# How long can you store an e-bike battery without using it?



## yaringa (2 mo ago)

I've got a Specialized Turbo Levo ebike that I want to keep in a second home out of state (where it's warm) - and that I only use during my winter months. Instructions say that the battery needs to be recharged every 3 month, which doesn't work with this travel arrangement (for various reasons, I can't permanently leave it on a charger while I'm away). But I have found a site (link below) that says e-bike batteries have inbuilt protective features that mean you can keep them without problem beyond a year. I realise that doing that means it shortens the battery life, but I'm assuming that's over the long term. Does anybody have insight into this?

Thanks









Like good wine – how to store your ebike battery


They say that sleep is the cousin of death and that holds true for eMTB batteries too. Ill-considered storage can kill this vital and expensive component, so it pays to know the facts! Together with the boffins at Bosch, Shimano and BMZ, we dispel the myths and show you how to safeguard your...




ebike-mtb.com


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## alexbn921 (Mar 31, 2009)

Batteries can be stored for very long periods as long as they don't have any draw on them.

DO NOT LEAVE IT PLUGED IN! This will heavily degrade it.

The best long term storage is 3.85v per cell and you have a 10s, so 38.5 volts. If I was leaving it for a full year and could not monitor it, would aim for a max of 3.9-3.95 volts as it will very slowly drain down over time.

Heat is the other factor that kills batteries. Keep it cool and it will last significantly longer.

You could also use a wifi outlet and charge the battery remotely every few months for an hour.


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## yaringa (2 mo ago)

alexbn921 said:


> Batteries can be stored for very long periods as long as they don't have any draw on them.
> 
> DO NOT LEAVE IT PLUGED IN! This will heavily degrade it.


Thanks, Alexbn921. Yes - battery out. Fortunately, that's easy with the Levo. 

But thinking about the point you make - I wonder whether that's the basis of the 3-month rule. A "catch-all" to include people who store their bikes with batteries connected (ie still on the bike). Hmmm.

Again, Thanks.


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## walkerwalker (Jul 17, 2020)

do they make trickle chargers for ebike batteries? The trickle charger I use on my motorcycle has an overcharge protection, so there is no problem leaving it on the charger for months at a time, as I do in the winter.


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## yaringa (2 mo ago)

walkerwalker said:


> do they make trickle chargers for ebike batteries? The trickle charger I use on my motorcycle has an overcharge protection, so there is no problem leaving it on the charger for months at a time, as I do in the winter.


Unfortunately, I don't have access to power where the e-bike is stored - so no trickle charging. But my motorcycle also takes long naps on a trickle here in winter.


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## mike0012 (Apr 27, 2006)

If you have internet at this location, get one of those timers you can control remotely from your phone. You can schedule remote charging sessions and have it off the rest of the time.


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## walkerwalker (Jul 17, 2020)

...but OP has no access to power. 


Can you take the battery out and keep it with you at your other home to charge it once in a while? Just have to be careful about flying with it, if that's what you're plan would be. If it's lithium you can't put it in a checked bag, but can have it in a carry-on.


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## idividebyzero (Sep 25, 2014)

Worst thing to do is leave it sitting at a low charge for too long because then it will outright die and you probably wont be able to charge it normally since the electronics inside it wont know when it's plugged in and to start charging. 2nd worst thing to do is to leave it at 100% all the time because it will degrade.

Best thing is to store it at 20-80%. Manufacturer's don't store batteries at full charge and EV's say to keep cars charged to 80% and only going up to 100% if you plan on using it soon after (so don't full charge the bike after every ride unless you plan on riding the next day). I would get it above 50% and not worry about it.

Modern lithium batteries are smart and will not overcharge if left plugged in, that was mainly an issue with NiCad batteries that has lived on as a wives tale.


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## DtEW (Jun 14, 2004)

walkerwalker said:


> Can you take the battery out and keep it with you at your other home to charge it once in a while? Just have to be careful about flying with it, if that's what you're plan would be. If it's lithium you can't put it in a checked bag, but can have it in a carry-on.


