I've had my kit running 2 years now nearly continuously in an off grid setup and recently discovered issues with the battery bank - last night it all switched off after just 3 hours of night time!!! 
My last post two years ago, I had good feedback on putting together 12 x 120ah SLA batteries together into a 24v system - here's the post https://diysolarforum.com/threads/r...s-in-series-parallel-which-way-is-best.55934/
- 12 x SuperBatt DT120 batteries (sealed lead acid) (3 x banks of 4 batteries each, 24v)
- Victron for SmartBMV shunt and bus bars
- 2 x Renogy RVR 40A controllers
- 2 banks of Renogy solar panels (6 x 200w on one bank (series/parallel), and 12 x 100w on the other bank (series/parallel))
- 1 x Giandel 2000w 24v inverter
Pictures attached.
I think I might have screwed my batteries... but I gave it all a strip down today so we'll see... fingers crossed it might recover...
I'm listing this so as get advice and feedback, and also to help others.
My biggest mistakes that I know of...:
1. Giandel inverter settings
This inverter has been brilliant and still is. On for virtually 2 years continuous, powering fridge freezer internet 24/7 plus occasionally heavy usage on a sunny day like washing machine hot cycle, jackhammer, kettles, distiller, etc. I bought it after seeing a number of Will's videos where he highly recommended it.
The problem: as it happens, this inverter has an automatic input under-voltage cut-off, which is great. However, the setting is 19v DC and so is only useful for lithium batteries, whereas mine are sealed lead acid and so the setting should be closer to 24v. And the settings cannot be changed.
This results in the battery bank, albeit sizeable, to be run down way below the 50% threshold for SLA batteries. When I'm around I usually monitor and check, and the weather in Italy is usually great, so its only a rare winter occurrence when the weather is shite for a few days that this might happen (in theory).
2. Renogy RVR40 controller settings
The Renogy controllers have also been excellent since I've got them. I slightly over-power the solar panels on each controller as the panels and not due south with optimum angle, so each controller rarely gets above 35A even on a sunny summer day (I've seen one once at 42A which is unusual, and within the protection threshold).
The controllers also detect the 24v and defaults to SLD battery type.
However, what I think I should have done on one of the controllers is change the settings to avoid the periodic equalisation charge, this should only be executed by one of the controllers not both as it puts some pressure on the batteries.
3. Battery maintenance
I'm not sure if this is a mistake, but because of the issue described in the top of this post, I took them out today to inspect them and switch them around.
These are SuperBatt DT120 deep cycle leisure batteries, sealed lead acid, so should be ok. There's mixed reports on the internet on these batteries but they've been holding up for 2 years without a problem so far.
The batteries have what's called the "magic eye" to view the electrolyte status, which is an indicator on one cell but not each of the 6 cells in a battery. When I took the batteries out today most were green, which is a good indicator, but 2 or 3 were clear which is an indicator to replace. Giving each battery a little knock or tap resulted in all being green. Not the best test approach but hey, I'm remote and off grid so working with what I've got.
I shuffled the batteries around. All tested individually around 12v so I reassembled. And we'll see how it progresses.
I'm assuming I should have had a periodic maintenance of some sort, but not sure what else I could have done except move them around.
=====
I've reassembled it all and switched on. Time will tell whether the batteries are damaged beyond a workable solution.
Couple of other points:
1. Incidentally, I've attached another image of one of the DC breakers I had between the solar panels and the controllers, where one of them almost caused a fire. I don't want this post to be all about fuses as that's a separate matter. But I'm still not clear what could have caused that to happen. It was a 50A breaker, DC with arc protection, etc so I'm guessing that the solar cable might have become less tight over time causing an increase in resistance or something similar. Either that or it's a manufacturing fault, it's a chinese amazon product but that doesn't mean it's not good per se.
2. The SmartBMV Shunt is normally great, but in the screenshot attached it seems to have glitched. It's showing 98% SoC but the voltage is 20.63v at 22:15 at night when it's dark. I'm used to the Renogy controllers being inaccurate when drawing a charge, but the Victron shunt is normally supposed to be very accurate. So not sure what's going on there exactly.
