# Battery care



## Sparticus (Dec 28, 1999)

So I think I might be doing it wrong.
I've had a Trek Rail 7 since Feb. 2021 -- 14 months now.
After I get home from a ride, I charge it up so it's ready to go next time.
But recent statements about batteries on this forum give me cause to believe I'm not supposed to do this.
"This" being keep the battery fully charged between rides.

Why?
What's the right way to care for an ebike battery?
Thanks,
=sParty


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## 127.0.0.1 (Nov 19, 2013)

the right way is based on battery chemistry

Bosch Power Tube uses lithium ion....
Lithium-ion must be stored in a charged state, ideally at 40 percent. 









BU-702: How to Store Batteries


BU meta description needed...




batteryuniversity.com




.


capacity loss at storage charge states


*Temperature**Lead acid*
at full charge*Nickel-based*
at any charge*Lithium-ion (Li-cobalt)*40% charge100% charge*0°C*97%99%98%94%*25°C*90%97%96%80%*40°C*62%95%85%65%*60°C*38%
(after 6 months)70%75%60%
(after 3 months)


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## alexbn921 (Mar 31, 2009)

Almost all Ebikes use 18650 or 21700 cells with a li-ion chemistry.
These batteries swell at 100% and contract at 0% internally. This ages the battery and is a time over charge difference from 50% function.

BAD
Heat. Don't let the batteries get too hot during charging or riding. Let batteries cool before charging after a ride.
Storing at 100% has a massive effect on life cycle and total capacity.
Draining the battery to below 10% has a negative effect and only gets worse the closer to 0% you get. Going all the way to zero and letting it sit can kill a battery permanently. 
Charging over 4.2v per cell significantly reduces cycle life. More voltage is an exponential decrease in life.


Good
Always store at 3.7-3.85 per cell. 50-60%
Charging to 100% and then immediately riding has very little to no effect on total cycles.

Bike apps that report battery health are complete garbage. Don't trust them.

I have a wifi plug timer $10 and charge after rides to 50-60%. Then I can setup or remotely charge my bike before rides. With this setup I expect 7-10 years of maximum performance from my battery with no drop off in capacity or power output.

You lose performance slowly so it's hard to notice the drop off in range and power. If you need to store your bike for more than a week it is absolutely critical that you drain the battery from full charge down to storage charge.


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## DtEW (Jun 14, 2004)

Batteryuniversity.com is a wealth of information.

But the short of it with lithium-ion chemistry batteries is that a deep discharge is very bad for them. A full charge isn’t great for them either (mostly for the disproportionate heat that is generated as you approach full), but less bad than the deep discharge.

The best thing to do for you Li-ion battery is to keep its charge state somewhere in the middle of its capacity. But that’s generally not practical for most of us. So what’s recommended for electric cars does well for us too: for everyday usage, charge to 80-90% charge close to when you want to use your vehicle. Only charge to 100% for the occasional heavy use day, which also achieves the goal of allowing cell balancing circuits to do their thing so the cells do not become too unbalanced. But for that usage, you might want to let the vehicle sit (esp. something without active thermal management, such as e-bikes) a little bit so that the cells cool down before you draw power from them (which also generates heat). How often you need to take the battery to 100% is a subject of intense debate.

In terms of practical e-bike usage, I charge my Levo the moment I roll out of bed with the rough calculation that I add ~10% charge every 20 minutes. I don’t use much charge (~30-40%) on my bread-and-butter rides, so I’ll always have what I’ll need by the time I’m done loading the car with everything but the bike. If I come home with a deeper discharge, I’ll immediately charge when I get home to ~60%, and that’s how I’ll let it sit. For all of these I just set a timer on my phone to remind myself when to disconnect.


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## RBoardman (Dec 27, 2014)

After I finish a ride I charge my bike up to 100%. It will sit until the next time I ride. Rinse and repeat. Showing up to the trail with a bike that’s not fully charged because I forgot to plug it in is a worse scenario for me than my battery slowing dying over time.


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## Sparticus (Dec 28, 1999)

RBoardman said:


> After I finish a ride I charge my bike up to 100%. It will sit until the next time I ride. Rinse and repeat. Showing up to the trail with a bike that’s not fully charged because I forgot to plug it in is a worse scenario for me than my battery slowing dying over time.


That's been my practice to date.
But considering a replacement battery costs ~$1000, today I ordered a couple WiFi / programmable plugs for the GF's and my ebikes.
This way I'll be able to turn the chargers on or off from anywhere, anytime via my phone.
If, say, we're at friends' place for dinner and they say they want to ride ebikes in the morning, I'll be able to turn the chargers on right then and there.
I'll give this a try. If it doesn't work out then I'll go back to the way things are now.

