Woke up to blank SCC and drained batteries, now won't charge

[lflock]

Hoping someone here will answer quicker than shopsolarkits.com will. This is the email I sent them:
New problem has arisen: System completely drained the batteries overnight, no warning bell, system was at 100% 13.5 volts when I went to bed. Woke up this morning and the SCC was blank, no power. SCC reading 68.9 volts, 0 on the SCC amps once the sun came out. This morning I hooked up the meters, showed volts the same as the SCC, but 6 amps. The sun came out and started showing it was charging, but the batteries did not increase (showing 0) and then it stopped, you know the arrow on the SCC stopped blinking.
Only thing on it overnight was the refrigerator and UPS. Now for a little background: System was operating with this load for over 2 weeks, no problems. Usually would wake up and find it around at a minimum of 95%.
UPDATE: Since I am an impatient person when it comes to stuff like this, I rehooked up the system (almost noon here) and it is now charging the batteries. However, the mystery of the overnight failure still persists.

 

[Adam De Lay]

What hardware are we talking about (inverter, scc, batteries?

 

[lflock]

What hardware are we talking about (inverter, scc, batteries?

Woke up and the SCC had no power from the batteries, so batteries must have been dead. To be certain, I flipped the inverter on and nothing, so dead batteries. Where the problem lies, I have no idea. Finally, it is charging, but where the failure occurred I have no idea.

 

[Adam De Lay]

We need make and model of hardware in order to help out.

 

[lflock]

Okay, something fishy is definitely going on. Had it hooked up for approx. 10 mins, now showing 13.1 v/97% for the batteries on the SCC.

 

[lflock]

We need make and model of hardware in order to help out.

Lite Solar Power Kits [LPK-MAX] - ShopSolar.com

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2000w inverter-renogy, 2 x 100ah lifepo4 batteries, rich solar 60a SCC and 3 x 200w rich solar panels

 

[Adam De Lay]

How much power does the refrigerator use? Also what was plugged into the UPS?

 

[sparrowhawk]

Lite Solar Power Kits [LPK-MAX] - ShopSolar.com

Lite Solar Power Kits [LPK-MAX] | Lifetime Customer Support (Email, Live Chat, Phone) | Shop Now

shopsolarkits.com

2000w inverter-renogy, 2 x 100ah lifepo4 batteries, rich solar 60a SCC and 3 x 200w rich solar panels

It's probable you batteries weren't fully charged and/or your loads are to much for your batteries to fullfill overnight.

 

[lflock]

fridge: 374 kwh a year - don't have anything more specific than whats on the sticker as it is about 10 years old and the manual, if it came with one, is long gone. The UPS has a monitor and laptop plugged into it, but those were off all night. As stated before, the system ran just fine for a couple of weeks with these items plugged in.

 

[lflock]

It's probable you batteries weren't fully charged and/or your loads are to much for your batteries to fullfill overnight.

even though it said it was 100% and 13.5 volts?

 

[Adam De Lay]

even though it said it was 100% and 13.5 volts?

What is telling you that you have 100% SOC?

 

[lflock]

What is telling you that you have 100% SOC?

The solar charge controller said the battery was 100% 13.5v last night

 

[Adam De Lay]

It's very hard to say with the limited information. The solar charge controller is probably displaying the state of charge based on the voltage of the batteries which is not very accurate with the LifePo4 chemistry due to the flat charge/discharge curve.

It's possible the batteries aren't truly being recharged to 100%. You said you "rehooked up the system" and it started working. Is it possible a connection was loose and prevented the batteries from discharging?

When your batteries get low enough, they will shut down due to a low voltage disconnect, so they'll read 0v. They'll need a 12v supply in order to "wake them back up". The problem is, some solar charge controllers won't work unless they detect a 12v battery connection. So your system could be discharging so low that you're getting into this kind of "rut".

 

[lflock]

It's very hard to say with the limited information. The solar charge controller is probably displaying the state of charge based on the voltage of the batteries which is not very accurate with the LifePo4 chemistry due to the flat charge/discharge curve.

It's possible the batteries aren't truly being recharged to 100%. You said you "rehooked up the system" and it started working. Is it possible a connection was loose and prevented the batteries from discharging?

When your batteries get low enough, they will shut down due to a low voltage disconnect, so they'll read 0v. They'll need a 12v supply in order to "wake them back up". The problem is, some solar charge controllers won't work unless they detect a 12v battery connection. So your system could be discharging so low that you're getting into this kind of "rut".

I know it wasn't "truly" 100 %, but it has always lasted through the night when it read 100% and 13+ volts. In my opinion, something is wrong somewhere since it suddenly couldn't make it through the night. And yes, it started working again after I re-hooked it up for the umteenth time around noon. And, it suddenly had the batteries charged to 100% in 15 minutes.
This system has always started charging once the sun hit it at around 8am, not a lot, but some. This morning the SCC wouldn't charge the batteries even though the panels were showing volts coming in.
As for a loose connection, considering how many times I unplugged and plugged everything back together, I highly doubt it.

