Can someone check my math on this? It feels… wrong:
After cycling a little over 8000km on our e-bike, our battery died. Rather inconvenient, but thankfully we had a variety of cycle shops nearby and one of them was able to find us a replacement.
Ours is a Bicicapace Just Long a fantastic cargo bike with a Shimano motor and battery. The battery that we originally purchased with the bike was no longer available, so the replacement battery is a newer model. It is however a legit Shimano battery rather than a cheap knockoff prone to exploding.
The total cost, just for the battery was £600. Interestingly, this is roughly what I paid for my entire road bike about six years ago.
The steep price tag got me thinking though: if all I can expect to get out of this battery is 8000km, what is the “mileage” of my e-bike? Math is not my strong suit, but the number I arrived at is not inspiring:
If we take the cost of travelling 8000km and ignore the marginal cost of electricity for the sake of my sanity, the cost per kilometre is:
£600 ÷ 8000km = £0.075/km
That feels… high. My kid’s school is almost 5 kilometres from our home, so every day we take her to school, we’re effectively paying £0.75 for the return trip and again to go pick her up, so £1.50. That’s £7.50/week (not including the weekends which are busier).
Given this, I wondered what it’d cost to do this with a car — only counting the fuel mind you — and the result wasn’t inspiring.
The average milage in the UK for a diesel car is 43MPG. I opted for diesel for this exercise 'cause that’s what it seems like everyone is driving here. Converting this to metric, you get:
1gal → 4.5461L
43mi → 69.2018km
69.2018km ÷ 4.5461L = 15.22 km/L
With this value, we can calculate how many litres of diesel one might use to travel 8000km:
8000km ÷ 15.22km/L = 525.62L
Finally, with the price of diesel currently here in Cambridge hovering at around £1.569/l, that means that the price to pay for the diesel alone for the same distance I travelled on that £600 battery was only a couple hundred bucks more:
1.569 * 525.62 = £824.70
That’s… not inspiring. It’s really hard to convince people that cycling is cheaper when the costs of regular use are so high compared to the ridiculously low cost of fossil fuels. Sure, the electricity cost is negligible, and there are many many other costs associated with cars, but having just bit the bullet on £600 battery after such a short time, let me tell you, that taste is bitter.
Hahaha, new battery vor my Stromer ST3 ist 2000 Euro! I bought that Bike used for just a bit more with 2800km in the clock. Dunno what to do If anything breaks…
That seems like a really shit battery life to me. 40km or so range isn’t unreasonable for an ebike and that would be just 200 charge/discharge cycles - absolutely terrible.
Had the warranty expired? Maybe you just got unlucky. For such an expensive of a battery I would expect far more.
My hybrid bike was also £600 and seems to be doing fine. Now doing about 50km a week.
I recently did similar math to determine if I should get an electric bike vs drive to work.
The trip is about 2.5 miles, meaning 5 miles round trip. The cheapest ebike I felt good about cost about $500. At the time gas was about $3.50 a gallon and my car got ~30mpg on that route.
So basically $3.50 / 6 trips. That means I’d need to ride the bike roughly 800 times to make back the investment. Given I don’t go into the office every day, it would take me around 5 years to make back the investment in the bike.
This math only works out this way though because I already own the car, and that little bit or mileage wouldn’t be too noticeable for wear and tear, so it’s really a cost of gas issue.
However, I did get the bike and ride it for a little bit of exercise, an excuse to be outside, and cause using less gas is overall a good goal.
That’s not how you calculate car costs.
You only accounted for gas. Which is only part of the running costs. I also think that 46 mpg diesel is ridiculously optimist. Double check the source’s numbers. They seem off.
What you do is count in the total cost of the vehicle and amortize it over your use case in a given period of time. Count in all running maintenance costs. This is the cost of purchase, plus insurances, registration, oil changes, scheduled maintenance and fuel. Over a period of time, divide by the total kms done or expected to be done in that time. That would be the real cost per km.
Do the same with the ebike and realize the difference is magnitudes more than comparing fuel and battery alone. Also, there is cualitative analysis to do as well. You’re comparing an ebike, assuming it will be used as an electric motorcycle exclusively. An ebike with a dead battery is just a heavy bike, you can still pedal it. A car without fuel is a useless steel hull.
If you were to do the cost analysis this way to a plain old bike, even including food costs. It comes out to be virtually free, except for the most expensive carbon fibre performance bikes.
Insurance for a car on its own will be a minimum of about £700 to £1000 pounds a year.
Bet you charge it back to full every trip. Li-ion should be good for at least 500 charges before noticeable range degradation and up to 1000 before being pretty useless, if the charge controller doesn’t die first. 8000/10 = 800 trips, so ballpark.
