OVR light came on

[Jacotenente]

The Kid was hot to the touch with an "OVR" fault light on. Checked the manual and it says it indicates an overvoltage condition. Garage temps at that time was 98 F. I did forget to turn the fan on this AM. I also took the backplate off the Kid and mounted some spacers (see attch pic). Not sure if it was heat related or not...suspect it was. -Chris

[Mario]

OVR light means OVer Rating.
The light can come on if the temperature is too high or if the Input/Battery Voltage is too High or If the unit is in current limit.

Was there more than 30 amps going out to the battery?

Mario

[zoneblue]

Hes got 600W/12v of panel hooked up to it.

[dgd]

Hes got 600W/12v of panel hooked up to it.

He's driving the KID to maximum power output and , surprise suprise, its overheating. 

dgd

[chris]

Hes got 600W/12v of panel hooked up to it.

He's driving the KID to maximum power output and , surprise suprise, its overheating. 

dgd

  come on now.....it has been stated many times on this forum that the Kid can be drastically over paneled and it would just "clip" the extra amps

  I have been considering adding another 2 X100 watt panels myself 

 

[acorn]

After some searching I did find the thermal derating spec in the manual: output current is 30A maximum @ 25 C, and derated to 20A at 40 C. If the derating is linear (probably worst case), that would be about .67A / degree C above 25. 98 F (his garage temperature) is 37 C, so derate by 12 * .67A = 8A. Maximum output should be around 22A? Since the Kid doesn't provide a configurable output limit (or I couldn't find it) it seems like it ought to do it's own output limiting based on temperature, or perhaps shut down to protect itself.

What output (amps & volts) were you seeing when the OVR light came on?

The manual only mentions over voltage as a condition causing the OVR light to come on. The other conditions make sense, but not documented. (It's great to have the developers contributing here).

As far as being over powered, in this thread http://midniteforum.com/index.php?topic=1995.0 dgd suggests that 270 watts of PV isn't enough for a users application and "Recommend installing, at least, a second identical panel". vtmaps does some panel derating math and suggests  "704 watts of panel.  That's more than the Kid can handle (in optimum conditions), but optimum conditions are not frequent."   To be fair, in the same thread westbranch suggests a more conservative approach to maximum power input.

The product spec should provide guidance on what the engineers intended the product to do. It's possible that current conditions for jacotenente's system are beyond the design spec, but I don't think we have all the evidence to know that yet.

-Scott

[dgd]

So is this analysis just academic?
Jacotenente has the solution already - just use both controllers so that neither is driven to its maximum loading and associated overheating.

dgd

[Jacotenente]

Acorn's summation is correct. From what I could tell, the Kid's input amps were about 29 amps...at the time it faulted out. It continued working even though the OVR light was blinking. I cut power from the panels and battery to the Kid, let it cool down, and everything was okay. When the light was blinking, the Kid only showed about 21 amps. After cooling off and turning it back on...it went back up to 28-29 amps...and didn't fault out (after spacer mods and turning the fan back on).

Running the Tracer and Kid together wasn't my idea...but, seems like it would work.

I wish a Midnite Solar tech could provide some design input here.

Chris

[acorn]

I'm not trying to be academic. I'm trying to help jacotenente understand the observed performance of his system.

My understanding of his situation: his original charge controller was a Tracer 3215RN, with which he had some issues. He mentions RFI and a need to be reset each morning in his Amazon review of that product (I stumbled on that review while trying to understand what a Tracer was). So he upgrades his charge controller to a more expensive product (the Kid) with a similar performance spec. He is surprised he's seeing lower output with the new charge controller so he comes to this forum and looks for help. With help from forum members he's able to mitigate some of his cabling related power loss and get closer to the output he's expecting. (Perhaps seasonal temperatures are affecting panel output power so the cabling issues have come to light?) Now that he can achieve full output he's running up against thermal issues. His Tracer didn't have those issues, either due to seasonal temperature differences, a lack of thermal management on the Tracer, or both.

Knowing what the thermal derating for the Kid is will help him understand the power output he can expect now that he has maximum input power available.

As far as array sizing, it depends. If you don't want to stress the charge controller then put about 300W peak input of panel on it and you will have fewer thermal issues. If you want to maximize solar harvest in less than optimum conditions then size the array around 500 to 700 watts and expect to throw some power away at peak insolation and also see some output limiting during the hot sunny months. (Or, add an external fan when it's hot to allow more output power).

If you switch to using two charge controllers, as dgd suggests, then the tradeoffs above are minimized. The only problem is that the RFI and morning reset issues on the Tracer come back. (dgd couldn't have known about those...)

-Scott

[Mario]

OK here is how the kid Works when OVR light comes ON:

The Kid will protect itself from getting too hot and damaging the internal components, It will also Limit excessive power output from an Oversized array.

The OVR light Means Warning,one or more limits have been reached, but does not mean a Fault. Depending on the type of warning the unit will behave differently:

OVR blinking rapidly: means that the unit has reached the battery current limit - unit will continue to work normally but limiting the battery current to the setpoint.

OVR Solid On/ blink: This means that the unit has reached the temperature Limit (65c displayed), the unit will limit the current output such that the temperature does not rise any more.

