Large-capacity Lithium-ion batteries will end in death

Large-capacity Lithium-ion batteries, as used in e-scooters, e-skateboards, and e-bikes, accounted for over 500 major fires in Australia in H1/2023. It must stop.

Let’s start with a few exceptions. Small-capacity Lithium-ion batteries (5000mAh/18Wh) for smartphones are a manageable risk. First, they don’t use dozens of 18650 cells but a flat pack. Second, there are enough charging safeguards in the USB-C (not older USB-A and micro-USB) standards to minimise risks.

And USB-C power banks (especially the newer ones using Graphene) using 18650 batteries up to 20,000mAh/74Wh are also relatively safe apart from physical damage (although there have been many recalls for these).

No, we are talking about battery packs from 250Wh (Watt hour) or more made up of highly energy-dense, individual 18650 (18 x 65mm), 3.6V/2.6A/9.4W (nominal), lithium-ion batteries.

Let’s do the science

Ten of these in serial (positive to negative end) make a 36V/2.6A/94Wh capacity battery. A 250Wh battery pack has about 30 batteries in three serial banks. A battery management system (BMS) manages discharge (usually set at a 3V lower limit) and charge (usually set at a 4.2V higher limit).

Batteries ain’t batteries

LG, Samsung, Panasonic, and Sanyo make high-quality 18650 Lithium-ion cells with 500+ recharge cycles. Tesla uses Panasonic batteries in its EVs. If we all used these, there would be fewer fires.

But there are hundreds if not thousands, of generic Chinese-manufactured Li-Ion cells, which vary significantly in quality and recharge cycles (300 is typical). You can buy these in China for <US$0.50 to $5.00 (Note that Australia Post and international couriers will not carry single-cell Li-Ion batteries anymore).

There is a huge counterfeit or remarking industry as well. In part, it is driven by the fact that 18650 batteries are also used in Vapes. But more so to fill the demand for generic e-scooters.

By comparison, a vastly safer 18650 LiPo battery has about 90% of the energy density (an extra battery is required for every 10 Li-Ion) and costs from $3.00 to $10. Even safer LiFePO4  uses Lithium Iron Phosphate but provides only 3.2V and lower 2000mAh energy density again. A 32V LiFePO4 e-scooter battery pack starts at US$285 and is 25-30% more costly, larger and heavier.

Battery Management systems ain’t battery management systems

You can buy a 3.7V BMS PC board from under US$1 to $10. You need one of these per bank of 10 batteries. The more you pay, the better the protection.

Chargers ain’t chargers

You can buy a 36V/2A/72W ‘brick’ charger for <US$20. This is for that theoretical 36V, 3 x 10-pack of 18650 batteries. A proper fan-cooled, over-current, overload and short circuit-protected charger will cost well north of $100.

Many e-scooters and e-bikes require 42/60/72V; these chargers cost even more.

Stop press!

The critical issue here is that these modified e-scooters use huge energy-dense Li-Ion battery packs and are dangerous fire risks.

CyberShack’s view – Money is the root of large-capacity lithium-ion fires.

We are not against the responsible use of e-scooters. It is just that we don’t see much of that. Read E-scooters – great but huge fines can apply for road use. The irresponsible ones are a danger to themselves and licensed road users.

Cheap e-scooters, at al., accounted for over 500 fires in Australian homes in the first half of this year. Some States report at least a fire a day! Large-capacity Lithium-ion battery fires have quadrupled since 2021.

There is a telling article, Lithium-ion e-scooters, e-skateboards, and e-bikes banned on UK on public transport. The Australian Firefighters’ Union says Australia is “categorically and catastrophically not prepared” for the thermal runaway risk posed by lithium-ion batteries — used in electric scooters, bikes, and cars (although most of these result from a crash).

There are calls to ban the use of large-capacity Lithium-Ion batteries in anything other than small devices, smartphones etc. If that were to happen, EVs, Solar Batteries, and e-mobility devices would need other safer battery packs. It could be a costly recall mess.

It is the old story – you get what you pay for. We can’t tell you which e-scooter brands are safer (in our opinion, all large-capacity Lithium-ion batteries are risky). Still, if you pay $1000 or more, you should expect a reliable battery system.

It is the cheapies that seem to suffer the most. Here, even better-known brands must cut corners, and batteries are the obvious start.

And while we have focused on e-scooters (the largest numerical proportion due to low cost), cheap e-bikes and e-skateboards are also culprits.

Don’t do this at home.

Update 10/8/23

Reader Tom writes

In general, this article is good and covers key points that everyone should be aware of “Take care with lithium batteries and avoid cut price/generic products with lithium-ion batteries”.

However, statements pertaining to USB-C are not entirely correct.

“There are enough charging safeguards in the USB-C (not older USB-A and micro-USB) standards to minimize risks.”

USB-C power banks (especially the newer ones using Graphene) using 18650 batteries up to 20,000mAh/74Wh are also relatively safe apart from physical damage”

USB-C itself does NOT guarantee a safer product. Yes, some USB-C products may integrate additional safeguards, but a bad product is a bad product regardless of its capacity or how it gets its power, whether it be USB-A, USB-C or a potato with wires sticking out.

What makes a product safe is a design that uses quality batteries and an appropriate charge controller/BMS that ensures batteries are kept within design limits. The power source/USB standards do not define how safe a product is.