# E-bike battery health



## Alba Zeus (15 Jun 2022)

Having seen lots of conflicting advice r.e battery health online I’m looking for some kind of best practice I can use in my Gain D50s battery. 

It looks like the below would be about right?

When the bike is not in use - keep battery between 20% & 80%
Before heading out on a ride - charge bike up to 100%
If not using the bike for over 4 weeks - charge the battery up to 100% to balance cells every 4 weeks.. 

Does this sound about right?


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## cheys03 (15 Jun 2022)

I'd alter the above very slightly, personally. But - the main thing is you're thinking about it and not abusing the battery willy-nilly, so already you're miles ahead in battery care.

When the bike is not in use - keep battery between *50*% & *70*%
Before heading out on a ride - charge bike up to 100%
If not using the bike for over 4 weeks - charge the battery up to 100% to balance cells every 4 weeks.. *then take the bike for a ride to bring the battery back down to 70% and store*

Couple more 'ideal world' tips

* Let the battery rest and cool after any ride before charging
* Charge at the lowest power you can, if you have the choice. e.g. if you have both a 'standard' and 'fast' charger, prefer the standard when you can

You can keep going with the tips to how you use the bike to get the most out of the battery, but eventually it takes from being an ebike and just becomes just a standard bike! Use and enjoy! A nice bike


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## CXRAndy (15 Jun 2022)

storing battery in winter, take indoors or keep from freezing by having an heated cabinet between 10-20 deg C


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## Mike_P (16 Jun 2022)

CXRAndy said:


> storing battery in winter, take indoors or keep from freezing by having an heated cabinet between 10-20 deg C


And at any time overnight tempatures are low which is most nights in the UK.


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## numbnuts (16 Jun 2022)

I do all of the above, but from May to October I will leave the battery in the garage overnight
My last battery lasted just over 5 years with a lot of mileage too.


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## gbb (16 Jun 2022)

Interestingly, my Crossfire battery has done IRO 3800 miles and while its original range was something like 55 miles ?...i suspect i'd be lucky to get 40 now.
Battery never generally left out in the cold.
I try not to discharge below 10%
I try not to leave it charged to 100% and then not use the bike for any lengthy period.
I do try to charge in stages to avoid overheating (of the battery or the charger). I tend to part charge, let it rest and cool, then top up...mainly to protect (hopefully) the charger, they do get quite hot through a full charge cycle.

How do you balance charge, assuming you're just using the standard charger that came with the bike ?


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## wiggydiggy (16 Jun 2022)

I'd alter the above very slightly, personally. But - the main thing is you're thinking about it and not abusing the battery willy-nilly, so already you're miles ahead in battery care.


cheys03 said:


> When the bike is not in use - keep battery between *50*% & *70*%
> Before heading out on a ride - charge bike up to 100%
> If not using the bike for over 4 weeks - charge the battery up to 100% to balance cells every 4 weeks.. *then take the bike for a ride to bring the battery back down to 70% and store*
> 
> ...



Is the storage advice absolutely essential? I know of 2 e-bike bikes that are not likely to be getting used soon for health reasons unfortunately. I can go and ride them myself (one at a time of course) if needed to keep the batteries ticking over.


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## youngoldbloke (16 Jun 2022)

In autumn 2019, after a long ride which completely exhausted my Orbea Gain's battery, I fully re-charged it to 100% with a view to riding again the following day. Unfortunately I was unable to ride again for more than 6 weeks due to Covid-like sickness. The battery lost 10% of it's capacity during that time. At that time e-bike manufacturer's information regarding battery care was often confusing and inadequate. Subsequently after much online research I followed the 20-80% regime, only charging to 100% prior to long rides, and as far as I can tell the battery has not lost any more capacity.


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## Alba Zeus (16 Jun 2022)

My bike is kept indoors all year round so no issues with it being out in the cold. 

Interestingly though I had an over voltage error number 193 on the bike when I turned it on yesterday. Spoke to Sigma who I purchased it from and the suggested running the battery down to 0% then full charge of 5 hours plus 2 hours additional to recalibrate the battery. Done this yesterday and turned the bike on today and unfortunately still the purple light with the error code and you can't engage any of the assist. Spoke to sigma who advised the bike would need ridden to clear the code then charge the bike again to 100% and the over voltage issue should be gone. 

Just back from a ride and indeed 1 mile in the purple light disappeared and the assist kicked in so was able to get all levels of assist again. 

Just letting it cool before I try the charge again that was advised by sigma.