Thanks to all who've provided input so far.
=sParty


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## 127.0.0.1 (Nov 19, 2013)

that remote control power strip idea, is ideal

I have an old one I could telnet into...


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## Mojave G (Jan 30, 2015)

Sparticus said:


> That's been my practice to date.


Same here, thanks for the thread start, didn't know this was a "thing" , might start leaving mine uncharged until I know I'm going for a ride soon.


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## eb1888 (Jan 27, 2012)

There is a 'normal' number of charge cycles before your battery degrades to 80% of its original capacity. You get hundreds more if you charge to 80 and deplete it to 10%.


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## RBoardman (Dec 27, 2014)

Sparticus said:


> That's been my practice to date.
> But considering a replacement battery costs ~$1000, today I ordered a couple WiFi / programmable plugs for the GF's and my ebikes.
> This way I'll be able to turn the chargers on or off from anywhere, anytime via my phone.
> If, say, we're at friends' place for dinner and they say they want to ride ebikes in the morning, I'll be able to turn the chargers on right then and there.
> ...


I normally get a new bike every ~12 months, so hopefully in that time span I see no ill effects from my poor battery management.


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## alexbn921 (Mar 31, 2009)

RBoardman said:


> I normally get a new bike every ~12 months, so hopefully in that time span I see no ill effects from my poor battery management.


You'll be fine, but the next guy is screwed.


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## Tickle (Dec 11, 2013)

So charging to 100% and letting the bike sit for 2 months over the winter was not good?  I'm in the same boat as Sparticus and Rboardman, I can easily enough just wait and fully charge before I ride again instead, probably at 20-40% battery after most rides is that ok to store at? Doubt I would remember to charge to 50% after the ride and then fully charge before I ride again


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## 127.0.0.1 (Nov 19, 2013)

Tickle said:


> So charging to 100% and letting the bike sit for 2 months over the winter was not good?  I'm in the same boat as Sparticus and Rboardman, I can easily enough just wait and fully charge before I ride again instead, probably at 20-40% battery after most rides is that ok to store at? Doubt I would remember to charge to 50% after the ride and then fully charge before I ride again


if you want to keep it topped up
take the battery pack at 100% charge, and stuff in the fridge. do not freeze it, but keep as close to 32 deg.
it will last long as possible on full charge. room temp, a bit less. hot sun room, even less.

pull from fridge, prep for your ride, go ride. 

just *never try to charge a pack that is at, or close to, freezing*... but using it fridge-cold at the start is not a problem
your charge circuit should have protection and not allow a charge on a cold pack, but don't trust that it is designed 
that way. 

charging a frozen lithium pack will render it garbage in no time. always let them warm up before charging li-ion


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## Tickle (Dec 11, 2013)

Thx but my battery is not removable w/o dropping motor, I was more curious if letting the bike sit for a few days between rides at say 20-30% battery is better than charging to 100% right after like I'm doing now. Sometimes the bike might sit for a week or more too so sounds like I need to change my charging habits if I want the battery to last


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## EliminatorMTB (Apr 28, 2009)

If they really want us to charge to xx% for long term storage, why doesn't the charger have a button to charge to xx% and 100%? And trickle charge to maintain that %? For the cost of the bike seems like they could include a smarter charger...

It takes quite a bit of riding to drop from 100% to 60% its not like you can just do a couple laps around the block. I too have been charging to 100% after each ride then unplug it when I remember, I ride at least once a week so its never sitting long at full charge.


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## alexbn921 (Mar 31, 2009)

EliminatorMTB said:


> If they really want us to charge to xx% for long term storage, why doesn't the charger have a button to charge to xx% and 100%? And trickle charge to maintain that %? For the cost of the bike seems like they could include a smarter charger...
> 
> It takes quite a bit of riding to drop from 100% to 60% its not like you can just do a couple laps around the block. I too have been charging to 100% after each ride then unplug it when I remember, I ride at least once a week so its never sitting long at full charge.


They should have. All and I mean all real RC chargers have a storage function.

You are basically always storing your battery at 100%. This shortens the life by 3-4X

Do you want to buy a new battery in 2-3 years or 8-10.


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## EliminatorMTB (Apr 28, 2009)

alexbn921 said:


> They should have. All and I mean all real RC chargers have a storage function.
> 
> You are basically always storing your battery at 100%. This shortens the life by 3-4X
> 
> ...


