Fuel EXe Trek Fuel Exe Battery Charging/balancing - for those who know about batteries

Has anyone noticed the following with the fuel exes.

If you plug in the charger it charges up to 100% charge - takes a couple of hours, maybe a little more, depending on the state of charge you started from.

Then if you unplug the charger, switch off the bike a leave it for a few hours (like 3 or 4) , then switch the bike back on, and the state of charge has dropped to 97% - 98%, so you plug it in again, and this time it takes 1 or 2 hours to slowly go from 97% to 100%. Then you unplug the charger, switch the bike off , leave for a few hours , turn it back on and the battery is showing 98% again, so you plug it in again, this time it charges up to 100% over a couple more hours and pretty much stays there when you unplug the charger.

I have a smart plug that the charger is plugged into that monitors how much energy the charger is using, first charge it takes ~330wh from the plug , second it takes ~35wh, third it takes 5-6wh.

Is this (ie the state of charge dropping after reaching 100%) just the battery balancing itself, so in order to get the proper max range you need to go through this charge/unplug/repeat charge/unplug process etc? ie you cant rely on the battery to actually be at 100% after the first charge, it seems that after the first charge the battery is holdingapprox 10% (~35-40wh) less WH than it should be.

anyone know anything about how bike batteries typically balance/charge?

Mine doesn’t do that. I charge it up, unplug it. When I go to use it, which could be several days later, it’s still at 100%.

Dave_B said:

Mine doesn’t do that. I charge it up, unplug it. When I go to use it, which could be several days later, it’s still at 100%.

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Hmmm, weird, mine has done it since day 1, and with 3 different batteries.

Dave_B said:

Mine doesn’t do that. I charge it up, unplug it. When I go to use it, which could be several days later, it’s still at 100%.

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You must have read frequent posts on here that it is recommended NOT to leave the battery charged to 100%, the shorter time the better, the longer time the worse. If I recall correctly, aim for 60-80% if you are going to leave the bike unused. Normally, when I've done with the bike, I charge it to anywhere between 60% and 80%. The night before I use the bike it gets charged to 100%. I set a timer so it finishes an hour before I need it.
If I was using the bike every single day, I would charge it to 100% every time.

Like you, once I've charged it to 100%, I don't have any subsequent decay when it is just sat there. My battery & charger are Shimano.

Ideally you would never charge the battery to 100%, as this is where the battery degrades the fastest. If you're only going for a short ride, or know you will only use, say 50% of the battery, then just charge it to 80%.

Lithium batteries are happiest in the middle of the range. 20% - 80%. Full charges and deep discharges aren't great for the battery.

If you will need the whole battery for your ride, then plug it in so that it reaches 100% just before you leave, so that it's not sat for ages at 100%. Then between rides aim to leave the battery at around 40% - 50% charge, ideally.

And, in anticipation of the responses, no, leaving it at 70% or 80% or 90% won't kill it, but leaving it at higher states of charge will cause it to degrade quicker, especially at 100% SOC.

That's why most EV manufacturers don't allow you to fully charge the battery. It will show 100% on the dash, but in reality the software is capping the max SOC below 100%. That's why you often see the "useable battery" size quoted in specs and reviews and it's always a lower number than the full size of the pack. Some percentage will be software blocked at the top and some at the bottom, so you can't charge to 100% or fully discharge to 0% even if that's what the dash is telling you. (So 100% on the dash may actually just be 95% in reality, for example.)

Apparently Tesla do not cap their cars at the top, so 100% is actually 100%, but the software tells you to ideally charge below that, and throws warnings up at you on the screen/app if you set the car to charge above 90%. It says to only charge to 100% for long trips and for daily driving to charge to a lower level. The same is true for ebikes, mobile phones, laptops, and anything else with a lithium battery.

Charging to 100% won't immediately cause the battery to fail, but it will cause it to degrade faster, meaning that you will lose battery capacity (range) more quickly than if you only charged to 80%, for example.

HTH

RJUK said:

Ideally you would never charge the battery to 100%, as this is where the battery degrades the fastest. If you're only going for a short ride, or know you will only use, say 50% of the battery, then just charge it to 80%.

Lithium batteries are happiest in the middle of the range. 20% - 80%. Full charges and deep discharges aren't great for the battery.

If you will need the whole battery for your ride, then plug it in so that it reaches 100% just before you leave, so that it's not sat for ages at 100%. Then between rides aim to leave the battery at around 40% - 50% charge, ideally.

