Kid overheating

Azdonc

living in the lower Arizona desert, I was skeptical of Midnite Solars advertising for their "Kid" of NO FAN. Last summer, I junked 2 150 Classics because of the incessant screaming fans! Replaced them with 3 Morningstar MPPT 60's, same production, No FANS.

I really like Midnites user interface and that you don't have to use a computer to program them so, like the moth to the flame, I bit on a Kid based on their advertising. Well, the ambient in my garage right now is 104, my Kid's fets are reading 67 degrees Celsius and it has derated to 17 amps output to the batteries to protect itself (survival)!

Two days ago, I installed a Morningstar Prostar MPPT 25 in its place with no fan and guess what, my solar production jumped 20 percent! With an ambient of 106.This particular solar circuit provides control to the rest of my off grid system so, is extremely important.

Maybe someday, I can move my controllers into my air conditioned house so I can enjoy the Midnite controllers many, rich functions.

Until then, Morningstar!!!

solar_dave

Well you certainly haven't hit the peak temp in that location yet! I hope it all works out in your favor when the July temps hit.

Johann

Look at the operating temperature data.
It stated that it will start to auto derate at 25C.
http://www.midnitesolar.com/pdfs/spec_sheet_kid_back.pdf

Here is a temperature converter.
http://www.mathsisfun.com/temperature-conversion.html

zoneblue

Out of curiously what are your PV and system voltages?

BB.

Also, how are you measuring power/performance from your array? It is not unusual to have controllers have a 10% "error"--especially between brands.

Also, given variations in solar output--20% difference (one day to the next) is not unusual. And since you can only measure "solar production" based on the needs of the loads/state of charge of the battery bank--It is difficult to accuratly measure production differences (unless your loads exceed the daily protection availability). For Grid tied systems where 100% of production goes to the AC mains--It is much easier to make these A:B comparisons.

But, I too like "quiet"/fan less equipment. One less thing to fail (fan), and you are not drawing dust/dirt/fur/bugs through the middle of your electronics.

And make sure you have good ventilation--Keeping electronics cool will greatly increase their life.

-Bill

Vic

Azdonc said,   "living in the lower Arizona desert, I was skeptical of Midnite Solars advertising for their "Kid" of NO FAN   ...   Well, the ambient in my garage right now is 104, my Kid's fets are reading 67 degrees Celsius   ..."

What WERE you thinking??   Electronics like and need a relatively cool environment,   and this is particularly true for Power Electronics.

A cooler environment  will increase longevity AND Production,  especially in the DESERT!
Assume that your batteries are also in that warm environment,  and if so,  heat is the enemy of battery longevity,  as well.

The Morningstar CCs are probably a bit more efficient than are the KID and Classics.  And that really better be the case,  as the Morningstar CCs have NOTHING in them other than a CC,  not even an LCD display ...  and 1970 era DIP switches.

It does seem that you would be much happier with a CC that has a very basic setup,  and NO frills,  at all ...  all of the little extra functions,  like an LCD display,  Aux Ins & Outputs,  the inexpensive battery Current module (WBjr),  etc are things that you do not value,  and there iS some overhead in many of these.

I am a real fan of MidNite Solar products in general,  and their CCs in particular ...   Have one Morningstar CC,  which is very clunky,  with poor docs,  and too-few DIP switch options for almost any Solar setup that I have found,  poor support,  etc.

Opinions,   Good Luck!   Vic

Azdonc

I love bells & whistles too, but what I llike the most with my solar systems is how many AMPS did they put back into my battery bank at the end of the day!

Amen

vtmaps

Azdonc said:

I love bells & whistles too, but what I like the most with my solar systems is how many AMPS did they put back into my battery bank at the end of the day!

Don't forget... the less efficient* controller may be the one that puts more amphours into your battery.  Midnite has admitted that their controllers are not the most efficient*, but that due to a more sophisticated sweeping algorithm their controllers harvest more energy. 

