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Discussion Starter · #1 ·
We are a second year EV team and are looking for alternatives to amphenol radlok maintenance plugs that we used last year. Also, if you have or have had self designed maintenance plugs, could you share some relevant information? It would be of great help.

Our battery configuration is 100s1p with a continuous current of 75A

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It will help to narrow down the large number of options if you rank your particular needs for the connector.

What is it about the Radloc that you are trying to avoid?

What goal were you trying to achieve by using Radloc in the first place?

Do you require no loose fasteners?

Do you require tool free connect/disconnect? (eliminates simple barrier strips)

Do you require test points or sealed contacts?

Must it be robust against arc damage?

Do you prefer individual connectors or gang connect/disconnect?

What is your "do not exceed" cost in terms of money and time?

One way to do DIY gang connect is: (n = number of cells)

X3 or more as needed: 3D print a jig/backshell/alignment fingers/mold cavity that holds n solid copper wires(or very consistent tinned wires) at constant height and pitch. Lay in all the wires and clamp down to jig with something temporary. Pour self leveling slow cure epoxy to just under 2/3 wire height. When cured, mill down 1/3 thickness of exposed side of conductors so milled surface remains just proud of epoxy surface. 2 identical parts should now be able to mate if held together. The 3rd connector is to be used as a positive mold plug to create silicone covers for one or both sides of the connection. Additional connectors can be made at the same time for external charger/conditioner, mock up battery built from array of lab supplies. Or a pair of connectors can be joined by n shunts with molded-in-plug A/D datalogger to create a plug in current monitor that can be taken out of loop for high performance runs.

One advantage of this design is the elimination of a 2nd or 3rd connection point which is created any time you use a crimp or solder on connector. This puts one wire directly in contact with another wire without any intermediate dissimilar conductor. As such, it might serve very well for high current connections directly to motor coil wires, though I'm a bit nervous to replace motor terminals with a home designed connector. Bye bye warranty.

In use, one half is on flexible wires, covered by silicone skin until last minute before connection. The vehicle half is fixed to something rigid which will accommodate the cam action clamp. Both ends of the vehicle side mount contain tabs with a 3/16" hole. Cam is made from 1/2" round nylon rod a bit longer than connector width. 3/16" pivot axles are carved out of the ends, off center creating the cam. The nylon rod is flexed so its axle nubs can be inserted into the tab holes. The cam tightens against the back side of the battery connector making a sandwich of cam, battery connector, fixed vehicle side connector.

You need to create some kind of lever to tighten/loosen the cam. This can be a slot or hole into which you insert a handle, or flats cut to accommodate an open end wrench, or strategically placed grooves to allow tapping screwdriver with a mallet. These may only be needed the first few times, but provide a backup mechanism in case the pip pin is lost. A pip pin is tethered to the vehicle side as the handle so it may also be used in the next step. A fiberglass rod might be a better material choice.

Mate/unmate several times and wiggle/vibrate the connection to 'break in' the cam and connector. When you are satisfied that the connection is stable and tight, we need to create the lock. With a hand drill and bit the nominal size of your pip pin, at a far end of the connector beyond the wires, drill a hole that passes through the nylon rod and both halves of the connector. You may have to file a flat on the rod before starting to drill.
For creating additional connectors as described above, repeat the process, but start the drillbit inside the existing holes in either the cam rod or the other connector. Secondary connectors might not line up exactly the same as the prime battery/vehicle pair if the milled height is slightly different. So first, try to keep the milled height consistent. If lock misalignment remains, try ovaling the hole in the secondary connector only. Do not enlarge the hole in the cam or prime connectors.
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