I have a Classic 150 with Rev 2096 firmware. I have an off-the-grid system with about 3.8 kW of solar charging a bank of Concorde AGM batteries. A Xantrex 6048 inverter supplies 120VAC to the house. It gets hot here in Texas, so I recently added a window unit air conditioner. The unit runs fine and produces a good amount of cold air, but it won't run on batteries for long. I would like to use AUX2 in Float High to control the A/C. I want the A/C to run flat-out the entire time the Classic is in Float. AUX1 drives a vent fan in my battery room. I found a Dayton relay with a 12V coil that will switch 30 amps of AC power. I got the system connected, but I am experiencing a problem. The A/C starts with the blower fan on. After a two minute delay, it tries to switch on the compressor, but the surge evidently causes the Classic to drop AUX2 for an instant, the relay opens, and the A/C powers down. A fraction of a second later, AUX2 goes back high and closes the relay and the A/C powers back up with just the blower fan. This cycle repeats. The A/C compressor never starts, so no cold air.
Has anyone experienced a similar problem with AUX2? Is this a bug or a feature? Is there some way to program a time delay on AUX2 to keep it high for a second?
I thought about connecting a capacitor across the relay coil to keep voltage on the coil for a fraction of a second. Is there a down side to this?
is that a solid state relay ? Are the contacts rated for resistive or inductive load ?
There is a discussion on the forum about how you need to use a diode for inductive loads .
I will see if I can find that .
Maybe this discussion will help you
http://kb1uas.com/mnsforum/index.php?topic=3352.0
Larry
Larry,
The relay is mechanical, Dayton 1EJH8. Its contacts are rated for 30 amps resistive, 15 amps inductive. The A/C draws several hundred watts, but I am not sure what the surge current is when the compressor starts. I read that solid state relays generate quite a bit of heat (waste energy) with large loads and require a heat sink, so I chose to go the mechanical route.
You make a good point. My problem could be with the relay instead of the Classic's AUX2. I'll try forcing AUX2 to high on on the front panel of the Classic and make sure that switches on the compressor. If that still doesn't work, I'll try hooking up 12VDC to the coil from a couple of lantern batteries and see if I can turn on the relay and A/C with that. If that doesn't work, the problem is definitely with the relay. If it does work, I'll connect an LED to my AUX2 line to see if it blinks when the compressor switches on. If it blinks, I can video it with my phone to measure how long it goes out (by counting frames 1/30 sec frames). Those tests should isolate the problem and help me design a solution.
Hi rw,
It sounds like you've got a robust inverter, but you didn't mention how big the battery bank is. I'm guessing the in-rush is high on the AC compressor and the voltage is sagging such that you're below the set-point of the aux2. Have you tried just manually turning it on via the aux2?
~ks
ks,
I have 24 Concorde Sunxtender AGM batteries (don't have model number or AH spec in front of me) wired in 3 strings of 8. This is a 48V system. Batteries are several years old. In a recent load test, I was able to pull 2200 watts of 120VAC load for 2 hours running on battery. Inverter is Xantrex 6048.
So if the motor start surge drops the battery voltage to less than 0.3 below float, then the Classic would drop AUX2, right?
As I said in my previous reply, my next step is to turn on AUX2 from the front panel of the Classic and see what happens.
Robert
Update:
When I switch AUX2 to high on the front panel of the Classic, the relay works fine and switches on the A/C. Two minutes later, the compressor switches on like it should. So the relay works as it should. I tried again to use AUX2 on Float High to control the relay. Today it got cloudy, and another nasty complication reared its ugly head. The system got into a short cycle mode where the A/C would come on (just the blower), and the Classic would drop out of Float, switch off AUX2 and then immediately go back into Float and switch on AUX2. So the A/C was turning on for a couple of seconds and off for a couple of seconds. It now looks pretty hopeless to use AUX2 Float High directly as a relay controller for my A/C.
Should I try Waste Not High?