You can't fly with a 500Wh or 700Wh lithium battery, period. Be careful with your advice.

If the OP shows-up at the TSA with his Levo battery, he would either have to cancel his flight, or throw away* his $1k battery. Because he can't mail it conventionally either, given that the USPS also has the 100Wh limit.

* He might even have trouble doing that. Such a large battery might require special disposal.

The only eMTB battery you can fly with (given airline approval) is the Levo SL's water-bottle-cage-fitting extender battery (160Wh).


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## mike_kelly (Jul 18, 2016)

Lithium ION batteries require a battery management system. This BMS controlls how the battery is charged. Ebike batteries are composed of many small cells. The cells must be equilized so they all charge at the same level and they can not be overcharged. The BMS does all this. But all Models and brands do this in a different way. Some have internal BMS on the battery. Some are dumb and the intelligence is in the charger rather than the battery. Lithium Ion batteries should be stored at roughly 65% of their capacity, not at full charge. Some BMS are smart enough that if the battery is unused for a period of time it will be discharged to the 65% level automagically.
So it is very dependent on the manufacturer and the design. Because of this each bike may be different.
Lithium ION batteries need to be treated with respect and care. Each cell is packaged in a Mylar pouch in a vacuum. If the package is punctured or fails the lithium will burn if exposed to air.


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## Gym123 (Dec 4, 2021)

yaringa said:


> I've got a Specialized Turbo Levo ebike that I want to keep in a second home out of state (where it's warm) - and that I only use during my winter months. Instructions say that the battery needs to be recharged every 3 month, which doesn't work with this travel arrangement (for various reasons, I can't permanently leave it on a charger while I'm away). But I have found a site (link below) that says e-bike batteries have inbuilt protective features that mean you can keep them without problem beyond a year. I realise that doing that means it shortens the battery life, but I'm assuming that's over the long term. Does anybody have insight into this?
> 
> Thanks
> 
> ...


Does this place have a decent internet or cellular connection? If so, you could use a smart outlet and schedule a charger to be powered, but I doubt the battery will like being connected to ANYTHING (the charger) for so long.


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## nilswalk (Nov 26, 2014)

I'm in exactly the same situation as you. I've also got decades of experience using lithium-based battery chemistries in a wide variety of applications. Short simple answer:

Before you leave, charge your battery to full capacity, then gently (i.e. low current, so for an e-bike an easy ride in ECO mode) run it down to about half capacity, take it out of the bike and store it at room temp. Charge it back up when you return and use it. Accept that your good fortune in being able to afford 2 houses means you'll have a slightly shorter but probably not noticeable lifetime for your e-bike battery.


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## walkerwalker (Jul 17, 2020)

DtEW thanks for clarifying on that. I only have experience flying with Lithium batteries for radios, which are much less watts.


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## Taroroot (Nov 6, 2013)

No, you cannot trickle charge li ions. When it reaches full charge, all proper li ion chargers shut off. Overcharging is bad. If disconnected, a charged battery should store for a long time. I forget what the self discharge rate of li ions are. You do want to make sure they do not fall below certain level. When cell drops below certain level, proper li ion batteries have a protection circuit that cut them off and renders them unusable. Most of the time permanently. 
so key things are, dont overcharge. Once its fully charged disconnect and do not charge again until you use some of the charge. Dont let the charge go to 0 and leave it. I have a couple items that i let that happen and the batteries no longer work, even though i didnt use them that many times. Oh, and do not charge if temp is below freezing. They dont like that.


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## mike0012 (Apr 27, 2006)

walkerwalker said:


> ...but OP has no access to power.
> 
> 
> Can you take the battery out and keep it with you at your other home to charge it once in a while? Just have to be careful about flying with it, if that's what you're plan would be. If it's lithium you can't put it in a checked bag, but can have it in a carry-on.


