Does the order matter on this electrical connector?

[Donald]

This is a picture of the brush area for bow thruster motor in a boat. The bottom screw holds the wire to the brush and below it a silver colored bracket to an overheat thermistor. The upper screw holds another wire to the brush and an electrical connector to the thermistor.

So for the lower screw I would think the motor brush wire would need the best electrical connection and would be first. Then the bracket for the overheat thermistor. But I could understand if someone said to do the best temp sensing in this area the bracket for the overheat thermistor comes first.

The upper screw I can see no reason why the electrical connector to the thermistor is first.

I think the picture is wrong.

It's many hours to get the motor off the flange and take it apart.

I assembled it thinking the brush wires need the best electrical connection and should go first. Then came across this picture. It's half assembled now. Easier now to take it apart and swap the order then to put it all back together and figure out I got it wrong.

 

[97prizm]

What's the yellow crimped wire on the left side that connects the top and bottom? I would have thought it would be black, red ( negative/positive) and a ground?

 

[Donald]

The yellow wire runs down to the thermistor on the lower screw. The yellow wire is pickup up ground from the upper screw (I think). The thermistor is sensing heat around the lower screw but is not electrically connected. There is a longish black wire from the thermistor running outside of the motor to the relays.

This is a picture from Vetus, the manufacturer.

 

[wings&wheels]

I would contact Vetus and see if they will provide a detailed schematic or advice on proper reassembly. Given the power draw and use, I'd be cautious about second guessing the manufacturer and want to get it right.

 

[Donald]

I would contact Vetus and see if they will provide a detailed schematic or advice on proper reassembly. Given the power draw and use, I'd be cautious about second guessing the manufacturer and want to get it right.

I did and they provided me the picture that I attached.

This is kind of a heavy duty motor and has its own dedicated battery a few feet away. It can only be run for a few minutes.

I would think the wires to the brushes would want the absolute best electrical connection and be on the bottom with the most contact area with the buss.

 

[wings&wheels]

I did and they provided me the picture that I attached.

This is kind of a heavy duty motor and has its own dedicated battery a few feet away. It can only be run for a few minutes.

I would think the wires to the brushes would want the absolute best electrical connection and be on the bottom with the most contact area with the buss.

Does yours charge from the main bus or is it truly a dedicated, isolated battery? I was surprised to learn that some boats are wired that way. We have a 33' on Buzzards Bay and I would be rather unhappy if we lost the bow thruster when it was needed....I treat ours very well!

I don't believe conducting through another clean piece of metal would be detrimental to any meaningful degree. Stacking terminals is common.

 

[Donald]

Does yours charge from the main bus or is it truly a dedicated, isolated battery? I was surprised to learn that some boats are wired that way. We have a 33' on Buzzards Bay and I would be rather unhappy if we lost the bow thruster when it was needed....I treat ours very well!

I don't believe conducting through another clean piece of metal would be detrimental to any meaningful degree. Stacking terminals is common.

When I stack the cables on my boat battery I stack the largest one first so it has the most contact area with the lead pad that surrounds the stud. The power must come mostly through that lead pad as the stud and nut are typically SS and a poor conductor of electricity.

Thus why I thought the wire for the brush should be at the bottom with the most contact area with the bus.

The thermistor just needs to sense temp in case someone runs the bow thruster for a long time and overheats the motor.

I have an AGM battery for the bow thruster and there are connections going back to the engine area to keep it charged. Unsure if it gets charged by shore power or the engine alternator. On my list to find out however.

My boat is on rack storage so basically never any shore power.

 

[Donald]

So a little more reading on stacking of ring terminals. The article was mainly about a battery terminal. The largest cable goes first then up to a max of four. Any washers go above the stack. This is from ABYC. So the bracket that the thermistor is attached to and pulls the heat for the thermistor to sense. I kind of assume it's stainless steel. It's skinny metal looking. If it's between the bus and brush wire it's acting like a SS washer and that should only be at the top of the stack. As a poor conductor of electricity the bracket may heat up because of how it's positioned in the stack rather than because the motor was run longer than in should.

The upper screw has the small ring terminals first then the larger brush wire. That's backwards also.

 

[wings&wheels]

So a little more reading on stacking of ring terminals. The article was mainly about a battery terminal. The largest cable goes first then up to a max of four. Any washers go above the stack. This is from ABYC. So the bracket that the thermistor is attached to and pulls the heat for the thermistor to sense. I kind of assume it's stainless steel. It's skinny metal looking. If it's between the bus and brush wire it's acting like a SS washer and that should only be at the top of the stack. As a poor conductor of electricity the bracket may heat up because of how it's positioned in the stack rather than because the motor was run longer than in should.

The upper screw has the small ring terminals first then the larger brush wire. That's backwards also.

While the stainless bracket may be acting as a washer, it is not as per your description it is part of the calibrated sensing circuit. Again, I would be reluctant to go against the manufacturers practice without a lot of research, but YMMV. Good luck.

 

[Donald]

While the stainless bracket may be acting as a washer, it is not as per your description it is part of the calibrated sensing circuit. Again, I would be reluctant to go against the manufacturers practice without a lot of research, but YMMV. Good luck.

I hear what you are saying but have two thoughts:

1) The upper screw has the small wire ring connector first. It pulls almost no current. The brush wire is on top of the small ring connector and pulls significant current. So no reason why the brush wire should not be first.

2) The lower screw has the SS bracket for the heat sensor first. The bracket needs to pick up heat from the brush area and move it to the thermistor. With it being first in the stack it will act as an insulator to the brush wire. So in reality it will cause the brush wire to get hotter (because it's insulated) than it would if it was first in the stack and so one might get a slightly higher temp reading because of the brush wire being second in the stack.

I do agree that the SS heat sensor bracket would probably pick up heat better if it was first in the stack. But the brush wire pulling high current should be first in the stack to get the best electrical connection.

I have asked the manufacturer this specific question.

 

[PontiacHO]

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