And, in anticipation of the responses, no, leaving it at 70% or 80% or 90% won't kill it, but leaving it at higher states of charge will cause it to degrade quicker, especially at 100% SOC.

That's why most EV manufacturers don't allow you to fully charge the battery. It will show 100% on the dash, but in reality the software is capping the max SOC below 100%. That's why you often see the "useable battery" size quoted in specs and reviews and it's always a lower number than the full size of the pack. Some percentage will be software blocked at the top and some at the bottom, so you can't charge to 100% or fully discharge to 0% even if that's what the dash is telling you. (So 100% on the dash may actually just be 95% in reality, for example.)

Apparently Tesla do not cap their cars at the top, so 100% is actually 100%, but the software tells you to ideally charge below that, and throws warnings up at you on the screen/app if you set the car to charge above 90%. It says to only charge to 100% for long trips and for daily driving to charge to a lower level. The same is true for ebikes, mobile phones, laptops, and anything else with a lithium battery.

Charging to 100% won't immediately cause the battery to fail, but it will cause it to degrade faster, meaning that you will lose battery capacity (range) more quickly than if you only charged to 80%, for example.

HTH

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I think this is spot on for the bike. Regarding Teslas, it depends on the battery chemistry. The older more energy dense batteries that contain Co and Mn should not be charged to 100% on a regular basis but the more recent LFP (Lithium Iron Phosphate) batteries can be charged to 100% without any issues. pretty sure TQ uses the former. I would also assume that the battery has headspace, meaning it doesn’t use all of the capacity, so it can balance But keeping it below 100% when a full charge is not required is the save choice.

most about charging best practices has been mentioned here but I like to add one more aspect that may or may not be related to the stated issue. Temperature can have an impact as well. If the battery balances, it may lose charge when not plugged in. Keeping the battery exposed to low temps in the garage is also not great for the battery. Luckily, the Fuel exe battery can be removed easily and stored in the house.

DBSwiss said:

most about charging best practices has been mentioned here but I like to add one more aspect that may or may not be related to the stated issue. Temperature can have an impact as well. If the battery balances, it may lose charge when not plugged in. Keeping the battery exposed to low temps in the garage is also not great for the battery. Luckily, the Fuel exe battery can be removed easily and stored in the house.

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Exactly this. When charging my Tesla the same thing happens. I might set it to 80%, then when it finishes it may cool and drop back to, say 78%.

Likewise, on my bike I store the battery in the house between rides. Leaving it in a hot or cold shed is bad for it. I think heat is actually worse for it as again it speeds up degradation, but if the battery is too cold it will struggle to charge quick and struggle to put out full power also.

DBSwiss said:

I think this is spot on for the bike. Regarding Teslas, it depends on the battery chemistry. The older more energy dense batteries that contain Co and Mn should not be charged to 100% on a regular basis but the more recent LFP (Lithium Iron Phosphate) batteries can be charged to 100% without any issues. pretty sure TQ uses the former. I would also assume that the battery has headspace, meaning it doesn’t use all of the capacity, so it can balance But keeping it below 100% when a full charge is not required is the save choice.

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Yeah, there are some differences between chemistries and each has their own positives/negatives.

I think this is also the reason for the common bad practice that we see for charging batteries in general.

A lot of people that I've spoken to still think that you're best off running your phone battery down as low as possible, then leaving it on charge overnight. Whilst that was the best practice for NiCad batteries with memory, it's the opposite of what you want to do with modern batteries. For lithium batteries without memory you're better off with more, shorter charges, than deep discharges followed by full top up charges.

Likewise, leaving it on charge overnight is generally not recommended as it tends to keep heat in the battery, degrading it faster.

It's annoying that manufacturers for the mort part don't include any way to have a phone/laptop restrict it's charge like you can with a car. Closest I can get with my phone is an automation that tells me when it hits 80%, but that's easy to miss. With upgrade cycles of 2 years though, most people don't care and just fully charge their phones each time. However, with a bike or a car, the battery is much larger and therefore a much costlier part of the product, so it's more beneficial to take steps to look after it. (With EVs close to half the price of the car can be the battery sometimes - or at one point was, prices may have fallen now.)

RJUK said:

Yeah, there are some differences between chemistries and each has their own positives/negatives.

I think this is also the reason for the common bad practice that we see for charging batteries in general.

A lot of people that I've spoken to still think that you're best off running your phone battery down as low as possible, then leaving it on charge overnight. Whilst that was the best practice for NiCad batteries with memory, it's the opposite of what you want to do with modern batteries. For lithium batteries without memory you're better off with more, shorter charges, than deep discharges followed by full top up charges.

