My public school math skills may have failed me.

[Ruff]

All of my "math" says it should last more that 4 days, but theory does not match reality.


I have a tiny "cabin" at the entry to my property. It serves multiple purposes, but its main purpose is to provide power for a few "first world" items. The cabin consumes about 45-50 watts each hour. This is for the 10 watt 12 volt street light and the 35 watt WiFi router as well as powering the gate actuator as people come and go. It also provides protection from the weather for my package deliveries.

I have two 100 Ah 12 volt batteries in parallel and a 30 amp charge controller being fed by a 100 watt solar panel. We had about 4 days of rain and cloudy skies and it ran the batteries down so much, I had to put a battery charger on it to get the batteries back 100%. The last time that happened was in February. When I check it in the morning, it usually has about 30% capacity and is usually at 100% at 5 pm

All components are cheap Amazon items except the solar panel. It is a Canadian Solar 400 watt panel that took a hit all of the glass is fragmented and makes about 122 watts at 34 volts. I would like to think that they are capable of meeting the demands of the tiny cabin, but I might be wrong.

I plan to get an actual solar panel mount with a 30 degree angle and pull it out from the fence so it is in the sun more. Failing that, I may need to add another 12 volt AGM battery or a more powerful panel.

I am starting to think I should replace everything with Solid reliable equipment. Any recommendations for charge controller or battery brands?

Jeff

 

[BerndL]

I'd remeasure your consumption. If the batteries drop 70% in 15hrs, you're either using an average of 112W (surely not), or the batteries don't actually have decent capacity.

In my area ~100W of solar definitely wouldn't keep that setup going, if it really is 50W continuous.

 

[Ruff]

Thanks. They are only a year or so old, but who knows, they have been outside all that time.
That is why I wrote that literary masterpiece asking for advice. What I should have just said was "things ain't addn' up".

The charge controller has a log, but I do not trust it. I will need to figure out another way to log 12 volt DC consumption.

 

[seneysolar]

All of my "math" says it should last more that 4 days, but theory does not match reality.
View attachment 299226

I have a tiny "cabin" at the entry to my property. It serves multiple purposes, but its main purpose is to provide power for a few "first world" items. The cabin consumes about 45-50 watts each hour. This is for the 10 watt 12 volt street light and the 35 watt WiFi router as well as powering the gate actuator as people come and go. It also provides protection from the weather for my package deliveries.

I have two 100 Ah 12 volt batteries in parallel and a 30 amp charge controller being fed by a 100 watt solar panel. We had about 4 days of rain and cloudy skies and it ran the batteries down so much, I had to put a battery charger on it to get the batteries back 100%. The last time that happened was in February.

Did the batteries freeze? If they froze they are toast.

When I check it in the morning, it usually has about 30% capacity and is usually at 100% at 5 pm

What are you using to measure state of charge?

All components are cheap Amazon items except the solar panel.

PWM controller?

It is a Canadian Solar 400 watt panel that took a hit all of the glass is fragmented and makes about 122 watts at 34 volts. I would like to think that they are capable of meeting the demands of the tiny cabin, but I might be wrong.

The broken panel is a bit of a wild card. Some work but - My default answer would be to replace it. Water is going to eventually get under the glass, freeze, expand and eventually kill itself completely. Its just not reliable anymore.

I plan to get an actual solar panel mount with a 30 degree angle and pull it out from the fence so it is in the sun more. Failing that, I may need to add another 12 volt AGM battery or a more powerful panel.

A good solar panel might be the best start.

I am starting to think I should replace everything with Solid reliable equipment. Any recommendations for charge controller

Victron 100/30 would be my recommendation. But it may not be necessary depending on what you already have, post a picture.

or battery brands?

Stay away from 12v marine/ rv batteries. They suck, they just cant take the cycling. The best value for a deep cycle lead acid is a pair of 6v golf cart batteries in series.

 

[OzSolar]

Tare losses of the inverter often make up 50% or more of a small system's energy production.

 

[Brucey]

I have a tiny "cabin" at the entry to my property. It serves multiple purposes, but its main purpose is to provide power for a few "first world" items. The cabin consumes about 45-50 watts each hour. This is for the 10 watt 12 volt street light and the 35 watt WiFi router as well as powering the gate actuator as people come and go. It also provides protection from the weather for my package deliveries.

Need to figure out your inverter zero load. (I.e what it uses just being on, prior to any loads being added), can be substantial with the cheapies.