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## ebikeerwidnes (16 Jun 2022)

It seems important not to charge when the battery is cold
I always remove the battery, especially in winter, and only put it back on the bike just before I set off


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## Alba Zeus (16 Jun 2022)

ebikeerwidnes said:


> It seems important not to charge when the battery is cold
> I always remove the battery, especially in winter, and only put it back on the bike just before I set off


I have an orbea gain so the battery is integrated


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## Alba Zeus (16 Jun 2022)

So charged the battery this evening up to 100% and no more error code. 

I have emailed sigma to ask
- when charging does the charger cut out when the bike is at full charge
- the battery care question I put above in the OP I have posed to them also. 

Hopefully hey have some concrete instructions for the Orbea at least.


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## CXRAndy (17 Jun 2022)

Our bikes don't have proprietary software regarding chargers, one being Tongscheng and the other Bafang. I use a 80/90/100% adjustable charger. I charge almost solely to 80%, and when wanting max power and range 100% just before the ride.


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## Alba Zeus (17 Jun 2022)

Answers in bold from sigma

When the bike is not in use - keep battery between 20% & 80% - *Allowing it to drain is more the issue than the amount of charge here, keeping an eye on it if not using is a good idea, apparently being left below 40% consistently for long periods of time is the issue.*

Before heading out on a ride - charge bike up to 100% - *this is good practice for range but charging batteries to 100% all the time isnt good for long term life so not needed here like with a phone*.

If not using the bike for a long period of time I.e winter - charge the battery up to 100% every 4 weeks to balance cells then ride it back to 80% to be stored - *just keep it topped up to a reasonable level*

Don’t let the bike sit on a full 100% charge for more than a day or 2 - *I wouldn't say this is needed here*


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## youngoldbloke (17 Jun 2022)

Alba Zeus said:


> Answers in bold from sigma
> 
> When the bike is not in use - keep battery between 20% & 80% - *Allowing it to drain is more the issue than the amount of charge here, keeping an eye on it if not using is a good idea, apparently being left below 40% consistently for long periods of time is the issue.*
> 
> ...



Thanks - a little vague - eg. what is 'a reasonable level'?


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## Alba Zeus (17 Jun 2022)

100% my thoughts as well. 

Will email back and try push for something more concrete


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## nickb (17 Jun 2022)

Alba Zeus said:


> - when charging does the charger cut out when the bike is at full charge



Lithium battery charging is simple compared with the old NiCd/NiMH tech.

It just requires a constant voltage. A fully charged 3.6/3.7V (nominal) lithium cell will be 4.2V and charging higher than this can permanently damage it. Battery pack are made-up of a number of cells in series to reach the required voltage and this is expanded in parallel to increase the total energy (Watt Hours).

Unless you absolutely need the full capacity of a pack, it's always better to charge to a slightly lower voltage, say 4V - 4.1V. This will extend the life of the pack considerably. For storage (more than a few months) I would charge to the nominal voltage and repeat this every few months.

The capacity of the pack will be specified in either Watt Hours (Wh) or Amp Hours (Ah). The former is the total energy in the pack and is the Ah figure multiplied by the nominal voltage. It is safe to charge the pack at 1C, i.e. the 'A' in the Ah figure, but a well-designed pack can be fast charged at much higher currents (5C or even higher).

For instance, a 36V pack with a capacity of 5.6Ah will have an energy capacity of 201.6 Wh. It will be built with 20 individual lithium cells of 2800mAh capacity. 2 parallel sets of 10 cells in series. You could charge it safely by applying a voltage of 42V and a current of 5.6A. The battery management system (BMS) will (or should) take care of charging each individual set of parallel cells and will not allow any to exceed around 4.2V. You could leave it attached to the charger for months without a problem as the BMS will not draw any further current when all the cells are at capacity.

Of course, most packs are supplied with a charger that supplies a fixed voltage/current over which the user has no control. These are usually the Achilles heel of any lithium-powered system and will likely be cheap crap from the Far East rebranded with a sticker.

A good, switched DC supply can often be bought for pretty much the same sort of price as a replacement charger would cost and will allow a wide spectrum of voltage/currents and will permit much more flexibility.

I have been building lithium-ion battery packs for a few year for scuba diving applications. I don't own a e-bike, but if I did I'd almost certainly have had a crack at this too


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## ebikeerwidnes (17 Jun 2022)

One problem I have if knowing how 'full' the battery is

I am fine with the Bpsch system as it has a button on it that I can press and it will light up some leds
but the Carrera system (Bafang) is just a plastic brick with a switch on it - no indicator
clearly I could put it on the bike and check - but even that is a bit dodgy because it tends to go from "all the lights" to "just one light" quite quickly

I presume putting a multimeter between the +ve and -ve terminals would give an indication - but the difference is pretty small
I suppose I shoul try recording it once a week next winter and see what happens


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## nickb (17 Jun 2022)

ebikeerwidnes said:


> One problem I have if knowing how 'full' the battery is
> 
> I am fine with the Bpsch system as it has a button on it that I can press and it will light up some leds
> but the Carrera system (Bafang) is just a plastic brick with a switch on it - no indicator
> ...



