Classic 150 startup... goes right to resting: high temp

[Kalsc]

Hi all! So grateful I found this forum.

I moved on to a property last year which is 100% off grid.  The one portion of the system I am currently having an issue with is the Classic 150 charge controller.

Backstory:
The outbuilding in which the batteries, Magnum and Classic are in looked like it had been sinking a little for a few years.  Because of the way the system was mounted, the conduit bringing in the PV leads was pushing up on the breaker box, this in turn was putting a side lifting force on the metal conduit between the breaker box and the classic.  Long story short, this in turn had torqued the classic housing, albeit aluminum, it didn't twist, BUT.... the plastic "tower" that draws air over the FET cooling on the side was quite distorted.  Who know how long it had been this way.  The system was still charging, but I am CERTAIN cooling of the FETs was challenged, again, who knows for how long.

I ended up fixing the problem by cutting the conduit that was putting the up pressure on the breaker box and re-assembling everything.  I re-aligned everything and put it back to a proper, normal mounting, while ensuring the cooling shroud for the FETs was fastened as it should be.  The fan works fine.

The issue:
As of a month ago, the unit is in Resting mode with an intermittent message High Temp.  I checked the Temp screen and it looks as though it is saying the FETs are 154.7??!!?? 

I have shut down the classic, tripped the breakers for the PV input.  When I reboot the classic, it automatically goes in to resting mode and begins to display the intermittent High Temp.  Does this mean the FETs are fried??

[boB]

Welcome to our little forum, Kalsc...

Interesting sequence of events there.    Glad you were able to get the turbo-fan attachment working at least.

OK, so does your system have a battery temperature sensor plugged in ?   If it does, then what happens with the temperature readings  when you unplug it ?   

Yes, 154 degrees would definitely be HIGH temperature.

The temperature sensor is a NTC thermistor, in which its resistance goes DOWN with rising temperature.  The fan also turns on fully when it shorts completely and the Classic will revert to nominal 25 degrees C when that happens as I remember.

Sounds like a simple problem though, more than likely.   Probably just gotta know the right spot to smack it but we'll see if we can bypass that step 

[Kalsc]

Thanks!! 

I may need to clarify something here... It is not the battery temp sensor that is showing 151.9C, it is on the right hand side of the Temp screen where it shows FETS and PCB.  Under FETS is shows 151.9 and under PCB it is showing 17.1

On the left side of the screen under battery it is showing what looks like n/a  25 C

So it is the FETS temp that I am wondering about?

What else would send the unit in to Resting mode with intermittent High Temp message right after bootup?

I should add that the RFR is 6.    ReasonForResting = 6    FETtemperature >= 100C Hot

[boB]

Thanks!! 

So it is the FETS temp that I am wondering about?

What else would send the unit in to Resting mode with intermittent High Temp message right after bootup?

AHA !!   This makes perfect sense !  On that side of the power PCB inside the unit is another NTC thermistor that reflects the temperature of the power FET transistors.  When it shorts or "almost" shorts, it will do exactly what you are saying.

I bet what has happened is that when things shifted and twisted, somehow that area of the circuit board has messed with that little NTC resistor/thermistor.

How is the "PCB TEMP"     Is it kind of normal looking ?   

If the unit charges fine when it  IS  running, in-between the high FET TEMP times, then there is luckily a workaround for this. 

Might be your lucky day but we will have to show you what buttons to push to get this to work.

The FET temperature reading is better at estimating the actual FET temperature but we can at least temporarily change it to the PCB TEMP to replace that reading which if the unit gets real hot, it will also get hot.

Kind of like NASA and alternate plans, huh ?  In fact, while I am working here I am listening to Apollo 13 communications playback on  https://apolloinrealtime.org/

OK, so  if this is what I think the problem is and nothing else has been hurt during the twist and pull, I think you should call our tech support guys and they should be able to help you make the change using the Classic's MNGP remote control.  I don't remember off hand but I'm pretty sure that they have had customers do this in the past.  If not, I can find the information.  Just let them know that you heard it from me, here.

