Classic 250 MPPT - Input voltage 0 Volt - Troubleshoot question

[solar2013]

Hi!

It has been a few month now and my Midnight Classic was working great... till now that is...
Some how The DV input voltage remains 0 Volt (From my Solar array)

I already did a few test to try to figure out what might be the problem, but I got stuck.

I found a similair issue on the Forum and did the same suggested checks:
(http://midnitesolar.com/smf_forum/index.php?topic=997.msg6985#msg6985)
>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 ??
YES it's 0 Volt

> 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 ?
YES it's 0 Volt

>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? 
YES it's 0 Volt

>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.
Hmmm, I hope not :-|

Plus :
- I double checked all wires are correctly installed (+ checked voltages)
- I disconnected the Solar DC wires and they do have a 180V Volatge. (during the day ;-)
- Midnight Classic shows no errors and fully functional other wise (feed from the 48V battery bank)
- When I measured the resistance of the DC input, it seems to be short circuited. (?)
- I tested connecting  (3*9V small batteries) 27V to the DC input, but the Voltage remained 0Volt, When I checked the Current, It drained 5 Amps out of the small 9V batteries ..
Is this normal ? (I would expect very limited current as the input voltage is too low for the charger and it will not charge the 48V battery bank...but I expected it will indicate a 27V DC input Voltage)

Do you have any idea what might be wrong?
What else can I check/test?

Thanks,
Ron

[TomW]

Ron;

> 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 ?
YES it's 0 Volt

Sounds like you need to back track to your panels and find the loose connection, blown breaker or fuse.

Check the voltage at the array or disconnect near it.

Sure sounds like it is between the controller and the array.

The disconnected feed from the solar array should show full array voltage.

If I am understanding your results.

Good luck with it!

Tom

[Vic]

Hi Ron,

Welcome to the Forum.

When the  input to the Classic is completely OPEN circuited,  the Classic should display about 2/3 of the battery voltage.

There could be a short in the input wiring,  however,  if you did remove the input wire from the PV input TERMINAL of the Classic itself,  and you measure 0 volts at that terminal with a Multi-meter,  then there could be a problem with the Classic.

Believe that if for some reason the + PV input to the Classic becomes shorted to the negative PV input terminal,  that the Classic can be damaged.

More later,   Vic

[dgd]

Believe that if for some reason the + PV input to the Classic becomes shorted to the negative PV input terminal,  that the Classic can be damaged.

Vic,

I'm not really sure about  this. boB has said not to short the inputs to avoid damaging the Classic.
However I did see a remote stand alone PV system powering an internet repeater station, 1Kwatt PVs 48V batts, C150 where in a storm a tree limb destroyed a PV junction box. The + and - were shorted and copper connectors welded together. This made a dead short across the C150 inputs.
After 2 days the tech visited the site, replaced some cables and jb and everthing started working again. The 10A Outback breaker on PV input had not opened and the C150 was in RESTING Low Light state.
This led me to believe there was protection in the C150  against input shorting or reversal..

dgd

[Vic]

Hi dgd,

I do not know,  personally,  about shorting the PV in terminals of  a Classic CC.  I have read here that this can cause some damage.  I do not know,  but I've been told.

I will let the MidNite folks comment further.  But,  0.0 V displayed as the input V of  the Classic would normally mean that there is a short currently at the very least,  if the Classic is powered from a battery with voltage in acceptable range for the Classic to operate correctly.

All just my opinions.  YMMV,  GL,  Thanks   Vic

[TomW]

Ron;

> 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 ?
YES it's 0 Volt

Sounds like you need to back track to your panels and find the loose connection, blown breaker or fuse.

Check the voltage at the array or disconnect near it.

Sure sounds like it is between the controller and the array.

The disconnected feed from the solar array should show full array voltage.

If I am understanding your results.

Good luck with it!

Tom

Duh, got tunnel vision and missed that he has full array voltage on the PV in when disconnected in daylight.

Senior moment. I will shut up now after rereading it.

Sorry if I confused matters. Just trying to help.

Tom

[dgd]

Hi Ron,

You have  had the cover off the lower part of the Classic so did you detect any smell of burning?
The 5A consumed from the 27v battery input test means over 100 watts of power going somewhere. If some component has let smoke out, and you were probably not there to see it,  it may be causing a short 

Sorry, not meaning to sound negative, I hope this is not the case 

dgd

[solar2013]

Hi all,

Thanks for thinking along with me!

@Tom
>Senior moment
No problem ;-)

@Vic
>When the  input to the Classic is completely OPEN circuited,  the Classic should display about 2/3 of the battery voltage.
Not any more, now at 0V, see also the small video of the batery test (link below)

>There could be a short in the input wiring,  however,  if you did remove the input wire from the
> PV input TERMINAL of the Classic itself,  and you measure 0 volts at that terminal with a
>Multi-meter,  then there could be a problem with the Classic.
Yes I did and also on the Multi-meter it reads 0 V on the PV input :-|

>But,  0.0 V displayed as the input V of  the Classic would normally mean that there is a short
> currently at the very least,  if the Classic is powered from a battery with voltage in acceptable
> range for the Classic to operate correctly.
That's what it also look like to me :-( 

@DGD
>You have  had the cover off the lower part of the Classic so did you detect any smell of burning?
No smell, nor sign of burning ;-)

>- I tested connecting  (3*9V small batteries) 27V to the DC input, but the Voltage remained 0Volt, When I checked the Current, It drained 3 Amps out of the small 9V batteries ..

You can see my test on this small video:
http://videobam.com/mEYkg


It looks like somehow the PV input circuit is short circuited.
May be something with the voltage protection circuit ?

Any way to test / see this?
Or should I return it to the reseller? (It's still under warrenty)

Have a good weekend,
Ron

[solar2013]

Just to close the question,

Tech support let me know last week:
"Following the thread on our Forum it sure looks like you have done all the troubleshooting necessary to point at a bad FET board. It will need to be repaired/replaced so if the distributor will work with you on that you will want to get that fixed."

Thanks all for your help!

Regards,
Ron

[nigel]

Ron,

We await the return of the unit we have the new parts in stock .

Nigel Prism Solar