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51

Product Reviews / Re: Mini Split

« Last post by lighthunter on June 25, 2022, 09:57:30 pm »

So, weve added two more of these units to the house. Now the solar panels can heat or cool the house and the garage for very low cost and the solar takes care of most if not all of the day use. The two 9ks were installed in march i think. The calculated usage to cool the house in 90F weather is about 315 kwh per month. Thats under $30usd/mo at our rates, much less with solar. With 7kw of solar one 3kw array doesnt even turn on when its sunny. These last two models are hyperheats wheras the first one was just the plain version. If anyone is confused about all the seers, hspfs, eers, 9k, 12k etc, there are so many things to consider, just go to a website called NEEP. Its like AHRI but way better. These guys do tests and record data for you to see. The COP heating performance at 5° tells the story. So any machine that can get close to 2.0 COP at 5° is very efficient at heating. The hyperheat version isnt necessarily more efficient, but it can hold the btu heat capacity output at 5° wheras the nonhyper models decline to 50% btu output at that temp. Colder than 5°F they will continue to decline output but hypers will just produce more heat at that temp and also use more electricnpower to do it, so long as COP stays above 1.5 or so its still a win. Ive been exposed to several brands now and ive not seen or heard of anyone that had a problem. Not sayin it couldnt happen but seems like a mature product, they have it figured out how to build em. Im not the kind to spend a lot on things. They dont give the things away but they werent too bad either if you put them in yourself. No higher cost than any other heating system and this does both. Its just such a great compliment to solar.
We are very happy so far. Cleaning cotton fuzz from radiators with garden hose has been only maint so far. The two 9ks are usually running 1.3 to 2.5 amps 240AC during the 90 degree weather.

52

Renewable Energy Q&A / Re: Max winding temp

« Last post by lighthunter on June 25, 2022, 07:05:10 pm »

Hey Pete, that Heco document is wonderful.  We still have no email service where i work so have not gotten info on winding class yet. Because the alarm temp control i put in only has a max setting of like 209F thats what i set it to. It runs at about 185°F so am real happy with it now. The motor current at 60 hz 3600ish rpm is 200A, nameplate is 166A, thats a bit concerning but it doesnt have to run there very often.
Again that heco document is better than any i had found on the subject.

 The heat here is crazy lately like near 100 with high humidity but it rained last night so its been nice today. Crops are doin great. Its hard to make it through June without your garden being wiped out by drifting farm chemicals but this year is a bit better, lost some peppers but the rest pulled through. Even the apple trees have leaves still looking like a leaf rather than the gnarled curled shape they usually get from sprays. Ha for years i thought it was cedar apple rust until i finally caught on to it. Hope everyone is doing well!

53

Renewable Energy Q&A / Re: Max winding temp

« Last post by Pete on June 15, 2022, 05:42:10 pm »

Hi Lh, well that was a novel solution.
Here is a link to a page about winding insulation temperature ratings.
A H class winding will have White Nomex slot insulation. The rest of the insulation will be mica or fibreglass for phase insulation and leads.
Pity that Siemens pack the motors windings in too tight and fit too big a motor into a small frame.
Gone are the days where open frame motors could be run at double their ratings. Nowadays the ratings are absolute max.
I hope you are well and that the workaround stays working.
I guess some sort of air dryer like spray painting sets have could work but sounds like you are putting a lot of air into the motor.
Cheers
pete
https://www.hecoinc.com/blog/electric-motor-insulation-class-what-is-it

54

Renewable Energy Q&A / Re: Max winding temp

« Last post by lighthunter on June 14, 2022, 06:26:59 pm »

Update:

Thanks again Pete for all the ideas and thoughts on this one. All attempts to adjust the volt/amp curve via vfd programming failed as the OEM disallows it. Weve yet to get any real support from those people.

 The compressor has been running fine for a while now. I drilled a hole near the bottom of the end frame and put compressed air to it so it blows cool air through the cage out the cover of electrical box. A co-worker drilled the fitting a bit larger as the cooling requirement was higher than i had anticipated. It takes around a 6hp efficiency hit just to cool it but it works. Runs about 175F now. Whats difficult for me is knowing exactly whats ok? A different unit had oiltemp that reached 221F today. Pressure washed cotton fuzz from radiator and now at 196 where thermostat regulates it. Maybe its fine for winding temp to be 250F no one i know will go there and articles written about it tiptoe around the subject. Oddly most manufacturers do not put temp sensors in windings yet a common house fan includes this as a safety device. A thermal cutoff or tco. As i write this im reminded of an event years ago... 1998... how time has gone... when a laser roots blower also siemens motor, failed due to a temp sensor in winding. I jumpered and machine ran, i ordered a temp switch in a T0220 package and inserted/epoxyed into winding at end of motor seems like i started at 110C and kept having to order higher ones till i got one that didnt trip under normal circumstances. Seems like the number was 115 or 120C when i finished and that one ran for years that way. So by that info i can set this at 250F and reduce the orfice size to maybe 4HP of cooling. Of course an air booster in reverse trading pressure to volume would reduce the flow requirement again.  Anyone else agree i can increase thermal trip point to 250F or 120C?