*NOTE: increased efficiency is defined here as less heat production in the controller.  By that definition, most PWM controllers are more efficient then most MPPT controllers.

--vtMaps

Azdonc

I agree with you that Pwm controllers are more efficient but, mppt controllers let us use cheaper grid tie modules to accomplish our goals.

Don't lose track of that amps returned to your battery bank is what determines the amount of work you can accomplish with your output systems regardless how you generate them.

BB.

And for Off Grid systems... You should probably only "schedule" around 65-75% of "predicted output" of your solar power system for daily use. Trying to use 100% every day is not likely to happen (weather, "wash day", water pumping day, crock pot day, etc.).

If you have a "good day" (past or forecast), then using more will not "hurt you or the battery bank".

-Bill

Vic

Hi Azdonc,

There are still a couple of -

QUESTIONS;

 1.  What is the String Vmp of the PVs that are connected to the KID?  That is,  what is the STC Vmp,  and out of curiosity,  what is the STC Voc?  OR,  what is your string configuration (number of PVs per string and power rating),  and what is the model number and manufacturer of those PVs?

 2. What is your nominal battery voltage?

3.  Are your batteries in the same environment as the KID?

Q1 & 2 have been asked by zoneblue,  and Q3  was not really asked,  just an assumption was stated.

As BB Bill noted above,  many CCs to not have accurate output current measurement capabilities,  and believe that the tendency is to err of the optimistic side of this.

And BB also noted that for off-grid systems,  Production numbers are even more difficult to compare,  as Absorb times vary from day-to-day,  and  loads can vary also widely.

The Classic's internal output current-measuring "Shunt"  is a Hall Effect device IIRC,  and is very,  very accurate.  Am not certain what the KID uses,  but it is quite accurate,  too.,  from my measurements,  comparing against an accurate external Shunt.

The Classics and KIDs have that Optional WBjr battery current measuring device that is very inexpensive,  and very,  very accurate.

And regarding your statement,  ...  "Don't lose track of that amps returned to your battery bank is what determines the amount of work you can accomplish with your output systems regardless how you generate them   ..."

For off-grid systems,   the total power delivered by the CC is important,  NOT just the total Ah returned to the battery.

Thanks!   Vic

mike95490

You may be able to get a chunk of plate (.25" or thicker) aluminum and mount the KID on it, use it as a large heat sink.  That should help. Spacer it from the wall, so both sides of the plate have air flow.

MStar1

To clarify a few of the comments here the meter versions of the Prostar MPPT controllers don't require a PC connection in order to be custom programmed. However, if you like using MSView's Setup Wizards and have a Windows based PC then it can be custom programmed using the UMC-1, USB to Meter adapter.
Mac users might want to try our new EMC-1 Ethernet to Meter adapter with Wine software if they have had difficulties making serial connections in the past with MSView. I don't think that NAW&S has the EMC-1 posted yet on the site.
The PS-MPPT can operate at full power up to 60C with 24V batteries or no de-rating up to 45C or higher with 12V batteries.
The PS-MPPT also includes load control and will display the load current and net current for the controller.

mathias

Hi,
Very happy with my Kid here in Borneo and high temps. No idea if it would be better or worst with Morningstar...

Some interesting reading, MIDNITE KID VS. MORNINGSTAR PROSTAR MPPT. Made by Midnite...

http://www.midnitesolar.com/images/frontPage/PSvsKID.pdf

Worth reading if you don't know which one to buy !

mathias

I can't resist to put a part of the match...