As I alluded-to above, a fully-charged pack will be at 4.2V/cell. For a 36V pack, that's 42V. For a 72V pack, that's 84V etc.

However, even when not at full capacity, the voltage can be at or around maximum but the pack can still accept a trickle charge so may only be at 85-90% full. A voltmeter will only show the potential. Under a load, the voltage will drop very quickly towards nominal, around which it will sit for most of the discharge.

You could put an ammeter inline and when the charge current has dropped to virtually zero, the pack will be full. If you were using a switched DC supply for charging, the current will always be displayed.

The current being applied by the charger will drop dramatically as the pack becomes full. A near-empty pack will take the full current that the charger can supply but this falls-off a cliff as the pack fills-up. It's not linear. You'd imagine that a 5Ah pack charged at five amps would be full after one hour but it might only be 85% and the remaining capacity might take many hours longer as the current drops, eventually to <0.1A or undetectable.

As I already said, if you don't absolutely need the full charge, then don't charge the pack fully. Charging to only 85-90% most of the time could help the battery pack last for many more charges.


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## youngoldbloke (17 Jun 2022)

For the Mahle X35 system (OrbeaGain, Ribble, etc) I use the 'My Smartbike' app to check charging level, of both the main battery and the extender battery. Nowadays I only ever charge to 100% if I'm going to need the range that I know a full charge will give me.


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## nickb (17 Jun 2022)

youngoldbloke said:


> For the Mahle X35 system (OrbeaGain, Ribble, etc) I use the 'My Smartbike' app to check charging level, of both the main battery and the extender battery. Nowadays I only ever charge to 100% if I'm going to need the range that I know a full charge will give me.


I wonder if the BMS has a Bluetooth module? 

I'm currently building a replacement pack for one of my underwater scooters with such a system so I can monitor the pack's health.


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## Alba Zeus (17 Jun 2022)

youngoldbloke said:


> For the Mahle X35 system (OrbeaGain, Ribble, etc) I use the 'My Smartbike' app to check charging level, of both the main battery and the extender battery. Nowadays I only ever charge to 100% if I'm going to need the range that I know a full charge will give me.


Yeah I think moving forward for me I will only take the bike to 100% power when I know I'll need the full power. I noticed the other day when I ran the battery to 0% that after it dropped below about 15% it was barely giving me any assist even on Level 3.

Ill follow the 20-80 rule when the bikes not is use. 

I tend to run my motor maps at 100% and 99% of the time I'm in L2 with the odd foray into L3 when on a particularly sharp incline. Orbea state their battery will take you circa 40 miles but is that on L3 at 100% or L1 at 100%. Appreciate there is variables but in general?


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## youngoldbloke (17 Jun 2022)

Alba Zeus said:


> Yeah I think moving forward for me I will only take the bike to 100% power when I know I'll need the full power. I noticed the other day when I ran the battery to 0% that after it dropped below about 15% it was barely giving me any assist even on Level 3.
> 
> Ill follow the 20-80 rule when the bikes not is use.
> 
> I tend to run my motor maps at 100% and 99% of the time I'm in L2 with the odd foray into L3 when on a particularly sharp incline. Orbea state their battery will take you circa 40 miles but is that on L3 at 100% or L1 at 100%. Appreciate there is variables but in general?



You are right - below 20% there is very little assistance left in the battery. For me. I estimate 2% of battery per mile absolute best case - level 1 only, above cut off as much as possible, in reality for most rides 40 - 45 miles is a safer assumption. That's why I bought a range extender power bank. 70 - 80 miles is now a realistic figure.


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## Alba Zeus (18 Jun 2022)

Found this in the blue paper. Interestingly it states to NOT let the battery drop below 80% during long periods of storage. So his goes against what my initial thoughts where and definitely against what Sigma advised. 

What a minefield 😩😩😩


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## nickb (19 Jun 2022)

Alba Zeus said:


> Found this in the blue paper. Interestingly it states to NOT let the battery drop below 80% during long periods of storage.


That's not how I read it. I think it means make sure it's charged to at least 80% BEFORE storing, then check it doesn't fall below 10% whilst IN storage.

