Ebike battery question....

[shawninvancouver]

Is it true if one cell in the whole battery dies, the battery will not charge or discharge properly??
that is like the size of one AA battery is not charging -then the battery is useless>???
can the one cell be fixed? or do you buy a new 500.00 battery when one cell fails??
i have a battery that has one dead cell - put new BMS in.. should the battery work??
help!!

 

[shawninvancouver]

any help here??

 

[mschwett]

yes; if one cell is dead the BMS should do its job and shut down the pack. the way they’re typically wired, you can’t have one cell out of balance.

there are companies that fix these packs by replacing one or more of the cells, but it’s fairly expensive.

it’s also not as easy as it sounds …

 

[shawninvancouver]

ya. got ya.. so what do most people do if one cell dies??? get a new battery??

 

[shawninvancouver]

oh.. also.. is it ok to have a bike battery with no on off switch? i dont leave my battery on my bike when not using bike... not sure what the use of the on off switch is for..

 

[shawninvancouver]

any ideas?

 

[Dave Rocks]

I don’t have an on off switch on my battery. There is no need to remove from the bike when it’s not in use.

 

[rich c]

Thanks to a new job I am considering buying an ebike for +30km commute. As I understand it is recommended to charge it after each use - twice a day, roughly 500 charges per year. What's the word on battery longevity with such use? Would it suffer after a year? I am not too keen to spend 3k on a bike to find out I would have to change the battery yearly...
Another question is how many different standards are there? Buying a Giant can I use aftermarket replacement product or no chance?

I sure don't charge it after every ride. Depends on how you ride of course, but why charge it with maybe 60% still in the pack? If the Giant has a Bosch battery, an aftermarket battery voids the warranty. And Bosch's software can certainly tell.

 

[indianajo]

I believe Giants are Yamaha mid drive & Yamaha battery. Big companies like Bosch, Yamaha, Shimano, patent their battery connections to make sure their batteries can't be substituted by anything else. I believe Bosch has a computer in the battery that must communicate with the controller before the bike will power up. A canadian company that did that, Bionx, is now bankrupt. But some people love Bosch. I wouldn't accept a Bosch mid drive bike as a gift. Most Bosch drag the motor with your feet with the power turned off. Sometime the rain shorts out the controls until I pedal home and use a hair dryer.
LiIon batteries are reputed to fail after 1000 charges. I have about 400 on mine; it is 4 years old and working fine. I bought generic hub drive so I could buy a generic battery. Still cost me $630 for 48 v 17.5 AH. Mine will take me 30 miles & 80 hills with 80 lb of groceries or ag supplies, arriving about 35% of charge. My battery is screwed to the frame at the front basket mounts and takes 25 minutes, 2 wrenches and a nail puller to get off. About 20 to put on. I lock my bike up frequently at stores, concerts, meetings, volunteer job. Wannabe thieves at the grocery have had a go twice at the battery, loosening 2 of 18 nuts, but not the critical ones.

 

[retiredNH]

Indianajo brings a wealth of experience from the point of view of a dedicated DIY cargo bike builder. But I'd like to correct a few mis-perceptions on his part. First, lion batteries don't fail after 1000 charges. Rather, good batteries have been found to take 300-500 charge discharge cycles while keeping 100% of capacity, and gradually lose capacity as cycles increase. In fact, most cells go well into the thousands of cycles before degrading significantly. Much depends too on how heavily the battery is loaded, how far it's discharged and how high it's charged.
Interestingly, I've read many a report on this board of battery failure, but all of them have been generic batteries. I've not seen any of failures of name brand ebike batteries, or even reports of significant loss of capacity. Seems to be a problem for the DIYers.
Finally, I don't think Indianajo speaks very authoritatively on Bosch powered bikes. I doubt he's been on one in years, since he's the only one that likes to talk about their drag. Seems to be missing for the rest of us.

 

[tomjasz]

Indianajo brings a wealth of experience from the point of view of a dedicated DIY cargo bike builder. But I'd like to correct a few mis-perceptions on his part. First, lion batteries don't fail after 1000 charges. Rather, good batteries have been found to take 300-500 charge discharge cycles while keeping 100% of capacity, and gradually lose capacity as cycles increase. In fact, most cells go well into the thousands of cycles before degrading significantly. Much depends too on how heavily the battery is loaded, how far it's discharged and how high it's charged.
Interestingly, I've read many a report on this board of battery failure, but all of them have been generic batteries. I've not seen any of failures of name brand ebike batteries, or even reports of significant loss of capacity. Seems to be a problem for the DIYers.
Finally, I don't think Indianajo speaks very authoritatively on Bosch powered bikes. I doubt he's been on one in years, since he's the only one that likes to talk about their drag. Seems to be missing for the rest of us.

Almost true. Cheap eBikes have cheap batteries. Some of us DIY guys buy good batteries. It’s those Amazon cheap seats that fail most often.

 

[harryS]

Is it true if one cell in the whole battery dies, the battery will not charge or discharge properly??
that is like the size of one AA battery is not charging -then the battery is useless>???
can the one cell be fixed? or do you buy a new 500.00 battery when one cell fails??
i have a battery that has one dead cell - put new BMS in.. should the battery work??
help!!

How dead is the cell? You really can't measure one cell. It's in parallel with two, three, or more other cells. So you have a dead group of cells. What is the voltage. If it's too low, it's not safe to recharge it. If it's above 2.5 volts, then it's possible a new BMS with balance capability "could" being it back. Let's hear your full story here.

While cells can be replaced, it's a labor of love. You can't pay a repair guy enough for the many hours it will take. It's cheaper to buy a new battery or have it re-celled. I'm looking at your pictures, and that's not economically feasible to replace cells.

 

[tomjasz]

it's a labor of love.

It's cheaper to buy a new battery or have it re-celled.

This!
I wouldn't call it love, but it sure does take some commitment.
There are MANY pitfalls as well as expenses. By the time all the pieces, parts, and tools are assembled it WILL be cheaper to buy a new battery.

I wish the OP would provide more details and pictures. Especially who made the battery or who was the seller. How long ago was it purchased? What was the claimed warranty?

There are cheap welders but the failure rate is high. Remember these batteries put out 15-30AMPS. If you've ever seen one arc and the fireworks, well sensible owners will walk away from that adventure.

Sadly the low resolution pictures make reading the cell versions impossible to read.

 

[Mr.MikeB]

Check this place. There are places that repair these, mostly the west coast.

Buy Products Online from China Wholesalers at Aliexpress.com

 

[tomjasz]

Check this place. There are places that repair these, mostly the west coast.

Buy Products Online from China Wholesalers at Aliexpress.com

Run don’t walk away from those cheap batteries. The west cost battery repair costs will be more than you paid once it’s shipped illegally and you pay both ways. Hazmat shipping fees apply.

 

[omitannoyed]

I'm not sure there is any solution to your problem...