Zwy
Solar Wizard
Recent post in a thread prompted this post, hope you like it, this is how I use poron foam for cell compression. I've charged em both ways, started snug (loose fit) or with poron foam compressed 25% and in 16P configuration, straight line of cells, both in parallel and series.
The amount of expansion was so small I couldn't really measure it, in fact, I couldn't measure any change. What matters is to always charge with a compression fixture in place.
Step 1: I calculate the full length of the pack of cells with the thickness of the stacked non compressed poron.
Step 2: I determine 25% of the thickness of all the non compressed poron and subtract that from the full length in step 1.
Step 3: I take a length of 5/16" threaded rod that is longer than the length in Step 2 with the added thickness of endplates and nuts and slide a pvc pipe over the rod. The pvc is cut to the length in Step 2 and ends are slightly bored out to accept a flange nut with the flange turned outwards.
Step 4: Thread a nut on one end of rod with the flange pointed towards the end not the middle. Thread it on far enough for the thickness of end plate and nut that will be on the outside of the plate. Then thread a nut with the flange outwardson the other end until it is fully inside the pvc pipe from Step 3. This is a full stop for the length of a compressed pack of 25%. It doesn't matter what voltage one starts at, but I never charge without compression fixture in place.
Now for some photos:
This is the end of the pipe reamed slightly to accept a flange nut, I just use a step drill.
Pipe with the nut inserted, flange outwards.
This is with the plate attached, I pulled the nut slightly out of the pipe so it was visible. I cut the pipe on the radial arm saw with a stop so they are all the same length but the actual length is adjusted by the nuts on the rod. The pipe is installed as an insulator to the threaded rod at the side of the cells. Simply thread the inner nuts to the computed compressed length and install cells, poron and end plates. Tighten the nut on the outside of the plate and you will have the right compressed length.
The amount of expansion was so small I couldn't really measure it, in fact, I couldn't measure any change. What matters is to always charge with a compression fixture in place.
Step 1: I calculate the full length of the pack of cells with the thickness of the stacked non compressed poron.
Step 2: I determine 25% of the thickness of all the non compressed poron and subtract that from the full length in step 1.
Step 3: I take a length of 5/16" threaded rod that is longer than the length in Step 2 with the added thickness of endplates and nuts and slide a pvc pipe over the rod. The pvc is cut to the length in Step 2 and ends are slightly bored out to accept a flange nut with the flange turned outwards.
Step 4: Thread a nut on one end of rod with the flange pointed towards the end not the middle. Thread it on far enough for the thickness of end plate and nut that will be on the outside of the plate. Then thread a nut with the flange outwardson the other end until it is fully inside the pvc pipe from Step 3. This is a full stop for the length of a compressed pack of 25%. It doesn't matter what voltage one starts at, but I never charge without compression fixture in place.
Now for some photos:
This is the end of the pipe reamed slightly to accept a flange nut, I just use a step drill.
Pipe with the nut inserted, flange outwards.
This is with the plate attached, I pulled the nut slightly out of the pipe so it was visible. I cut the pipe on the radial arm saw with a stop so they are all the same length but the actual length is adjusted by the nuts on the rod. The pipe is installed as an insulator to the threaded rod at the side of the cells. Simply thread the inner nuts to the computed compressed length and install cells, poron and end plates. Tighten the nut on the outside of the plate and you will have the right compressed length.
