Sponsored: this article includes paid promotion on behalf of Tern Bicycles
An ebike is a fun, efficient and healthy form of transport. And, if you have an e-cargo bike, it’s an easy way to move stuff, kids and friends about too. That’s not to say there can’t be issues, though: you may have seen how devastating an ebike battery fire can be, and heavy loads can mean broken components and even frames if a bike’s not up to the job.
When you’re buying a new ebike, you need to make sure you’re getting something that’s safe and fit for purpose. And if you already have an ebike read on to the end for some great tips for safe charging.
Some basics
Before we delve into more detail, Let’s go over a few quick basics. It’s always a good idea to get an ebike from a reputable dealer who can look over the bike beforehand, and can offer you an after-sales service to iron out any issues. Components can take a while to bed in, and they often need a tweak to get things running just right; lots of bike shops will offer a free first service as part of the sale.
If you’re looking into a bike’s certification, then the rest of this article goes into some depth about that. The TL;DR is: look for well-regarded standards, and testing carried out by an independent body. With those in mind, let’s look at the testing itself.
General safety
Every bike should be built to be roadworthy. ISO 4210 is the global standard for bicycles; it’s not mandatory but nearly all bikes will be built to pass it. Other standards build on top of that, and in the ebike world in Europe, where ebiketips is based, the main one to look for is EN 15194, which is the European standard for electrically-assisted pedal cycles. Here that means a bike that can assist you up to 25 kilometres an hour, with a maximum continuous power of 250 watts. Around the world those numbers can be different, and the standard will be too, so if you’re in another territory it’s a good idea to check what the rules are.
For something like your average commuter ebike that’s not meant for carrying passengers or a big load, EN 15194 is quite comprehensive: it covers everything in the ISO bike standard but goes a lot further, looking at the performance and durability of both the mechanical and the electrical bits of an ebike. In Europe you can lLook for a CE mark on the bike’s frame: any ebike bearing that mark will have been tested to this standard, and that’s a good start.
Battery safety
No doubt about it, a lithium battery fire is a pretty terrifying thing. You may have seen footage of an ebike fire on the news, and things escalate very, very quickly. And the number of fires, is increasing. So why do the batteries catch fire?
From a chemistry point of view the answer is something called thermal runaway, where the temperature and pressure within the lithium-ion cells suddenly increase, and a flammable gas is formed, which can ignite. The resulting fire is very hard to put out, and there are a lot of toxic fumes.
The practical reasons for the fires are normally low-grade components, poor battery management and poor quality control. If batteries use cells that are badly made, or cells that are mismatched within the battery, that can cause thermal runaway and a fire. A charger that’s not the right spec for the battery can also be the cause, and so can physical damage to the battery. It's no surprise that cheap ebikes and ebike conversions that get heavy daily use are often the ones that end up in flames.
The best way to protect yourself is to get a bike that's independently certified. Ebike regulations around the world will cover the battery system to some extent, but the best standard to look for is one called UL 2849, and it evaluates the entire e-bike electrical system. So that’s the battery, and charger, of course, but also the motor, the display unit and all the cables and wiring. Everything’s assessed for fire safety, but also electrical and mechanical safety. It’s really the gold standard for ebike systems. The Tern Quick Haul Long above uses a Bosch Cargo Line motor, and all of Bosch’s motor systems are UL-2849-certified. Many other systems are certified too.
Load carrying safety
The standards we’ve covered so far are pretty good for normal, single-rider ebikes where the weight of the bike plus the rider isn’t more than about 120 kilos. But it’s more and more common to find bikes designed to carry much more than that. For example, Tern has three bikes in its range that are designed to be able to carry two kids on the back, or a fully-grown adult, and there are lots of bikes in the market with this kind of capacity, or even bigger. There have been some quite high profile recalls in the last few years where bikes designed to carry big loads haven’t been up to the job. So how can you ensure that your bike is strong enough?
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Any respectable manufacturer will will have conducted some testing of course. Check to see if a bike has a maximum gross vehicle weight, which is the weight of the bike, the rider and any cargo or passengers. And then check to see how that’s been certified. It’s not just the frame, either: bikes designed to carry loads also need strong forks, wheels and powerful brakes. Check that those components on any bike are good quality before you buy.
Like with the electrical system, there are independent standards you can look for. For cargo bikes, Tern and some other brands take the German cargo bike standard, DIN 79010 as the baseline because it encompasses everything, from structural integrity of the frame and fork to those critical components like the brakes and wheels. In Tern’s case that’s just a baseline though: Tern works with EFBE, an independent testing lab, which puts its frames and forks through a series of punishing stress tests that go even beyond the requirements of the standard. It’s good to have that peace of mind if you’re sticking your kids on the back!
Charging safety
Lastly, let’s run through a few tips on charging your ebike safely. Ebike fires can be devastating, so it’s good to take precautions.
Firstly, you should never charge your ebike in a corridor, or anywhere else you might need to get past to evacuate if there’s a fire. Charging away from living space in a shed or garage is best, but If you’re charging indoors, keep in mind that an ebike with a reputable testing agency mark, like UL-certified batteries and chargers, is your best option.
Choose a well-ventilated room with no soft furnishings, like a kitchen, and make sure you charge away from heat sources.
Never attempt to charge your battery if you’ve damaged it, and only ever use the charger that came with the bike.
If you can, charge during the day, rather than at night, and don’t leave the bike plugged in any longer than necessary.
It’s a good idea to keep an extinguisher nearby; a dry powder one is a good option, a bucket of sand is better than nothing. You should never try and put out a Lithium battery fire with water: Lithium and water do NOT play nicely!