Instead, only charge when (nearly) empty. If you’ve got a practical range of 60, you can make 5 trips before charging with a 10 km safety margin, now you get 40000 km out of the battery, much nicer. Bonus points for keeping charge between 20% and 80% which will get you significantly more charges (they say it doesn’t matter, they lie).
Inspections, licensing, insurance, maintenance, and maybe even parking, all need to be factored into the cost of the car and not just the direct operating costs of the energy required for the mode of transportation.
A £600 battery is not a huge expense when compared to a car that might need brake and rotor replacements ~£900, or a radiator replacement ~£500, etc. Heck, even a wheel and tire damaged by a pothole, if replaced to OEM, can be £400.
Where I live, I have to replace the battery in my car every 3-5 years at ~$300 too.
Yeah, car batteries have gotten crazy expensive, too.
I have checked and my Yamaha battery has an official lifespan of 700 charges. I am probably at around 200 and I have noticed that the battery holds maybe about half the capacity it used to. Which is still usable. So 8000 Kilometers feels to little to me and more like a defective battery than a problem with the technology.
Interesting. That’s good to know. Perhaps this new one will last longer?
The thing is though, 700 charges doesn’t sound like much as we end up charging it every day given the distance we put on the bike. We’d go through 700 charges in less than 2 years.
If your school is 5 kilometers away and you do the round trip twice a, you would go 20 kilometers a day. Even my old battery can do 40 kilometers on one charge. Something feels off.
You had a faulty battery, li-ion batteries last a LOT longer if nothing goes wrong.
That’s both encouraging and annoying. The battery was conveniently out of warranty when it finally died.
As it’s usual the case with warranty. 🤬
Feels like the issue here is you having to swap out the whole pack instead of sending it to be fixed. If it’s unfixable as in the whole battery is flooded with resin, then the design is the issue. This is akin to just swapping the fuel tank when the fuel pump failed(which we might get there one day if car maker have their way!), easily bumping the cost from 3 figure to 4 figure. Battery pack failure are usually fixable, either a few cell failed(which shouldn’t be that early, could be faulty battery or bad welding), bad bms resulting in bad battery balance(which my diy pack experienced), or wiring issue.
Bosch have 5 years warranty, can’t see why Shimano can’t guarantee minimum of 3 or 4 years usage. All in all i feels like this is a faulty battry issue.
whole battery is flooded with resin
This is a significant fire retardant, desirable for Li-ion not to be ‘prone to exploding’ as one cell going off doesn’t chain react the whole battery (hopefully). Which is not to say it isn’t also engineered obsolescence and lock in.
Sure would be nice if batteries became standardized (preferably as LiFePo which is much less likely to go boom for like 10-20% more weight, which the resin obviates) so they all used some combination of the same battery packs. But capitalism. It’ll come along, probably when legislated, but it could be a cartel seeking competitive advantage (grim chuckle).
Bosch have 5 years warranty
Nope, it’s 2 years.
You are right on the rest, I have a 14k km pack that runs good.
I am more worried about my bosch motor that seems to fail after 16-20k km, and having to pay 1000€ for a new one.
You missed a zero it’s 0.075 cents not 0.75 cents. Also the math only makes sense if you have a free car that’s paid of and have zero maintenance cost. Also if your Battery cost more than a new bike … just buy a new bike.
They didn’t miss a zero, unless I’m misunderstanding where you think that happened:
£600 ÷ 8000km = £0.075/km
The school is 5km away, so a round trip is 10km, and 10 * £0.075 = £0.75, and 2 round trips a day is £1.50, and 5 days a week that’s £7.50.
Yeah, I thought OP was off at first, then I reread it and they’re correct.
My question here is what does that bike, or an equivalent model cost now?
Also, as others have said your maths isn’t very fair to the bike - as cars have a whole lot more regular maintenance and legal/admin costs to them than a bike ever will, which really need to be factored into this.
Like others, I suspect that would shift things in favour of the bike by quite a lot, even despite the battery cost being a hard pill to swallow.
Be nice if they just made the damn things rebuildable with oem cells. They’re usually just spot welded packs of 18650 batteries. Cheap as shit by comparison.
kid’s school is almost 5 kilometres from our home,
Not sure if this math apply for everyone, but in my experience, I only use half the kilometers of the trip with the battery. If the trip go and back is 10km, I only use 5km with the battery and motor and the other 5km with the inercia.
I think there is a small mistake in your numbers, please correct me if I misunderstood: 5km trip is £0.375, roundtrip £0.75, which totals £3.75/week
edit: The numbers will jump up quickly when you start comparing the numbers when those maintenance windows start to hit for the car vs bike
They probably aren’t staying at school so each round trip from home to school and back home is 10km.
It’s 2 round trips per day, 10 round trips per school week.
