Mizanur Rahman death: Coroner calls for e-bike battery standards
The recommendations come after Mizanur Rahman, 41, died following a fire caused by a faulty battery.
www.bbc.co.uk
Mizanur Rahman death: Coroner calls for e-bike battery standards
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Whoever said that is probably not technical and didn't understand the actual cause of the fire. All that means is that the bike had two separate kits fitted - either front and rear motors or mid-drive and rear motor. That isn't something that is more likely to cause a fire than two ebikes parked next to each other.
Additional battery in a cage implies that it had two rack batteries. I've seen that a few time. I don't think it's particularly unsafe.
Without seeing the bike before the accident, it's impossible to judge whether the conversion was unsafe, and we don't know whether the cause was fast charging, a different mistake when charging, rats chewing the wires or anything else.
Modifying things correctly and with understanding isn't unsafe. The problems come when people do it incorrectly without understanding. That's why it's important to give advice. If we don't give it, they might just decide to experiment, which could cost lives!
Each time when I see news like this I ask myself a question if person involved was a member of this forum and what advice did he get.
Many more could have died as apparently up to 21 people were living in that flat.
From the linked article
Mr Smith wrote there was a risk of a "catastrophic failure" when a lithium ion battery was plugged into a charger with a different voltage rating.
Mr Smith wrote there was a risk of a "catastrophic failure" when a lithium ion battery was plugged into a charger with a different voltage rating.
If that was the cause of the problem, you can see why the Coroner might call for standardisation of connectors. It would make sense to have foolproof methods, where if you have the wrong voltage, it doesn't fit, like a different size connector for each different voltage.
Let's say that the bike in the accident had two batteries in a stack with the same RCA or 5.5mm jack charge connectors. The battery for the front motor is 36v and the one for the rear is 48v. Think how easy it would be to put the 48v charger in the 36v battery if you didn't understand electrical things, or even if you did.
I think people are reading far too much into those headlines. They want to use them to stir up hysteria to support their agendas rather than find simple solutions to actual problems and their causes.
I'm surprised chargers which automatically recognise battery voltage, BMS continuity etc are not widely available. All the chargers (Some quite ancient) I use for my toy planes have this facility and confirm pack voltage and balance connection status before charging. Any cell over volt etc during charging automatically terminates the charging cycle.
TTFN
John.
TTFN
John.
I still wonder when differing voltages are mentioned if even the so called experts don't know or understand the volltage ratings, for instance a charger for a 36v will often have thr 42v max charge rating .
A lot of lipo chargers do work like that, esp when they can charge various battery series.
My SKYRC dual charge is a 1 - 6 s charger and as you say you have to input the correct series and in my case I can input the Battery AH rating. It won't even consider charging if the series count isn't recognised, which is confirmed by connecting to the balance wires.
Problem with such a charger for lion is it would need to recognise battery voltage as balance leads aren't available to
My SKYRC dual charge is a 1 - 6 s charger and as you say you have to input the correct series and in my case I can input the Battery AH rating. It won't even consider charging if the series count isn't recognised, which is confirmed by connecting to the balance wires.
Problem with such a charger for lion is it would need to recognise battery voltage as balance leads aren't available to
There are intelligent chargers. All the expensive bikes have them. Bosch chargers cost from £80 to £150, Yamaha is £100 to £160 and Carrera ones are £60. A typical Chinese dumb charger is around £10.
I'm sure there is a logical reason, but one thing which surprised me when I bought my 1st E-Bike (Assuming I understand correctly) was the BMS was in the battery not the charger. I appreciate the extra up front cost of an intelligent charger but as it would be expected to be a one time purchase whereas batteries are by their nature "Consumables" it can't be the cost?
TTFN
John.
TTFN
John.
When the battery is operating in the bike, you need at least two control functions: Overcurrent protection in case of short; and low voltage protection to stop the battery over-draining. There are some bikes that have regeneration, so they need over-voltage protection too.
if you had a specific battery for a specific bike or family of bikes, your idea could work, but you'd need at least 11 pins and conductors in the charge cable for a 36v battery, which would mean a special connector. The main problem is the over-discharge protection, which is controlled by both the controller and BMS, so there's a belt and braces approach. There's always a possibility that sonething could cause current drain even when the controller is switched off, as I found out a couple of times when I used to use lipos, so the battery would still need some sort of low voltage control.
Considering everything, it's easier and safer to put the BMS in the battery and keep it there.
The missing standard is requiring the battery to be resilient to a wrong voltage charger.
This. For cell protection to be reliable it must be inside the battery, not reliant on user training or on protocols like plug shapes or stickers. Which is not to say that those can't improve safety.
With the market buying on price and scant product details and the brands pushing proprietary solutions, perhaps we'll only get reliable BMS's if there's an open source project along the lines of the VESC controller. Meanwhile, charging bikes catch fire and the chargers get the blame
GitHub - Green-bms/SmartBMS: Open source Smart Battery Management System
Open source Smart Battery Management System. Contribute to Green-bms/SmartBMS development by creating an account on GitHub.
github.com
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