So, what's going to happen when e-MTB batteries start dying? Specialized wants over a $1k for a battery.

[Binhill1]

Best advise for battery health and longevity is to never store the battery at full or low charge. Keep it around 60-70 percent charge. Also ride your bike regularly so the battery doesn't sit idle. Happy shredding!

Agree with storage level but must say I worked on ship so bike unused for up to 7 weeks at a time and battery still ok.

 

[Planemo]

Agree with storage level but must say I worked on ship so bike unused for up to 7 weeks at a time and battery still ok.

Agreed. Theres zero Li-Ion tech requirement to give them a 'regular workout'.

Leaving them at 100% for extended periods and repeatedly not charging to 100% are the only two real killers.

 

[jonmat]

I’m on my third ebike and have treated them all the same. Ride and charge to 100% leave on charge for 7 days sometimes in winter. Mainly ride two or three times a week when the weathers good, done thousands of miles on all three bikes, 2,200 miles on current Bosch 625Ah not noticed any degradation. I think the BMS does more than people think. My bikes stored in an unheated garage.

 

[Alexbn921]

I’m on my third ebike and have treated them all the same. Ride and charge to 100% leave on charge for 7 days sometimes in winter. Mainly ride two or three times a week when the weathers good, done thousands of miles on all three bikes, 2,200 miles on current Bosch 625Ah not noticed any degradation. I think the BMS does more than people think. My bikes stored in an unheated garage.

No the bms doesn't. It's a fundamental function of battery chemistry.

 

[jonmat]

No the bms doesn't. It's a fundamental function of battery chemistry.

 

[Alexbn921]

Just out of curiosity, what do you think the bms actually does?

A good BMS monitors cell voltage, current draw, temperature and balances cells at full charge.

The most a manufacturer can do is under rate a pack and lower it's max voltage. Most try to squeeze every ounce of capacity they can though.

Bosch charges to 4.2(max of lipo) with a resting voltage of 4.18-4.19 per cell. Specialized does the same.

Storing at lower temperature is a huge benefit to battery life.

 

[jonmat]

Hi Alex,

I do understand what you are saying. Lets consider this. If a manufacturer rates the battery for 1,000 recharge cycles, it’s in their best interest to make sure it does just that. My point being, that when a battery has a 100% charge, it may not be a 100%, also the charge capacity may not be 625Ah. Do you understand what I’m saying? If you were going to create a decent warranty time, it would make sense to make the charge levels appropriate. I can’t evidence that by the way, I’m using my judgement having had 45 year's of experience in the electrical and electronics industry. I don’t want this to be argumentative, I’m relating my thoughts to my personal and technical experience and this is clearly not the same for everyone.

 

[Alexbn921]

Bosch charges to full voltage with ZERO protections. Simply look at your charged voltage and it's easy to see.

I've been into rc batteries for over 30 years and am a senior electrical engineer. Kind of something I've spent some time working on.

 

[R3Z3N]

^I agree with the above, also in the IT/Electronics industry.

As far as cost, $1k sounds reasonable if that is the case. Just because it's a battery doesn't mean the cost needs to be lower than what you think. Shoot, some people pay $450 for a cassette. IS that unreasonable? $100/tire? What is wrong with $200/tire?

 

[randycpu]

Hi Alex,

I do understand what you are saying. Lets consider this. If a manufacturer rates the battery for 1,000 recharge cycles, it’s in their best interest to make sure it does just that. My point being, that when a battery has a 100% charge, it may not be a 100%, also the charge capacity may not be 625Ah. Do you understand what I’m saying? If you were going to create a decent warranty time, it would make sense to make the charge levels appropriate. I can’t evidence that by the way, I’m using my judgement having had 45 year's of experience in the electrical and electronics industry. I don’t want this to be argumentative, I’m relating my thoughts to my personal and technical experience and this is clearly not the same for everyone.

I WISH that the bike industry had the "morals" and accountability of the electronics industry. The semi manufacturers know that their customers will sample test and measure the performance of what they paid for. Forced morals and accountability.

