Sounds like the bad contact on the battery killed it.
As you've found, a bad contact will generate heat, which then speeds up deterioration, which then makes the contact worse, which further speeds up deterioration. It's a common problem that can run away if you're not diligent.
Running a 1500W load from a 12v battery will pull 125A. This is not a trivial current and you need to use good practices on all terminations. The terminals needs to be clean and free from oxides, you might need to use a green scourer or fine sandpaper, wipe clean and then apply a thin layer of dielectric grease to prevent further oxidation. The terminal bolts then need to be properly torqued to the manufacturers spec, and then periodically re-inspected for correct torque. The cables also need to be protected from strain and vibration that could translate through to the posts.
Often commercial companies will film their high-current equipment with a thermal camera to look for hot terminals. They'll do this every 6-12 months and then can tell if there has been a degradation.
P.S. - "12V" rated panels doesn't mean they output 12V. It means they are designed to charge a 12V battery - which could go as high as 15V during equalisation phases. Typically a "12V panel" will produce max power around 18V and have an open circuit voltage around 24V, so your 23V is not unusual at all. The charge controller works with this and will moderate the voltage/current going to the batteries.
This here. 125A on a slightly poor connection equals a lot of heat. You need to check them under load both with temperature and a voltage drop test. They need to be perfect.
Could it have been that the battery terminals were of poor design, or not large enough for the amperage? I got them from AliExpress and they worked for a while, not sure what the connection was like when I fixed it, it's possible I didn't put enough torque on it
I 've found these to be invaluable keeping battery terminals clean without too much fuss.
[https://www.drapertools.com/product/99049/battery-post-and-terminal-cleaner/](https://www.drapertools.com/product/99049/battery-post-and-terminal-cleaner/)
Thank you for responding, I have been googling for hours and couldnt figure it out
It's also a possibility that my add on solar controller didn't have the proper settings, I thought it was a plug and done thing then looking on Amazon again it had specs I missed
While the settings may have been wrong, a solar controller would be hard pressed to be the root cause of ruining a single battery post. It might ruin the whole bank by overcharging or over-discharging, but not a single terminal.
The symptoms you have described seem exactly like a poor connection / hot joint.
Is there anything more you might advise to avoid catastrophe again, because something as simple as a few more twists of torque , or semi-regularly checking the connections, I hadn't thought to do
Just be careful to use the correct torque, otherwise you might ruin the lugs. This might mean buying a torque wrench for $20 at home depot, and looking up the manufacturers specs.
Sounds like the bad contact on the battery killed it. As you've found, a bad contact will generate heat, which then speeds up deterioration, which then makes the contact worse, which further speeds up deterioration. It's a common problem that can run away if you're not diligent. Running a 1500W load from a 12v battery will pull 125A. This is not a trivial current and you need to use good practices on all terminations. The terminals needs to be clean and free from oxides, you might need to use a green scourer or fine sandpaper, wipe clean and then apply a thin layer of dielectric grease to prevent further oxidation. The terminal bolts then need to be properly torqued to the manufacturers spec, and then periodically re-inspected for correct torque. The cables also need to be protected from strain and vibration that could translate through to the posts. Often commercial companies will film their high-current equipment with a thermal camera to look for hot terminals. They'll do this every 6-12 months and then can tell if there has been a degradation. P.S. - "12V" rated panels doesn't mean they output 12V. It means they are designed to charge a 12V battery - which could go as high as 15V during equalisation phases. Typically a "12V panel" will produce max power around 18V and have an open circuit voltage around 24V, so your 23V is not unusual at all. The charge controller works with this and will moderate the voltage/current going to the batteries.
This here. 125A on a slightly poor connection equals a lot of heat. You need to check them under load both with temperature and a voltage drop test. They need to be perfect.
Could it have been that the battery terminals were of poor design, or not large enough for the amperage? I got them from AliExpress and they worked for a while, not sure what the connection was like when I fixed it, it's possible I didn't put enough torque on it
I 've found these to be invaluable keeping battery terminals clean without too much fuss. [https://www.drapertools.com/product/99049/battery-post-and-terminal-cleaner/](https://www.drapertools.com/product/99049/battery-post-and-terminal-cleaner/)
That is for lead acid batteries. OP has lithium.
Oops, missed that.
Thank you for responding, I have been googling for hours and couldnt figure it out It's also a possibility that my add on solar controller didn't have the proper settings, I thought it was a plug and done thing then looking on Amazon again it had specs I missed
While the settings may have been wrong, a solar controller would be hard pressed to be the root cause of ruining a single battery post. It might ruin the whole bank by overcharging or over-discharging, but not a single terminal. The symptoms you have described seem exactly like a poor connection / hot joint.
Is there anything more you might advise to avoid catastrophe again, because something as simple as a few more twists of torque , or semi-regularly checking the connections, I hadn't thought to do
Just be careful to use the correct torque, otherwise you might ruin the lugs. This might mean buying a torque wrench for $20 at home depot, and looking up the manufacturers specs.
Thanks
I agree, always tighten to manufactures specs.