That's a pretty significant loss of battery life! If that's true I'll consider changing my habits and try to let it sit around 50% charge between rides and try not to do full 100% charges unless I know it's going to be a big ride. Think I'll start pulling the battery out to charge since it's pretty easy to do on the Levo.


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## DtEW (Jun 14, 2004)

EliminatorMTB said:


> Think I'll start pulling the battery out to charge since it's pretty easy to do on the Levo.


Not that I've done any experiments to further this theory... but even with an air-gap, an aluminum frame could behave as a large heat-sink... or at least one less of an insulator than a carbon-composite frame.


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## matt4x4 (Dec 21, 2013)

Having a fully charged battery for long periods of time is not worth the degradation, even if its for 12-15hrs if you dont ride, its best just to charge to some higher then average "storage" voltage and before you ride, just charge it up at a charge rate of 8-10a or something, and it bumps it up quite quickly and doesnt take long at all. From my 58.80v fresh off the charge 52v battery with the lvc set at I believe 14s x 3 is what????? 42v looks about right, probably more close to 41.00v when the bms lvc kicks in. When I get home I charge to 55v or 3.9v/cell. And I will ride it no matter what, even if its just to dump down to 3.70v/cell the next day. My other battery charges max to 20.20v with split 36.


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## Sparticus (Dec 28, 1999)

matt4x4 said:


> Having a fully charged battery for long periods of time is not worth the degradation, even if its for 12-15hrs if you dont ride, its best just to charge to some higher then average "storage" voltage and before you ride, just charge it up at a charge rate of 8-10a or something, and it bumps it up quite quickly and doesnt take long at all. From my 58.80v fresh off the charge 52v battery with the lvc set at I believe 14s x 3 is what????? 42v looks about right, probably more close to 41.00v when the bms lvc kicks in. When I get home I charge to 55v or 3.9v/cell. And I will ride it no matter what, even if its just to dump down to 3.70v/cell the next day. My other battery charges max to 20.20v with split 36.


Matt, those of us who don't speak Electricese have no idea what you just said means.
=sParty


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## BansheeRune (Nov 27, 2011)

sParty needs a translator!


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## Sparticus (Dec 28, 1999)

BansheeRune said:


> sParty needs a translator!


Did you say I need a transistor? 
=sParty


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## BansheeRune (Nov 27, 2011)

Sparticus said:


> Did you say I need a transistor?
> =sParty


You do! Jus sayin'...


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## Jack7782 (Jan 1, 2009)

Will you rebuild your battery yourself or are there shops in Europe that do this kind of service?


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## alexbn921 (Mar 31, 2009)

First off you don't replace bad cells in a well used pack. The internal resistances will be off and the stress will not be spread evenly. This causes all kinds of problems. The only way around this would be to combine 2 bad packs with the same usage by testing every battery. Not worth the effort as the "new" pack would still be most of it's way thru it's life.

Second, No super cell is coming and you for sure would absolutely not use it in an old pack.

Some BMS's have a kill switch in them so you can't just rebuild a pack. Actually building of a pack isn't too bad with new quality batteries. It's still a lot effort and special skills are required to do it reliably in a dynamic environment like a bike.

Care for your batty and it will last a long time. If you need a new one, buy it. Leave the DIY packs to the guys that have been doing it for years and have a higher prepensely for risk. IMO it's not worth the time, effort and danger. This comes from someone that has built several small-medium packs for other projects.


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## Taroroot (Nov 6, 2013)

The worsr for lithium ion batteries is to let them drain too far. Drop to far and the cells are done, protection kick in and they wont take any charge.
Also do not recharge at or below freezing. Messes up the cells chemistry and can even lead to internal shorting, very bad! 
in comparison charging to 100% isnt so bad. Do not trickle charge after 100%, that is bad, there is no such thingon chargers for li-ion, they shut off.That is why you do not want to put it back on charger after reaching 100%. Charging beyond 100% is very bad. Cells can pop, go into thermal runaway and the famous videos of lithium battery fires.
Reputable cells and bms systems have protections for both under andnover charging conditions.


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## alexbn921 (Mar 31, 2009)

isolator said:


> New Battery coming soon!


That's just a higher nickel battery and while it increases the energy density it hurts cycle life. We are only talking a 3ish% increase year over year. AKA nothing new. 

Solid state is going to be a break threw, but is 10 years away at least and by then conventional batteries will be on par. Eventually they will ramp to scale and be the next thing is 15-20 years.


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## Sparticus (Dec 28, 1999)

What does ‘ramp to scale’ mean?
=sParty


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## alexbn921 (Mar 31, 2009)

1 solid state battery cost $1000's and take hours to make. In order to make any new technology cost effective you need to spread the R&D out over lots of units. For batteries that would be a yearly run rate in the Multi-millions.