Lithium cells in good conditions can be stored for a lot longer than older technologies before needing a top-up. Buy a cheap voltmeter and just check that the pack isn't falling below 3V per cell. For a 36V pack (10S) that's 30V, for a 52V pack (14S) that's 42V etc.

A good BMS will attempt to prevent individual parallel cell groups falling below a minimum voltage but it can't prevent damage once all groups have fallen below the minimum. So just top-up to the storage voltage periodically (the nominal pack voltage is fine).

Of course, the real question here is: why are the packs being put into storage? Just keep riding the bike!!


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## Alba Zeus (19 Jun 2022)

The blue paper states

“When storing the bike for long periods of time, make sure the battery level is ABOVE 80% charge”


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## nickb (20 Jun 2022)

Alba Zeus said:


> The blue paper states
> 
> “When storing the bike for long periods of time, make sure the battery level is ABOVE 80% charge”



Yes, I read that and addressed it. It doesn't say make sure it STAYS above 80% charge; it says make sure it never drops below 10%.


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## youngoldbloke (20 Jun 2022)

nickb said:


> Yes, I read that and addressed it. It doesn't say make sure it STAYS above 80% charge; it says make sure it never drops below 10%.



It's not clear - you could interpret it either way.


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## nickb (21 Jun 2022)

youngoldbloke said:


> It's not clear - you could interpret it either way.



That's why I elaborated on it.

However, I'll try again...
To store a lithium battery pack: charge to around 80% and store the pack somewhere where it won't be subjected to extremes of temperature or shock and periodically make sure that the charge hasn't fallen anywhere close to 10%. Lithium packs don't lose charge very quickly and this would take ages for a pack in good shape. If you're storing the pack for that long, consider selling the bike as you're obviously not using it!

Clearly, the 80% and 10% won't be very easy for most people to check. So, to make things simpler, charge the pack to somewhere around its nominal voltage and ensure it doesn't fall lower than 3V per cell (explained above, but a 36V pack would be made-up of 10 groups of cells in series (10s) - so that's 30V minimum. A 14s pack should fall no lower than 42V etc.)

OR: just check it every day and keep it at 80% - your call. I know which option I'd take.


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## youngoldbloke (21 Jun 2022)

nickb said:


> That's why I elaborated on it.
> 
> However, I'll try again...
> To store a lithium battery pack: charge to around 80% and store the pack somewhere where it won't be subjected to extremes of temperature or shock and periodically make sure that the charge hasn't fallen anywhere close to 10%. Lithium packs don't lose charge very quickly and this would take ages for a pack in good shape. If you're storing the pack for that long, consider selling the bike as you're obviously not using it!
> ...



Thank you - but I don't know how I would check the voltage of the Mahle internal battery. They use a unique charging port. However battery levels can easily be checked using their app. 
I detect a somewhat censorious tone to your comment regarding bike usage and sale - when my bike was left fully charged I had every intention of using it within the next 12 hours - before I could do that I was laid low for the next 6 weeks, almost hospitalized, by a severe Covid-like viral infection. I would normally be riding throughout the year, all seasons. Sometimes one's activities are affected by circumstances beyond one's control


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## ebikeerwidnes (21 Jun 2022)

You don't need to check it every day - tape a piece of paper to it and note the charge every few weeks
You should see it drop slowly
If you want to be extra sure then take it for a long ride at some point so it drops to minimal charge left then measure it before charging it again
Then measure it when fully charged and you know the range

I would note that there are some batteries where you cannot check the charge due to complicated internal stuff - Bosch for example
However my Bosh has a button and some LEDs so you can check it easily - I suppose some others may be more difficult


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## nickb (21 Jun 2022)

youngoldbloke said:


> Thank you - but I don't know how I would check the voltage of the Mahle internal battery. They use a unique charging port. However battery levels can easily be checked using their app.
> I detect a somewhat censorious tone to your comment regarding bike usage and sale - when my bike was left fully charged I had every intention of using it within the next 12 hours - before I could do that I was laid low for the next 6 weeks, almost hospitalized, by a severe Covid-like viral infection. I would normally be riding throughout the year, all seasons. Sometimes one's activities are affected by circumstances beyond one's control



Most packs will have some contact points where you could poke a voltmeter in but it sounds like you're sorted via the app.

I wasn't being 'censorious', just having a joke. Although 6 weeks is nowhere near enough time to have to worry about a lithium pack discharging too low if it's been put in 'storage mode'. They can go much longer without having to top-up. If they drain quickly when just left alone, that would indicate a serious problem where the pack is probably knackered.

Trust me on this, I have some very expensive packs (>£1000 each) here that I leave for many months without using.


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