Anyway, there's a bit of feedback.
Any suggestions welcome.
My last post two years ago, I had good feedback on putting together 12 x 120ah SLA batteries together into a 24v system - here's the post https://diysolarforum.com/threads/r...s-in-series-parallel-which-way-is-best.55934/
- 12 x SuperBatt DT120 batteries (sealed lead acid) (3 x banks of 4 batteries each, 24v)
- Victron for SmartBMV shunt and bus bars
- 2 x Renogy RVR 40A controllers
- 2 banks of Renogy solar panels (6 x 200w on one bank (series/parallel), and 12 x 100w on the other bank (series/parallel))
- 1 x Giandel 2000w 24v inverter
Pictures attached.
I think I might have screwed my batteries... but I gave it all a strip down today so we'll see... fingers crossed it might recover...
I'm listing this so as get advice and feedback, and also to help others.
My biggest mistakes that I know of...:
1. Giandel inverter settings
This inverter has been brilliant and still is. On for virtually 2 years continuous, powering fridge freezer internet 24/7 plus occasionally heavy usage on a sunny day like washing machine hot cycle, jackhammer, kettles, distiller, etc. I bought it after seeing a number of Will's videos where he highly recommended it.
The problem: as it happens, this inverter has an automatic input under-voltage cut-off, which is great. However, the setting is 19v DC and so is only useful for lithium batteries, whereas mine are sealed lead acid and so the setting should be closer to 24v. And the settings cannot be changed.
This results in the battery bank, albeit sizeable, to be run down way below the 50% threshold for SLA batteries. When I'm around I usually monitor and check, and the weather in Italy is usually great, so its only a rare winter occurrence when the weather is shite for a few days that this might happen (in theory).
2. Renogy RVR40 controller settings
The Renogy controllers have also been excellent since I've got them. I slightly over-power the solar panels on each controller as the panels and not due south with optimum angle, so each controller rarely gets above 35A even on a sunny summer day (I've seen one once at 42A which is unusual, and within the protection threshold).
The controllers also detect the 24v and defaults to SLD battery type.
However, what I think I should have done on one of the controllers is change the settings to avoid the periodic equalisation charge, this should only be executed by one of the controllers not both as it puts some pressure on the batteries.
3. Battery maintenance
I'm not sure if this is a mistake, but because of the issue described in the top of this post, I took them out today to inspect them and switch them around.
These are SuperBatt DT120 deep cycle leisure batteries, sealed lead acid, so should be ok. There's mixed reports on the internet on these batteries but they've been holding up for 2 years without a problem so far.
The batteries have what's called the "magic eye" to view the electrolyte status, which is an indicator on one cell but not each of the 6 cells in a battery. When I took the batteries out today most were green, which is a good indicator, but 2 or 3 were clear which is an indicator to replace. Giving each battery a little knock or tap resulted in all being green. Not the best test approach but hey, I'm remote and off grid so working with what I've got.
I shuffled the batteries around. All tested individually around 12v so I reassembled. And we'll see how it progresses.
I'm assuming I should have had a periodic maintenance of some sort, but not sure what else I could have done except move them around.
=====
I've reassembled it all and switched on. Time will tell whether the batteries are damaged beyond a workable solution.
Couple of other points:
1. Incidentally, I've attached another image of one of the DC breakers I had between the solar panels and the controllers, where one of them almost caused a fire. I don't want this post to be all about fuses as that's a separate matter. But I'm still not clear what could have caused that to happen. It was a 50A breaker, DC with arc protection, etc so I'm guessing that the solar cable might have become less tight over time causing an increase in resistance or something similar. Either that or it's a manufacturing fault, it's a chinese amazon product but that doesn't mean it's not good per se.
2. The SmartBMV Shunt is normally great, but in the screenshot attached it seems to have glitched. It's showing 98% SoC but the voltage is 20.63v at 22:15 at night when it's dark. I'm used to the Renogy controllers being inaccurate when drawing a charge, but the Victron shunt is normally supposed to be very accurate. So not sure what's going on there exactly.
Anyway, there's a bit of feedback.
Any suggestions welcome.
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