For example just 18650 cells where over 6 Billion in sales for 2020. or 3ish billion cells.


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## blammo585 (Apr 24, 2012)

Ugh...you guys are hurting my head and making me rethink an e-bike purchase. I haven't been thinking about needing to be so particular about battery care. Now you've got me worried about storage, charging percentage, lifespan, buying a new one, etc. Maybe you've just given me a reason to buy the "regular" bike I've been eyeing.


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## Sparticus (Dec 28, 1999)

blammo585 said:


> Ugh...you guys are hurting my head and making me rethink an e-bike purchase. I haven't been thinking about needing to be so particular about battery care. Now you've got me worried about storage, charging percentage, lifespan, buying a new one, etc. Maybe you've just given me a reason to buy the "regular" bike I've been eyeing.


As long as you get a new bike, whatever that may be!
We're here for you, man. 💙
=sParty


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## blammo585 (Apr 24, 2012)

Sparticus said:


> As long as you get a new bike, whatever that may be!
> We're here for you, man. 💙
> =sParty


 I'm so torn. I should have never test rode that Rail that the bike shop convinced me to "take for a spin".


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## nilswalk (Nov 26, 2014)

Sparticus said:


> As long as you get a new bike, whatever that may be!
> We're here for you, man. 💙
> =sParty


Exactly! I really only have one well-proven, documented skill in life, and that's convincing people to spend more money on bikes than they planned to. Let me know how I can help.


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## Sparticus (Dec 28, 1999)

blammo585 said:


> I'm so torn. I should have never test rode that Rail that the bike shop convinced me to "take for a spin".


I made the same mistake.
Then, I bought one.
My test ride was just downtown through the waterfront park on paved paths.
I can tell you they're even more fun on real singletrack.
=sParty


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## 127.0.0.1 (Nov 19, 2013)

Sparticus said:


> What does ‘ramp to scale’ mean?
> =sParty


probably means actual production runs at factory vs one-off test lots


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## MountainHead (Apr 4, 2012)

Matt is saying that to avoid storing your battery in a fully charged state, charge it to a "storage" voltage, then charge at 8-10 amps to quickly get up to capacity.

The packs are made of individual lithium ion cells (18650) which are 3.2 volts discharged, 4.2 volts fully charged.

The LVC is the low voltage cutoff, which is a voltage at or below which the BMS (battery management system = electronic circuits to protect the battery back from over/undercharge and too high a discharge rate) turns off the power to prevent draining the cells too low.

Matt says the individual cells for his battery are probably wired together in a 14S x 3P configuration. That means 14 cells in series, and 3 cells in parallel. Parallel connection means positive to positive, negative to negative. Putting 3 cells in parallel means the current capacity will be 3X that of a single cell.
The units of 3 cells in parallel (there are 14 sets of these 3 cell parallel units) are connected in series. To connect 2 cells in series, the first cell's negative is connected to system ground, and its positive terminal is connected to the 2nd cell's negative terminal. Then the 2nd cell's positive terminal is the system power output. The voltage will be twice the standard cell voltage.

So Matt's battery has 14 triple cell batteries connected in series. That means the total voltage is single cell voltage X 14.
So for a fully charged 4.2 volt cell, 4.2 x 14 = 58.8 volts. This is the voltage of Matt's battery pack when charged to 100% capacity. 

Matt can run his battery down fully and the LVC (low voltage cutoff) will activate, turning off the power. That happens at a pack voltage of about 41 volts to avoid the pack being discharged too far. And the next thing that happens is everything goes dead because the LVC circuit kicked in.
To calculate the individual cells voltage, take 42 volts / 14 = 3 volts. This is a fully discharged 3.7V lithium ion cell.

Lithium ion cells should be stored at 40-50% of capacity. That corresponds to a voltage of 3.8 volts. So the pack voltage would be 3.87 x 14 = 53.2 volts

Matt charges to 55 volts after his ride. Individual cell voltage is 55 / 14 = 3.93 volts. This is about 70% capacity.

A more conservative plan would be to charge to 40-50% of capacity which is 3.8 volts. So 3.8 volts x 14 = 53.2 volts
So charge to a pack voltage of 53.2 volts and the battery will be at 40-50% capacity. This is appropriate for storage.

When he rides the bike, he drains the cells to 3.7 volts. This is a pretty deep discharge, to about 15% of the battery pack's capacity.