Missed that as that response came in while I was writing.

Unfortunately no good solution here.


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## DtEW (Jun 14, 2004)

yaringa said:


> Unfortunately, I don't have access to power where the e-bike is stored - so no trickle charging. But my motorcycle also takes long naps on a trickle here in winter.


Is your second house completely unpowered when you're gone? If not, can't you just take the Levo's battery into the house to charge through a network-control-able switch (eg. Kasa)?


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## Taroroot (Nov 6, 2013)

DtEW said:


> Is your second house completely unpowered when you're gone? If not, can't you just take the Levo's battery into the house to charge through a network-control-able switch (eg. Kasa)?


Unattended recharging is not recommended. I myself have never had a problem but good friends have had imac, phone batteries do the swelling thing. If your not around to see that and it continues, that is not good!


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## eb1888 (Jan 27, 2012)

How about giving it to your neighbor? 
What are friends for.


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## _CJ (May 1, 2014)

Charge/discharge to 60% if you need to store the battery for extended periods.

These batteries "like" to be at 50%, so charging to 60% allows for some degradation over time without putting the battery under stress. How long? Hard to say. Maybe do a storage test of a week or a month, see how much it loses, and extrapolate from there? Personally, I can't imagine even a year would be a problem if the battery was removed from the bike and stored in a temperature controlled environment.


.


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## dadadada (3 mo ago)

In winter when I don't ride much, I store my ebike batteries at 60%, off the bike, in my house. 

"Storage during winter – Store the
batteries in a dry location at room
temperature. Fully charging or fully
discharging results in higher loading
of the battery. The ideal charge sta-
tus for lengthy periods of storage is
approx. 30 to 60 % or two to three
LEDs on the battery indicator "

"Storage – Excessive heating and di-
rect sunlight must be avoided.
Bosch batteries and chargers must
not be stored in the vicinity of heat
sources or flammable materials. We
recommend disconnecting the bat-
tery from the eBike for storage pur-
poses and storing it in rooms fitted
with smoke detectors. Dry locations
with an ambient temperature of
roughly 20 °C are the most suitable.
Bosch batteries must not be stored
below –10 °C or above 60 °C."



Here is the Bosch brochure about battery care, it probably applies to other brands as well.



https://www.bosch-ebike.com/fileadmin/EBC/Service/Downloads/Akku_Guide/Akku_Guide_MY20_2/Bosch-eBike-Battery-Guide-MY2020-EN.pdf


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## fos'l (May 27, 2009)

I'm with CJ, but would charge to 80%, then leave at room temp. I doubt it would degrade past the "safe" 20% level in the intervening months. Personally, I'd be surprised of ot got below 50% (based on leaving my Haibike-Yamaha battery unattended for months at a time.


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## ejhc11 (2 mo ago)

fos'l said:


> I'm with CJ, but would charge to 80%, then leave at room temp. I doubt it would degrade past the "safe" 20% level in the intervening months. Personally, I'd be surprised of ot got below 50% (based on leaving my Haibike-Yamaha battery unattended for months at a time.


This works for me too -^


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## Varaxis (Mar 16, 2010)

Most wear-and-tear damage comes from the materials physically expanding and contracting. Micro cracks form, reducing the battery's energy storing capacity.

There's damage from overcharging and from being empty too. A battery that continues to self-discharge while "empty" will seriously damage the battery's capacity. This is the main thing to be worried about in long-term storage.

Temps going from warm to cold act as expansion/contraction cycles, causing wear-and-tear similar to a charge and discharge cycle. This is how a battery can wear from age even without being used.

I do wonder if there exists a battery tender/trickle charger that auto-starts and auto-shuts off at like 33V (for a 36V battery), to ensure it doesn't overcharge, and have it hooked up to solar or whatever.

* The micro-fracture issue is something that battery researchers are trying to address, by finding ways to have the materials self-repair their micro-cracks. Like some sort of protein-web binder or whatever...


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