Robert
rwsaustin
You may want someone from MS to confirm, but I would think you'd want to do this task with Aux1 and not Aux2. Aux2 as I understand it is better suited to a SSR with a load that can except 0 to full power (like a heating element, or I suppose some sort of VSD pump, fan). When Aux2 is fully active you would be fine, but when it is pulsing it should be hitting a SSR and not a mechanical relay and I can't imagine it is good for the AC unit. Aux1 would allow you to determine set-point, delay and hold time. It seems like you want an all (on) or nothing (off) mode for this application.
The Float High is a fully on off signal with no duty cycle. I believe you are referring to PWM (Pulse Width Modulation) which is only used on some of the modes. I am using AUX1 for my vent fan, so I am trying first with AUX2.
Robert
i have the same problem with aux float high. when bigger current drawn from battery the float high signal turns off until the high current eases again. try the aux SOC and put in a value that suits your battery.
besides using the float high signal to turn on the aircon, it will drain the battery. the float high signal only turns off when the sun stops shining in the evening. say it is overcast after the midnite goes into float ......... >>> low charge in battery possible or low volt disconnect or something.
Robert in Austin TX
Howdy
Your 120Vac AC unit , do you know what it draws for power ? I have a mini-split seer 23 12,500BTU bought from FL for 900.00 $ draws 1200 watt on full in turbo mode , softstart , uses 6-800 watt in normal mode . Being in Canada I set mine to 18* and hope it snows ;) ..
The window units seem to be power hungry .
VT
I'll edit this so it's EZ , them window ac units are 1800watts run & have a spike till they are let to settle down .
the rest I'll say is not to be posted here .
Im moving into the Euro style fridge & freezers , we in AME are so far behind , it's NUTS .
VT
Maybe the it was going out of float ? Bob was just talking about similar issue in this post
http://kb1uas.com/mnsforum/index.php?topic=3384.new;topicseen#new
Larry
As I understand the Classic's Float Hi setting, the Classic will lower the AUX line when the battery voltage drops to 0.3 V below the Float setting, so it should not keep discharging the batteries. When the sun goes down, the system goes from Float to Rest. That was not my issue with Float Hi. My problem was short-cycling. When the A/C compressor would switch on, the surge would cause the Classic to lower the line and cycle the power on the A/C.
Update: I have switched to using AUX1's Waste Not Hi setting to controlling the relay. At some later time, I'll move my vent fan to AUX2, probably using an external relay. The AUX1 has delay settings that should solve my short-cycling woes I faced with Float Hi setting. The Waste Not setting of AX2 is indeed PWM and not compatible with my mechanical relay.
Waste Not Hi has four numbers to set, two voltages offsets and two time delay settings. I think I need to set the turn off "hold" delay to something bigger than the two minute (120 sex) delay of the A/C. I need to pick a number for the turn on delay to prevent short cycling when the sun goes behind a cloud, say a minute. The two voltage thresholds are a mystery to me. These numbers are offsets relative to the Bulk, Absorb and Float settings. The Classic manual seems to imply that these two thresholds should both be negative. I tried setting the High threshold to -0.1 and the Low threshold to -0.3, but the Classic never switched on the A/C even though it was in Float and the array had full sun. Any clues on how to set these voltage thresholds?
My A/C is a Frigidaire 12000 BTU/hr window unit, FFRE12L3S1. It has EER 12. From the definition of EER, it draws about 1000 watts. My inverter happily runs this A/C, and I have enough battery storage to run the A/C for an hour or more and still have charge for my continuous nighttime loads (refrigerator, sewage treatment aerator, smoke l alarms and a few phantom loads). I hope to replace this A/C with one or two ductless mini-split units in a few years. For now, I want to learn what I can do with a single A/C in the bedroom and to find out how many hours a day I can run it with my existing solar array.
A whizbang and shunt really give a lot of monitoring capability and control .
But of course you have to give up one of your AUX to use it but there are other ways to turn on a vent fan.
Larry
Agreed , BUT the AC spikes are huge & the MN150 see's a huge drop as the AC unit starts , after a 2 min (120 sec) all is at (so called min WATTAGE ) back to what is reported .
