Information on Classic Low Voltage Shutdown and Restart

[mcsarge]

I am looking for information on what the Midnight Classic does if the batteries get depleted so low the Classic shuts down. We have a remote installation and the panels are covered with snow and I fear that the daily current the Classic uses will drain the battery bank before the panels are uncovered. If the Classic shuts down, will it restart again when the panels are uncovered? Next year we plan on putting in an additional set of panels that will be nearly vertical so that they will not get cover with snow and provide the current needed to keep the batteries topped off.

Matt

[ClassicCrazy]

Someone just asked a similar question in another post.
You answer should be here
http://midniteftp.com/forum/index.php?topic=4230.0

Larry

[ClassicCrazy]

So basically if your batteries run down low enough to shut down the Classic it would disconnect the PV and with no PV to the batteries it wouldn't ever wake up and start charging again.
But if your battery is full to begin with and is of decent capacity and there are no other loads on it seems like the standby current of the Classic would take a long time to depleted the battery so low to shut it off. Guess  you could do that math.
If the panels get some light through them even if snow covered they probably will make some charge - of course if there is that much light it might melt at least some of the snow - depending on what angle the panels are at.
And yes it is nice to have steep panels in the winter so the snow will slide off. Even with me sweeping them here in Wisconsin it helps quite a bit during the snow to slide off .

Larry

[boB]

The Classic will draw approximately 3W just sitting there.  Possibly a bit less if the MNGP remote is unplugged.

The Classic, after it's powered up will run down to about 5 volts or so of battery voltage.

Unfortunately, it won't be able to turn back on by itself if it shuts off because the battery voltage falls below that 4 or 5 volts unless you can touch the PV positive to the battery positive for a minute while the sun is shining and no snow on the panels.

boB

[mcsarge]

Many thanks for the input. I had a communication system in there so I was using about 9.5 Watts (it has gone dark the last 9 days - I think because of a Raspberry Pi failure). In any event, the LVC that powers it cuts off at 22.8 V, so after that it will just be the Classic. I am hoping enough light gets to the panels to give a charge, some melting is supposed to happen in the next 10 days or so so I am hoping they will get some charge. This is the first winter with the Classic, so there clearly was a whole lot I did not know when I set it up. Next year we will have the winter rack of old panels and the old controller online - so we should not get into this situation again. Looks like we may be shopping for new batteries in the Spring. I will also have a better communications system -

Follow up question, if I was to shut down the controller, is there a way to make it boot up from a computer or other device located with the Midnight? I guess I could control the power to the Classic to shut it down then restore the power to get it back up again... Anybody done this before?

Matt

[australsolarier]

me thinks this is not a problem of the midnite classic. but the design of battery capacity and climate.

[mcsarge]

Yes, the solar controller they have previously would do the same thing, but it drew a bit less quiescent watts. Each year in the Spring they would arrive to a functioning system with fully charged batteries, but they would have had no idea what went on during the winter. With the communication system I was able to monitor the system until that stopped (from a design flaw on my part). We are hoping for the best, but the batteries are due for replacement in any case, they have been treated harshly because the old solar panels could not keep up with demand and they have been depleted below 50% many times. A new set of batteries is looking like about $2K, but if we replace them, I want to make sure we can take care of them over the winter, so I am designing a way to use the best of the old panels and the old MPPT controller to create a auxiliary system that will not be covered by snow and that we can setup in the Fall and takedown in the Spring.

Matt

[ClassicCrazy]

How do you communicate with this remote station ?  Curious how you used the raspberry pi in that .

Larry

[mcsarge]

So this system is on a remote island in Ontario, Canada - 16 miles from the cell tower. I set up a Raspberry Pi with a Huawei E8372 "Wingle" 3G/4G Cell moem dongle and a T-Mobile SIM. I used a wide band Log periodic directional antenna placed on our radio tower and pointed it toward the cell tower. I got decent 3G speeds and some 4G on occasion. Using a small WiFi router I connected the Midnite Solar to the Wingle and Pi. Unfortunately, a problem with the WiFi router caused it to die (it was cheap), then the Raspberry Pi locked up due to pilot error (me), so that ceased all communications. It may get restored if the LVC gets engaged when the battery voltage drops (shutting down all systems) and then if the voltage goes back up the LVC will restore power - rebooting all the systems. But if the power never goes low enough it will not happen until someone goes to the island in the Spring and pushes the reset button.

I have begun to design "comm system 2.0" for next year - it will use a Cradlepoint LTE router, 2 antennas to get MIMO and much more loosely coupled systems. The Cradlepoint is very hardened and has all sorts of internal watchdog features to keep it alive so things should be much more solid next year.

Incidentally, you can go into T-Mobile right now and get a SIM for $10 and pay $10/month for 2Gigs of LTE speed data per month - when that is used, it switches to slower speeds but there is no limit to the amount of data. That is a great deal.

[mcsarge]

Oh and the Raspberry Pi had a camera attached to it that could take picture of the panels (and how much snow they had on them)

Matt

[ClassicCrazy]

Ever consider getting your ham radio license ? I have used an Argent Data Tracker otm2( they have a new model coming out )  in the past - it would send out my weather data on the aprs network at the same time it also had some telemetry , and had a built in switch that could turn loads on and off via aprs messaging - meaning  you can remote control it anywhere from the internet . Of course this is all dependent on if it was in range of another ham radio digipeater that is in range of a gateway . Always nice to get the weather info posted for everyone to see.  Seems like if your wifi makes it 16 miles the two meter aprs signal might make it to some area ham radio digipeater.  Look it up here for what is in your area.   - hmm maybe nothing in your area !
https://aprs.fi/#!addr=ontario%20canada%20
You will have to zoom in on that map or maybe put in an address to see if any local stations are there.

Larry

[mcsarge]

KG4EUF here and unfortunately, there are no digipeaters near the island - and it is in Canada... I also have a weather station that would be posting weather from the island on the WU, if comms were up...

Matt

[ClassicCrazy]

Oh too bad !   Funny how they put cell towers all over everywhere !  Ask the cell phone company if they want to sponsor your digipeater with gateway  on their tower - ha ha !

Larry