Classic 150 reading 0 for input voltage

[Web4Deb]

New problem...a bit more severe than my past ones.  Today I went to check on my building and saw that one charger was working normally and the other said 0 for the input voltage.  Thinking I had a bad wire, I tripped the disconnect and  climbed on the roof to check the panels and they were ok.

At the disconnect I have a voltage reading of around 125-130.  As soon as I reconnect, the voltage drops back down to zero.  I don't have an amp meter, but I'm assuming the Classic is shorting the line.  I have also disconnected the classic from the battery/load (so it stayed off) and I got the same results.

Did something happen to my Classic that's causing a short?  Thanks!

[Westbranch]

what load do you have occurring  overnight?

[Vic]

Hi Web ..,

If you have a disconnect near the Classic that you can open,  you could measure the voltage at the input side of the disconnect to see if it matches the output of any combiner  for the PV.  This could eliminate any short in the run from the roof to near the CC.

The way the post was written,  seems that you may not have a breaker on the output of the CC to the battery.   If this is the case,  you need a protective device to protect the CC from fault currents that may occur.   It is a bit ambiguous weather you have a circuit breaker on the output (this is the most common way to protect the CC,  as a Fuse is not a disconnect).

As you know,  it is common to see about 50 - 65% of battery voltage at the input of the CC when it is resting.

If you are comfortable doing so,  you could OPEN the disconnect for the input to this CC,   and the battery disconnect.  Use your voltmeter to measure between the input terminal  and the PV negterminal  on the CC .  Is it zero ??  You could then carefully disconnect the wire on the CC's input terminal,  and measure the voltage between the wire and PV ground (without touching it) ... is it zero ?

Now switch ON the battery to CC disconnect,  and  measure the voltage on the input terminal of the CC to CC PV negative terminal,   is it still zero?  If you see50 -65-ish percent of battery V on the input terminal,  then there is some short in the input wiring.  If still zero,  then there may be an issue with that CC.

With the PV voltage that you reported,  is can be very dangerous to do the above steps,  as DC voltages at this level can be lethal.  So be very careful,  and do not make these measurements if you are not certain that you can do so without mishap.  Do not do the above steps without someone else available to help you in case of mishap.

More details on your system would be very helpful.

Good Luck,  Vic

[boB]

This does not sound good but might be something other than a broken Classic.

If it is broken, you will need to get an RMA number and we will replace or fix that
Classic.

Hopefully it is something less severe than smoke released.

boB

[niel]

this might sound stupid, but did you check that the breaker itself did not fail?

[Web4Deb]

Hi Everyone, thanks for the replies...here's the answers to all the questions that were asked:

Westbranch:
-I'm drawing a load of 5-9 amps (@ 12 volts) all the time.  This is in a greenhouse and it runs the pumps to circulate water for the aquatics - one pump is on all the time, the other is on a float switch.

Vic:
- Thanks for the safety concerns...I'm an electronic engineer and am well aware of the dangers of DC.  ;-)
- There is a circuit breaker on the input and output of the CC.  To test the wiring, I also disconnected the wiring at the terminals of the CC and get the appropriate voltage readings on the PV panel and battery wires.
- With the PV physically disconnected, if I turn on the CC, the power on the PV terminals stays at 0, unlike my working CC which does show a % of the battery voltage.

boB:
- I'm willing to try other experiments if you think there could be other issues.  Also willing to dismantle unit to inspect providing it doesn't void warranty.  ;-)

niel:
- I don't think it's the breaker as I'm getting the proper voltage through them.  But since I don't have any spares, I can't switch it out and I don't want to direct wire the CC to the PV.

Thanks again!

[Halfcrazy]

Sounds like you have successfully trouble shot it to completion. Email me so we can arrange to get this fixed for you, ryan at midnitesolar dot com

[Vic]

Hi Web ..,

Sorry to talk down to you.   Often it is difficult to know the level of knowledge/experience of members,  and would hate to set up someone to do something that could have personal consequences.

Good Luck,  Vic