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There isn't much innovation here, just the experience gained from trying so many different types.

Connectors, in one form or another, probably account for the greater part of reliability issues. E-Bikes expose connectors to 3 hostile environments:

  • damp
  • current
  • vibration

The first two form a deadly partnership: as connections corrode from damp that causes their resistance to rise and the high current causes heat that damages insulation etc.

The Bad Guys

Most e-bikes have some or all of the following types of connector:

2 Pole Power
Male and Female Bullets
0.1" Latching Signal Connectors

All of these I have found to be at fault in the past and better alternatives exist!

2-Pole Power Connector

These are moulded on and so the only way to reuse them is to splice other wires on. The wire is designed for crimping, so you will need a lot of flux and remember to put some heatshrink tube on, first. These generally don't shake loose (a cable tie can be fitted between the wires to hold both parts together), but they do corrode in the damp. To protect them I use 250mm inner tube with cable ties both ends.

Consider Neutrik Speakon for chassis connectors, Deans Ultra or Andersen Powerpole for wire-to-wire.

Male and Female Bullets

These are very widely used, but are not up to the job - the metal simply isn't strong or springy enough. There is no positive latching or good friction surface and they either come loose or the crimp fails. If you must keep them:

  • solder the wires, after sliding the plastic sleeve back
  • squeeze the female bullets tighter
  • fit cable ties to pull the connectors closed
  • Sleeve them with inner tube if they could get wet

Don't fit them to your life-support system: consider 4.0mm bullets for multi-wire connections or Deans connectors for pairs

0.1" Latching Connectors

Once in place and kept dry these work OK, but they are not designed for frequent detachment (Currie, take note) and they WILL corrode in the damp. Pins and sockets can be soldered on with care, but they aren't reusable, so get spares.

The Good Guys

Deans Ultra

This connector is cheap, easily sourced (any Radio Model Shop), easily soldered, good for 30-40Amps and relatively undegraded by damp.

The terminals readily 'tin' for soldering but don't get it so hot that the plastic melts (it can). If in doubt, fit an 'opposite sex' connector when soldering.

For compatibility, make the 'across' pole positive (Red).

Once pushed together, they won't fall apart. Get 'em on ebay, along with bullets.

Neutrik Speakon

Standard issue to all Rock-Band Roadies, these connectors are good for 30 Amps and hundreds of operations. They are intended for wire-to-chassis use, but in-line couplers are available. The plugs have screw terminals for eaasy fitting

The basic 2 or 4-way plug and chassis socket are cheap and stocked by Maplin, RS, Farnell, Rapid etc. There is an 8-way plug, but it is huge.

They aren't waterproof, but don't mind a bit of a splash.

Andersen Powerpole

For high currents, these rock.

These are not waterproof but are great for high currents - the heavy duty type carries 100Amps and more. The holders are symmetrical and can be linked together to make polarised, multiway heavy-duty connectors.

The pins can be crimped or soldered. They must be covered to prevent corrosion. Get them From RS, Farnell or 4QD

Bullets

Again from the world of Radio Modelling these 4mm bullets are ideal for single wire connections of 80-100 Amps. Use heatsrink sleeves to cover the sockets and the exposed part of the plug. Try to coliur code them Red +ve and Black -ve to avoid mistakes! Also use a female socket for battery +ve and a Male plug for battery -ve. That way the 'live' pin has a heatshrink cover and it is harder to accidentaly revwerse the polarity,

Once pushed together these will not fall apart. Get 'em on ebay, along with Deans parts.

These 2mm bullets are good for 20 Amps These 8mm bullets are good for 160 Amps!
2mm Bullets 20A 8mm Bullets 160A

Sureseal

The Sureseal is WATERPROOF down to 10m and resistant to just about anything. Rated to 15 Amps, this is an ideal motor connector. The 3-pole connector is relatively compact but they get a lot bigger as # poles increases, because they are insulated well in excess of ebike voltages.

Made by ITT and available from RS and Farnell and specialists. The Mini Sureseal are available for 2 and 3-pole up to 8 Amps.

The tooling is a frightening price, but pliers and solder do a good job and the pin/socket can be inserted without the special tool. Heat thr rubber and it becomes a bit less rigid when inserting pins. Use glue lined heatshrink to seal to the cable and forget motor connection problems

Superseal

The Superseal is favoured in the auto business and widely available - start at Vehicle Wiring Products for this and other wirimg bits.

I haven't used these a lot and the seals are quite fiddly, but they do a perfectly good job and more compact than Sureseal for 5-pole and above

Signal Connectors

I try to avoid wire-to-wire connectors and design most of my gear so that the cable enters through a gland and the fits wire-to-board. In this territory there is a huge range of 0.1" DIL (Dual In-Line) IDT (Insulation Displacement Terminal) connectors that are gold flashed. AMP and Molex are the main suppliers and stocked by RS, Farnell, Rapid

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