 

[Alexbn921]

Maybe a better way to explain storing a a battery at 100% is like redlining your car the whole time. As long as it's at 100% it's sitting there wearing itself out. I can sit here all day at red line because it has a rev limiter.

The BMS is the rev limiter and stops you from over revving to total destruction. It lets you extract the maximum performance within the capabilities of the battery.

Another thing is that NO new magic battery is coming!!!!! I don't care what you read about so and so. NO breakthroughs are just around the corner. It takes an absolutely missive amount of R and D just to squeeze out a couple percent improvement per year. No Nope Never going to happen. Better batteries will come, but the improvements are at least 10 years off and will start at energy density parity to current chemistry. Plus ramping production to scale we will take decades, just like it took current technology. Safety is the number one improvement I'm looking for.

 

[Planemo]

As far as cost, $1k sounds reasonable if that is the case.

I feel it's unreasonable because 50 high quality Sanyo cells would cost around £250.

Bosch bricking the BMS if you so much as sneeze at it means I have to pay them around 3x that for a complete new battery.

I DO like the Bosch PowerTube. I trust the battery management 100% and it's incredibly well built. But not being able to re-pack it is just annoying. It is what it is. But I'm not convinced the price of a new one is 'reasonable'.

 

[1oldfart]

It is like going to a sport stadium.
We become a captive customer.
There is one beer supplier, one food supplier they decide the price.
Our frame can accept one motor, one battery, they decide the price.
The freedom to shop around to look for a better price is not an option.
We buy a replacement = they win
We buy a new one = they win
This is a WIN, WIN FOR THEM.

 

[Pdoz]

It is like going to a sport stadium.
We become a captive customer.
There is one beer supplier, one food supplier they decide the price.
Our frame can accept one motor, one battery, they decide the price.
The freedom to shop around to look for a better price is not an option.
We buy a replacement = they win
We buy a new one = they win
This is a WIN, WIN FOR THEM.

But did you enjoy the game?

 

[randycpu]

I feel it's unreasonable because 50 high quality Sanyo cells would cost around £250.

Bosch bricking the BMS if you so much as sneeze at it means I have to pay them around 3x that for a complete new battery.

I DO like the Bosch PowerTube. I trust the battery management 100% and it's incredibly well built. But not being able to re-pack it is just annoying. It is what it is. But I'm not convinced the price of a new one is 'reasonable'.

I totally agree with you on the retail cost of the parts being WAY lower than the retail cost of finished goods. But the mfger must amortized R&D, warranty replacements, profits,
On the "bricking" of the BMS: Most BMSs are very sensitive to the power-on sequence. If you simply connect the output terminals you will blow up the limited "processor" or output FETs of most BMSs. We simply need to learn the power-on sequence of these BMSs as we rebuild the packs.

 

[2WheelsNot4]

If you look at how many charges, and divide that by the cost of new, its only a couple of quid per charge.
Buy a box and each charge stick in a £2 coin. When they reaches £100, stick it in a separate bank account and before you know it, most of the replacement cost will be sitting there waiting.

 

[Planemo]

I totally agree with you on the retail cost of the parts being WAY lower than the retail cost of finished goods. But the mfger must amortized R&D, warranty replacements, profits,

Oh I do understand and appreciate all that. And Bosch aren't doing anything new with this 'dealer only' serviceability/replace policy, it's been going on for years with many other products. I'm just moaning that it's come to ebikes because I've had totally open systems in the past. Only last year I re-celled the Mrs hub drive bike and the year before that I had replaced the BMS. All super easy, cheap, and will give it another 5 years minimum lease of life. And after that...I can re-cell again etc etc. It's a 'for life' bike for minimum cost. I like that. But I do also like Bosch's engineering, so there is that.

On the "bricking" of the BMS: Most BMSs are very sensitive to the power-on sequence. If you simply connect the output terminals you will blow up the limited "processor" or output FETs of most BMSs. We simply need to learn the power-on sequence of these BMSs as we rebuild the packs.

