E-Bike battery concerns


New member
Local time
5:00 AM
Aug 21, 2020
Never thought I would be thinking of purchasing an E Mt.bike, but after riding one I was hooked. Turning 60 in February and the e bike option sure does look like a way to keep riding in my 60's and beyond. My only concern is battery longevity what's going to happen 3-5 years down the road when its time maybe to replace the battery? The way bike company's change frame layout from year to year a new battery might not be available, now I have a 50lb lug of a bike sitting in the garage. There's always after market batteries, but they never seem to work as well as the OEM battery. What's peoples experience with this or is this a non issue, do company's like Trek, Giant etc rebuild battery packs?

If you go by how batteries are being used in energy storage and vehicles you are looking at (depending on the battery chemistry) 500 to 1500 full battery cycles. A full battery cycle is 100% state of charge to 0% of charge and back again. For these bikes and such you would rarely do that type of thing so you are right looking at that 3-5 (or more) years of life.

Rebuilding battery packs?? Lithium ion packs are generally not torn apart and rebuilt. It is not a hard thing to do but it is a bit of a PITA. Depending on how the pack was sealed the housing maybe destroyed in the process. So in most cases new battery packs are used and old ones discarded, even if some or most of the cells are still good.

Just a note it only takes a single cell to make a set of paralleled cells to be considered bad, which is not an issue in systems where you can mix and match but in the packs being built for these bikes not so much.

So long story short it is a crap shoot and you could be SOL in the long range.
There seem to be a few European companies that will re-cell Bosch batteries but none for my Yamaha PW-SE battery; you should probably get a Bosch-powered bike if you want to re-cell. I’ve seen a teardown of a Yamaha battery so I’m pretty sure I could re-cell myself but I’ll probably just buy a new battery and use two interchangeably if I think that my odometer is going to reach 20000 miles; only 800 miles in 3 months so I’m not sure whether I’ll ever need a new battery.
The battery issue was actually one factor in my going with a Bosch powered ebike, I figured they were so popular in Europe already that I should be able to find replacements until something else goes really bad. I can't see buying one from Bosch though, $900!

If they keep selling the frame mounted version that I have, I'm guessing it might end up being cheaper in a few years to buy a used bike that the owner hasn't ridden much, take the battery, and resell the bike to someone who already has a good battery.

Performance is going under, and locally they have a couple of Bosch powered Fuji eMTBs for about $1700. If they hit under $1000 I might buy one just to part out. The motors, controllers, chargers, batteries are all easily sellable on eBay. Or, buy a Chinese FS eMTB frame made for Bosch and move everything over.

I have a feeling when batteries start dying and the replacement costs are realized, there will be a lot of cheap ebikes from all manufacturers being sold on eBay and craigslist.
3-5 years sounds good but not real good guess one could purchase a new backup battery around the 3 year mark to have on standby. These bikes with the integrated battery in the frame look real nice they almost don't look like an e bike, but like I mentioned the damn bike company's change frame designs so much that in 3 years one could be SOL for a new custom fit battery. Its safe to say I won't be purchasing a Specialize S-works e bike $12,000 + is down right highway robbery to have sitting in the garage useless in 5 years.
I don't think this is an issue at all. If you have water bottle mounts you just buy a battery for $300-500 that's the right voltage and bolt it on. Worst-case scenario you need to put a rear rack on the back of the bike. You may need help for the wiring (lord knows I did) but other than that, in theory any e-powered bike can have an external battery with matching voltage. Some guys even have two batteries for all-wheel drive, this is all very flexible, doesn't matter what the original setup was. I've even seen 36V batteries paired with 48V motors, so this is not a huge deal, the biggest thing is that you'll have a very conspicuous battery and everyone will know you have an e-bike. It is a big deal for integrated hybrid or e-car batteries to die but not for bike batteries. Do not let something trivial like this discourage you!
As you suggest the industry will go through many forms of battery designs in the years ahead and in fact already have. Not only the motor manufacturers but also the demands made by the brands that want to have their designs be proprietary. However it should be possible to take any battery apart and replace the cells down the road. Question being will the manufacturers have fresh batteries of your type in stock 5 yrs. from now or ones that have been sitting on a shelf for 5 years or so. Big difference there especially if they haven't been maintained at a sustainable level of charge over that time.