Likewise, leaving it on charge overnight is generally not recommended as it tends to keep heat in the battery, degrading it faster.

It's annoying that manufacturers for the mort part don't include any way to have a phone/laptop restrict it's charge like you can with a car. Closest I can get with my phone is an automation that tells me when it hits 80%, but that's easy to miss. With upgrade cycles of 2 years though, most people don't care and just fully charge their phones each time. However, with a bike or a car, the battery is much larger and therefore a much costlier part of the product, so it's more beneficial to take steps to look after it. (With EVs close to half the price of the car can be the battery sometimes - or at one point was, prices may have fallen now.)

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Hi all,
My last 2 Samsung models have / had a Settings option that can be enabled called "Battery Protect" which it says: "To extend the lifespan of your battery, limit the charging to 85%."

Re the Original Post... like some others have said, when I have charged my battery to 100% I do not see any drop for days... and actually I recently (unexpectedly and at no notice) had a medical incident where I could not ride for 3 weeks and the battery did not drop at all from 100%. The only time I saw my battery level dropping without riding was when I had what ended being a faulty Display Unit, and it was draining the battery. Once Trek changed the Display Unit it was resolved. This was just my experience - I am not saying it is the reason for anyone else's level dropping.
Hope this helps.

There definitely seems to be a benefit to not charging these types of batteries fully...if you can get away with it on different ride lengths...and not fully charging them and leaving them unused for a lengthy period. This has already been touched upon and fits with every technical info I've researched when I got into an ebike.

I've also experienced it first hand with a home built 2003 Santa Cruz Bullit mid-drive with the Bafang BBSHD motor. The bike has been used for 3 years exclusively and aggressively off road with many, many charge cycles in the bag. I avoided those somewhat bargain Chinese ebike battery packages and went with a Bicycle Motor Works 17.5ah, 52-volt battery that uses LG batteries.

The part that fits this discussion about charge rates, charge levels, and such involve the charger. I got a Luna Cycle variable charger that had a digital readout and switch that allowed you to select lower charge percentages/levels. I never went higher than 90% and more often was at the 80% level. This battery is still showing almost full performance after 3 years of real, extensive use, and I attribute this to a good battery pack and a great charger.

I wish my newly purchased Trek Rail 7/Bosch combination had such a charger. Heck, it doesn't have a light to indicate that it's on...yes...I get that the Purion display more or less addresses that function. Still, the ability to control certain levels of charging and such would be nice.

Just a further comment re using a "Battery Protect" approach ... ala the setting on my Samsung phone (where it stops charging at 85%).....

I have had my Exe since Oct 2022 (16 months) so I have some long experience with it.

After discovering this 85% setting in my phone a few months ago, my logic was that "If it is good enough for a phone then it should be an appropriate process to use on my Exe battery". So for the past few months after rides when charging the battery I would have a guess and set my timer for when it should get to about 80-85% and I would then stop the charging. Also I don't recharge the bike for every ride - if I expect I have have enough battery then I don't charge up.

I have done this for about the past 2 months. Then when on a ride recently the battery dropped from 20% to Zero basically within 10 seconds. . This really took me by surprise. It didn't even go into Derated (10%) mode - it just went straight to Zero.

So I was wondering if stopping at 85% messed up the battery "memory" and caused this drop off the cliff to happen. I guess I would have to do some experimenting over many rides to prove it but I can't be bothered with the hassle really - I just want to ride and keep things simple . I spoke with my Trek store and they said there were the trickle charge protections incorporated and as per TQ to charge up to 100% (except for long storage).

Just wondering if anyone else has seen their battery %age drop from 20% to zero in literally a few seconds? (ignoring brand new bikes / batteries of course).

Free_Tibet said:

Just a further comment re using a "Battery Protect" approach ... ala the setting on my Samsung phone (where it stops charging at 85%).....

I have had my Exe since Oct 2022 (16 months) so I have some long experience with it.

After discovering this 85% setting in my phone a few months ago, my logic was that "If it is good enough for a phone then it should be an appropriate process to use on my Exe battery". So for the past few months after rides when charging the battery I would have a guess and set my timer for when it should get to about 80-85% and I would then stop the charging. Also I don't recharge the bike for every ride - if I expect I have have enough battery then I don't charge up.

I have done this for about the past 2 months. Then when on a ride recently the battery dropped from 20% to Zero basically within 10 seconds. . This really took me by surprise. It didn't even go into Derated (10%) mode - it just went straight to Zero.

