After selecting AWG 12 for the copper wires that will act as fuse, it is time to solder those on the copper busbars.
Due to the difference in thermal mass between a wire and a busbar, soldering them together can be a challenge. A common soldering iron is not powerful enough to locally heat the bus bar. And heating the busbar in an oven will make it impossible to solder a bunch of wires without having to hold all of them somehow until the busbar's temperature drops below the solder's melting temp.
So I bought a hot plate ($10 @ Walmart) and used it to heat up each busbar enough for the soldering iron to melt the solder on a small local area. This video shows that method:
By the way, the results were disappointing for a while, with poor solder melting transition, weak solder joints, and messy looking solders. That is, until I switched to lead based solder instead of silver bearing solder. Was a breeze from then on, with fast and homogeneous melting, fast hardening and clean shiny looking solders. So, onward to 8 bars and 96 wires...
Overall, this method worked well, if not quickly, and I was soon attaching the busbars to the subpacks:
And, voila, the completed installation with the 2 subpacks:
"All" that's left now is to connect the new battery pack to the inverter ! What a nice feeling 😎 Boop !
Well, wait, sounds easier that it actually is though... Both the inverter and charge controllers need to be reprogrammed from a lead battery setup's parameters to a lithium pack with very different characteristics: max / min voltages and currents, no re-float/bulk, no equalization, different temperature compensation, etc. Frankly that's probably one of the riskiest areas of this project, as I did not do a full programming compatibility analysis before jumping in and committing money and elbow grease.
So for now I will be using a narrow capacity / voltage range, staying well clear from the full SOC and DOD possible with these batteries. Until a BMC is installed (coming DIY project), and until the inverter charger's parameters get carefully analyzed and updated.
Hmmm, does that possibly mean disappointment, disillusion, and an embarrassing face-plant around the corner ? Maybe. Frankly I don't fully know 😟 Oh the suspense...
Due to the difference in thermal mass between a wire and a busbar, soldering them together can be a challenge. A common soldering iron is not powerful enough to locally heat the bus bar. And heating the busbar in an oven will make it impossible to solder a bunch of wires without having to hold all of them somehow until the busbar's temperature drops below the solder's melting temp.
So I bought a hot plate ($10 @ Walmart) and used it to heat up each busbar enough for the soldering iron to melt the solder on a small local area. This video shows that method:
By the way, the results were disappointing for a while, with poor solder melting transition, weak solder joints, and messy looking solders. That is, until I switched to lead based solder instead of silver bearing solder. Was a breeze from then on, with fast and homogeneous melting, fast hardening and clean shiny looking solders. So, onward to 8 bars and 96 wires...
Overall, this method worked well, if not quickly, and I was soon attaching the busbars to the subpacks:
And, voila, the completed installation with the 2 subpacks:
"All" that's left now is to connect the new battery pack to the inverter ! What a nice feeling 😎 Boop !
Well, wait, sounds easier that it actually is though... Both the inverter and charge controllers need to be reprogrammed from a lead battery setup's parameters to a lithium pack with very different characteristics: max / min voltages and currents, no re-float/bulk, no equalization, different temperature compensation, etc. Frankly that's probably one of the riskiest areas of this project, as I did not do a full programming compatibility analysis before jumping in and committing money and elbow grease.
So for now I will be using a narrow capacity / voltage range, staying well clear from the full SOC and DOD possible with these batteries. Until a BMC is installed (coming DIY project), and until the inverter charger's parameters get carefully analyzed and updated.
Hmmm, does that possibly mean disappointment, disillusion, and an embarrassing face-plant around the corner ? Maybe. Frankly I don't fully know 😟 Oh the suspense...
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