Max operating temp:
Both products will operate at 60C. We chose 50C as the published maximum, but there is nothing to limit the
maximum operating temperature. It will operate at 80C, but you just won’t get any power out of it. The KID will de- rate as they claim. That is what pretty much all electronics do. As the ambient temperature rises, engineers turn the
current limit down. Temperature performance on the KID is the same regardless if you have 12, 24 or 48V batteries. We do not understand why the Morningstar doesn’t do as well at 12V? Funny how Morningstar never ever
mentions things like 48V when comparing against the KID
The KID uses the UL required method for temperature testing. Morningstar has elected to go above that for
standard operating temperatures. We keep the fets cooler by de-rating starting at 25C. This can improve reliability. Morningstar makes no mention of our 48V max operating temperature at 48V because they cannot support it. They
also mention that their product “MAY” de-rate above 45C for 12V systems. How did they come up with the word “MAY”? Of course it de-rates.

Full reading at the above link...

Have fun !

MStar1

Many 48V systems do not have DC load control requirements. Therefore the TriStar MPPT TS-MPPT-30 or TS-MPPT-45 controllers seem like a good options for many 48V inverter systems. They can both operate at full rated power up to 45C/113F ambient temperatures.
The higher the input to output voltage ratio, the less efficient Morningstar MPPT controllers will operate. Efficiency curves for Morningstar MPPT controllers are included in the manuals. Efficiency losses create more heat inside the controller. Derating is based on heat sink temperatures so the lower the PV array voltage is, the cooler the controller will operate.
Taking a realistic scenario, if you have a Vmp = 31V (1 X 72 cell module) with a PS-MPPT-25 on a 12V system it will not derate with 52C/125F ambient temperatures. Another example, a Vmp = 50V (2 X 60 cell modules in series) with a PS-MPPT-40 with a 12V system will not derate with 46C/115F ambient temperatures.
Air circulation is also a factor and installing the controller protected from direct sunlight is recommended.
Heat is not a friend of electronics even if the heat sink does not reach it's max. temperature so it is good if the heat sink and internal components don't get too hot very often. 
For anyone planning installations inside of enclosures here is a white paper on how to calculate heat dissipation inside enclosures with Morningstar's TS & TS-MPPT controllers. The info about the TS-MPPT can be used for the PS-MPPT as well.
http://www.morningstarcorp.com/wp-content/uploads/2014/02/TechTip-EnclosureHeatDissipation.pdf
Driving over the ProStar MPPT controller with a forklift will void it's 5 year warranty.

halfcrazy

To Echo Morning Star above "The higher the input to output voltage ratio, the less efficient Morningstar MPPT controllers will operate." I would say that is true of ANY MPPT controller and one of the biggest mistakes I see people make all the time is to assume that the higher they can get the PV voltage the better it is. If you look at an MPPT controller on a 12v battery with 2 modules that are 72 cell. it is so much easier to plug them in series and feed them to a Kid or TS but you will generate a bit more heat than if you took the time to wire them in series.

Think about this, Take a Morning Star or a MidNite charge controller casting and stick a 5 watt light bulb inside it, the casting is going to get hot. My point is that losses are not that great but a very little bit of loss over time creates a lot of heat.

Generally speaking the rule of thumb on ANY MPPT controller is to make sure the LOWEST VOC of the array is at least 130% of the highest battery voltage you will ever charge to. So for a 12v battery that may be say 16v to EQ. We would want the array to have a minimum of 20.8 volts open circuit on the hottest day of the year. Anything higher is just extra work for the controller, That being said if you use a 60 or 72 cell module 1 in series is a good match.

At the end of the day if the system is living in a 106F ambient derating charge controllers are not the biggest worry, Your battery bank will be.

littleharbor2

Curious as to how much heat we are talking about and how it is dealt with one of the Schneider or Morningstar 600 volt controllers.

MStar1

Schneider includes fans and a very large enclosure to dissipate heat.
The efficiency is not that bad but not as good as the TriStar MPPT 600V.
It has a bigger heat sink and no fan.
We include efficiency graphs for 200V, 300V and 400V inputs in the manual.
Of these 3 input voltages it has the best efficiency at 300V.
Comparing to the efficiency of the 150V version it might be 1-3% less efficient for 48V batteries.
Thermal Dissipation = (100 - Efficiency)/100 X Power