 

[MTM98290]

Replace the panel first.

Do you need a router that consumes 35w there? You could do a lot better without that load. What is the router used for?

 

[Solar Guppy]

Even new / perfect batteries have significantly lower capacity in cold weather. Lifpo04 actually shutdown typically below freezing an agm / lead acid might only have 30-40% of rated capacity in sub freezing weather.

Also a 100 watt panel in short winter months would have maybe 2-300 watt hours at best.

 

[Hedges]

Ruff didn't say he had an inverter. That was my first thought until I read the post.

Does the 12V 10W street light really consume 10W? Have you measured it?

Battery actual/remaining capacity, and whether it gets fully charged, is first place to look.
I don't see battery ratings. If AGM, you might be able to use 70% DoD and expect 650 cycles, depending on brand and model.
[Edit: "two 100 Ah 12 volt batteries in parallel"]

That's 2400 Wh total.

50W continuous x 24 hours = 1200 Wh/day. Battery should be flat in 2 days flat. Not 4 days.
75% DoD would be 1.5 days, so one day without sun is all you can hope to make it through without over-discharging the battery.

"fed by a 100 watt solar panel"

AGM probably wants to be charged at 0.2C, mine do. FLA at 0.13C. So with 2400 Wh battery, you need 480W production (about 600 to 800W of panels) or a bit less for FLA.

Expect 5 or 6 effective sun hours on average around the year, maybe 2 hours in December.
Right now in May say you get 6 hours. And it is cool, so panel produces 100W. That's 600 Wh. Half your consumption. Can't even power loads for a day, much less charge battery for a cloudy day.


Start with design before replacing equipment.

 

[billvon]

Any recommendations for charge controller or battery brands?

Jeff

Consider a lithium titanate (LTO) battery. They have a wider temperature range (down to -40C) and they last forever. Pricey, though.

RSV-23 XS Power Battery Titan8 12V Lithium LTO Titanate 69aH Equivalent 5,000 Watts Max - BCI Group 34

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[OzSolar]

My next step would be to add a Victron Smart Shunt a Cerbo GX so you can see it remotely. There's few sayings in my industrial engineering life. "You can't control what aren't measuring" or "If you aren't measuring it, you can't control it".

 

[marionw]

Your "Math" may be inaccurate due to:
1) Idle consumption of the gate actuator electronics. I have experience with several "Mighty Mule" systems where the the control board as well as any sensors (particularly the "proximity" ones) do have an "Idle" consumption.
2) The WIFI router also has an "Idle" consumption.
3) What actually is controlling the street light. I imaging it is not on 24/7 so I suspect the "charge controller" manages it, possibly with a "streetlight mode" setting, also an "Idle" consumption, particularly when the PV array in under producing.
4) Your picture indicates the PV Panel is mounted in a vertical position which may place the PV Panel at a less than optimal angle, generally the angle should be the latitude of the location.

Your first option may be to add a second PV Panel with a an angel that is the most optimal for your location.

 

[BerndL]

Honestly I'd be tempted to just run 240VAC out there, hot hot ground. You can use tiny wires for that load. Most power supplies can run on 240

 

[Kid Solar]

Lol.

A smashed panel doesn't produce much.

Who'd have thought eh?

The mysteries of Solar...

 

[jgh]

Put a PIR on the light, and investigate a lower-powered router.

 

[efficientPV]

One tiny solar panel! I have a small stand alone system with two 225W panels and it could barely supply that load in winter.

 

[MTM98290]

I am a big fan of the GLi-net AR3000m usb mini travel routers. They are cheap and use 5v usb for power. They are rated at 2W. If it meets your needs you could reduce your power use by a large amount. They are up to $30 last time I bought one a few months ago. Our original one is about 3 years old now and going strong.

 

[Ruff]

Wow what a response. I take a few minutes in the afternoon to brush the teeth on my Alpaca and suddenly everyone on the forum has a response for me. I hope to give answers in a way that will not disappoint Mrs. Pickiewicz my high school English teacher.

1.The batteries are simple deep cycle AGM batteries. The temp hit -16 degrees F this winter, so They may have frozen.

2. I am guessing the state of charge by the battery indicator in the Charge controller. It is an Epever MPPT Charge Controller 30 amp 12 volt from Amazon.

3. Yes, the solar panel is suspect. I was surprised it made any power at all. I had it when we put the cottage up and it seems to have only failed me twice in the last year or so.