I see these start at 1800 watts on hot . CB's will take the load for the start.
VT
That surge is why I went with the recommended 4/0 wires for my 24v inverter even though seemed like 2/0 would do it okay .
Larry
Success! The A/C controller is now working. Need to change title of thread to Using AUX2 AUX1 to control Air Conditioner. I moved relay to AUX1 and used the Waste Not Hi logic with the following set points:
VON: -0.1V
VOFF: -0.3V
ON DELAY: 10 seconds
OFF DELAY: 240 seconds (4 minutes)
The on and off delay effectively solved the short cycle and surge problem I was having with Float Hi setting. As kitestrings pointed out, AUX1 is strictly on or off, whereas AUX2 is PWM.
These settings cause the Classic to turn on the A/C when the charge voltage is 0.1V below the bulk/absorb/float target after a 10 second delay. When the voltage falls to 0.3V below the target, it waits for 4 minutes. If in the meantime, the voltage did not climb back up to the start voltage threshold, it switches off the A/C. The off delay needs to be bigger than the 2 minute start delay of the A/C, else a surge might cause the voltage to drop for a short time. If this drop were to happen beyond the delay time, the surge would cause the Classic to turn off AUX1. The delay effectively ignores the start surge of the compressor. I set the delay at 4 minutes so the compressor would run at least 2 minutes. If we are going to all the trouble to turn it on, we might as well leave it on a couple of minutes. The 10 second delay is a bit of extra insurance against short cycling.
Today, it was 91F and clear after the clouds burned off. The A/C switched on at 11:45 and off at 5:30. CC still read Float, and battery state of charge read full.
I plan to post some photos of my relay box.
great - thanks for the info on how you figured it out.
I have a solid state relay that I will be hooking up soon and will try it out using AUX 1 Waste Not
Larry
Great & Thanks for the report .
2 mins run the load is down from starting , after 4 mins it will be at it's lowest , but that is temperature depended . Use a kill -a-watt or an amp meter .
VT
Quote from: rwsaustin on September 08, 2016, 07:39:48 PM
Success! The A/C controller is now working. Need to change title of thread to Using AUX2 AUX1 to control Air Conditioner.
I tried to do that for you but I don't see how to do a
strikethrough in the title.
Tom
CDN-VT,
With my settings, at the end of the day, the A/C will run for a full 240 seconds (4 minutes) after voltage drops to 0.3V below float. I think I am willing to live with that. I have enough battery to run the A/C for at hour or so and still have enough for my nighttime loads. I will make sure that my float setting is at the upper end of my battery specification.
Does anyone know what will happen if I set VHI to zero? What happens when the voltage reaches the bulk voltage target? Does the Classic then immediately go to absorb? Can I set VHI to 0 and VLO to -0.1? I may also try reducing my Hold delay to something on the order of 130 seconds, just 10 seconds beyond the compressor start-up time delay, but if it causes the A/C to stop cooling for 2 minutes every time a cloud passes by, I think I would prefer to leave the batteries a bit less than fully charged at the end of the day.
The first cold front of the season is due to arrive this afternoon.
Robert
Robert , You'll need to play a bit & write all readings down , give the the time trial a week( the batterys are the ones to reference ) . I just ""TUNED"" in one of systems for summer , Winter ,well cloud & wet rain is the norm. My summer tweak is a few months , so every week I recorded & made slight changes . NOW Im hoping that next summer My recorded settings on the laptop will be uploaded for the summer.
If the Creator / (who ever yur name is ) changes the poles etc. Please keep the fireball as it is. ;)
VT
Use the local app to save the register settings to a .CSV format file.
It will be english readable text and very handy to scroll though and to
use to restore after a firmware update
Thats what I use in summer or winter mode . Name all systems & date the files .
VT
Attached are two photos of my A/C relay control box. (Sorry, but the photos are rotated 90 degrees.) The first photo shows the box mounted on the wall. The other shows the relay inside. The outlet on the left is a 12VDC outlet. I routed AUX1 through this into an 1/8" audio jack mounted to the face plate of the outlet. (Behind the wall is a closet, and the closet shares a wall with the battery room.) I mounted a fuse in line with AUX1 in the battery room near the Classic.