So I was wondering if stopping at 85% messed up the battery "memory" and caused this drop off the cliff to happen. I guess I would have to do some experimenting over many rides to prove it but I can't be bothered with the hassle really - I just want to ride and keep things simple . I spoke with my Trek store and they said there were the trickle charge protections incorporated and as per TQ to charge up to 100% (except for long storage).

Just wondering if anyone else s has seen their battery %age drop from 20% to zero in literally a few seconds? (ignoring brand new bikes / batteries of course).

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Seems like a BMS issue - the battery thinking it had more charge than it really did.

I would still suggest not charging to 100% unless you need the full battery for your ride, but of course everyone is free to do whatever they like with their bikes/batteries.

Doing any amount of research into lithium ion batteries online will show though, that charging them to 100% and especially leaving them sat at 100% for long periods, is detrimental to the battery and will cause accelerated degradation.

Many people read this sort of thing and try to justify their constant 100% to 0% usage and their lack of being able to notice the degradation as anecdotal evidence that charging to 100% for storage and discharging to 0% every ride is fine, but the battery isn't going to suddenly fail from this type of usage. It will just degrade more quickly than a battery that has seen more careful use.

Some people don't care and just continue to charge the battery to 100% anyway. Others probably are annoyed that the information wasn't made more clear to them at the time of purchase. I think the reason this information isn't more commonly known, is that brands a.) don't want to worry customers that are making a purchase, b.) don't want to give customers an excuse to ask more tricky/technical questions, and c.) don't necessarily want customers' batteries to last a long time. After all, they just need the batteries to retain whatever their warranty agrees to, over a given period. Usually something like 70% capacity over 3 years. The likelihood being that they know poorly looking after the battery won't cause 30% capacity loss in that time. However, if they tell you how to treat the battery in order to retain, say, 95% capacity over the same period, they don't gain anything. In fact, they may lose a customer who would otherwise have bought a new bike because his old one no longer has enough power for the lengths of rides he does.

That's also likely why we probably don't see battery preserving features like a maximum charge level on mobile phones. The phone companies know that a common driver of people upgrading their phone is that the battery on their old one is no longer sufficient to get through a whole day. As long as the battery retains a decent percentage over the 2 year contract then they won't have to worry about any warranty claims, but beyond that it works out better for them if their customers' batteries degrade to the point where it pushes them to upgrade.

Being somewhat new to this ebike thing, instead of chucking the bike because the battery finally gives up, will a replacement battery from Trek, Bosch, or whoever be available when that day comes? Or...will there be some kind of aftermarket alternative option available? In that Santa Cruz Bullit mid-drive I built that I mentioned above, I was able to get a good, reputable battery that fit the voltage and other requirements for that bike. I carried that battery in a backpack with a break-away plug-in cable, and it worked for 3 years...and still working...with plenty of get-offs/crashes without issue. I rode this bike only on trails and off road, and the backpack deal was no real issue.

I admit I rather like my Trek Rail being all self contained and such, but before I threw away the bike because of lack of a factory replacement battery, I think I'd figure something else out.

For me, I go on long rides and run the battery from 100% down to empty. Instead or worrying about how many cycles my battery will last, I’ll just buy a new one when needed.

Did you guys know that there is a setting in the Trek Central app to alert you when the battery charge exceeds a level you define, say 80%?

Obviously your phone has to be in range of the bike whilst it is charging for this to work, and it doesn't actually stop it charging at this point it just sends you a notification, but I thought some of you might like to use this function.

Free_Tibet said:

Just a further comment re using a "Battery Protect" approach ... ala the setting on my Samsung phone (where it stops charging at 85%).....

I have had my Exe since Oct 2022 (16 months) so I have some long experience with it.

After discovering this 85% setting in my phone a few months ago, my logic was that "If it is good enough for a phone then it should be an appropriate process to use on my Exe battery". So for the past few months after rides when charging the battery I would have a guess and set my timer for when it should get to about 80-85% and I would then stop the charging. Also I don't recharge the bike for every ride - if I expect I have have enough battery then I don't charge up.

I have done this for about the past 2 months. Then when on a ride recently the battery dropped from 20% to Zero basically within 10 seconds. . This really took me by surprise. It didn't even go into Derated (10%) mode - it just went straight to Zero.

