Classic running warm, now dead

[wrt]

I may perhaps not understand the graph properly, I was referring to the maximum output available at 48v with various inputs, 70v input will give you a maximum output of 5022w 120v input drops this figure to 4438w.

[wrt]

Kurt provided your panels are oriented roughly the same you are in a perfect position to judge the difference in output.

[offgridQLD]

Sorry one array north east and the other north west. and different tilts to.To try and spread the power throughout the day and year.

I have questioned the same graphs you are referring to but It sounds like to much heat. over 400w would be like a blow heater on low all the time . Thinking now a classic working full tilt at 4000w output and high voltage input sure can pump out some heat from that front grill. Kind of similar siting in front of a portable domestic fan heater on low (500w) setting

Though I don't think so it just dont sound correct. I just know one classic  runs so much more cooler than the other. Its not just the fets Especially around the area of the top inductor at idle loads high voc. and that radiant heat from that cant help the fets trying to cool in the same case. I was mucking around with a liquid cooling system but in the end its treating the symptoms rather than solving what creating the symptoms.


So Im going to bite the bullet and just rewire that new array at 2s it's just got to be better for the longevity to be running much cooler.I only need to do it once and enjoy the benefits for years.

Kurt

[vtmaps]

So Im going to bite the bullet and just rewire that new array at 2s it's just got to be better for the longevity to be running much cooler.I only need to do it once and enjoy the benefits for years.

Another option (that also costs time and money, but perhaps less of one or both) is to buy another controller (maybe a kid?).  Reducing the watts through each controller will make them run cooler.

--vtMaps

[offgridQLD]

Yes it will somewhat though . As I mentioned before even when the classic is just idling along in float with say 100w being produced and a high voltage ..120v input . The top inductor is throwing out so much heat that it still runs reasonably hot. I  have my classic mounted so I can feel the back of them the one at 80v is not even warm in float 100w or so and the 120v one (the back where the inductor is imbedded in the case is like holding a steaming hot cup of coffee in your hand

Classics in Australia  (and almost every product  under the sun) Is considerably more expensive than in the US. so I would be looking at perhaps only $200 for extra cable, conduit and higher rating main breaker but $1200 or so for another classic $1100 for a lite or $500 for a kid + more wire and fusing to install it .

Though I am coming to the US mid year for a holiday so perhaps I can smuggle one home in my carry on

Kurt

[wrt]

Unfortunately not in this case vtmaps, part of the problem is the less load on them the higher the input volts go and the more heat they generate. Mine was at its hottest when on float

[offgridQLD]

Unfortunately not in this case vtmaps, part of the problem is the less load on them the higher the input volts go and the more heat they generate. Mine was at its hottest when on float

While you can see I totaly agree with my post up the page reflect that. There is some thought in my mind that by the time the cells are on float the charge controller has done some hard work  getting there. So already heat soaked somewhat. Then by the time they are on float Is usually the hottest part of the day. bulk and absorb where done in the early morning.

Again I agree just idling that inductor dropping the voltage is a real toaster but some consideration to the time of day it's on float (ambient temps at midday) and heat soak from getting the cells to float before hand. Vs a fresh cool charger at 7am getting the batteries to float for a few hrs.

I beat around the bush trying to convince myself there was a better way to solve the issue than just going 2s. water cooling, extra fans, diversions loads so it wont sit in float for long periods. In the end the answer to the issue is kind simple  (2s)

Kurt

[Westbranch]

Kurt, since you have 2 Classics is it feasible to swap the inputs to see if it is just that classic or a common-to-all issue?

[boB]

Unfortunately not in this case vtmaps, part of the problem is the less load on them the higher the input volts go and the more heat they generate. Mine was at its hottest when on float

To keep the battery voltage low (float V) the input voltage has to rise higher than it does when it is MPPT'ing...

