The repairman: "Not the customers fault that the battery shuts down prematurely"

- I see no possibility that it could be the customers' fault that the batteries shut down themselves prematurely. Especially not when there are so many batteries with identical faults, says Patrik, who is one of the few repairmen in Sweden who uses electric bicycle batteries.

Patrik says he has made a couple of thousand bicycle batteries in his workshop since its start in 2016, and that the most common problem he encounters is batteries whose cells are worn.

- Then the battery has been used a lot, maybe thousands of miles, and the batteries are usually at least five years old and the capacity has slowly deteriorated.

But when Patrik started getting Biltema batteries this spring, the symptoms were different. When the batteries were not very old and the cells seemed to be in good condition, Patrik first thought that this was a single defective control unit (BMS) in the battery, which interpreted the voltage incorrectly and therefore prevented the battery from being fully charged.

- In normal cases it is usually possible to blame for fluid damage, short circuit or the like. But then more and more identical batteries came in.

And Patrik's investigations usually showed no damage whatsoever in the batteries, which could justify charging the battery for safety reasons.

So in the end he tried to disconnect, and back, the current between the BMS and the battery cells. Just like when you unplug the cord from a computer that hung, and then the batteries suddenly started charging again. He has since made about 60 batteries in the same way.

- It tells me that there is something stored in the BMS that tells the battery to stop charging. But when you disconnect the power, the BMS forgets this.

According to Biltema, there seem to be many different reasons why batteries have stopped working. But Patrick's conclusion is that there is something in the batteries' BMS that tells the batteries to stop charging unjustified early.

According to Patrik, it could, purely hypothetically, be a bug in the software, or a setting by the manufacturer. Exactly what it is Patrik cannot prove, but that the error is not due to customer care or normal wear and tear, he says is clear.

- What makes me most upset is that Biltema neither has any solution to the problem nor has spare batteries in stock. After all, it is unnecessary for customers to have to scrap their batteries even though the cells are still in new condition.

Follow the whole Plus review of the problems with electric bicycles here.