Cycling UK Forum

Thanks for the advice on my previous thread. Can I now get advice on wiring in the battery.
The motor has these wires coming out of it The battery has this connector and was supplied with this short bit of wire The other end of the wire is bare cable I assume I attach the bare cable ends to the connectors coming from the motor. Do they need to be soldered in? The battery will be on the downtube so I do not need the extra length of wire. Could I just cut off the connectors coming from the motor and fit a yellow male connector?

Sorry to ask what I am sure are basic questions but the kit came with virtually no instructions.
Steve

One way to deal with this issue is to:

• cut off the bullet connectors on the lead from the motor

and then

• solder the motor wires to the short lead with the male socket supplied with the battery (which looks like a connector type called an XT60)

• RED to RED and BLACK to BLACK of course

• then cover the soldered joins with heat shrink tubing - be sure to make a very good job of this as you do not want to leave any chance of allowing the wires to short out. Personally I'd cut the wires so that the joins weren't directly opposite each other but staggered

• heat shrink over the two individual joins and then heat shrink over the whole lot

An example of a staggered crimped join (but don't use crimps for the bike battery - soldering is what's best).

The Yellow connector is indeed an xt60 high current rating 60a, so much better then the thin tin bullets on the motor.
If using the xt60 cut the bullets off and solder the wires of the tail direct self colour to self colour, before soldering slide a piece of heat shrink up the tail end to insulate the join.

Hi,
I would avoid soldering or modifying the connections of either the battery or motor it will likely void any warranty. The easiest way would be to source an adapter. The connectors look like xt60 and 4mm bullet? check ebay after you have identified them, you might have to look under RC as well as e- bikes. Double check connector sizes and the polarity. I made one up but on hindsight it would have been better to just buy one.

One won't void warrant as one is not opening the battery, it is common place to change the connector. 4mm bullets are pants as a connector for current.

I'd strongly consider the heat shrink solder combination doodads for wiring like this...

Something like
https://uk.farnell.com/raychem-te-conne ... dp/2765598

These have adhesive rings at either end to make the whole shooting match waterproof and a nice low temperature solder in the sleeve to make a really good connection very easy.

[XAP]Bob wrote: ↑11 Jan 2022, 4:38pm I'd strongly consider the heat shrink solder combination doodads for wiring like this...

Something like
https://uk.farnell.com/raychem-te-conne ... dp/2765598

These have adhesive rings at either end to make the whole shooting match waterproof and a nice low temperature solder in the sleeve to make a really good connection very easy.

Discussions about connections often identify that some people are confident solderers and others aren't.

I've used and recommended these for cars and they don't require skilful soldering. They're very neat.

But I've never used them for anything near 60 A. Are they suitable, and any special precautions?

Thanks

Jonathan

The existing connectors might be good to 60 amps, but the controller should be limited to 20amps very maximum, probably a bit less. 20 amps is still a significant current so you do need decent connectors.

I have had bullet shrouds melt at 20a with a hub kit using 12s, the bullets can't handle the heat at 20a very well and can get to hot. For a 36v BBS 18a is the max unless it is the ETM version of 25a.

hemo wrote: ↑11 Jan 2022, 5:39pm I have had bullet shrouds melt at 20a with a hub kit using 12s, the bullets cantt handle the heat at 20a very well and can get to hot. For a 36v BBS 18a is the max unless it is the ETM version of 25a.

Thankyou

Jonathan

Just out of interest (I'm not an engineer), with solder in high current applications, is there a risk of the solder softening as things warm up under high current? Also, depending on the nature of the cable, if multi-strand, the soldered section will be rigid so any risk of vibration and/or movement fatiguing the wire each side of the solder joint?

Ian

The current path would have to reach approx. 190/200 centigrade for 60/40 solder to become fluid, that is one heck of a heat though other protection would come in to play well before this could happen.
I have had a 6 mosfets controller thermally cut out due to high/extreme heat, typically 80-100c is there max temp range. Said controller was to hot to the touch to handle and I had ride with no power until the temp had cooled for the controller to allow current flow again.