reading voltage after fuse removal

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landyacht.318
landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
After concluding there was no way my PV panel would top off my batteries, I decided to plug in my 25 amp wall charger. It did not seem to like the 2.5 amps that my kyc 130 panel was putting out at the time, so I removed the Fuse from between the panel and charge controller.

After doing this my battery monitor claimed it was still seeing 2.7 volts from the panel. The monitor does not read any voltage after dark.

What's going on?

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,477 admin
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    Re: reading voltage after fuse removal

    I guess my first questions would be what is brand/model of solar charge controller and brand/model of your battery monitor.

    There would be no reason to remove the fuse between the solar panel and charge controller--if you wanted to disconnect your charge controller, remove the fuse/connection between the charge controller and the battery (unless you are using the Low Voltage Disconnect, LVD, to power other items).

    And, are you looking at a "true" battery monitor, or the "battery monitor" function in your charge controller? The fact that you get zero volts with no sun is confusing--sounds like it is the meter on your charge controller (unless your battery bank is DEAD, zero volts, when there is nothing charging it).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: reading voltage after fuse removal

    Sorry for being Vague in my OP.

    Blue sky 2512i
    IPN pro remote
    KC 130 tm

    When adding my Schumacher "smart charger" during the day it would not put out any amps. I figure it was confused because of the incoming PV amps.

    When I removed the pv/charge controller fuse it worked normally.

    If I remove the fuse between the batteries and the charge controller, the battery monitor does not work as it is powered by the charge controller.
    I like to be able to see the amp flow when plugged in to AC, and it (the ipn pro remote) seems to be the only way I have of verifying that the wall charger is putting out amps, as the internal fan runs either way.

    The 2.7 volt reading with the fuse disconnected was displayed in the PV in/out screen on the Pro remote.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,477 admin
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    Re: reading voltage after fuse removal

    The IPN appears to be a combination Battery Monitor and BlueSky remote interface... So--It should work the way you want it too...

    So, what % of battery charge/capacity charge/voltage does your IPN show?

    The solar charging, at best, is around 10 amps... If your batteries are low, then the wall powered charger should be charging properly too... Both will simply add up together until each reaches the "voltage" cutoff point... It is certainly possible, if the batteries are near fully charged and the solar charger is outputting its 10 or so amps--that the wall charger will decide that the battery is fully charged and stop charging (say blue sky is set to 14.5 volts and external charger is set to 14.1 volts--bluesky will continue to charge and external charger will stop/float).

    I am still not convinced everything is working properly... Going around with a working/calibrated DVM/volt/amp meter and measuring, checking connections, and such would seem to make sense.

    A 130 watt panel should certainly be able to trickle charge 300 amp*hours worth of 12 volt batteries pretty easily.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: reading voltage after fuse removal

    Bill has it right. The Blue Sky shouldn't have any problem with the amperage from the wall charger. The only question would be, is the wall charger getting confused with the amperage from the BS/Panels. It would seem odd. I know when I run my Xantrex TC charger, it just adds to the amps that the panels are putting in. MY Tri-metric shows the combined amperage. Is it possible that your batteries are charged more than you think they are, so that the controller and or the wall charger are going into absorb (acceptance with the BS controllers) and are therefore reducing the amperage.

    I suggest you play with a DVM a bit to figure out what is going on.

    Tony

    PS. Most meter shunts are wired on the negative side of the battery leads, while the fuses are on the positive. You could still be getting voltage if you are measuring it at the shunt, it would just be completing the circuit through the meter.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: reading voltage after fuse removal

    if one is configured differently than the other it could have the effect of one of them seeing a charged battery instead of just another charging source with a high dc voltage. recheck what settings you have for each charging sources' operations. this does happen when more than 1 source is used and each of them have different settings such as one having an absorb voltage at 14.1v and the other at 14.8v. the 14.1v source would see the too high of dc volts at the battery and more or less stop operation. during a bulk stage both should be able to contribute if they don't exceed the absorb voltage that would force the absorb stage of charge to occur.
    i may be confusing you so think of it as the bulbs in a toilet tank only you would have 2 differing sources of water and both have their own bulb for water height. if one says it's full it will shut off that water source even though the other is still allowing water to flow because it is set higher.
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: reading voltage after fuse removal

    I appreciate the responses and the info.

    To clarify a couple points.

    My batteries according to the IPN pro remote were at ~ 82% when I added the Schumacher wall charger to the mix @ 4 pm with about 2.5 amps coming from the PV.

    I have 3 115 a/h "deep cycle" everstarts.

    The schumacher charger would appear to go right into 'float mode' where it merely lights it's green "charged" light. Nol amperage was coming from the schumacher charger at this point, only from the PV.

