Charging times; a table

[urastus]

Hello all. I have just learnt about the 80% charge advantage for life of the battery. I'll be buying a timer - for me 80% is fine for the majority of rides that I do, so with a timer, not a big issue.

With that in mind, how do you know when the battery is at 80%? Mine (e8000 with e7000 display) doesn't show power bars during charge. So, I've been setting a timer, then unplugging charger, powering on bike to see what the charge is. I thought I might as well record what I've found; maybe others can contribute any times they find reasonably accurate. This of course is all ball park stuff, and for me doesn't warrant much more effort. However, my first result, fairly new bike, 500km, probably around 15 C at the time.

From 1 bar to 4 bars, 2hours 30mins. I'm pretty sure that the 1 bar was close to 20%, and that the 4 bars were close to 80%.

 

[OldGoatMTB]

Your power bars don't light up on the battery when it's charging? Mine do. I figure when the last light starts flashing then the charge is about 80%, so can unplug then if that's when you want to stop.

 

[urastus]

Your power bars don't light up on the battery when it's charging? Mine do. I figure when the last light starts flashing then the charge is about 80%, so can unplug then if that's when you want to stop.

No. I looked at mine after reading your post in another topic. It powers up with the shimano logo, and that's all. I have to disconnect power to the charger, then hit the power button to start up as normal, then I can see the power bars. That's normal for my set up (e8000 motor, e7000 display) according to shimano manual too. I have an internal battery.

 

[OldGoatMTB]

I have the 8000 motor and 7000 display. I also have internal battery, under the down tube. I have to reach under to power on, and the charge port is also underneath, right next to the LEDs. I'm looking on the battery itself, not the display.

 

[papab]

I have this written down someplace, but can't find it, but I think it was about 40 minutes for each bar until the last one, which takes about 60 minutes. I have an external battery.

 

[urastus]

No, no such thing; that would be much easier. I have a merida e140 ltd (aluminium). Power switch on top of the top tube - no bars. It lights up green. I leave the battery inside the bike. I don't really want to remove it unless I have to. The port is also on top, right over the motor, no light there at all.

 

[urastus]

I have this written down someplace, but can't find it, but I think it was about 40 minutes for each bar until the last one, which takes about 60 minutes. I have an external battery.

That works out at 2hrs for 3 bars - mine was 2.5 hrs for 3 bars, but internal battery, if that makes any difference. I could have also started with less than 1 bar, and charged a bit over 4 bars. I thought I was close to one full bar and 4 full bars...This may be a futile exercise for general use . Geez, even the charger may have changed! Although I still think we can work with that; 40 - 50 mins per bar up to 4 bars (which is what we're interested in), at this point. That's already a ballpark for people to start with.

 

[salko]

Why don't you just measure your charging speed? When your battery is pretty flat, charge it for exactly 1 hour and check for how many % did you charge it up, then you'll have your charging speed per hour in rage 0-80%, after 80-85% charging speed usually slows down gradually to preserve the battery health ...

 

[Flatslide]

With daily use and the helpful app, I've worked out how much time=charge% for my bike. I use the timer function on my phone to let me know when to switch it off. Effective - although the bike lives in the house in its own room making it easy.

 

[urastus]

Why don't you just measure your charging speed? When your battery is pretty flat, charge it for exactly 1 hour and check for how many % did you charge it up, then you'll have your charging speed per hour in rage 0-80%, after 80-85% charging speed usually slows down gradually to preserve the battery health ...

I've been doing that - although it is pretty hit and miss for me. I don't see a percentage of charge, just up to 5 bars. So, what I have, as accurately as I can (checking every 30min), is 2.5 hrs for 3 bars; that equates to 50mins a bar. A few more measurements from others wouldn't go astray, for example papab has 40mins a bar.

 

[steve_sordy]

Are you all using the same size battery? I'm guessing 504 W-hr.

 

[steve_sordy]

And the same charger as well of course! 4.5Amp?

 

[urastus]

And the same charger as well of course! 4.5Amp?

I assumed all shimano batteries and chargers are the same, but I don't know. Just looked; e7000 can have 504 or 418. So this survey is for 504. Chargers seem to be the same.