 

[sunshine_eggo]

I know it wasn't "truly" 100 %, but it has always lasted through the night when it read 100% and 13+ volts. In my opinion, something is wrong somewhere since it suddenly couldn't make it through the night. And yes, it started working again after I re-hooked it up for the umteenth time around noon. And, it suddenly had the batteries charged to 100% in 15 minutes.
This system has always started charging once the sun hit it at around 8am, not a lot, but some. This morning the SCC wouldn't charge the batteries even though the panels were showing volts coming in.
As for a loose connection, considering how many times I unplugged and plugged everything back together, I highly doubt it.

You need to ignore the % meter. It is always wrong.

Always lasted the night at 13V+? You sure about that?

For LFP at rest:

13.1V = 40%
13.2V = 70%

30% charge difference based on 0.1V difference. You sure you want to rely on voltage?

You will know your battery is fully charged when it has hit 13.8V and held there or above for 2 hours OR hitting 14.2-14.4V for about 15 minutes.

Let's do some basic math:

12.8V * 100Ah * 2 = 2560Wh

2560Wh / 600W = 4.3 hours of full power (600W) charging... but somehow you believe it hit 100% in 15 minutes?

You have likely been slowly using a little bit more than you can resupply on a daily basis.

Get a battery monitor that actually counts current in and out of the battery and provides a TRUE state of charge.

Concerning your hubris on connections, a staggering number of issues are caused by poor connections... a bolt that's not fully torqued, a bad crimp, a washer where it shouldn't be, a specialized connector that's not making a good connection, etc.

 

[lflock]

Yes, I am certain about the 13+ volts, as for the percentage, I know it is not accurate since the voltage can show a wide variety of numbers at 100%.
And no, I don't believe it hit 100% in 15 minutes, that is why I am asking about the problem. And hubris, really?!! Considering it was running for 2 weeks with no problems, I fail to see how it might have been a loose connection. And, I plugged and replugged everything in multiple times, not just once!

 

[sunshine_eggo]

Yes, I am certain about the 13+ volts, as for the percentage, I know it is not accurate since the voltage can show a wide variety of numbers at 100%.

Then why are you even mentioning it (multiple times)?

And no, I don't believe it hit 100% in 15 minutes, that is why I am asking about the problem. And hubris, really?!! Considering it was running for 2 weeks with no problems, I fail to see how it might have been a loose connection. And, I plugged and replugged everything in multiple times, not just once!

Yes. Hubris. Again, a staggering number of issues are resolved by correcting a bad connection somewhere in the system. Additionally, bad connections tend to worsen over time.

The prior two weeks success is not relevant UNLESS you've had two weeks of great sun, but yesterday (the day before the shutdown, it was crap) OR you had a new load running overnight.

So, you re-torqued all the:

battery terminals?
Inverter terminals?
MPPT battery terminals?
MPPT PV terminals?

Have you tested all three panels to confirm Voc and Isc ratings?

There are three likely possibilities here:

1. Bad connection.
2. Over-use of system (too much consumption for PV).
3. Defective component.

Listed in order of likelihood.

Your fridge and inverter likely consume about 1.5kWh/day. 1/3rd of that is the inverter itself assuming a 20W idle consumption, which is typical for that size. With 600W of solar, 1-2 mildly cloudy days may put you behind the curve. Again, that's if you're ONLY running the fridge and NOTHING else.

Array wattage and solar conditions determine how much you can use per day.
Battery capacity determines how long you can go without charging.

Consume more than your PV can supply daily, and it's a countdown to shutdown.

Lastly, you're here asking for help. Maybe don't dismiss those trying to help you especially when someone is recommending you check the #1 cause of issues.

 

[lflock]

I don't dismiss anyones suggestions, however, I do believe both parties should be polite and HUBRIS is not. I am here because I know exceedingly little about electricity and need assistance when there is a problem since the company I bought it from doesn't seem fit to respond in a timely manner. I did state that I repeatedly unhooked/re-hooked up everything. And, yes, I have had 2 weeks of blue, sunny skies here, it's almost always sunny here. I checked the panels at the source and the SCC repeatedly this morning. Also checked the other connections. The only thing different last night was that I closed up the compartment at dusk and didn't recheck it before going to bed like I have for the past 2 weeks. Also strange that it didn't start charging when the sun hit the panels this morning as it has done for the past 2 weeks.

 

[Q-Dog]

I don't dismiss anyones suggestions, however, I do believe both parties should be polite and HUBRIS is not. I am here because I know exceedingly little about electricity and need assistance when there is a problem since the company I bought it from doesn't seem fit to respond in a timely manner. I did state that I repeatedly unhooked/re-hooked up everything. And, yes, I have had 2 weeks of blue, sunny skies here, it's almost always sunny here. I checked the panels at the source and the SCC repeatedly this morning. Also checked the other connections. The only thing different last night was that I closed up the compartment at dusk and didn't recheck it before going to bed like I have for the past 2 weeks. Also strange that it didn't start charging when the sun hit the panels this morning as it has done for the past 2 weeks.

If the battery BMS disconnected from low voltage, the charge controller may not start, because it doesn't see any battery.

 

[lflock]

If the battery BMS disconnected from low voltage, the charge controller may not start, because it doesn't see any battery.

Okay, figured out BMS is battery management system, but doesn't the SCC do the same thing, essentially? Or, do I need one?