I think the Bosch BMS requires more than just a connection sequence. For sure theres some handshaking going on and I think thats what the problem is. I believe my main re-celler used to slave power the BMS when swopping out cells, but he said even that doesn't work with the Gen4 batts.

 

[michael.kozera]

Every second a battery spends at full charge damages it. Its a time over charge function. I charge mine within hours of use. In the last 6 months it's spend a total of about 60 hours at full charge. 40 of that's was because my wheel broke and I couldn't ride.

A fully charged battery losses 25-35% per year depending on temperature. Gone with no work done.

A well maintained battery should last 10 years or over a 1000 cycles to 80%.

no....just no.

Again, do you have a reference for this?

From my reading, eg https://core.ac.uk/download/pdf/323272674.pdf

The annual degradation only gets into those 25-35 % ranges if you are storing above 30 degrees, and the difference between storing at 50% to 100 % only gets significant at those higher temperatures. Also, once you get past the first year the rate of degradation seems to drop off, so If you leave a li battery for 10 years, the difference in degradation between 60% and 100% is less than 10%.

Is it really worth worrying about a 10% difference over a 10 year period , and do we actually end up doing more damage from the occasionally fully discharged cycle when we forget to charge before use?

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agreed.


i keep track of my batties mah/wh used vs charged and i notice about a 2% degradation over 1 year, and thats riding well over 10,000km a year per bike ( roughly 100 charge cycles per year). and at that point i would say leaving my battery fully charged ( which i do often during the summer months) has little to no effect on that 2% loss. yes if i leave my battery for 2 weeks or longer ill discharge it to 60-80% for storage.


funny u mention the fully charge thing, as i tell all my friends and family. leaving a battery 10% state of charge or lower is 100x worse then leaving it fully charged.

 

[RobG]

Assuming Specialized used good-quality cells, these batteries should easily last 5-7 years or more. I bought an "SOK" brand 206 amp-hour LiFePo4 battery for my RV a few months ago, and it came with a SEVEN year warranty. In addition, it comes in a metal case that can be opened so you can replace bad cells if needed, and even the BMS.

I think what I would do, assuming the battery wasn't covered under warranty, is, assuming I was in no rush to ride, I'd split the thing open and start testing all the cells in it to find the bad one. Or maybe the BMS is bad. And replace the bad parts. OR, if I want to ride, buy a replacement, and THEN split the old one open to work on it. Heck, if you have the 500w version like me, you could buy new cells and rebuild the battery to be 700w (or more, depending on what capacities are available when this happens).

Do a lot of searching on YouTube... there are some great tutorials on how to build your own batteries. Just be forewarmed that it's a dangerous activity and there are safety precautions that must be taken. You've seen the stories about Teslas bursting into flames. That could happen to you while working on them if you aren't careful.

 

[Peajay]

Don’t worry about your Tesla unless you plan keeping over 8 years old and over 100k miles, the degradation is pretty low too by most accounts , I have one and getting a puncture is more of a worry than the battery!

 

[Planemo]

I think what I would do, assuming the battery wasn't covered under warranty, is, assuming I was in no rush to ride, I'd split the thing open and start testing all the cells in it to find the bad one. Or maybe the BMS is bad. And replace the bad parts. OR, if I want to ride, buy a replacement, and THEN split the old one open to work on it.

You can't, assuming its Bosch.

If you disconnect any cells (to replace) the BMS will brick. If you replace the BMS with anything other than Bosch it won't handshake with the rest of the system and will never work. So the only solution is to buy a complete (Bosch) battery.

 

[jimbob]

You can't, assuming its Bosch.

If you disconnect any cells (to replace) the BMS will brick. If you replace the BMS with anything other than Bosch it won't handshake with the rest of the system and will never work. So the only solution is to buy a complete (Bosch) battery.

The same as shimano so I read in another thread.

A great pain and a shame as that was always my plan. I guess it may be possible if you kept power applied to the bms when replacing cells?

