Battery Enclosure - Part II, Milling Terminal Blocks

One of our goals is to be able to easily remove and add individual batteries to the group.

To do this we would use terminal blocks to connect them together.

Below is a picture of some blocks we used in our distribution panels. The second one at the bottom has the four large holes for the large battery cable we are using and a bunch of smaller ones we don't need. However, we need up to 6 large holes and a nice big chunk of metal to take all the power going through it.

After some searching, we discovered there was nothing we could purchase that would meet our needs without spending upwards of $50 per block, and we need 3 of them. We were able to make 3 of them at a cost of about $13 each, not including our labor.

This is the first time we have made a terminal block. At the far right is the 5/8 in by 5/8 in, 1 foot long bar of copper. We are planing on two blocks with length of 4 in and one with length of 3.5 in (for the ground connection).

Right off the bat, by using copper instead of the commonly used aluminum bars, we are using a material that has around 40% less electrical resistance (source).

The CAD design.

Starting to make the wire holes.

Doing the top holes. The edge-most two are the mounting holes. The ones that are right above the wire holes are where the screws go to pin the wire.

After drilling many holes, one lesson learned was to drill the top set screw holes first, then mill the wire holes second. Otherwise, there is all this burr (rough metalness) that appears on the inside, that is difficult to remove.

Looking good.

Tapping the top holes (5/16-18 tap) for the set screws.

Et voila.

We have been doodling the idea around that we could crank out a couple dozen of these. Before we do that, we will use these and see how well they work for us. Possible problems and obvious design improvements should be seen fairly quickly.

After some time, they would need more design work, calculations and some standard requirements such as UL certifications and so forth. In the end, we would end up doing our own testing most likely.

The main requirements of the terminal blocks are to make good electrical connections and to withstand the current throughput without exceeding in temperature by some reasonable amount, touchable to the human hand. This assuming no harsh environmental conditions.