 

[salko]

I've been doing that - although it is pretty hit and miss for me. I don't see a percentage of charge, just up to 5 bars. So, what I have, as accurately as I can (checking every 30min), is 2.5 hrs for 3 bars; that equates to 50mins a bar. A few more measurements from others wouldn't go astray, for example papab has 40mins a bar.

I'm sorry but maybe Shimano has some different or variable charging speeds during charging. I have Specialized 700Wh battery and charging speed with 4A charger is pretty consistent with 22%/hour up to about 80% ...

 

[urastus]

I'm sorry but maybe Shimano has some different or variable charging speeds during charging. I have Specialized 700Wh battery and charging speed with 4A charger is pretty consistent with 22%/hour up to about 80% ...

maybe. I found this on shimano site yesterday: "Quick charging time (EC-E6000 charger) of 504 Wh: 80% in 2.5 hours, from 0 to 100% in 5 hours". They state the same for the e8000. This is in line with pabab's findings. So I assume I've had less than 1 bar, and more than 4 bars. It could also be like a microwave: if you heat a glass of water for 30" at a time, it might take 2 minutes or more to boil. If you put it in for a straight 1'30" it will bring it to boil. I was charging in 30' increments.

So, it's looking like 40mins per bar up to 4 bars. Wish I had of seen that on shimano's site earlier

 

[urastus]

Well, my theory about intermittent charging not being as effective is looking true. I went for a ride today, and lost one bar within the first 10 mins. Admittedly that was a 1km steep climb - as steep as I can climb. So I'm guessing I barely had the 4th bar charged even after 2 1/2 hours of charging in 30min increments. I'm back down to one bar now; I did one steep climb of about 300m on that one bar and some undulating track. I think I can safely say it's at .5 or greater. So, I'll try charging in one hit for 2 1/4 hours. That should give me 3 bars and a top up of number 1, around 75 - 80% in theory.

 

[steve_sordy]

I assumed all shimano batteries and chargers are the same, but I don't know. Just looked; e7000 can have 504 or 418. So this survey is for 504. Chargers seem to be the same.

My Focus has an E8000 system, with a Shimano motor, but I'm not sure whether the 378Whr battery is also Shimano. I had a 4.5A charger that was faulty and replaced with a 4A charger. Hence my questions.

 

[urastus]

My Focus has an E8000 system, with a Shimano motor, but I'm not sure whether the 378Whr battery is also Shimano. I had a 4.5A charger that was faulty and replaced with a 4A charger. Hence my questions.

It looks like shimano only has the 504wh batteries for the e8000. One is an external model, the other internal. So I'm guessing your charger won't be shimano either. It looks as though the only other battery they do is 418wh (not for the e8000). If you're not in a hurry, I believe a slower (eg your new 4A charger) charger is better for battery health than a faster charger. Unfortunately my findings won't be of much use to you, except for the generic stuff ie charge in one hit, not in increments of time.

 

[urastus]

I’ve always assumed the 5 bars on my bt-e8010 are non linear. I’ve always worked on the principal that the 5th bar is the fattest. Something like:
1 bar in range 0-5%, 2 bar to (+15%=) 20%, 3 bar to (+20%=) 40%, 4 bar to (+25%=) 65%, 5 bar to (+35%=)100%
For that reason, I charge back to 3-4 bars after a ride, aiming for 50% charge, give or take.
Not sure of the physics, but that’s my experience on the trail.

That seems logical - 2 1/2 hours to charge 80%, but 5 hours for a full charge (according to shimano). So I could be over simplifying it. According to your theory, and what shimano say: 5 bar to 100% is +50%. Working out anything more with the limited feedback of my system is too problematic, except that the remaining 4 bars take up 50% of the charge time . I'll stick to the 40min per bar as a starting point, and refine it from trial and error . It will be a slow process. That's why feedback from others would be good too. Update: 2 1/4 hours and it's only at 3 bars (from .5 to 1 bar), sheesh! So much for shimano's 0 - 80% in 2 1/2 hours. Update 2: 3 1/4 hours and still at 3 bars! Maybe it is because of the temperature? 13 C now. I'm ignoring shimano's figures.

 

[OldGoatMTB]

So, it's looking like 40mins per bar up to 4 bars. Wish I had of seen that on shimano's site earlier

Then I guess a rule of thumb would be 2 minutes for each 1% of battery increase, below 80%. YMMV

 

[urastus]

Then I guess a rule of thumb would be 2 minutes for each 1% of battery increase, below 80%. YMMV

I have no idea; I'm learning less I think what plugger said above makes sense, although his figures don't work for my setup. I also think there are gremlins in the garage playing psychological warfare.