OVR solid On: could mean the battery voltage is too high, a message will also appear on the LCD Status screen "Batt Over"
                     It will also stay ON if the PV voltage is higher than 150v and display "HyperVOC" on the LCD,
                     in both of these cases the unit will not charge the batteries.



These explanations will go in to the manual.

Mario

[Jacotenente]

Thanks Acorn...spot on correct. Just looking for some help/insight/guidance with this unit. RFI from the Kid and the Power Bright 3,500 watt inverter didn't change...still washing out my CB base station. It is too hot in the garage during the day anyways and at night, if I want to listen in on the CB (and enjoy talking on skip) I can turn off the solar equipment and put everything back on mains...easy. No big deal. I can also bring the Tracer back inline if I choose to go that route. Thanks again. No heat problems today so far...

[dgd]

Acorn,

I think your analysis of the situation was good. I was just not sure that it would lead to a solution for Jacotenente.
As you pointed out I have recommended before to oversubscribe PV input to a controller. The motive here is to increase power generation in poor weather and not to drive the controller to its maximum in better weather.
What surprised me was that he was talking about adding another two 100 watt panels to have 800w of PV into the KID hence my suggestion to use both controllers.

However, if he is happy with 400 watts when the existing 600watts of PV could probably generate between 500 and near 600 watts on a bright cool day then thats his decision.
I see he has taken steps to mitigate the overheating using a fan then having the KID on standoffs to let air flow behind it. I would have suggested mounting the KID directly on a plate of aluminium, I have used a 10mm thick, 300mm by 150mm plate on my KID and it definitely keeps the KID cooler.

Pity about the RFI, not sure if much of this is from the KID as I have it along with two Classics on a wall with 2.4Ghz ethernet wireless plus I often listen to FM radio about 3 metres from the controllers and it seems to work without interference.

dgd

[acorn]

jacotenente, I did have a thought about your cooling fan setup. Since you're not using the load output (as far as I know) you could set up a 12V DC fan on the load output, and then configure the Kid for "Day Light" mode in the Load options menu. If I understand correctly, this should turn the load output on when there's sunshine, and off at night. Then you won't forget to manually operate the fan. (An RV, marine, or trucker supply shop ought to have a suitable fan.)

Also, since it's so hot in your garage, and you've got a sizable investment in batteries, I would suggest adding the battery temperature sensor if you don't have it. This will compensate the charging voltage for the actual battery temperature. The BTS is discussed on page 18 of the manual. b4solar suggested this in your other thread, and I suspect there is wisdom there...

Mario and another forum poster both mentioned a charge current setpoint, so if you want to you can set the charge current lower than 30A to limit output and run the Kid cooler. (I couldn't find this setting in the current manual, and I don't own a Kid, yet.)

Along with dgd, I'm curious about the RFI from the Kid. (I like to play with ham radios.) Have you tried leaving the Kid on and turning off the inverter to see which is the source of the RFI? I guess this test only works if the CB is DC powered...

-Scott

[TomW]

Neither my hand held or my mobile (now base) Ham rig gets RFI in my Ham shack which is also my power room and houses Classics, Kids and inverters just feet from the gear.

Tracking the source of RFI is sometimes interesting. Is it on the antenna system, power line, it can be daunting to find the cause.  A couple turns of the power lead through a ferrite tube / donut might help? Check the grounds.

Just a few thoughts

Tom

[Vic]

Regarding RFI from Power Electronics.

Generally,  most of the Emissions are Conducted -- they tend to follow wires/cables connected to electronic devices that create/use power by switching the power source at a fairly high rate,  and fairly frequently.

Charge Controllers and Inverters can and do create a reasonable amount of these emissions.  On systems in use here,  the cables that connect the PV modules/array/s to the CC seem to emit a considerable portion of these emissions.  This is not a surprise,  as these leads are generally long,  and are outside of structures,  as are radio antennas,  usually.

Separating antennas from the PV array/s,  placing wires/cables in metal conduit which has a common ground point,  placing AC power conductors underground,  and in metal conduit or shielded cable,  when above ground all help.

Here is a bit of a long discussion on the wind-sun Forum:
http://forum.solar-electric.com/showthread.php?5887-Radio-Noise-from-PV-System

EDIT:  I should add,  regarding the Thread on wind-sun above,  that I did not realize at the time that that thread began,  that solar CCs were not tested at frequencies below 30.0 MHz,  because the method of testing Conducted Emissions is defined by attaching the emissions-measuring system (through a standard interface network)  to the AC power lines that connect to the Device Under Test -- there are no such connections in DC systems,  and generally for FCC B,  the measurements  below 30.0 MHz are for AC Line Conducted ...   and so on.

For frequencies of interest,  into the VHF range,  Ferrite toroidal cores,  with as many turns of the cables connected to the power electronics as possible are also simple,  and can be quite effective.

For HF frequencies,  Charge Controllers that pass FCC Class B emissions,  may have no lower emissions than CCs that have not been certified to FCC B,  because  DC-connected electronic devices are generally not tested for emissions in the HF frequency range -- 1.8 - 30.0 MHz ... actually these devices are usually not tested for any frequency below 30.0 MHz.  And the emissions generated by them are usually strongest in the lower frequency ranges.

My opinions,  73     Vic