The relay box screws to the wall. In the winter, I can remove the A/C from the window and remove the relay box.
The relay is mounted into a gray plastic single gang conduit box. Relay is Dayton 1EJH8. The relay is double pole, so the relay switches both hot and neutral lines. I cut an A/C extension cord in three pieces, discarded the middle piece, stripped the ends and crimped on spade connectors. The relay is bolted to the side of the box. There are strain reliefs on each end of the box, so moving the cables won't wiggle the spade connectors. I mounted a corresponding 1/8" jack on the side of the box. A short patch cable connects the relay box to the wall jack. A short audio patch cable might suffice, but you need to check the current capacity.
It is important that you get an A/C that remembers its state when it loses power. If you can't unplug it and plug it back in and have it come back on to the same setting then my set-up won't work.
My AUX1 Waste Not Hi settings:
- VHI turn on: -0.1V
- VLO turn off: -0.3V
- Start delay: 10 sec
- Hold delay: 240 sec
To do:
- Choose the right fuse for AUX1 protection
- Raise my charge settings to the top end of the recommended voltages for my particular batteries to compensate for the -0.1V VHI setting.
- I may do some math and decrease the magnitude of the temperature compensation so that it accounts for the 0.1V drop in the summer when the unit is connected but not the winter. My battery room hovers around 90F in the summer.
- I have about 1300 square feet of conditioned space. A one ton (12,000 btu/hr) window unit won't cool the whole house. The plan is to install two ductless mini-split units. The window unit was mainly to learn and plan.
glad it works out for you.
when you get the new aircons, get INVERTER REVERSE CYCLE SPLIT air conditioners. they are more expensive to buy and set up (you need a aircon plumber) but much more efficient. they also ramp up slowly and ramp down to almost zero power. (they also have them in 48volt dc versions, but more expensive) besides you can heat with them. some have wifi to turn them on or off. mine remembers the setting. i have one in the shed to keep the battery and electronics cool. if things in there last a year longer, it has paid for itself plus the solar electricity is there anyway.
@
australsolarier
Please take a few pictures of your units .
Also whats the make & model of yours , so I can look up the type you speak of.
VT
http://www.ebay.com.au/itm/NEW-Panasonic-CS-CU-Z9RKR-C2-5kW-H3-2kW-Reverse-Cycle-Split-System-/142003073893?hash=item21100af365:g:4CcAAOSwsTxXihoT
something like that,
you just have to do the research what's on the market in the us/canada. the smaller the unit the more efficient they are. the one with wifi is more expensive. there are also remote control extenders that work via the smart phone, a bit pricey though. there are hundreds of different models on the market. keep off made in china, prefer made in korea, japan if possible.
all inverter aircons ramp up and down slowly. they are more expensive than the box ones you install in the window. but also not so noisy and much more efficient, sort of double the efficiency if i remember correctly. they also got timers on them as well.
Thanks , thats what I have & use :
http://www.ebay.com/itm/12-000-BTU-22-Seer-Fujitsu-Single-Zone-Mini-Split-Heat-Pump-System-AC-/272185949996?hash=item3f5f8bff2c:g:RgYAAOxy4c5RrlO9
It's the same type of unit , but called differently .
INVERTER REVERSE CYCLE SPLIT is what got me
VT
https://www.youtube.com/watch?v=fVV6GIVc5BA
here my electronics room if you are interested.
Thanks for the View Urs Odermatt.
Thats some wiring .
So you are using PV breakers that open both Pos+ and NEG- string wires . Double pole ?
VT
yes the 48volt system has all double pole breakers. because it is grid feed in it is required by australian/NZ standards. the 12v system ( island) has single breakers. here you also have to install non polarized dc breakers. for example if a string shortens, there is a reverse flow from all the other strings and can set the polarized breaker a fire. also many installers installed them the wrong way. the standards for solar installations between north america and australia are really different.