SW4024 power Issues

stmar

Power cut out completely this morning. Got this fault warning:

Time	Action	Device	ID	Code	Description
2019/12/21 09:27:53	Cleared	CSW4024	847509	F47	DC Under Voltage OK
2019/12/21 09:27:44	Set	CSW4024	847509	F47	DC Under Voltage

Disconnected from load, batteries and grid. Left it disconnected from loads, connected to grid and batteries. Inverter started up, started charging as usual but only at about 3 amps, it usually is about 30 amps when first starting to charge in Bulk, and went to AC Good at 25.3 in just a few minutes which is unusual.

I have the charge setting at 180 minutes, Bulk Absorb at 28.6 and float at 26.8. It was at the normal Bulk voltage when it was charging.

I have a 24 volt Sun Frost refrigerator, turned it back on so that is the only load on the batteries and it seems to be working okay. Cloudy so only getting a few amps from solar array, batteries are still at low 25's voltage.

Any ideas on why the charge rate is so low and is there a fix or is the inverter done for?

stmar

Reset again with refrigerator on and it charged at 8 amps for about 10 minutes. Quit charging and battery voltage is 25.2, solar charging at 1.4 amps and only load on batteries is the refrigerator. Disconnected and cut all power to inverter.

Estragon

Is the low 25s battery voltage; as measured at the battery, as measured at the inverter DC terminals, or what the inverter thinks it is?

A simple possible explanation might be something causing excessive voltage drop between the inverter and bank.  Reading and comparing the above 3 values may help?

stmar

The 25's is showing at the inverter combox and the controller (solar to battery bank) so I have to assume it is the correct voltage.

stmar

Still cloudy but getting a bit more solar (2 amps) and batteries are coming up to mid 25's. Sorry for all the posts but trying to narrow the culprit. Since the batteries are recovering with just solar would that point me to the inverter malfunctioning? Draining the batteries and not using the grid when the battery voltages dropped below 26 volts where I have my AC Support set? My LVC is set at 21 and my battery bank has rarely fallen even to 24 volts where I have my charge setting. Then since the inverter is not charging as it normally does would that not point to a malfunctioning inverter? If so then my next question would be what to do, repair or replace?  I do have the Modbus Combox and SCP so would probably stay with Schneider.

stmar

If the batteries were going bad then maybe the inverter/charger is sensing that and is the reason the charger is cutting out to keep from frying the batteries. Since I have the battery bank isolated I will see what it does overnight with the frig load on them. In the past I have run the frig on the battery bank a couple of times for a prolonged length of time, several months, while I had an inverter repaired and one time replaced. The good thing is that I  have my system where I can go strictly grid and can isolate and work on the alternative system. Just need to figure out what component is the problem.

Estragon

Are grid AC voltage and frequency within spec?  I'm not very familiar with this gear, but I would have thought if it was dropping it as out of spec it would log a warning at least?

How old is the inverter?

stmar

Inverter is about 2 years old. It did not give a warning about being out of spec and seemed to be working okay except for the length of charge and the amperage of charge, both extremely low. I did take a meter and checked the voltage at points in the system and they were all consistent, up to mid 25's with solar charging.

stmar

Kept battery bank isolated, only solar and refig. Voltage reading is 25.2 at 9:40 PM so that is about normal, no charging and frig load. Will see what it is in the morning. Looking more like the inverter. Does anybody repair these newer SW4024 inverters?

stmar

Overnight batteries held to 24.9 volts which would be normal with frig load and nominal solar charging yesterday. Still trying to figure out why the inverter would use battery power and drain the bank. I have it set AC Support 26 volts, Charge 24 volts and LVC 21 volts, so with those settings the inverter should not have called for battery power since the overnight reading would be less than 26 volts. AC Support, when the inverter calls for battery power, normally kicks in when the solar array charges the batteries to the 26 volts set point and it was too early in the morning for the bank to reach that voltage. Pointing to the inverter but will leave the battery bank disconnected from the main system with solar charging it and only frig load. Need a way to test the inverter.

Dave Angelini

Log the voltage!

 It probably is the battery/connections causing LBCO. Combox and the config tool can log just about anything system wise.

The new gateway will have custom logging in the next firmware. The mobile app will also get lots of updates this coming year.
The CSW should have surge protection especially with a grid source.

stmar

Will reboot inverter and see what the logs say, Combox shows no info with the inverter shut down correct? Batteries are Lifeline L16's and are only 5-1/2 years old so that does not seem that old to go that low of a voltage. If it is the batteries would the inverter not attempt to charge as it normally does?

stmar

Connections are tight and bright, no issues.

stmar

Rebooted the inverter, all fault warnings have been wiped out, probably because I powered system down. Powered up with no loads and it went to Bulk 28.8 - 29 volts @ 3 amps for about 5 minutes, then Absorption same voltage/amperage for 5 minutes, then Float 25.7 volts for less than a minute @ -1 amp. I had AC Support disabled but when it rebooted it was enabled. Disabled it. Batteries are being charged by solar 25.8 volts @ 2.5 amps, cloudy day, status is AC Good and AC Qualifying Good for both L1 and L2.