 

[Planemo]

I guess it may be possible if you kept power applied to the bms when replacing cells?

Already been tried, doesn't work. I don't know exactly why but I suspect the BMS is constantly looking at the parallel string voltages, not just the total output voltage. I guess potentially you could bring all your new cell strings to exactly the same voltage as the old ones and connect them in parallel to the old before disconnecting the old one by one and praying (visions of diffusing a bomb here) but who knows what variation in voltage will trigger the BMS to brick, it could be as little as 0.05v. Plus even if it did work you would likely end up with a pretty nasty mess of incorrect length string wiring without any ability to alter it afterwards. For all these reasons, it wasn't deemed commercially viable for Insat (BGA re-working) who are very experienced in re-cells.

Waiting for some private individual to give it a go though...

 

[jimbob]

Already been tried, doesn't work. I don't know exactly why but I suspect the BMS is constantly looking at the parallel string voltages, not just the total output voltage. I guess potentially you could bring all your new cell strings to exactly the same voltage as the old ones and connect them in parallel to the old before disconnecting the old one by one and praying (visions of diffusing a bomb here) but who knows what variation in voltage will trigger the BMS to brick, it could be as little as 0.05v. Plus even if it did work you would likely end up with a pretty nasty mess of incorrect length string wiring without any ability to alter it afterwards. For all these reasons, it wasn't deemed commercially viable for Insat (BGA re-working) who are very experienced in re-cells.

Waiting for some private individual to give it a go though...

Interesting, thanks. I can't imagine it would be that difficult to reverse engineer the protocols between the battery and bike and make a new BMS. There just probably isn't the demand (yet, at least) to make it commercially viable.

 

[dobbyhasfriends]

meh, by the time my current batteries have had it, the nuclear ones will have been sorted and weigh about 3oz.
BTW, nuclear batteries are actually a thing.

 

[TheRealPoMo]

I can't see the great unwashed being trusted with enough radioactive material to power a 250w eBike.

 

[Planemo]

the reason jimmy stopped recelling the bosch batts and all the other ones to boot as now wont touch any of these batts is because of can bus programming and encryption that each manufacture uses on these bikes same as cars!, bosch invented can bus.

if power is removed from the bms it looses its can bus programming and needs to be flashed back on for it to work again that only bosch can do at the factory.

Yeah thats what we've been saying mate. Remove the power and it's kaput. And it's not as simple as running a slave pack to swop out cells, as Jimmy found out.
Good to see you here, come over from the other side I see

 

[irie]

In the same vein, what's going to happen in a few years time when current electric car batteries start failing and new battery technologies take over? They're not going to look very ecological then ...

 

[TheRealPoMo]

Remains to be seen if battery or chemical storage (H2 fuel cell) comes out on top for automotive applications.

 

[Mteam]

now with can bus and these new smart displays have a full can bus chip in them rather than the dumb ones in like the purion displays just just see the can signal and now serialize the numbers of each part connected to the system so motor display and batt.

i got a new cx motor from peter and with my purion display and both of my batts worked and not a problem untill i got a kiox display as wanted my batt to display 100-0% than 5 bars.

as soon as i turned it on it said dealer update required so to clear it had to go to a bosch dealer and charged me 30 quid to plug in a usb cable and push a button!

i did say i had 2 batts but they said it will be fine.

week later i put on my other batt and dealer update required again as the display now sees the sn has changed and must be blessed with a can shake from the bosch dealers software because i have 2 batts and there that fkn stupid.

and when i get a new one it will do it again as got no choice but to buy one from magura/bosch or pay even more for a 3rd party one but i doubt it will work with these smart displays and esp gen 4 motors with the nyon displays.

Thats odd, I have a bosch cx (gen4) bike with the kiox display, and the 625wh powertube battery. I wanted a spare battery, so I just bought a new 500wh powertube battery from the internet, plugged it in and it worked fine, no messing around having to take it to the dealers for programming etc.