Lowest resistance phase connections??

[StudEbiker]

I want to eliminate as much waste as I can in my system and I feel like the phase connections are not as good as they could be. Right now, I just have them plugged into the standard bullet connectors. I just sold a kit that I had been riding awhile and I saw that even on only 22A the phase connectors had seen some heat.

I am thinking that soldering the wires is the best option for the least resistance, but I thought I would ask here and see what the conventional wisdom is.

 

[Drunkskunk]

If you mean those craptastic automotive grade bullit connectors, then yes, ditch them. They're high resistance and don't make a very solid connection.

But RC grade bullit connectors are fairly good. So are Anderson Power Poles.

 

[StudEbiker]

Andersons are so bulky. If soldering is as good as an Anderson or RC bullet, then I think I'd rather just solder them.

Is soldering as good as another type of connector? I want to use the lowest resistance possible connection there. Beyond running one wire directly from the motor to the controller, what is the best?

 

[999zip999]

Anderson are easy but not that good. They will melt with amps. I would solder shrink wrap. Not hard to unsolder.

 

[neptronix]

I use dual 4mm hobbyking bullets. Usually have a crapload of those lying around, so why not.

 

[ZOMGVTEK]

If you want the next closest to a single run of wire, crimp the wires together with a crimp collar and solder it up. Only issue with this design is roadside flats, or controller shorts can be a serious issue. Thats why quality connectors are a good idea.

45A Power Poles are not that large. They would be my recommended route, and they tend to be happy around 100 phase amps or less with thick wire to heatsink the contacts, and proper crimping and soldering. Above 100 phase amps, or if you just want an easier to use connector with lower contact resistance and easier assembly, run the 75A PP's. They are a bit large, but they're a solid connector.

I'm not a big fan of the 4mm bullets, but they are cheap, and do work fine for most applications. The larger bullets tend to be better.

 

[friedwires]

ring terminals and bolts work great

 

[StudEbiker]

If you want the next closest to a single run of wire, crimp the wires together with a crimp collar and solder it up. Only issue with this design is roadside flats, or controller shorts can be a serious issue. Thats why quality connectors are a good idea.

This is in a mid-drive application so no worries about flats being a problem.

 

[rkosiorek]

solder is made from a mixture of 60% tin and 40% lead. both of which are terrible conductors of electricity compared to copper. lead free solders are usually 96% tin and 4% silver. silver may be a better conductor than copper, but there is hardly any of it there.

a good clean, tight, properly compressed copper to copper crimp connection will always be a better than a soldered joint. or a poorly crimped and later soldered connection. although i guess the solder does help a poor crimp by giving it some mechanical strength.

copper is 12X as conductive as lead and 6.5X as conductive as tin. the use of solder should only be to add mechanical strength plus some corrosion protection, and never to try to lower the resistance, because it won't. it can't because it is less conductive. ideally on pc boards the solder is used only for mechanical strength. plus the fluxes used for lead free solders are chemically aggressive and really suck at the corrosion resistance part. use a regular rosin core solder if you can.

best connections, brush the wire and the inside of the connector clean of all oxides using a copper brush, the surfaces should be shiny. crimp them immediately before an oxide layer can form. coat lightly with a dielectric grease to prevent oxidation.

if you must solder use only enough to lightly tin the surface and provide corrosion protection.

rick

 

[ZOMGVTEK]

Solder isn't super low resistance, which is why you should strive to make a solid mechanical connection first. Adding solder afterwards really helps to ensure the connection is robust, and its not going to raise resistance.

The idea is to use a crimp collar to compress the strands of one wire onto the other. This makes the crimp collars composition dramatically less significant than if you were to rely on it to conduct by compressing the wires on each end of the collar. The soldering process tends to clean the surface of the conductors, and protects the metal from further corrosion, while generally wicking into the strands past where the insulation was removed, acting as a strain relief. Basically, crimp the wires well enough so that you don't need to solder, then solder it anyways.

This really sounds like an extremely unnecessary step to take unless you plan on running a few hundred amps, or you are awfully low on space. It's going to make servicing a motor/controller a bit harder.

 

[recumbent]

Crimp collars are what i use for my ebike after cutting off the connectors, and thicken the phase wires.

Had nothing but good luck for years, and it's fast work to boot.

 

[dogman dan]

I tend to agree with the crimpers. Nothing beats a good crimp, while nothings worse than a bad crimp.

But unless you are looking for more than 40 amps, I would have to say the soldered 4mm bullets are pretty good connections that may be easier to learn to do than really good crimping.

But in the long run, learn to both solder, and do a good crimp.

 

[cwah]

How much wh is actually lost from soldering? It's maybe so low that it doesn't worth considering. Any way to measure that?