Peace of Mind

Intelligent Deterrence

E-bikes’ Battery Packs

Heard across a street. Highly intelligent. A bike alarm like no other! $210 CAD. Direct from manufacturer: $120 CAD.

There is a huge amount of misinformation, out there, about the battery packs used in micro-mobility.
I am by no means an expert, but I know enough to know that I don’t know–a wisdom yet to be achieved by nearly all riders and service-personnel out there.

As a firmware engineer, my expertise has been in real-time, embedded systems–mainly the equipment used in the infrastructure of telephone systems and the Internet. These are equipments you rarely get to see, the closest of which would be a box, with half a million lines of extremely complex code, in a cell tower (which I’ve not directly worked on) or a wifi/ADSL/cable modem with 100,000+ lines of extremely fast, complex code (which I have worked on). Typically, however, they are invisible to people, running the infrastructure of the Internet and telecommunication.
As such, I’d never really had to deal with the charging system of a mobile hand-set.

Until recently! With the Covid-19 stock crisis, the task of adding a charger IC has become very difficult. (This is the main Integrated Circuit chip that controls the charging cycle of a battery pack, provides various protections, and might even manage the relationship between the power distributed to the device versus to the battery pack.) Simply, nearly all are out of stock!
This limits options, in addition to the cost of the redesigns it entails. And there aren’t many engineers out there with relevant expertise.

That brings us to the folksy wisdom circulating around the community of ebike riders. I see no indication of any understanding of charging cycles, or of the various actors involved (charger IC, PCM, BMS, balancing IC, battery chemistry). (If you want to begin to dip your toe into that territory, you could start with this overview of battery management.) The specification for only the battery pack of the M!nder is a dozen pages, let alone those for the other ICs involved!

So, what is a user to do?
Read the instructions that come with your device, and try your best to stick to them. This does not mean that that info is the most accurate it can be in technical terms, but it is your best bet as a user.
In practice, the life of the battery pack has more to do with you than with the pack: How often you ride; for how long; how often you recharge; for how long; the temperature/environmental conditions of your rides, and of where you recharge; whether you leave it unused for a long time; etc.
I will also note that lithium batteries have a limited life anyway: There is a limit to how many times they can be recharged, and how many years they will last even if not used. A good pack may last five years or so, depending upon various factors.
These vary significantly with the manufacturing process. Brand-name packs are likely to last far longer, for more recharge cycles, under a broader set of conditions, than a no-name pack. Ebike packs are very expensive, comprising dozens of cells, and circuitry, adding easily up to $500. Yet, the consumer could not tell by looking at them. As such, they can be an area for cost-cutting by the manufacturers.

I’d be remiss not to step back, take a look at the larger picture, and point out the dominant subject of this site: You are far, far, far, far more likely to lose your ride to theft than to any shortcoming by the pack! The endless series of ebikes I see with inadequate locks is disheartening. Why spend gobs of money on a bike you will love, then quickly lose it like a pile of cash left on the sidewalk!

Battery Capacity, and Efficiency

As in elsewhere, I can’t help but comment upon the construction of today’s ebikes. While there is no shortage of conversion kits for regular bicycles, and the mainstream of the bicycle market is very weight-conscious, most of the new ebikers I see nowadays use fat bikes suitable for a Mad Max movie!
Why this is, I do not know. At first, I thought that, well, this is a new, emerging market-segment; they will behave differently from the existing riders. But then I saw little variation in this user-base: Most get over-weight, over-sized, bulky, SUVs of cycling! Is this mimetic behaviour, arising from unfamiliarity (“That’s what everyone else is getting”)? Is it because too many vendors sell only those?
I’ve observed the same with cargo bikes. There is no need for them to be as heavy as they are! It does not take that much metal to carry an adult, 2 kids, and some groceries! If you doubt that, take a look at any bike trailer you see out there!

The impact of this is on power consumption. Batteries deplete quicker, and battery capacities need to be higher (as do discharge rates).

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