I kinda feel stupid i forgot the eqperience i learned back then about winding temp.

Perhaps i better ask the elder gentleman what class wind wire he used for this one.

Its not an ideal solution but it is a solution and it does run welll now. Anyone have an idea on a moisture sensor for air line. I will need it to fault on humidity as moisture will kill windings too. So far our dryer is flawless but theres no feedback to stop anything if it doesnt remove all moisture.

Hope everyone is doing well, i havent had much time to post as garden, work and other odd jobs have been over the top lately.

55

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by solarnewbee on June 04, 2022, 02:28:40 am »

I meant to say put one battery on top of the other. They are sealed so no checking levels.

On the other subject, I have a short across the battery connections on this inverter board. Thought it might be the caps or the mosfet over by the egs board but not so. I reckon I was sold at least 1 bad hy4008. Jumped the gun and didn’t get out the tester before putting them in. I am officially trashing this board because I would have to desolder every single fet. No thanks.

Thanks for your help tho. Adios!

56

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by Pete on June 03, 2022, 03:12:21 am »

Hi Solar not sure what you mean by " can I stack the VRLA batteries  2 together, if you mean parallel two banks then sure.
It is not the greatest practice but from what I read up to 4 banks is not too bad to parallel.
I have had heaps of parallel banks of Flooded batteries in the past, no real problems.
As long as a cell doesn't short out then all is good. And as long as the battery banks are similar age and capacity.
Hope it all goes good with the repairs when the parts turn up.
Pete

57

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by solarnewbee on June 03, 2022, 01:28:52 am »

Found that a IRF640 fet was shorted. Removed it and the current went to zero. Have new ones on order. Extras in case something goes wrong again. The diode mur680g seemed ok. I have a feeling it will come to life when a fresh fet  is installed. Some people power up using an incandescent light bulb to charge the caps slowly. Hard to find in a country that outlawed incandescent bulb sales and now florescent bulbs too.

On another subject I am replacing 1 bank of lfp’s with 4. 200ah VRLA batteries. The lfp’s are running on 15 pieces and appear to be giving out about 2/3 ah they used to. I replaced a cell and the new cell immediately went bad and bloated. I bought 4 new and so 1 out of 4 was bad and I installed another. That one goes bad. I call the factory. They tell me that since my internal resistance of the old batteries is so far apart from the new battery that this is what happens. Stop and don’t put anymore. It’s like changing tires on a dual tire truck if you don’t change both tires the new one will fail early. Surprisingly the bank charges up to 57.8 volts then settles to 54.3 ish most days. Unknown to me the breaker to the good bank had tripped and wasn’t being charged. I was getting 9 hours out of the bad bank. These are 200ah batts. Just weird stuff.

Question, I am short on space, can I stack these VRLA batts 2 together?

58

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by Pete on May 29, 2022, 03:55:09 am »

Hi Solar from memory, I started with a 20 watt 10 ohm resistor in series with the power supply to my board, then after I checked the current drain and gate drives of the mosfets I reduced it to 10 ohm then to 5 ohm.
When the board still ran with that I connected the supply directly to the board.
As I said the big capacitors need to be removed or they store enough power to blow mosfets if there is still a problem.
Usually when mosfets blow they take out their driver transistors and sometimes resistors too.
Make sure that they are all getting a clean gate drive when you fire it up.
If it all runs good then replace the caps
pete

59

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by Pete on May 28, 2022, 05:48:04 pm »

HI Solar, I used Oz's ideas when repairing my inverter boards.
It requires that  you take out the big capacitors in the centre of the heatsinks. This reduces the inrush current and prevents the caps from supplying power to the mosfets and blowing more up
Then use a resistor in the supply line to limit the current (in case there is a shorted mosfet).
It will need a transformer connected as there is a feedback loop there that needs to see a return.
Good luck
Pete

60

Users Projects / Re: y Philippines Retirement Solar Off Grid System

« Last post by solarnewbee on May 28, 2022, 05:28:50 am »

Howdy Pete,

I finally got around to repairing my AliExpress special, inverter. Changed the egs board and all the resistors and diodes. Also replaced the small caps and tip41/42 transistors that blew. I tried powering up with a variable power supply but no joy. It goes into cc mode and pulls the voltage down to 2 volts from 48. There is a mosfet  on the end near the egs marked 12v on the board irf640n. Another maybe diode mur860g on the board u860g on the device.

Does the transformer have to be attached for it to fire up? I remember you saying there was a way to do it with a resistor or something but I can’t find it. Pics below. 4 views since none of these boards are ever completely the same.

Cheerio!