Part of the compression fitting (the part with an external thread) = spacer.
Lawrence.
Lawrence.
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Roberts R66
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23-02-2019, 12:43 PM
You've got me even more confused than ever now, Lawrence!
Surely the part with the external thread has a 15mm clearance hole in it with a slightly larger, tapered section equivalent in length to half the width of the olive. It is the cap that fits over that that has the internal thread and a much larger cavity which ends in the back end, again with the 15mm clearance hole and taper for the other end of the olive. Without one to physically examine and measure, what I'm have trouble in visualising is that, even with the minimum amount of engagement between the two parts is that the length of the internal space could possibly be as great as the 16mm required.
23-02-2019, 01:09 PM
Subtract the total length of the stacked cells from the total length of the original battery....a spacer is need.... the compression type stop end (part thereof)
Lawrence.
23-02-2019, 02:26 PM
Well done.
You have spotted that you have to subtract the 16mm for the stack of the cells from the 35mm length of the BLT121 battery to get the required length of the spacer needed. Once we have worked out what part of the stop end I used we can go on to work out why it is polarity sensitive. There is a reason. Look at the two photos to establish what part of the pipe fitting I used and then we can see about this polarity issue.
What-ho chaps….Wrong spacer polarity = reduced effective length of the new battery so far as the Avo conacts are concerned.
Lawrence.
23-02-2019, 05:55 PM
It is not the length Lawrence. That is the same both ways round.
Terry almost got there with why the polarity matters. There are two reasons to go for.
23-02-2019, 07:06 PM
The cell won't care which end of the fitting its +ve is connected to but the battery contact in the Avo will care which end of the fitting is presented to it if a sharp point contact connection is required for the +ve.
The cells -ve connection route to the Avo's -ve battery contact should be obvious, even to a blind man. Lawrence.
And just to reiterate another way.....fitting ID approx. 15mm, diameter of the -ve end area of the cell =:
http://www.farnell.com/datasheets/1496885.pdf Chamfer interference would be inevitable. Lawrence.
24-02-2019, 01:09 AM
You have got it Lawrence.
The pipe end of the fitting has a 15mm bore right where the dart shaped contact needs to make contact with the battery. So the pipe end has to face the stack of cells. So now there is that polarity issue. You say chamfer interference and I guess you mean that when looking at page#7 of the data sheet for the cells you have spotted that the negative end of the cell would sit perfectly in the chamfer shorting the cell out. That is right the positive end of the cell is flat and is almost the same size as the male thread. The pipe fitting has to go on the positive end of the stack to avoid a short making it truly polarity sensitive. |
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