ssmith1952: AC inverter shuts solar system down



  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    I haven’t had a chance to use this solar set up yet. Turned on the fan just to see if it worked then turned it off. The inverter, not wired at present, will be wired directly to the battery with a 150 amp fuse on the positive line. Pos to pos, neg to neg. I am on my second battery. We tested the panels with a dc tester and they are putting out 200 watts as required.

  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    edited April 2019 #34

    When running with no solar, the fan likely draws not far off what the inverter would with nothing plugged in. When running the fan, does it draw the battery down faster than expected? At 3a draw, the fan should be able to run for quite a few hours (~16 to 50%SOC) on a good, 100ah battery. Running it on battery alone for a few minutes should have little effect on a good battery.

    What size wire will the inverter be hooked up with?

    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    Fusing the fan and the meter won’t be a problem. I don’t know the amp draw on the fan. I’m guessing around 3-4 amps I’ve not run the fan. Only to turn it on and off to check that it worked. I could turn it on the see if it does pull from the battery a lot but I really don’t want to drain the battery again. I understand that it damages it. Since I have another inverter coming Friday, I’ll try that. If it happens again, I’ll try another new battery ☹️( this will make the third).

  • littleharbor2littleharbor2 Solar Expert Posts: 1,626 ✭✭✭✭
    edited April 2019 #36

    Either that, or a bad/shorted connection to the inverter. As mentioned earlier, taking a good, fully charged, 100ah battery down to 10v cut-off in a matter of seconds takes a lot of current. Enough that I'd expect something to get pretty hot in the process.

    You mean like molten metal and smoke hot? If the battery is healthy and fully charged, that's what I'd expect to see

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    Inverter comes with two 3ft #4thhn with a 150 watt and fuse installed on the positive side. We have already taken the connections apart and cut any extra insulation on them that may be pinched, then reassembled. That wasn’t it. It does have a temperature shut off. But nothing felt hot. Maybe the fan wired is pinched and is shorting out the system. I’ll try unhooking that next time.

  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin

    And to clarify... Yes, to take a good 100 AH @ 12 volt GEL/AGM type battery from fully charged to less than 10 volts in a few seconds, we are talking about turning the 4 AWG cable pretty close to red hot.

    That is why I asked about the battery terminal voltage when you saw the voltage drop. If the battery is going "dead" in that short of time without smoke/melting metal, it is likely that battery has failed.

    Of course, there is always the question as to why the battery failed... Mfg. Failure, left dead for days/weeks/months, battery was dropped and broke internal bus connections, etc....


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    So even if the new battery was fully charged, it may be defective by not holding a charge? Nothing gets hot and that little meter says the battery is 100% (connected to panels). I’ll try whatever you may suggest to get it working. Thanks

  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin

    I don't know what is happening... It is possible for a battery to be bad, even if new. It is rare, and not my first guess where the issue really is.

    I still am leaning towards the AC inverter was not bolted to the battery terminal clamps, but instead your friend was holding the copper wires just to the terminals & Clamps. And non-bolted electrical connections that are supposed to carry 100's of amperes--They just don't.

    My suggested test... Bolt of the DC wiring to the AC inverter, and connect your DC meter to the battery terminals too, and fire the inverter up without any AC loads. Assuming there is no Solar Charging going one, you should see the battery voltage drop to ~12.5 volts or so and stay there. And then you can add a few loads to your AC inverter's output and you should see the voltage stay relatively stable or drop a bit towards 12.0 volts and hold. I would suggest that the "nominal" AC loads for your inverter would be in the 100-200 Watt range.

    If you have your solar charge controller connected and full sun on the array, your battery voltage will probably be in the 13.5 to 14.2 volt range--At least until your AC loads exceed the available solar power.

    If the inverter was bad or its +/- connections were connected backwards to the battery, There would be some smoke and heavy sparks if the inverter was shorting out the battery bank and you were just pushing bare wire to the battery terminals.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    inverter cables were indeed bolted to battery terminals. We only did the hand held thing for a test. With nothing else attached, my friend held, not bare wires, but the inverter cable connectors (rings)to the battery terminals. Inverter read 13.4 and held. Then we went to van and connected inverter to the battery along with everything else that is connected and that’s when it took a dive. WTH. I’m so discouraged with this.

    We will try your suggestion tomorrow or Saturday after the new inverter arrives. Or may try on the old new inverter.

    Nothing has been done backwards. At least we got that part down. We have a dc meter now so will try your suggestion. Without solar panel connections. Thanks


  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin


    I am very sorry. Debugging can be a bit of a pain, especially if you do not have a meter/test hardware/known good equipment, etc...

    There is nice test equipment that can make checking the battery much easier/quicker, but few people (or even shops) will have the gear--It mostly gathers dust from non-use. I don't suggest you buy one for a one-time-test, but here are some examples.

    If you have a local auto parts store nearby, frequently they will have a battery tester that could verify if your battery is good or bad.

    Can you find somebody nearby that has a bit more car/boat/DC power experience to help?


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    Yes there’s a mobile rv tech I plan to call if it fails after the new inverter and/or after their new battery

  • SolfyrSolfyr Registered Users Posts: 22 ✭✭

    Renogy seems not to have that charge controller Wanderer 30A anymore on their website,

    but a newer one 30A-Li .

    Manual downloaded and read ?

    Overall , I would have spend $20 for the 10A version , since that includes a

    display , or spend also for the bluetooth box additionally .

    The battery might not been charged much , and the voltage is a "ghost" value ,

    bounced back up under no-load conditions up to those 13 V .

    Those 100W panels might even not deliver enough Volts under overcast conditions and hot outside temperatures

    to charge the battery , and probably would need to be wired in series during Summer ;

    50 Vdc are some 72 cells 300+Watts panels alone , so those two 100 Watts need to

    be wired in series , and not parallel , and then the 10A version would be good enough .

    I would also charge that battery by a grid connected charger , and try again .

  • ssmith1952ssmith1952 Registered Users Posts: 25 ✭✭

    Final outcome: hooked up new Renogy inverter today and switched out the painted battery connectors for bare metal ones. I dont which one made the dif but it works like a charm. Plugged in a small fan, great. Ran the exhaust fan, great. Plugged in coffee maker and made coffee, worked. So happy. Thank you all for your time and many suggestions.


  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin

    I am happy to hear Sherri that all is working well...

    Not sure what size AH battery bank, Watts for your AC inverter, and your final solar array Wattage is/will be... But be careful, it is very easy for a large AC inverter (and AC loads) to suck dry your batteries unless you have enough solar array+sun to keep up.

    And batteries are the major item that is easy to kill (in days/weeks/few months if over discharged/undercharged.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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