4. I have a 3'x3' platform in the cottage to work with, I may or may not have room to use large 6 volt golf cart batteries. remember I also use this for storing deliveries. I will remeasure when I go down there when I go to take some pictures.

5. I agree that I do not know how much power the charge controller is consuming. I will put a meter on it and see.

6. I don't "need" a router, but it allows my wife to open the gate with the Ghost Control app on her phone. The gate does have the ability to open by pushing a button. I ran over 1200' of 2 conductor 28 gauge wire from the gate to the house for a contact switch so I can open it from the garage if need be. The router also allows us to have a Wifi camera and we can use our phone through Wifi calling when we are down by the gate (mowing/cleanup etc.). We are not isolated per se, but we do not have cell phone coverage on any part of the property, so Wifi calling though Starlink is our only option. And yes not to get off topic, but getting an internet connection at the gate 1200 feet away is a whole other topic I could write about.

7. I plan to put the panel on a "real stand" angle it at 30 degrees and move it out from the fence into the yard for better exposure. after that, I have a 400 watt bifacial panel. The controller is limited to 100 volts and 390 watts PV power.

8. I had a dusk to dawn controller on the light, it did consume some power until it did not (stopped working).

Like many things around here, this is an experiment. I am retired now with more time than money (or sense). I have plenty of things to do that are not solar power related and plenty of things that are. This only became an issue after these last storms as I had to unpin the actuators on the gate and leave it open for a day while I charged the batteries.

Running power down there may be a viable option. Not sure if I have room in the conduit. I already have a Cat 6 shielded cable and a 2 conductor contact wire in a 1' PVC. Not sure if I can get 12 or 14 ga wire in there. I will do a voltage drop for 16 and 18 ga wire. I suppose a 14 or 16 ga wire to a small trickle charger connected to the batteries would solve the power problem.

Right now my next big project is to get a fence around the front of the house for the grandkids and dogs and to add 2 more strings of panels in the back yard for the inverters. I hate it if my answer to the solar issue it to run AC power to it from the house.

Thanks for all of your responses, they were helpful. I will think it over for a few days (it is raining so what else can I do?) and get back with you as I continue to work the problem.

Again, thanks

Jeff

 

[Solar Guppy]

I already have a Cat 6 shielded cable and a 2 conductor contact wire in a 1' PVC. Not sure if I can get 12 or 14 ga wire in there. I will do a voltage drop for 16 and 18 ga wire. I suppose a 14 or 16 ga wire to a small trickle charger connected to the batteries would solve the power problem.

Then use POE ( power over ethernet ) into the mppt to keep the batteries trickle charged?

 

[MTM98290]

Then use POE ( power over ethernet ) into the mppt to keep the batteries trickle charged?

I would assume that this would only be possible with a mppt that has current limit capability? Or am I mistaken?

 

[Supervstech]

If you get the 400W panel installed, you should be able to keep the batteries charged.

Odds are good they are toast from repeated discharge.
Looks like you have 1200Wh per day usage... and you have 1200Wh above the 50% threshold for sla...
So, you need more battery, and more solar.
I would ditch the 30A controller, get a 60, install 400Ah of battery, and try it.

 

[seneysolar]

Wow what a response. I take a few minutes in the afternoon to brush the teeth on my Alpaca and suddenly everyone on the forum has a response for me. I hope to give answers in a way that will not disappoint Mrs. Pickiewicz my high school English teacher.

1.The batteries are simple deep cycle AGM batteries. The temp hit -16 degrees F this winter, so They may have frozen.

A charged battery will not freeze. A dead battery will freeze. Were the batteries dead during the low temps?

2. I am guessing the state of charge by the battery indicator in the Charge controller. It is an Epever MPPT Charge Controller 30 amp 12 volt from Amazon.

No, that wont keep track of state of charge accurately. It cannot measure useage, only production.

4. I have a 3'x3' platform in the cottage to work with, I may or may not have room to use large 6 volt golf cart batteries. remember I also use this for storing deliveries. I will remeasure when I go down there when I go to take some pictures.

If you decide to go that route, 2 golf cart 200ah batteries wont take up any more space than 2 regular 12v 100ah batteries.

