Twist, tape, pray.

Sungei Kadut, 9:12pm

Illustrative shop scene and virtual chat.

9:12pm. Sungei Kadut. Every workshop on the road has its shutters down, the lorries have gone home and one streetlamp is working. Irfan is pushing his bike down the middle of the road, phone at 9%.

The bike went quiet two minutes ago. A spark, a pop, then nothing. Display blank, mid-throttle.

It started on Carousell. A secondhand battery, good price. Wrong plug. The battery came with an XT60. His bike takes an XT90.

At WarehouseSG he found an XT90 connector with a short lead for $5. The shop offered to fit it for him, properly soldered, for $30.

“$30? I do myself lah.”

Scissors. Cut the XT60 off the battery. Stripped the wires with the same scissors. Twisted the XT90 set on. A bit of tape over the joint. Ten minutes.

His friends told him not to.

“Masuk. Confirm jalan.”

It went in. It worked. He rode off. Tonight, halfway through the ride, the wires came off and touched each other. A spark. A pop. The whole bike went dead on the spot.

Now he stood under the streetlamp with the bike on its side and did what everyone does at this point. He sent a photo to the group chat.

A CHAT WE SEE A LOT

He called us at 9:38, from under the streetlamp, at 4%. We asked where he was. “Sungei Kadut.” We asked what happened. He told us, slowly, in order. Nothing we could do from there. Irfan pushed the bike all the way from Sungei Kadut to Marsiling.

The $150 bill

Next morning Irfan put the battery on our bench and pointed at the joint. The wires had come off right where he twisted them.

We tested the pack. The BMS had fried. Repair: $150.

$30 would have paid for a proper joint. $150 paid for the board.

Pulled by hand

This isn’t Irfan’s joint. Same idea. Two wires on a bench pack, just twisted together. No solder. No crimp. Clear tape over it, then a green sleeve. One hand holds the pack side. The other pulls.

About two seconds. No tool. A joint that’s soldered or crimped doesn’t come off in a bare hand.

Look at what’s left. A bare copper tip on a pack lead can touch a bracket, a frame, another wire. The tape was never holding anything together.

Another bench pack, another joint. This one was never made properly in the first place.

SCDF’s advisories for active mobility device users warn about the fire risk of modifying a device. How bad it gets depends on the exact joint, the wire and the load. But this is the kind of thing that starts fires and puts the whole e-bike community in a bad light. We never condone it.

What tape does, and what it doesn’t

Tape wraps a joint. It doesn’t make one.

On a high-current lead like a battery lead, twisting two wires together and taping them is a reliability problem and a safety problem. Not a shortcut. Not a temporary fix.

A twisted joint can look fine under tape and still be loose, or hot, or about to touch something it shouldn’t. You can’t tell which. That’s the problem: the tape hides it from you too.

That’s what “meant to be there” looks like: a moulded connector, shaped for its plug, on the end of a lead that was made for it. No twist, no tape.

So “the plug masuk” answers a different question from “will it hold?”. A plug that fits the socket still has to be joined to the wire properly.

What to do instead

Sources (2)

• Ministry of Home Affairs: guidance on storage and charging of lithium-ion batteries (written reply citing SCDF advisories)
• Singapore Consumer Product Safety Office: lithium-ion battery safety