Horsefly
Solar Wizard
After the early adopters complained about how easy it was to strip the threads on their prismatic LiFePO4 terminal pads, the market seemed to have responded by offering studs welded onto the original pad, rather than drilling and threading a hole for a bolt. That certainly sounded good to those of us who read all the posts about stripped threads.
For some with the studs, it appears the contact area on the terminal is quite sufficient, and may be almost as big as the original terminal pad. For others of us, the stud is mounted to a pretty small 10mm round pad, as shown in this photo:
That is already a very small area to give enough contact to a bus bar if you intend to carry significant current. There is a slightly larger circular pad (13mm diameter) below the 10mm pad, and then the original terminal pad. To make it worse, most of the good bus bars have a groove rather than a single hole, to allow some variance in spacing the cells. With the hole / groove sized a bit larger than the 6mm stud, it is obvious that the bus bar makes only a small amount of contact with the terminal:
When I noticed this issue I brought it up in @Michael B Caro's thread for the group buy (my original post about it was here). After some discussion about it, my good buddy @Brett V made the brilliant suggestion (here) that some aluminum crush washers (like used to seal the plug on the bottom of some oil pans). So I went out and bought some.
I found two that kinda fit the bill, so I thought I would post about them. First there these: https://www.amazon.com/gp/product/B01ER3U3XY
They have an inside diameter of 12mm, so it is a bit of a loose fit around the 10mm pad, but it does then make contact with the 13mm pad below, and at 2mm thick the top is level with the other pad, so a bus bar can make pretty good contact.
The second one I bought wasn't even a oil pan crush washer, but some sort of stamped then for making jewelry (?): https://www.amazon.com/gp/product/B07SR2BDCK
These have an inside diameter of around 9.3mm, so it is too small to fit over the 10mm pad. However, with a small amount of filing it fits well. It's tight, and makes good contact with both the 10mm pad and the 13mm pad below it. It again looks to be the right thickness so that it is level with the 10mm pad. Here's a photo with both on the studs. The one on the left is the 9.3mm jewelry washers, and the one on the right is the 12mm compression oil pan washer.
Anyway, I hope this helps!
For some with the studs, it appears the contact area on the terminal is quite sufficient, and may be almost as big as the original terminal pad. For others of us, the stud is mounted to a pretty small 10mm round pad, as shown in this photo:
That is already a very small area to give enough contact to a bus bar if you intend to carry significant current. There is a slightly larger circular pad (13mm diameter) below the 10mm pad, and then the original terminal pad. To make it worse, most of the good bus bars have a groove rather than a single hole, to allow some variance in spacing the cells. With the hole / groove sized a bit larger than the 6mm stud, it is obvious that the bus bar makes only a small amount of contact with the terminal:
When I noticed this issue I brought it up in @Michael B Caro's thread for the group buy (my original post about it was here). After some discussion about it, my good buddy @Brett V made the brilliant suggestion (here) that some aluminum crush washers (like used to seal the plug on the bottom of some oil pans). So I went out and bought some.
I found two that kinda fit the bill, so I thought I would post about them. First there these: https://www.amazon.com/gp/product/B01ER3U3XY
They have an inside diameter of 12mm, so it is a bit of a loose fit around the 10mm pad, but it does then make contact with the 13mm pad below, and at 2mm thick the top is level with the other pad, so a bus bar can make pretty good contact.
The second one I bought wasn't even a oil pan crush washer, but some sort of stamped then for making jewelry (?): https://www.amazon.com/gp/product/B07SR2BDCK
These have an inside diameter of around 9.3mm, so it is too small to fit over the 10mm pad. However, with a small amount of filing it fits well. It's tight, and makes good contact with both the 10mm pad and the 13mm pad below it. It again looks to be the right thickness so that it is level with the 10mm pad. Here's a photo with both on the studs. The one on the left is the 9.3mm jewelry washers, and the one on the right is the 12mm compression oil pan washer.
Anyway, I hope this helps!
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