5. I agree that I do not know how much power the charge controller is consuming. I will put a meter on it and see.

6. I don't "need" a router, but it allows my wife to open the gate with the Ghost Control app on her phone. The gate does have the ability to open by pushing a button. I ran over 1200' of 2 conductor 28 gauge wire from the gate to the house for a contact switch so I can open it from the garage if need be. The router also allows us to have a Wifi camera and we can use our phone through Wifi calling when we are down by the gate (mowing/cleanup etc.). We are not isolated per se, but we do not have cell phone coverage on any part of the property, so Wifi calling though Starlink is our only option. And yes not to get off topic, but getting an internet connection at the gate 1200 feet away is a whole other topic I could write about.

7. I plan to put the panel on a "real stand" angle it at 30 degrees and move it out from the fence into the yard for better exposure. after that, I have a 400 watt bifacial panel. The controller is limited to 100 volts and 390 watts PV power.

Vertical can be good in the winter as it doesn't accumulate snow.

8. I had a dusk to dawn controller on the light, it did consume some power until it did not (stopped working).

The Midnite Brat charge controller has a built in lighting control thats pretty neat. Something to look at.

Like many things around here, this is an experiment. I am retired now with more time than money (or sense). I have plenty of things to do that are not solar power related and plenty of things that are. This only became an issue after these last storms as I had to unpin the actuators on the gate and leave it open for a day while I charged the batteries.

Running power down there may be a viable option. Not sure if I have room in the conduit. I already have a Cat 6 shielded cable and a 2 conductor contact wire in a 1' PVC. Not sure if I can get 12 or 14 ga wire in there. I will do a voltage drop for 16 and 18 ga wire. I suppose a 14 or 16 ga wire to a small trickle charger connected to the batteries would solve the power problem.

Yes, if you already have conduit ran, this is the best choice. I wouldnt worry about voltage drop for a trickle charger.

Right now my next big project is to get a fence around the front of the house for the grandkids and dogs and to add 2 more strings of panels in the back yard for the inverters. I hate it if my answer to the solar issue it to run AC power to it from the house.

Thanks for all of your responses, they were helpful. I will think it over for a few days (it is raining so what else can I do?) and get back with you as I continue to work the problem.

Again, thanks

Jeff

 

[Hedges]

For a mall system, you don't want FLA golf cart batteries, not worth the maintenance.
AGM is good, forgiving of freezing weather so long as kept charged. More so than FLA, more concentrated acid tolerates lower temperature.
Unless cracked, freezing wasn't a problem.

What kills lead-acid batteries is spending too much time not charged fully. But AGM is more forgiving.
What AGM doesn't tolerate is over-charging, loss of water which can't be replaced.
You need voltage-regulated charger (PWM is fine with correct settings), no "equalize", and it needs temperature sensor to adjust charging voltage (higher when colder).

POE to charge sounds good. Or un-used pair of wires in your Ethernet cable. They might work fed about 18VDC to a voltage regulator, or (possibly through a resistor) into your charge controller. A CV/CC power supply feeding through the cable to PWM charger (possibly with a diode) would let the charger keep battery charged all night. or feed higher voltage like 48VDC and step down with DC/DC converter.

 

[SoTxUser]

Without taking any measurements I'd first suspect that your broken panel isn't doing good. Also are you converting the 12V to AC (like for the router)? If so that will have a 24/7/365 draw on the batteries. Gotta factor that in especially on a small system.

HTH,
tsp

 

[Ruff]

1. The batteries were charged.....until they weren't
2 I will look at the midnight Brat and see if it fits my needs
3.PoE is a GIANT ball of fur. Getting the right amplifiers that had the correct size grommet for the cat 6 shielded wire to prevent water intrusion was difficult. I have a PoE camera a few hundred feet from the gate and getting PoE power 1350 feet to a PTZ camera that required an amplifier every 300 feet, it was an expensive route to take. The route for the cable is along the back wall, then the north wall where it runs 210 feet in buried conduit to a junction box near out Grid utility service. From there is runs in 1 inch conduit for 1000 feet to the tiny cottage where it terminates.
4. The internet part is VDSL. I could have put it in with the twisted wire, but I had the Cat 6 reel laying around so...... I do have a few spare wires on that cable , but I don't think it will carry to current needed.
5. The router is fed directly with DC.
6. When the panel mount gets here, I will see if the charge controller can handle the power from a new panel.

I am leaning toward buying a couple of rolls 16 gauge speaker wire, taking it and the generator and go down to the gate and see If I can get enough current to charge the batteries and run the router. (this is looking like a weekend project as I am still Fred the fence builder these next few days).

I will update when I know more.