @ 44%?

Anyone have a guess or diagnostics for me to try?

I have attached a picture from the early setup of the system, wattsup is removed, other terminations made...(image is upside down)
Dave

Attachment not found.

Comments

  • BrluxBrlux Solar Expert Posts: 73 ✭✭✭
    The 70A at 13VDC and 42% load sounds about right. Do you have a Kill-A-Watt meter you can use to see what the AC numbers looks like? Do you have some other loads like a small space heater or incandescent light bulbs so see what your numbers look like with these more ideal loads?
  • audiodave1audiodave1 Registered Users Posts: 10
    Thank you for your response.

    I did put a KWM in line and the current is close. The main question is how is 4a 42% of a 15a RMS inverter? Seems I am a couple amps short...

    I just installed another amp meter for AC @ the inverter. Reads very lose to the one on the transfer switch.

    I have run my office on it, sump pumps, small fridge etc...the numbers track closely as a percentage/Amp draw/voltage from what I can tell.

    Dave
  • BrluxBrlux Solar Expert Posts: 73 ✭✭✭
    Did the wattage on the KWM relate appropriately with 4.3A ~500W? Are you sure there are no other AC loads drawing power that are not being accounted for in your amp measurments?
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    audiodave1 wrote: »
    Hello Group,
    I have built a small 12v off grid system connected to the house thru a 6 circuit transfer switch.
    Midnite kid+WBJR, Prowatt2000 (GFI removed), (2) energizer 230Ah 6v, (3)245w panels parallel 36v.

    40' of 10awg from the panels to the CC
    5' #8 from the CC to the batteries
    3' of (pair) parallel #1 from the inverter to the batteries.
    20' of 12AWG to the Reliance transfer switch. (works fine with a Honda EU2000 connected to it @ 14a)

    No charging issues or operational issues. no blown breakers. no hot wires.

    BUT...

    If I am drawing 70a of current @ 13v (according to the KID) , the Prowatt says it is @ 42% capacity on it's screen and a digital AC current meter on the input to the transfer switch is showing 4.3a (It's within 300ma of the Fluke) which is the draw of the HVAC fan on high speed.

    This does not add up to me. Should I not be seeing higher current like about 7a @ 44%?

    Anyone have a guess or diagnostics for me to try?

    I have attached a picture from the early setup of the system, wattsup is removed, other terminations made...(image is upside down)
    Dave

    Attachment not found.

    70 x 13 (if that is the measured battery voltage, do not use the nominal voltage) is 910. That is very close to 42% of 2000. (Actually = 45.5%.)
    On the output side 4.3 x 120 is 516, which is a lot less than 42% of 2000 (or even 1800). I do not have an explanation for that. The amperage would make sense with a 240V AC output, but not with 120V AC,

    SMA SB 3000, old BP panels.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    audiodave1 wrote: »
    Thank you for your response.

    I did put a KWM in line and the current is close. The main question is how is 4a 42% of a 15a RMS inverter? Seems I am a couple amps short...

    I just installed another amp meter for AC @ the inverter. Reads very lose to the one on the transfer switch.

    I have run my office on it, sump pumps, small fridge etc...the numbers track closely as a percentage/Amp draw/voltage from what I can tell.

    Dave

    The only thing that comes to mind is that the HVAC compressor is inverter driven and therefore has a low distortion power factor. The reading of an averaging AC meter (rather than a true RMS meter) might understate the current drain in that situation. But not by 50%.

    Is there an AC input battery charger or something of that sort connected on the inverter side of the transfer switch?
    SMA SB 3000, old BP panels.
  • BrluxBrlux Solar Expert Posts: 73 ✭✭✭
    When you run the same load from another source, generator, grid power, what does the AC consumption look like?
  • audiodave1audiodave1 Registered Users Posts: 10
    Hello,
    inetdog- It is likely inverter driven as it is a multispeed very new system. I do use a true Fluke 867 and an 87 meter. No other charging circuits in the house (yet). I swap twist-loc plugs to go between generator/solar power.

    Brlux- The consumption is basically the same when the EU2000 runs the transfer switch. I have also used a clamp on right by the HVAC and get similar current readings. I will do some more testing tonight with steady resistive loads. I have mapped out the power to the whole house outlet by outlet. When the fan on the HVAC stops draw goes back down to .2a for the control circuits etc. It is a dedicated circuit.

    Thank you for the input folks, I will run thru the suggestions tonight.

  • audiodave1audiodave1 Registered Users Posts: 10
    Hello group.
    I am still trying to get to the bottom of this but got distracted by a 10 day business trip initially and am now far away on vacation.what I did learn in my week between travels is the system works about as one would expect. I needed it a few days when some nasty storms rolled thru the Philly area last week and knocked out power for a couple of days. I have a Honda eu2000 that made up for the shortfall. This is just a hobby system...

    For about 10 hours a day I was able to power necessary circuits. 2 sump pumps, Big fridge, small freezer, tv and internet (until their batteries died anyway) I was running the batteries down to about 11.3v loaded and was easily able to recharge since it was sunny each day.

    The only time it would choke was when the big fridge would start up. The inverter would cycle on and off a few times before stabilizing. 220a draw on the 12v bank at those moments that would stabilize to the expected Draw.

    Usually I was drawing 2-3a save for sump and small freezer peaks then a continious 5-7A draw for short periods.

    I did notice on the kw meter the power factor for the hvac only was 70. Might have something to do with it. I did run the hvac some to circulate air during the hot days when the grid was down. I will get back with better info next week or so but the short story is success in general under trial by fire.
  • BB.BB. Super Moderators, Administrators Posts: 29,696 admin
    220 Amps * 12 volts = 2,640 Watts -- That is a lot of power from a 12 volt battery bank/system. I would be seriously looking at a 24 or even 48 volt system if this is your loads for significant periods of time (i.e., more than a few seconds of startup current for a well pump).

    If this is startup current--Then you have the choice of looking at up sizing your off grid power system or picking more "solar friendly devices". A softstart well well pump may cost you $2,000+ vs a "new" off grid solar system (which will cost you >>$2,000). Similar for the AC system--A mini-split/softstart AC system vs a much larger off grid power system.

    Note that "poor" power factor does not really affect battery current/DC side of the system (other than poor PF motors tend to have high starting loads too). However, poor PF/Inductive loads can cause the AC inverter "issues" (depends on inverter design).

    -Bil
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • audiodave1audiodave1 Registered Users Posts: 10
    Thank you Bill,
    Yeah,220a that is the hardest starting device and it is not a regular need. The huge fridge came with the house. The well pumps are easy to start as is the hvac as it is a variable speed system that ramps up slowly.
    Its a hobby system. I will go 24v next year once I convince myself I am over any noob mistakes. So far so good aside from the OP question I need to figure out.
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