And, IF you have large loads while in Float, that is a lot of DC output current at the Float voltage and the
input voltage will be just slightly higher than it is during MPPT Float so that might make one Classic
get hotter ?

boB

[offgridQLD]

Yes I guess I could do that but given that others have had similar findings due to similar configurations. I think I would be barking up the wrong tree.

Regarding large loads while in float I think WRT was saying his controller is hottest under light loads during foat not heavy loads.

My experience has been light loads say 150w and high voltage input = hot inductor and radiated heat through the case builds up . Heavy 3500w loads in float = lower voltage input and heat from the fet area as expected.

So what feels odd is to go up to a charge controller on a mild day that's sitting in float producing 50w output from 120v input and hase the fan running and what feels like 80w of heat radiating from the upper rear left of the case.....inductor location area.

Kurt

[wrt]

Hi guys, on the day my unit broke, Maximum bulk charge built from 1kwh at 8am to 3kw at 10am. 3kw was only evident over one 15 min logging block befor dropping to float and a constant 700w The max load for at least one hour prior to the incident was 700w @ 54.4v battery and 118v-120v input the input varies constantly between the two.

[boB]

Hi guys, on the day my unit broke, Maximum bulk charge built from 1kwh at 8am to 3kw at 10am. 3kw was only evident over one 15 min logging block befor dropping to float and a constant 700w The max load for at least one hour prior to the incident was 700w @ 54.4v battery and 118v-120v input the input varies constantly between the two.

When you say "charge built from 1kwh at 8am to 3kw at 10am."  do you mean kW-Hours (kWh) or power (kW) ?

[wrt]

Sorry Bob, because I am on a phone at work, sometimes spellcheck will choose what it wants.

Both should read kW, this is the charge rate being fed to the battery as displayed on the classic. I was also taking a constant 700w load from the inverter.

[vtmaps]

Unfortunately not in this case vtmaps, part of the problem is the less load on them the higher the input volts go and the more heat they generate. Mine was at its hottest when on float

True, but if you have two controllers, each with half the array, then only half as much heat needs to be dissipated by each controller. 

Regarding large loads while in float I think WRT was saying his controller is hottest under light loads during float not heavy loads.

My experience has been light loads say 150w and high voltage input = hot inductor and radiated heat through the case builds up . Heavy 3500w loads in float = lower voltage input and heat from the fet area as expected.

So what feels odd is to go up to a charge controller on a mild day that's sitting in float producing 50w output from 120v input and have the fan running and what feels like 80w of heat radiating from the upper rear left of the case.....inductor location area.

So, if you want to transmit high voltage to your controller, you should try to match your load to the size of your array.... a large load (relative to the array) pulls the PV voltage down to a more efficient operating voltage. 

One way to match the array's (potential) power output to the load, is to disconnect strings from the array when they are not needed.  This can be automated.  As far as I know, there is no good plug and play solution to do this, but it is coming.  There is new emphasis in the NEC on rapid remote shut down of modules and strings, and Midnite and others are developing products to do this.   

Other than disconnecting an entire string, there's another way to control array size with switches...  I recall seeing a discussion over at wind-sun where someone had six or seven 12 volt panels in series, with a high string voltage that would, in winter, exceed Vmax of his controller.  He put a switch across one panel in each string, and each autumn when he set his winter tilt, he shorted out one panel in each string.

--vtMaps

[dgd]

I beat around the bush trying to convince myself there was a better way to solve the issue than just going 2s. water cooling, extra fans, diversions loads so it wont sit in float for long periods. In the end the answer to the issue is kind simple  (2s)

So what happened to your water cooling scheme?  It looked like it was resolving your heat issues to some extent. Was the ambient temperature and heat being produced just too much for it to be effective?

Strange effect with greater heat in Float, this is something I just do not see with my 150 working 70+ amps, PV in of about 90v and battery at 28v then float at 27.4v PV in at 108v and under 20a the classic runs on the same temperature.
The only addition I have is the classic mounted on an 8mm thick aluminium plate 400 by 250mm.
It all get warm but not coffee cup hot.

Dgd