So I was wondering if stopping at 85% messed up the battery "memory" and caused this drop off the cliff to happen. I guess I would have to do some experimenting over many rides to prove it but I can't be bothered with the hassle really - I just want to ride and keep things simple . I spoke with my Trek store and they said there were the trickle charge protections incorporated and as per TQ to charge up to 100% (except for long storage).

Just wondering if anyone else has seen their battery %age drop from 20% to zero in literally a few seconds? (ignoring brand new bikes / batteries of course).

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I have never seen this happen. Like you I also skip charging if I have enough battery left after a ride. I often use about 40% or 60% of the battery depending on the trails I ride. If I have 60% left, I often leave it for the next ride. That means I go below 20% pretty often But I have never seen it drop off. Recently it didn’t even feel like it was in limp mode under 10%. One thing to try on your end could be to just run a full charge once in a while to reset the battery memory. Trek recommends this before the first ride. That means draining to zero and then charging to 100%. One time should be enough. This also works with my Tesla that I usually charge to 70% unless I need more for a road trip.

Things move on so I dont know if this is still the case, but about 3 years back I read a research paper on best use of Lithium batteries and it stated that some chargers go through different stages rather than just pump in the amps! So a charger may charge at a low rate initially then ramp up to its full rating, then switch to a very low input for a while etc. It also stated ( as per posts a bove) it was best if possible to use the battery between 30% and 80% and a void leaving the battery for any length of time at 100%. Another couple of points were that charging to only 80 or 85% if a full charge was not needed was beneficial for battery life but that the battery should be charged to 100% occasionally since with many chargers/BMS that was when cell balancing took place. Lastly it was also deemed beneficial to leave a fully charged battery to cool for a few hours before use ( so charge the night before a ride).

All of this supposedly represents progress over more conventional power sources!!

Yes, most chargers will charge quickly to 80 or 90% then slow down at the end for the benefit of the battery. It's one reason That Tesla drivers are encouraged by their cars to stop charging at 90% and carry on driving. That last 10% is very slow.

Heat isn't great for the batteries, but if the batteries are too cold they also won't deliver full power. That's why Teslas heat the batteries for drag strip mode (and also for charging, as they can be charged faster when warm). Batteries give better performance in warmer weather than in the cold. Basically the opposite to a conventional car, with loses power in hot weather and gains power in cold weather.

I'd suggest the electric way round is better, as generally you can put down more power in warm conditions than in cold ones.

RJUK said:

Yes, most chargers will charge quickly to 80 or 90% then slow down at the end for the benefit of the battery. It's one reason That Tesla drivers are encouraged by their cars to stop charging at 90% and carry on driving. That last 10% is very slow.

Heat isn't great for the batteries, but if the batteries are too cold they also won't deliver full power. That's why Teslas heat the batteries for drag strip mode (and also for charging, as they can be charged faster when warm). Batteries give better performance in warmer weather than in the cold. Basically the opposite to a conventional car, with loses power in hot weather and gains power in cold weather.

I'd suggest the electric way round is better, as generally you can put down more power in warm conditions than in cold ones.

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I dont think air temperature makes a lot of difference to an ICE engine. Typically an ICE engine performs better when there is more moisture in the air.........especially diesel engines because that improves the combustion.

RJUK said:

Yes, most chargers will charge quickly to 80 or 90% then slow down at the end for the benefit of the battery. It's one reason That Tesla drivers are encouraged by their cars to stop charging at 90% and carry on driving. That last 10% is very slow.

Heat isn't great for the batteries, but if the batteries are too cold they also won't deliver full power. That's why Teslas heat the batteries for drag strip mode (and also for charging, as they can be charged faster when warm). Batteries give better performance in warmer weather than in the cold. Basically the opposite to a conventional car, with loses power in hot weather and gains power in cold weather.

I'd suggest the electric way round is better, as generally you can put down more power in warm conditions than in cold ones.

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I have a Tesla Plaid and I thought it cools the battery for Dragstrip mode. Because in Dragstrip mode it’s running so much electricity, that it has to be cooled down. I also have a Tesla Raodster and it is constantly cooling the battery.

I have almost 1,800 miles on my EXe. My battery is still working great. Charges to 100%. Even if I don’t ride it for more than a week, when I turn it on, it still has 100% charge. I have not noticed any reduction in power supply. I am getting the same distance and elevation as when new. I never charge it to less than 100%. I like it ready to grab and go. As someone else said, I’ll buy another battery when needed for the convenience of not having to be careful how I charge the battery.

Cell4soul said:

As someone else said, I’ll buy another battery when needed for the convenience of not having to be careful how I charge the battery.

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That was me!