Is it good to shorten the 3 phase wires?

[Mark42]

I have a 48v/1000w rear wheel kit I am currently installing. Because of where the controller will be mounted (in a hard saddle bag right near the axle) I can cut at least 20" off the 3 phase wire lengths. From the axle to the controller will only be about 12 inches.

1) Should I shorten the 3 phase wires for reduced resistance and loss?

2) The kit came with a cooling block. Should I use the 3 phase cooling block even if the wires are shortened?

Thanks for your help!

 

[motomech]

Go ahead and shorten the wires to make your install neater.
I doubt their length makes any difference in performance.
Of more importance are the connectors, in most kits, they are the weak link.
Some folks eliminate them altogether and solder.
I use 3.5 bullet connectors(From Hobbyking, Hobby Partz, Progressive RC, Etc.).

 

[dogman dan]

Since you mention cooling, did it occur to you that the controller should not be inside a box, if you live in anything close to a warm climate? Or have some vents in that box, at least.

At 1000w, wire length won't matter a whole lot, but shortening them to avoid a big coil of wire on the bike is fine. If the kit has molded round waterproof plugs, it might be worth it to leave that intact if you live in a wet climate. But if you have the white square scooter stlye plugs, bullets, or andersons on the kit, then cutting off the plug and replacing it with new contacts is easy, and should be done.

 

[Mark42]

Since you mention cooling, did it occur to you that the controller should not be inside a box, if you live in anything close to a warm climate? Or have some vents in that box, at least.

At 1000w, wire length won't matter a whole lot, but shortening them to avoid a big coil of wire on the bike is fine. If the kit has molded round waterproof plugs, it might be worth it to leave that intact if you live in a wet climate. But if you have the white square scooter stlye plugs, bullets, or andersons on the kit, then cutting off the plug and replacing it with new contacts is easy, and should be done.

Thanks for your response! The saddle bag the controller will be mounted in has a little more than 1/2 cubic foot of interior volume.



Was thinking of putting some vent holes in the front and rear bottom to get some air flow. Also have some heavy gauge aluminum sheet metal that additional cooling fin(s) could be made from. Will see how warm it gets in there after testing.

The wires have eyelets crimped on, both the motor and controller wires, and are supposed to be connected with a ceramic feeling three lug "cooling block". I assume seeing as the block is included with the kit, it is important to use it. Another source of heat, I assume? That tells me that energy is being wasted as heat. Thats what got me to thinking about shortening the wires to reduce resistance.

This same kit is available under a variety of retailers names, some include the cooling block, others do not.

Should I not worry about this and solder the motor wires directly to the controller?



I'm obsessing, aren't I......

 

[wesnewell]

I use 4mm gold bullets and then heat shrink them to waterproof them. That block sucks.

 

[Mark42]

I use 4mm gold bullets and then heat shrink them to waterproof them. That block sucks.

That is encouraging! I have some 2 prong and 3 prong automotive grade water proof quick disconnects that I'll use for the battery and the 3 phase. I'll see how they perform.

 

[bowlofsalad]

http://www.powerstream.com/Wire_Size.htm

 

[dogman dan]

Cooling block? That's creative. In your case, definitely shorten the wires, lose the piece of shit lug connector block, and put a decent connector on that connection.

4 or 5 mm RC bullets, 45 amps Anderson power poles, something like that. Andersons good for experienced crimpers, bullets better for those that prefer a solder on connector.

Re the controller, as long as enough air can get at it, I can see that box being ok for the controller. I'd be inclined to install a sheet of aluminum to the top of the saddlebag, then attach the controller to it so it can have a larger heat sink. So the controller is part of the lid, not underneath stuff you are carrying.

Then possibly some vent holes, but only if they would not let water into the cargo area.

 

[999zip999]

Shorter and fatter the better. I use 4mm bullet connectors. Yes still have Anderson's on some for now.

 

[Doctorbass]

Phase wires between controlle rnad motor:

The shorter and bigger the wires are best it is!

btw I am moving from Anderson pp30 to XT-150 for high current on controller and motor and batt.

Doc

 

[Mark42]

Yes, I have to agree. After driving around a while, the "cooling block" junction block showed that the thinner wires from the motor were warm where the thicker wires from the controller were cool. So I will cut about 2 feet off the motor wires. This will reduce resistance, and increace the wattage carrying capacity of the remaining 12 inches of wire.

Will do this next week and report back.

 

[dogman dan]

Good to do it for sure. But at your level of watts, it's not as crucial as when you run the kind of power the Doc does.

Sure, you are losing some, but you won't gain 5 mph by shortening those wires. Mostly, you need to be rid of that cheesy connector, which could heat up and melt wires. A poor connection will definitely melt down.

 

[Mark42]

Thanks, Dogman. I totally expect to gain 25 or 30 mph! LOL!

But seriously, all I am really interested in is distance. Anything that will cut wasted watts is a good thing. Even if its only just a fraction of a percent!

 

[manman]

Thinking of making my phase wires a little shorter to make the cramp space more tidy,but will it effect the performance of the bike.

 

[E-HP]

Not a problem. In general, shorter is usually better for any wiring, as long as you aren’t planning on moving stuff around later and need the longer conductors.

 

[manman]

Thank you for the reply and info