An article appeared in the Tyee on June 20, 2022 titled “E-Bike Batteries Can Kill. Here’s What You Need To Know”.
The title of the article was certainly ‘inflammatory’ (pun intended).
January 19th, 2023, the Vancouver Fire Dept was featured on a Global News article with good information and warnings about battery tinkering…
Since Modern Outpost is in the business of selling batteries, and I personally own an e-bike, these articles were destined to catch my attention. What follows is a brief addendum to these articles, adding a few notes to help people truly understand the lithium battery landscape.
The Tyee article starts by listing 3 apartment fires apparently started by lithium-ion batteries.
But, which type of lithium-ion battery? There are several different types of Lithium chemistry. The article unfortunately doesn’t say.
The Tyee article continues its somewhat ignorant accounting by stating that since 2016, fires caused by lithium-ion batteries are up 500%. However, there is no mention of what exactly they are comparing this figure to. The decade prior? All of lithium battery history? In what jurisdiction? There is very likely more than a 1,000% increase in lithium battery sales over the past 10 years alone worldwide, so proper distillation of statistics is important.
The Tyee article attempts to pin the blame for fires on e-bikes and motorized scooters. Interestingly, none of the cases of fires that the article cited had mentioned scooters and e-bikes. Were they cell phone fires? Wireless audio fires? How about a “I put a lithium AA battery in a Ni-Cd charger and it burst”? Not only did this article throw a blanket statement over all lithium battery-powered technology, but they also failed to provide proper education for how people can avoid making the same mistakes. Relying on ‘shock and awe’ in an article such as this is a strange way to promote safety in battery care and handling.
The Tyee article then quotes the Vancouver Fire Department’s public information officer stating that “[W]e’re in big trouble”, and that “[W]e need to educate, we need to protect and we need to save lives”.
We’re not in ‘big trouble’ as battery failures are statistically extremely rare, but agreed, we should take every opportunity to learn. Let’s start by educating the Tyee’s contributing author, and find out ‘what we really need to know’.
1. Are Lithium-Ion Batteries Safe?
Failure rate of lithium-ion batteries (as a battery chemistry general type) is in the order of 1:10-million. Extremely low.
Lithium batteries also include a ‘Battery Management System’, which is a circuit that keeps an eye on things. A good BMS protects the battery from over-voltage, over-current, over-charging, and over-temperature. A bad BMS, or no BMS leaves you with little protection.
2. Are All Lithium-Ion Batteries The Same?
Here are 3 major types of Lithium battery…
LiPo : Cell phones, cameras, & laptops use Lithium-Polymer batteries (LiPo). Often called pouch cells. These are built to fit a certain form-factor, and for low-cost performance. They do not have the high-energy capacity that you find in e-bikes or cars, and clearly cannot be replaced easily.
It is very easy to find cheap knock-off cells on Amazon & Alibaba for a great price… that is if you want to take the risk that the cells aren’t damaged, faulty, or lacking proper protection circuitry.
LFP : E-Bike, EV, & residential Lithium batteries are typically, but not always, Lithium-Iron-Phosphate batteries (LiFePO4 or LFP). This is the most stable Lithium chemistry, and provides some of the highest cycle life available, which is why you find this lithium chemistry used in drop-in replacement batteries for AGM/lead-acid, and residential-scale back-up battery systems.
NMC : Many EVs and consumer products also use Lithium-Manganese-Coblat (NMC) batteries. This Lithium chemistry is not quite as stable as LFP (LiFePO4), and doesn’t provide nearly as many cycles, but does have higher energy density and higher discharge rates. Excellent for situations where power-to-weight ratio is very important. But, NMC is somewhat falling out of favour due to the need for Cobalt – a highly toxic element that is often unethically sourced from conflict regions of the planet. Even Tesla is making the move away from NMC.
3. Can I drain my Lithium battery 100%?
Yes, but you should avoid doing so.
Lithium chemistries do not suffer from a memory effect – that loss of capacity that used to be problem with aging rechargeable batteries (especially NiCd). However, like all batteries, there is a relationship between how hard you cycle your battery (depth of cycles) and how many cycles you get out of it. And the relationship is not linear, meaning that you get closer to 3x the number of 50% cycles than you do 100% cycles. For example, the performance specs for an LFP battery might say 3500 cycles to 100% DoD (Depth Of Discharge), but 10,000 cycles to 80% DoD.
If you have a cell phone, you are likely very familiar with having a battery that will no longer hold a charge after 1-2 years. This is normal for a LiPo battery which has a 500-cycle expected lifespan when cycled to 100%. Bring your phone down to under 5% on the battery meter on a regular basis, and expect the battery to quit working well after 1-2 years.
To avoid a premature death of your battery investment, it is recommended to NOT go below 20% state-of-charge (ie. 1 bar out of 5) on a regular basis.
4. Is cold weather a problem?
Lithium chemistry can provide power down to -20 Celcius, but does NOT like to be charged below 0 Celcius. So, if you bring your E-Bike inside after a commute on a chilly winter morning, best to wait until the battery warms-up to room temperature before plugging it in. Smart battery management circuits inside the battery will prevent any charging below 0C, while dumb ones won’t. Again, assume you have a dumb one, and do what you must to protect your battery by not trying to charge it when below 5 Celcius.
In the Tyee article, two of the cited fires happened in January, and thus the cold weather may have been a factor in the battery failures.
5. Are 3rd party, or ‘borrowed’ chargers a problem?
Short answer? Maybe.
Firstly, there is not an E-Bike, phone, or laptop that I know of that doesn’t use a highly proprietary charger or connector. You cannot plug any other charger other than their own into the bike or phone.
Second, any lithium battery with a built-in battery management circuit will disconnect the battery if the charging system is out of range (ie too much current or too much/not enough voltage). So the issue returns to the battery management system, and the need to source reputable batteries with reputable management circuits.
6. Is warranty & safety certifications important?
If you purchase a battery that comes from a reputable company, it will feature a warranty. The warranty is an indication of the quality of the battery, and no company wants to offer a warranty and then have to honour thousands of claims because their product was garbage.
Safety certifications are arguably even more important. They are an indication of a manufacturers’ quality controls, safety processes, and product randomized testing by 3rd party labs. You get none of this when you purchase cells or batteries from a no-name battery corp on a ‘made in who-knows-where’ off-sales website, or even Alibaba or Amazon.
I’ve heard people say that even if the battery is crap, at the low price they could afford to replace it and still come out ahead. That works as long as it doesn’t burn your house down.
We vote with our wallets, so by purchasing cheap crap, you are tacitly approving a cradle-to-early-grave economy. Please don’t do it. We are at the point in history when we need to support best practices.
I’ll end this blog post with a few simple rules of thumb that will keep you out of battery trouble regardless of the type you’re using…
1. Charge batteries at room temperatures
2. Use the charger designed for your battery
3. Read your manual
4. Never leave batteries unattended while charging
5. Purchase high-quality batteries, employing full-featured battery management circuits, from proven manufacturers.
And, the battery ‘Golden Rule’…
The nicer you are to your batteries, the nicer they will be to you.
Treat them gently. Like they are the last batteries you will ever purchase. Charge them gently, use them gently, and don’t stress them by keeping them plugged into the charger too long, or depleting them too far for too long.
As our energy future depends greatly on batteries, we collectively need to be more aware of how we handle them.
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