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## EliminatorMTB (Apr 28, 2009)

Who is Matt? The issue is still that the chargers don't have a charge to 50% mode which is ridiculous if that is what is needed to maintain the batteries life.... but probably smart if you're in the business of celling +$1,000 batteries. I think I'll set up a cheap timer and guestimate charge levels and I can set it to turn back on if I plan on riding within a day.


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## Sparticus (Dec 28, 1999)

MountainHead said:


> Matt is saying that to avoid storing your battery in a fully charged state, charge it to a "storage" voltage, then charge at 8-10 amps to quickly get up to capacity.
> ...


I'll try to follow these guidelines as best I can.
When I got home from my last ride (couple weeks ago, before I came down with COVID), my batt was down to between 40-50%.
I left it like that.
Going for a ride later today so I'm charging now.
The battery will probably get up to 80-90% of full, then I'll go ride.
Don't know how much I'll drain my battery today but will hope to get it back down to 40ish%.
Then leave it alone until just before my next ride.
Repeat ad infinitum.
Sound like a reasonable plan?
=sParty


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## MountainHead (Apr 4, 2012)

sParty you're always a quick study. That's why you get the big sprocket


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## Sparticus (Dec 28, 1999)

MountainHead said:


> sParty you're always a quick study. That's why you get the big sprocket


Simple minds require simple instructions. 
=sParty


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## Jack7782 (Jan 1, 2009)

Sparticus said:


> I'll try to follow these guidelines as best I can.
> When I got home from my last ride (couple weeks ago, before I came down with COVID), my batt was down to between 40-50%.
> I left it like that.
> Going for a ride later today so I'm charging now.
> ...


Matt4x4 is a DIY guy on our forum that has years of experience etc. 

In regard to 80% charge, I believe the Giant (Yamaha) sells a 'smart charger' that gives you that handy option.








EnergyPak Chargers | Giant Bicycles Official site


Fast & Smart Battery Chargers for your Giant Electric Bikes




www.giant-bicycles.com


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## EliminatorMTB (Apr 28, 2009)

Jack7782 said:


> Matt4x4 is a DIY guy on our forum that has years of experience etc.
> 
> In regard to 80% charge, I believe the Giant (Yamaha) sells a 'smart charger' that gives you that handy option.
> 
> ...


Can these chargers be modified to work with other bike manufacturers? Is it just a matter of changing the plug end?


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## 33red (Jan 5, 2016)

I would suggest you read your booklet. Also talk to your shop and why not email the manufacturer.
I own a Yamaha/Giant and i recently read tons about batteries. In short, ride recharge. The do not fill is for storage like 3 months or more.
Maybe your brand is different. I ride almost daily so i ride and recharge.
Just avoid the extreme cold or heat.Last november i put one of my Ebike in storage at about 60? charge. In 2 days i will get it back and charge it.


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## RBoardman (Dec 27, 2014)

Was going to start doing better battery care, but I ended up not using my range extender on todays ride so that’s gonna sit at 100% until I use it. And I didn’t go check on my bike soon enough after plugging it in, so that’s at 100% now. Oh well, next time. Lol


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## Sparticus (Dec 28, 1999)

Meanwhile my plan worked perfectly.
Yesterday I charged my bike up to about 90%, rode it down to about 50%, put it away just like that.
I'll try to do likewise in the future but I'm not going to worry about it if I don't.
Life's too short.
I bought the ebike to serve me, not the other way 'round.
=sParty


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## Tickle (Dec 11, 2013)

I've changed up my routine, leave it alone after the ride and charge before the ride instead, worked so far but I have no idea where the battery is after the ride as I have to go into app to see-no display.


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## RBoardman (Dec 27, 2014)

Question, is it better to leave an ebike battery sitting for 2 weeks at 100% charge or 0% charge?


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## DtEW (Jun 14, 2004)

RBoardman said:


> Question, is it better to leave an ebike battery sitting for 2 weeks at 100% charge or 0% charge?


Without question, leaving it fully charged is the lesser of two evils. Fully-depleting a lithium-chemistry battery and letting it stay like that might result in outright cell failure.


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## Taroroot (Nov 6, 2013)

DtEW said:


> Without question, leaving it fully charged is the lesser of two evils. Fully-depleting a lithium-chemistry battery and letting it stay like that might result in outright cell failure.


Definitely. Its not like when you store it at 100% it can go more, but store it at 0% and it will go below, at which point it is toast.


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## blammo585 (Apr 24, 2012)

Can these batteries be rebuilt? I read something about it. I'm afraid of getting a bike, using it for a few years, and then they change the battery style and there's no stock to buy to replace it.


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