Dave Angelini

Actually to me, it is the battery. You are not charging it.

stmar

I do have a surge suppressor on my main panel. According to the Combox graph the batteries were at 25 volts and then instantly went to 0 volts and that is when the F47 fault occurred, see first post. I tried to post the graph but having issues doing that.

stmar

Here is the Graph.

Estragon

With voltage dropping to zero like that, it looks a problem somewhere in the battery circuit (breaker, battery series interconnect wire, etc)?

Failing that, something in the voltage sense circuit?  

stmar

I checked connections and they all seem clean and tight. What bothers me is the lack of charge, time and amperage, when I initiate a charge cycle. If the SW4024 senses the battery condition and will not charge as normal then it would probably be the batteries as Dave said. I have a few more operations to do over the next few days and hopefully I can pin it down. We are a bit spoiled because our last Lifelines lasted 10 years and these are only 5.

Dave Angelini

adding to Estragons list a cell in the bank internally opening. Get a couple of 12 V batteries and sub the bank.

stmar

Good idea, AGMS are hard to test so will grab a couple of 12v batteries and test. Will probably be after Christmas, I have it so that we are functional. I will update when I have results. Thanks for the input.

mike95490

stmar said:

....... Batteries are Lifeline L16's and are only 5-1/2 years old so that does not seem that old to go that low of a voltage. .....

Could be that the AGM's are at the end of life.  If your solar is not able to charge them and your inverter stops charging so very quickly, they are likely done.  Have they ever had other instances where they went so low ?

stmar

Definitely batteries so thanks for all the input. Isolated batteries with only frig load and this morning the Morningstar controller was  LVD, low voltage disconnect, same as the 21st and voltage was down to 21 volts. Now the decision on what batteries to get. I like the Lifeliines, could go with 12 volt and increase the amp hours but the L16s seemed to do the job, just didn't last as long as I expected. I will try and get some input on the battery group. Thanks again.

stmar

My definite is beginning to have doubt creep in so need some encouragement. When I put the load of the 24 volt refrig on the voltage fluctuates, take the load off and voltage stabilizes, solar is charging a few amps, cloudy. When I turn on the inverter without the frig load it still does the short duration low amp cycle and finishes at low 25's voltage. Put the load of the frig back on and the voltage drops and fluctuates. Still think it is the batteries but paranoid it may be the frig. Will leave the frig and inverter off and see what happens with just the solar charging the bank.

Estragon

Some DC fridges can do either 12v or 24v.  If yours does, you might want to temporarily run it off different 12v segments off the 24v bank.  Assuming it's one battery failing with an open circuit cell, this may help confirm and narrow down the problem battery.

stmar

I will check that out. Have the batteries resting right now, no load no charge. Will check individually check them after they rest a few hours and see if one stands out. I guess with a bad battery when you put a load on it weird things happen throughout the system.

Estragon

Yes, if the open cell thought is right it's sort of like a loose wire.  Might show voltage/continuity with little current but go OC when loaded.  With the cells all in series, the whole bank would then be open circuit.

stmar

Frig only has 24 VDC compressors so no option to run it on 12 volts. After letting them rest for a few hours with no load and no charge the controller showed the LVD error, voltage was down to 21. Don't have time to take cables off and test individual batteries today. Sun is out and solar is charging so running the refrig and will disconnect tonight. Hopefully we can limp along until I get new batteries.

Estragon

You may not need to disconnect to test, just read with multimeter at individual battery posts.  The string as a whole might read open or low with current, but good batteries (assuming 6v nominal L16s) may read ~6.x volts?  A bad one may read zero (open cell) or ~4v (shorted).

stmar

Estragon said:

You may not need to disconnect to test, just read with multimeter at individual battery posts.  The string as a whole might read open or low with current, but good batteries (assuming 6v nominal L16s) may read ~6.x volts?  A bad one may read zero (open cell) or ~4v (shorted).

I disconnected and separated the batteries overnight, hours of rest, and have a consistent 6.2 volts per battery. Had this reading last night and again this morning. Next I will turn on the inverter and see how the inverter charger and batteries act without the frig load.Then I will try and disconnect each compressor on the frig and see if I can determine if it is one of the frig compressors.

Dave Angelini

You need to load test the batteries. There are quite a few ways a cell can open up. Load test each battery. I have 2V and 6v loads here for this. bring them over and some canadian whiskey, blended only. Will have you home by Christmas