360-403-7207 is MidNite's main number.  The receptionist can direct you or the automatic system can also get you there.

Will love to hear how it works but I think at this point that this is the fix for now.  At least until you can send it in for a checkup.  Or maybe it will just keep going and going ?

[Kalsc]

OK, I will give them a call and see what they have to say.

Regarding the PCB temp, as noted above, yes, it looks pretty normal sitting at about 17C

I will let you know what I find out.

[Kalsc]

Excellent tech guys!  Reminds me of the awesome support for my Magnum inverter/charger as well!

He walked me through a few checks, a reset... the FETS temp still showing 151.xC

He stated that the unit needs to be sent in for service.  Likely an issue with the thermistor for the FETS.  I asked him about the change to bypass the FETS thermistor reading, he did not recommend doing that. 

He was surprised at the age of the unit, the serial is CL00611.

[KyleM]

There is a post in the forums that explains how to adjust the Classic

http://midniteftp.com/tbase2/index.php?topic=606.0

If you have any troubles with this please let me know or call our support number and ask for me.

-Kyle

[boB]

I am so sorry, Kalsc !  But congratulations on buying a Classic of that vintage.  It's a vintage AND a classic !!

I guess that a Classic that old can't be updated to a version of software that has the capability of making that program adjustment.

It is possible to do but the software would evidently have an issue with hardware that old.

I cannot remember why !

At least this is a pretty simple fix.  We might even change out the electrolytic capacitors which can dry out sometimes if used for many years and in the heat.  It may be that yours is just fine though.  We will see.   If it does need / get  new caps, it should be like new.  But not sure what it takes for the newer software to be put into it ?   Maybe Kyle knows ?

boB

[Kalsc]

Thanks so much for all this great feedback and support! 

I can't seem to access the link below, maybe because my account is too new??  Not sure.

The link opens a new tab with a login screen, but my credentials don't work.   

There is a post in the forums that explains how to adjust the Classic

http://midniteftp.com/tbase2/index.php?topic=606.0

If you have any troubles with this please let me know or call our support number and ask for me.

-Kyle

[Vic]

Hi Kalssc,

That Link does not open here,  either.

But,  it may not be useful for the Classic that you have (?).

Vic

[boB]

That section is evidently for tech support only.  I never get on there anymore but I was still able to access it...

If you cannot update your Classic, or if it gets "bricked" because of being an older Classic, then it needed to be fixed anyway   

Here is a capture of that page...

[KyleM]

oh I am soooo embarrassed     sorry about the bad link

Glad boB is here to make it right.
-Kyle

[Kalsc]

No worries.  Everything sorts itself out.

Cheers!

[Kalsc]

OK, I am looking to purchase a NEW Classic 150 as it is matched quite well to my array, after having double checking the set up in the calculator.

In the spring I am looking to double my array at which time I will need another Classic 150 to handle the additional array.

[ANSWERED MY OWN QUESTION]  Nothing to see here.  LOL!
Forgive my ignorance, but will these two units work independently of each other?  Or can they be "tied" together and work in parallel?  I know my Magnums are parallel capable, not sure about the Classic chargers?

Cheers!
Kalsc

[boB]

When you say "parallel", the PV input cannot be connected to two Classics at the same time.

The PT100 doesn't do this either. As far as I know anyway ?   That would require some kind
of stacking cable between them.

The Classics are able to be coordinated though by using "Follow-Me" and cables between the Classics.
This Follow Me assures that when one Classic goes to Float, the other Classic(s) will follow it.
This goes for other modes too.  EQ, Bulk from whatever, etc.   

One battery temperature sensor (BTS) can also be used for multiple Classics in the Follow Me configuration.

But, parallel as far as the same battery of course is almost always the case.