Chris Down Under
New Member
Hi everyone,
Newbie here, however I've been off grid for more than a dozen years. Three years ago I replaced the ageing 48V bank of 600Ah sealed gel lead acid 2V batteries with some LiFePO4 batteries. 4x 12V 300Ah (apparently 306Ah) Pro Power LiFePO4 batteries to be precise. They've worked without fault for three years, and the difference between LiFePO4 batteries and sealed lead acid batteries during the few weeks around the winter solstice is a marked improvement. I have 42x 24V 72 cell solar panels connected to the batteries with locally made Plasmatronics solar charge controllers, but some winter days here you only get 15 minutes of peak sun. That's life. The LiFePO4 work great as the voltage drop issues and inverter cut-out were now a thing of the past.
However, during a recent inspection of the battery room I discovered that the battery terminals were running hot. Hot enough that you'd burn your fingers if left on the terminals during charging. Turns out that BMS cables 6x 10AWG / 6mm2 were soldered to the underside of the battery terminals. I probably wouldn't have arranged the battery design that way myself. You see you have copper wires - tin/lead solder - aluminium battery terminal - copper lugs - stainless steel bolt. All of those different metals have different properties and the end result was that electricity was being converted into heat. And the terminals got hot enough that the epoxy holding them in place on the lid of the battery, no longer held them firmly. Tightening the bolts holding the battery lugs in place was difficult which further compounded the resistance / heat issue. Not to mention that aluminium expands and contracts with heat and the bolts can loosen under even normal conditions.
Anyway, I made a fix for the terminals and connections, and it seems to be working well. The fix might be of interest to other folks experiencing hot battery terminals.
Hot battery terminal fix Pro Power LiFePO4 12V 300Ah battery
Cheers
Chris
Newbie here, however I've been off grid for more than a dozen years. Three years ago I replaced the ageing 48V bank of 600Ah sealed gel lead acid 2V batteries with some LiFePO4 batteries. 4x 12V 300Ah (apparently 306Ah) Pro Power LiFePO4 batteries to be precise. They've worked without fault for three years, and the difference between LiFePO4 batteries and sealed lead acid batteries during the few weeks around the winter solstice is a marked improvement. I have 42x 24V 72 cell solar panels connected to the batteries with locally made Plasmatronics solar charge controllers, but some winter days here you only get 15 minutes of peak sun. That's life. The LiFePO4 work great as the voltage drop issues and inverter cut-out were now a thing of the past.
However, during a recent inspection of the battery room I discovered that the battery terminals were running hot. Hot enough that you'd burn your fingers if left on the terminals during charging. Turns out that BMS cables 6x 10AWG / 6mm2 were soldered to the underside of the battery terminals. I probably wouldn't have arranged the battery design that way myself. You see you have copper wires - tin/lead solder - aluminium battery terminal - copper lugs - stainless steel bolt. All of those different metals have different properties and the end result was that electricity was being converted into heat. And the terminals got hot enough that the epoxy holding them in place on the lid of the battery, no longer held them firmly. Tightening the bolts holding the battery lugs in place was difficult which further compounded the resistance / heat issue. Not to mention that aluminium expands and contracts with heat and the bolts can loosen under even normal conditions.
Anyway, I made a fix for the terminals and connections, and it seems to be working well. The fix might be of interest to other folks experiencing hot battery terminals.
Hot battery terminal fix Pro Power LiFePO4 12V 300Ah battery
Cheers
Chris
