What's the best plug-in wire connector to install on the motor to battery wire?

[npt45]

I am currently installing a used and assembled bbs02 kit setup that I recently bought, removing it from its original bicycle onto my own mountain bike. It's my first attempt at building. From install videos I've watched on these Bafang kits, I think there should have been some kind of plug-in connector along the wire that goes from the motor to the controller/battery.

But on mine now, the original installer apparently made a homemade spliced solder connection along that wire (well 2, red and white), but also first routed it through a 1" welded gap in the old bike frame before soldering, so there was zero way to remove the motor and controller from the old bike without cutting those connections, which I did.

I'd like to make a reliable and sturdy slide-in or plug type connection along this wire again, for easy future disassembly for maintenance or whatnot.

What is the best method and product for the job (waterproof, secure, and adding minimal wire resistance)? Or, should I just do a lineman splice and resolder it for the most reliable connection?

[stts]

My BBS02 came with an XT60 connector. So that should be adaquate. May as well get the anti spark variety with the green marking. Then you won't get a big sparking when you plug your battery in.

[AZguy]

A very sizable portion of folks are using the XT90 for discharge, in particular the anti-spark version (XT90-S)

They are very robust, handle large gauge wires and assembled properly are quite weathertight and handle high vibration environments very well

They anti-spark version is almost essential for batteries without a power switch since plugging a live battery into a controller will always generate a very lark arc that will damage the contacts - last time I checked XT60's weren't offered in anti-spark and most folks opt for the similarly priced XT90's anyway... In electric bikes I mostly see XT60's on the charging side of the battery

They are relatively inexpensive when compared to other suitable connectors and will handle far more current than the BBS02 will ever draw - better to have a lot of margin in these applications though

Likely the only downside to any of the XT connectors is they require soldering and to do it properly requires a good decent iron and some reasonable skill.. anderson connectors are common for BBS02 sized installations and are crimp instead of solder but I can't recommend them for any application where arcing is a potential (it will kill them in short order) or for outdoor or high-vibe applications like a bicycle - IMO they are more suited for "bench" applications and for that they are very good

YMMV

[73Eldo]

What sort of connector is on the battery that you have or are getting? I would just put the matching connector on the motor unless is something completely inappropriate.

Its easier to replace the motor end connectors for reasons. Biggest reason is there is no power there so there are no extra concerns or worries while you are working like there will be when working on the battery end. 2nd reason is the motor usually has wires extending out of the housing were some batteries or sled/mounts the connectors are mounted to the housings. If your battery is the type that has a docking sled mount sort of thing then that at least allows you to disconnect the battery so you don't have to work 'live'.

The danger in working around or with 'live' battery wires isn't really that you are going to shock yourself. With some systems and voltages that can start to be a real concern but the bigger issue is accidentally shorting or connecting the wires in some way. Many e bike batteries are storing a heck of a lot of energy and accidentally shorting the wires can let it all out real quick.

[AZguy]

Sounds like it was just butt spliced/soldered so no connector at all and he's asking what's best for an inline solution

[npt45]

Yup, there is presently no connector, one wire end goes into the motor housing somewhere, and the other end goes mysteriously into the battery dock (docking sled type mount) and controller (didn't disassemble to look). I'm leaving those two ends alone, just need a pluggable bridge between them. The system worked and tested great on the original bike, so presumably no need to mess with it. The original installer was quite picky about putting dielectric grease on all connection points too. And, no risk of working on a live wire with the battery removed.

[npt45]

A very sizable portion of folks are using the XT90 for discharge, in particular the anti-spark version (XT90-S)

I think that sounds like a winning solution, and I see they're inexpensive enough.

Would you suggest buying just the yellow ends (and then how should you solder into it? easy enough?), or buying a set with pigtails already joined, and then soldering wire to wire? I haven't soldered either way before, only watched some how-to videos.

[AZguy]

I would say by far the optimal is to just solder to the connectors but it wouldn't necessarily be the best place to learn to solder

Large wire soldering presents some challenges. The large wires will act like a really good heat sink and just suck the heat from the work into the wires (same issue if just soldering wires together which I don't recommend, I'd use proper crimp sans solder) and this promotes melting the connector body and wire insulation. It's not just about having a powerful iron, it's more about having an iron that has very low thermal resistance between the heating element and the tip and can react very quickly to the decrease in tip temperature. I also plug the connector I'm soldering to into an unused mating connector - this helps draw some of the heat from the contacts to minimize softening the connector body and if it does soften it will keep the contacts straight. Another important thing to do is use a proper solder (Sn63 with mildly activated flux is best IMO) and *very* important to also use additional good electronic grade flux on the wire and contact prior to applying heat - do not use any other type of flux or solder, only those specifically for electronics!

The floor price for what I consider a proper iron is going to be around $100 or a bit more (I can give a recommendation) which may seem like a lot but you can get a lot of iron (a true soldering station) that will do anything from the tiniest of tiny to ultra grande and everything in between.

But it does take some practice and if you know someone that truly knows their stuff - unfortunately I've met so many people that think they know but aren't really in the business and don't really get it - and a "garage shop" electronics guy is generally worse than a "garage shop" mechanic this way - or bite the bullet and learn... If you were nearby I'd just do it for you, I do this often, it doesn't take any time at all but then again I've got a well provisioned electronics shop... OTOH it's a good skill and tools to have if you are going to be around electric bikes and any other electronics (which is only going to pervade our lives more with time)... Just buy extra connectors (getting a five pack often cost about what two singles would and it's good to have spares anyway), cut the wire long, and just be patient when things get messed up since it's all part of the learning process...

Heat shrink, self-amalgamating silicone tape and dielectric grease are your friends too ;-}