No doubt some enterprising folks will be able to rebuild batteries in the coming years and in fact there are already services set to do so both here and abroad.

I am not sure that the scenario described by richj will work as he describes though due to the proprietary BMS/CAN BUS communications that the manufacturers have built in to their systems. In a rebuild they can be re-used but it will take some doing for anybody other than the manufacturer of origin to replicate this aspect so not as flexible as it might appear. Open source systems will be able to retro easily though.

Another thing is that as battery technology progresses, as it already is with the introduction of the 2170 cells, the size of the new cells will make retrofitting into the old formats difficult but doable if the manufacturers once again support it. Of course the 18650 cells can still be used but I would bet that the manufacturers are betting that the new cells will spur new whole bike sales to get on board. Planned obsolescence is the name of the game in the bike industry.

The biggest factor though, at least now and into the foreseeable future is shipping batteries to a repair facility.

Guide to Shipping Lithium Batteries

Already seeing issues with this and unless the rules change it won't get any better and the average person is not going to find it easy and expensive to ship their battery. However as time goes on there will be more certified shipping agents. On the way back the repair outfit should already be UN certified. Also shouldn't be a problem getting replacement batteries from your manufacturer if they have them.
I just spent $500 on custom 1160wh battery for a DIY eBike built with Sanyo 30q cells. Considering Shimano charges about $500 for a 504wh battery, i'm guessing once eBikes get more popular, aftermarket companies will be able to offer a similar battery for quite a bit less.

I just hope manufactures publish what cells they use to give an idea of quality. The BMS can be a weak link, although given time, aftermarket manufactures / rebuilders will develop a reputation for themselves
The problem is that you can't just slap a random battery onto a Bosch/Yamaha/Shimano mid drive ebike. There is firmware in the batteries themselves that identify the battery to the motor controller as being "approved". Without that communication, the bike won't even powerup properly.

For Bosch, that is why there are companies in Europe that dissect the original battery casing and replace the cells. Apparently this is not easy, as some of the wiring inside is very delicate. Also, if you short out the BMS, you ruin the entire battery, because the BMS is not something you can get from Bosch.

BTW, the retail on the Shimano battery is actually $650, for a Bosch 500wh it is over $900!
Someone will eventually come along and figure out this communication if there is money to be made. The Chinese are great at stealing intellectual property (y)
No surprise here, but batteries are dangerous!
Rebuilding them takes special tools. You also have to ensure that the factory safety systems are retained. If you look back 5 years most batteries are different now. They use different cells and have changed form factor. The new 2170 will be the standard moving forward and since they are larger will not fit in most internal battery frames.
Electronics are also non standard and evolving at a rapid rate. No guarantee that parts or compatibility will be maintained.

Anyway 2 to 4 years depending on cycles, storage and use. Heat kills them fast.
If you can stay in the 30-80% range and don't charge them to 100% they will last much longer.

I have no interest in burning down my house charging an ebike with suspect batteries.
I'm pretty convinced there is a steep markup on batteries and chargers at the moment, much like when 11 speed or 12 speed came out. Even if you bought the top 18650 cells - Sanyo GA's, Samsung 35e, or Sony MJ cells or whatever... you're probably not looking at more than $150 for the cells in a 504wh pack plus $50 for the BMS. Sure the cost that goes into designing a sophisticated BMS that communicates with the bike computer isn't cheap, but that cost will come down greatly once they start selling more units.

It will be very interesting to see how things develop in the next 5, 10 years...
Hey Delta kilo,

As others have said, if this of real concern for you, select a bike with a big name (Bosch, Yamaha, Shimano) drive system and a standardized battery. Today, Bosch offers a downtube integrated battery that is standardized (the Bosch PowerTube). So, the bike looks sleek, but the batteries are readily available. Haibike, Trek, and many companies are offering a wide range of eMTB's with an integrated standard battery. The Pivot Shuttle uses a standard Shimano battery, but enclosed in their downtube (also one of the lightest on the market). Cheers,
Well battery longevity will matter how far you discharge the battery to, how long you leave it there, if you leave the controller plugged in, because the controller does take mAh of juice, at what level and temp you store the battery at, how many cycles you go through, how well the battery pack is built. The generic batteries off of Alie/baba/ebay are a gamblers game. I prefer to build my own so I know exactly how its built. Buy a big enough pack that will get you there and back with some to spare and you should be good to go.