Lewmar ELS part two

In the picture above the modifications that I decided on for modifying my Lewmar 58 single speed ELS control box from 12V to 24V. The important difference is that I went back to the original 12V contactor and added a LM2596 DC-DC buck converter that outputs 12V to power the whole ELS.

I made this decision after working on my 2-speed ELS controllers that use a double set of double-throw contactors to reverse the motor direction. I can’t simply buy those for a 12-36V voltage range so I would have to replace them with a 24V version which costs $125 for a knockoff set or double that for original (SW182 contactor). A knockoff means it will probably be fine, but the 12V versions I have are better. Also, at 1A coil current and very little consumption by the ELS circuit itself, I can add the LM2596 based DC-DC converter for just a couple dollars and these have proven very reliable for me.

I also decided to change the housing: I wanted the contactor studs opposite of the shunt studs so that the DC negative cables pass on one side and the DC positive cables on the opposite side, eliminating 90 degree bends in big cables.
Also, I added a nice connector for the winch operation switch instead of the extra junction box. If we want to use the motor thermal cutout, those connections can be made externally with crimp connectors. You can see the tiny converter mounted underneath the connector chassis part. There is free space on the other side of the contactor, where I plan for a microcontroller in the future.

Next is the 2-speed controllers for our Lewmar 66 primary winches which are more complicated. Below pictures showing details:

There’s 4 cables going from the controller to the winch motor: Field1, Field2, Armature and Negative. There’s 6 studs on the housing. The circuit board is larger of course but basically the same for the shunt and comparator part, even with the same test points. Of course there’s two power transistors for the two contactors and the added logic for the two speeds. A quick test showed that the reference is set to 220A. This is much less than for the 58 single speed winch so what happens here is that at 220A the controller reverses the motor direction with engages the low gearing high power second speed of the winch. After owning Jedi for 24 years I now discover these winches switch to low gearing automatically. I always assumed they didn’t install the second switch but it’s automatic and I never noticed 😃

I decided that if I want to modify these to 24V, I can simply add the same converter here as only one contactor is energized at a time. Also, there’s enough room in the box for that, so for now the only modification will be adding the connector for the winch switch instead of the annoying junction box.