December 2, 20232 yr Hi everyone I need some help, please… Last weekend we moved into a house we recently bought. It has a PV system with batteries that is grid tied, and a Mecer inverter. Last night during load shedding my wife put the kettle on and it tripped out the power (which was obviously running off the batteries, though we didn’t realize it was load shedding at the time). We had used the kettle in load shedding before, during the day, so I believe that the fact it was at night without any support from the PVs meant the backup (batteries) couldn’t cope. Lesson learned that we need to be conscious of which appliances we use during load shedding! However, since then we haven’t been able to use the backup system (batteries) at all. When the system “tripped”, I switched over from using the backup (batteries) to fully drawing from the grid, put since then I haven’t been able to switch back to the backup - there’s just no power coming through. I’ve checked the DB boards and there aren’t any switches that tripped. I also checked the two 22x58 fuses on the line between the batteries and the inverter: I’m not sure how to tell if they’re blown or not but they don’t look damaged in any way. Any ideas on what could be wrong or how to trouble shoot this? We weren’t given any manuals or instructions or anything. Hoping it’s something simple and I can avoid paying for a call-out. thanks!
December 4, 20232 yr On 2023/12/02 at 9:48 PM, CapeSean said: Hi everyone I need some help, please… Last weekend we moved into a house we recently bought. It has a PV system with batteries that is grid tied, and a Mecer inverter. Last night during load shedding my wife put the kettle on and it tripped out the power (which was obviously running off the batteries, though we didn’t realize it was load shedding at the time). We had used the kettle in load shedding before, during the day, so I believe that the fact it was at night without any support from the PVs meant the backup (batteries) couldn’t cope. Lesson learned that we need to be conscious of which appliances we use during load shedding! However, since then we haven’t been able to use the backup system (batteries) at all. When the system “tripped”, I switched over from using the backup (batteries) to fully drawing from the grid, put since then I haven’t been able to switch back to the backup - there’s just no power coming through. I’ve checked the DB boards and there aren’t any switches that tripped. I also checked the two 22x58 fuses on the line between the batteries and the inverter: I’m not sure how to tell if they’re blown or not but they don’t look damaged in any way. Any ideas on what could be wrong or how to trouble shoot this? We weren’t given any manuals or instructions or anything. Hoping it’s something simple and I can avoid paying for a call-out. thanks! For starting remove the guess work. Fuses are tested if OK and not just looking at them. If you don't have a multimeter to test use a few pieces of wire and a car 12V bulb and a car battery. The bulb should light if it is OK.
December 4, 20232 yr Post pictures of your batteries, the side label on the mercer inverter and the screen of the inverter. Is the screen completely dead is there a red error light on bottom left of screen.
December 7, 20232 yr Author On 2023/12/04 at 7:15 PM, Scorp007 said: For starting remove the guess work. Fuses are tested if OK and not just looking at them. If you don't have a multimeter to test use a few pieces of wire and a car 12V bulb and a car battery. The bulb should light if it is OK. I've borrowed a multimeter and the fuses are fine...
December 7, 20232 yr Author On 2023/12/04 at 7:34 PM, TaliaB said: Post pictures of your batteries, the side label on the mercer inverter and the screen of the inverter. Is the screen completely dead is there a red error light on bottom left of screen. Images attached.
December 7, 20232 yr 7 minutes ago, CapeSean said: Images attached. Let me guess, those are lead acid batteries, without any balancing between them... they are probably no more, would be my guess, for a 10kW inverter you should have 10kWhp batteries, in lead acid terms, if there are 4 in series (don't every buy lead acid again, a huge waste of money) only and no parallel batteries, at 0.2C, they would have to be 4000Ah batteries to be correctly sized, my guess is, they are 200Ah or 100Ah batteries, really too small and presumably they've done some duty and the kettle just gave them the last shove over the cliff's edge... Measure each battery for voltage, maybe only one is totally dof, but I'd say, save up for a 10kW or larger 51.2V LiFePO4 battery or multiple parallel 5kW-ers...
December 7, 20232 yr Yeah i agree with @Kalahari Meerkat4 x SLA batteries in series 1 or 2 dead cells in the series string damaged or kaput. What is your solar array capacity. The inverter is a 10kw 3ph with 2 x hv mppt charge controllers. What you can do when you have adequate pv input remove all the load , then add small load and see if the inverter supplies power on the output side. If you have adequate pv input you can disconnect the batteries and it should have ac output on the 3ph and neutral should the inverter not be damaged. Maybe the batteries has an internal short creating low resistance across the dc bus.
December 8, 20232 yr Author Just had a PV guy come take a look and tell me the batteries are ok, it’s the inverter, which is flashing error codes 2 and 4. So I have to take it in to Mustek to have it looked at, which means getting an electrician to dismount it. sheesh. Two weeks into having this system and it’s killing me.
December 8, 20232 yr 22 minutes ago, CapeSean said: Just had a PV guy come take a look and tell me the batteries are ok, it’s the inverter, which is flashing error codes 2 and 4. So I have to take it in to Mustek to have it looked at, which means getting an electrician to dismount it. sheesh. Two weeks into having this system and it’s killing me. Did he actually do a load test on the Sla batteries by just looking at the open curcuit voltage is not going to cut it. Take some good advice, for the inverter you have get at least 10kwh of lifep04 batteries the 4 a lead acid batteries are going to give you endless problems on a 10kw inverter. 17 hours ago, TaliaB said: What is your solar array capacity ??
December 9, 20232 yr 20 hours ago, CapeSean said: flashing error codes 2 and 4 Error code 4 is Battery Voltage Too Low. As a few have mentioned above, it is likely the batteries. The voltage might look fine when disconnected, but as soon as the inverter switches on and draws power the voltage is probably collapsing. It looks like you have 8 batteries in the bank? If only 1 is bad it will pull the whole bank down under load. If you can load test the batteries properly and find the 4 best ones you could possibly get the inverter to run and then limit your load until you can get new batteries. At least that way you can test if the inverter works before taking it off the wall.
December 9, 20232 yr 22 minutes ago, jumper said: Error code 4 is Battery Voltage Too Low. As a few have mentioned above, it is likely the batteries. The voltage might look fine when disconnected, but as soon as the inverter switches on and draws power the voltage is probably collapsing. It looks like you have 8 batteries in the bank? If only 1 is bad it will pull the whole bank down under load. If you can load test the batteries properly and find the 4 best ones you could possibly get the inverter to run and then limit your load until you can get new batteries. At least that way you can test if the inverter works before taking it off the wall. Good advice BUT discharged batteries cannot be tested. All batteries should 1st be subjected to some charging before the test. Get them disconnected from the inverter and charge each one on their own for about the same time before load testing with a highish 12V charger. Also disconnect the parallel path if indeed 8 batteries. At this stage with the batteries already discharged they are further discharging themselves. Edited December 9, 20232 yr by Scorp007
December 9, 20232 yr 12 minutes ago, Scorp007 said: Good advice BUT discharged batteries cannot be tested. All batteries should 1st be subjected to some charging before the test. Get them disconnected from the inverter and charge each one on their own for about the same time before load testing with a highish 12V charger. At this stage with the batteries already discharged they are further discharging themselves. Totally agree, that's kinda what I meant by "load test them properly", but thanks for clarifying 😀👍
December 11, 20232 yr Author It turns out I needed to press the "On" button for exactly 3 seconds. I was told to "long press" it and was holding it for 10, 20, 30+ seconds but it had to be 3. Seems to be working fine now.
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