Negative amps

tomsun
tomsun Registered Users Posts: 8 ✭✭
Hi, new to the forum and somewhat new to solar. 
I have had one of those harbor freight 45 watt systems for several years, it just runs a couple of those cheap lights that come with it, in the basement. 
I have been wanting to upgrade a little bit so first I bought a epever 2210an series controller. Just installed it a few days ago, the only thing is I keep getting - 1.1 or - 1.2 amps reading for the battery, sometimes just 0.0 amps.
I tested the battery ( Walmart everstart marine) and the specific gravity is okay and it's reading 12.8 volts.
I have read that this controller is only going to work right with a 24 volt system, so I don't know if that has anything to do with it or not. 
I bought this controller thinking of the future. My plan is to get one or two 100 watt panels and another battery to get 24 volts. 
Any thoughts? Thanks 

Comments

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    What is being used to measure the current?  Clamp on ammeters will display negative values if positioned in a reverse orientationto to current flow.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • tomsun
    tomsun Registered Users Posts: 8 ✭✭
    This is what the charge controller is showing. 
    I installed a different battery just to test it and I get the same reading, - 1.2 amps, which makes me think it isn't the battery. 
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Which controller? This one?:

    https://www.amazon.com/EPEVER-Controller-Regulator-Negative-Grounded/dp/B07DK5B63K

    One suggestion... Disconnect the solar array from controller (or turn off switch/breaker, if installed), then disconnect Battery leads to charger... (you only need to "disconnect" the positive leads--Not both + and - leads).

    Let sit for 30 seconds.

    Now connect the charger to the battery bank first, then connect the solar array. It is possible to "confuse" a charge controller if you connect the solar array first.

    If I got the right controller, it does support both 12 and 24 volt battery banks.

    Also check the array configuration... For an MPPT charge controller, you should have 2x of your Vmp~17.5 volt panels in series, for Vmp-array~35 volts... MPPT controllers do not work well with Vmp-array~17.5 volts charging a 12 volt battery bank.

    Also, what solar panels do you have now? Those 45 Watt panels are not the best and have been known to slowly lose output current over time just from being in the sunlight.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • tomsun
    tomsun Registered Users Posts: 8 ✭✭
    Yes, that is the correct controller. 
    I'm 99% sure that is how I hooked it up as that is what it says in the manual. Connect the system in the order of 1)battery 2)load 3)pv array. But I will try disconnecting and reconnecting.
    I still have the 45 watt system, I need to check their output, although I am going to get new panels soon anyway. Do you think that low output of these panels could be causing this negative amps thing? I find it very strange.

    Thank you for responding. 
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    How did you wire the panels? 1x series, 2x series, etc.?

    In general, you should look for new panels (a complete set). I have not read the manual, but getting pairs of panels and wiring in 2x series is a good start (assuming Vmp~17.5 volt panels). 1x series can work OK with Vmp~30 volts or higher).

    Putting panels in series (up to what the controller supports), can let you use smaller wire from the array to the charge controller (i.e., if you need to get the panels into full sun 50+ feet away).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    tomsun said:
    Connect the system in the order of 1)battery 2)load 3)pv array. 

    If you're using the load terminals, the battery amps will be negative (draining the battery) whenever the panels are producing less than the load is drawing. What happens when you shut off the load (lights?)

  • tomsun
    tomsun Registered Users Posts: 8 ✭✭
    Ah, now that makes sense to me. I was sort of thinking along those lines, but couldn't understand how the current could be flowing in the opposite direction. The panels definitely aren't the best.
    When I turn the lights off, it goes from    - 1.1 amps with the lights on to 0.0 amps with the lights off. So this makes sense to me now. Thank you. 
  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited June 2019 #9
    Tomsun 

    your harbor freight charge controller is of the PWM type and needs a voltage closer to the battery voltage, but your new controller is of the MPPT type and needs about twice the battery voltage from the panels to operate correctly. The fix is simple, wire your 3 HF panels in series to get about 38 volts into the new controller. The MPPT designs convert the extra voltage into current feeding the battery. As others have said the harbor freight panels are not the best available, now with a MPPT controller you are free to use 60 cell "grid tie" type of panel which are much more available than the 36 cell "12 volt" panels.  I would suggest 60 cell polycrystalline panels as the best bang for the buck 
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • tomsun
    tomsun Registered Users Posts: 8 ✭✭
    First off I want to thank everyone for their input, I've learned a great deal already. Sometimes it's hard to wrap your head around all this solar stuff. 

    So my next question is, with the mppt controller, will one battery be okay with 38 volts input or do I need to have two batteries. 

    I was thinking that I needed two batteries for that voltage, but would rather stick with 12 volts since I am probably just going to run 12 volt loads. 
    I guess what I'm trying to figure out is, can I have a 24 volt system with one 12 volt battery with the mppt controller, so that I can use smaller wire. I hope this makes sense. 

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    Yes it is possible with a MPPT controller to have 38V from the panels charging a single 12V battery, just remember to hook up the battery first to reference the controller to its nominal voltage. For a 24V nominal system two 12V  batteries in series would be required, or 12 cells total, if all loads are small and 12V, then it would make sense to stick with 12V. Higher voltage is benificial when dealing with larger systems or where higher current is involved, current is inversely proportional to voltage.

    This link will answer many questions you may have https://www.solar-electric.com/learning-center
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,037 ✭✭✭✭✭
    Your 20 amp controller will keep a pair of 6 volt, (wired in series for 12 volt).  golf cart batteries happy provided you run enough solar through it to produce something nearing 20 amps.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • tomsun
    tomsun Registered Users Posts: 8 ✭✭
    So I tested my panels today (the harbor freight ones), and lo and behold, only one out of three is working, guess I should have started there. Oh well, live and learn.
    Thanks for all the help. 
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,037 ✭✭✭✭✭
    At one time, when solar panels were expensive, Harbor Freight panels were a deal. Nowadays that's not the case. The fact that they burn out so quickly doesn't help either.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    tomsun,

    live and learn,  scrap the harbor freight stuff and move on. You have a reasonable controller, now look for some 60 cell grid tie type panels. The 250 watt grid tie 60 cell panels are selling for about 125-175 dollars each and are available much cheaper if you look around. I recently bought Sanyo HIT 200 watt panels for $40.00 each .  These were removed from a large commercial installation during an upgrade. Stick with what is commonly available. It will be less expensive and be more available when you expand your system. Best bang for the buck.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,