    Usually when the Schu. charger is in this 'float' mode it will add 1 to 2 amps above what ever the load draw is. With the pv connected it refused to even perform it's normal 'float' function.

    That is why I removed the fuse between the panel and charge controller.
    The schumacher charger worked normally when I did so. This occurence in not my concern. It is very easy for me to remove my PV panel fuse, and in a year this is the first time I've tried to use both at once.

    When the schumacher was putting 25 amps into my batteries, the pro remote was indicating that the disconnected PV panel itself was putting out 2.7 volts. I would assume that with no fuse in the positive side this reading would be zero. As it is at night, with or without the schumacher charger operating.

    It is just this 2.7 volt reading (when the PV is disconnected during daylight) which makes me think something is not quite right.

    My only complaint with my system is that the batteries drop much more quickly down to 12.2 volts than when new. There was a couple month span, when new, that the controller would not go into acceptance mode, which no doubt shortened the life of the batteries.

    However Starting the engine (5.2 liter v8) using the 3 batteries will not draw the 3 batteries below 11.9 volts during cranking. This number has remained consistent in the year long life of my current batteries.

    So forget about my schumacher charger, that is not important, my concern is only with the 2.7 volt reading I get with the fuse removed from between the PV panel and the charge controller.

    What might cause this?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,477 admin
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    Re: reading voltage after fuse removal

    The 2.7 volt reading with the PV fuse disconnected may be perfectly fine... Many electronic components (diodes, FETs, switches, etc.) can have a little bit of reverse leakage current. And if the "volt meter" function is also very sensitive (high impedance or high input resistance)--even a little bit of stray current can be measured as a voltage.

    If you really want to check--disconnect the PV fuse and connect a DVM or other volt meter across the Charge Controllers PV Input leads. Either it too will measure ~2.7 volts, or it may load down the circuit enough to make both the DVM and the BlueSky read zero volts (or something in between).

    Then reconnect the solar panel... If the BlueSky and DVM read approximately the same voltage on the PV inputs--then everything is probably fine (on that side anyway).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: reading voltage after fuse removal

    "The 2.7 volt reading with the PV fuse disconnected may be perfectly fine... Many electronic components (diodes, FETs, switches, etc.) can have a little bit of reverse leakage current. And if the "volt meter" function is also very sensitive (high impedance or high input resistance)--even a little bit of stray current can be measured as a volt"

    Okay. This is along the lines of what I wanted to hear.

    I will perform the test you mentioned using a DVM with the PV disconnected. Before and after the charge controller, although before might be a little tricky with my setup.

    Thanks again, I'll post the results tomorrow.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: reading voltage after fuse removal

    don't forget bluesky has some electrolytic caps on the input and they will hold a small charge in them for a time. if it is the caps doing this then with no input power to the controller(no pvs feeding the cc), short out the input leads going into the controller and this will discharge the caps. to be sure, do not short out the side of the controller connected to the batteries or one nasty arc weld could occur, especially if you don't have the batteries fused. the meter will probably have little effect on discharging of the caps due to its high input resistance. after the caps are discharged then see what it says.
  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: reading voltage after fuse removal

    Due to the large amount of noise insulation(compressor fridge) covering the input leads behind the charge controllers and monitor, my intended experiment turned into a case of it aint broke, don't fix it.
    I could check the voltage after the controller, before the batteries easily enough, but didn't.

    I'm going to assume everything's fine as by 5:15 pm today It claims it replaced 62 a/h into the batteries, with the panel flat on the roof.
    Thanks again for the info and replies
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
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    Re: reading voltage after fuse removal
    I'm going to assume everything's fine as by 5:15 pm today It claims it replaced 62 a/h into the batteries, with the panel flat on the roof.

    Calibration Check !

    130W panel @ 14V = 9.28A * 5 hours of charging in good sun = 46 AH.
    So unless you have a lot of good sun, directly overhead, for more than 5 hours, I think the 62AH number is overly generous. If it was really cold, and the panel was in the STC range all day, 6.7 full power hours would be needed, and I don't see how that can happen in one day, with a flat panel.
    Maybe if this was over 2 days, its possible, but unlikely for 1 day of harvest.
    Or were you using shore power to charge from ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • landyacht.318
    landyacht.318 Solar Expert Posts: 82 ✭✭✭✭
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    Re: reading voltage after fuse removal

    Your right, usually I reset the amp hour every night after dark and the day before yesterday I did it mid afternoon, when I had the panel tilted.

    Sorry for the error.

    I also get 35 mpg city in a 3 ton van with a v8:D
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
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    Re: reading voltage after fuse removal
    I also get 35 mpg city in a 3 ton van with a v8:D

    I had one like that too, I had to be careful on long trips and siphon gas out every 150 miles, or else the tank would overflow, and mess the paint up. Sold it because the ash trays filled up with gum wrappers.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,