Charge connector

In many cases, the charge connector breaks on the Yamaha batteries, but the BMS is still okay. It is not possible to buy the original connectors. Our solution idea now is to swap the BMS, and go over to normal jack plug. This works, but it is a lot of work, and we need to sell a new charger too. It would be preferable to just swap to another 4-pin connector, and maintain the communication.

The connectors are:

4 pin
Must support at least 4A - the original chargers are 4A
16 mm outermost diameter
11 mm inner circle diameter
9.4 mm diameter in the innermost cut

The charger cable is 4-core:

Red
Black
Yellow
Blue

The BMS needs 4 wires:

Red
Black
White
Blue

No-collar version

Collared version

The outer diameter of the collar is 22 mm.

Jack socket

The jack socket's thread has to be machined off to be able to slide it in to the hole on the lower part of the battery housing. Other than that, it fits in nice!

Possible solutions

Hirose

Hirose produces the original plugs for Yamaha.

This might be a compatible socket.

The HR34B series is similar, HR10, HRS4F.

SP16

This one would work, and it has a socket (called flange) which is slightly too big, but not crazy too big. We would need to drill the hole. Supports 5A.

GX16

Rated 20A!

Circular round type - back mount placed in:

The hole diameter would have to be 15.5 mm to install it.

XLR

The hole diameter would have to be 23/24 mm to install it. On the ones we have, I measured that a 21.5 mm hole would do it.

Mini XLR

Rated 5A.

On ali, buy socket here.

On ELFA:

Socket
Plug

GX12

Available here.

The competition

Powatechnic

Based in Sheffield
See eBay listing. They just swap the plug on the charger itself. It is a charger repair, not a battery repair.
They also repair the battery side for more money.
Their main focus is wheelchair battery solutions, not bicycle batteries.
They also used to sell compatible chargers on this listing. They make it clear that "This charger is an aftermarket alternative NOT the original type."

Powerbutler

Powerbutler sells adapters to fit their fancy chargers to Yamaha batteries. Not really competition, but it shows that they have access to the right part!