 

[OldGoatMTB]

That seems logical - 2 1/2 hours to charge 80%, but 5 hours for a full charge (according to shimano). So I could be over simplifying it. According to your theory, and what shimano say: 5 bar to 100% is +50%. Working out anything more with the limited feedback of my system is too problematic, except that the remaining 4 bars take up 50% of the charge time . I'll stick to the 40min per bar as a starting point, and refine it from trial and error . It will be a slow process. That's why feedback from others would be good too. Update: 2 1/4 hours and it's only at 3 bars (from .5 to 1 bar), sheesh! So much for shimano's 0 - 80% in 2 1/2 hours. Update 2: 3 1/4 hours and still at 3 bars! Maybe it is because of the temperature? 13 C now. I'm ignoring shimano's figures.

I really don't think going by the number of bars is giving enough precision as 4 bars could be anything between 60% and 80%. Invest a couple of dollars in ST Unlocker and you can see exactly what the battery charge state and health are, as well as the number of cycles on the battery! This info alone was worth purchasing the app, but it's nice been able to tune the motor, also. Not talking about de-restricting as I have no interest in that. Amurican!

 

[MattyB]

I really don't think going by the number of bars is giving enough precision as 4 bars could be anything between 60% and 80%. Invest a couple of dollars in ST Unlocker and you can see exactly what the battery charge state and health are, as well as the number of cycles on the battery! This info alone was worth purchasing the app, but it's nice been able to tune the motor, also.

Agreed, there is no way you can look at this scientifically without access to either the pack/cell voltages (not easy with commercially assembled packs with an inbuilt BMS) or the calculated SOC based on that voltage (i.e. the % in the app). TBH the charging of Li ion packs is very consistently achieved and predictable - to learn more about how it works and the different phases read this:

Charging Lithium-Ion Batteries

This is also useful in understanding what happens in the final phase of charging, and why this slows the average charge rate (due to cell balancing):

What are Cell Balancing Techniques and How to Use Them

 

[OldGoatMTB]

I collected some data this morning when charging my Shimano BT-E8020 internal battery. The battery has 10 cycles on it and is at 100% battery health. I used my old darkroom timer to control the EC-E6000* charger and recorded the battery charge level every 10 minutes. The starting charge level was 57%.

Based on this data is appears that below 80% the rule of thumb would be about 2 minutes for each 1% increase in charge. Above 80% and the charge rate drops to about 3% every 10 minutes or 3.3 minutes per 1%, and above 90% the charge rate dropsto about 5 minutes per 1% increase in charge. Do with this information what you will!

*2.5 amp?

 

[urastus]

I collected some data this morning when charging my Shimano BT-E8020 internal battery. The battery has 10 cycles on it and is at 100% battery health. I used my old darkroom timer to control the EC-E6000* charger and recorded the battery charge level every 10 minutes. The starting charge level was 57%.
View attachment 31169
Based on this data is appears that below 80% the rule of thumb would be about 2 minutes for each 1% increase in charge. Above 80% and the charge rate drops to about 3% every 10 minutes or 3.3 minutes per 1%, and above 90% the charge rate dropsto about 5 minutes per 1% increase in charge. Do with this information what you will!

*2.5 amp?

Wow, that's awesome. Part of my problem is I can't see the percentage in that detail. How do you get those percentage values? Is it with stunlocker? Does stunlocker show you that level of information afterwards? Or have you stopped every 10 mins, hooked up with stunlocker, and recorded the info?

Although something else is going on here - my bike is taking longer. If I assume mine was at 10% (it hadn't done much on one bar) and I charged initially for 2hrs 15mins, and I was still on 3 bars. I charged for another hour and was still on 3 bars (3hrs, 15mins). I eventually went to 4hrs and now have 4 bars, so anything from 61 - 80%. Thankyou for your figures. I might have to pull my battery out.

 

[OldGoatMTB]

Yes, I charged for 10 minutes at a time, and then connected ST Unlocker to check the charge percentage.

 

[urastus]

Yes, I charged for 10 minutes at a time, and then connected ST Unlocker to check the charge percentage.

Thanks for that. There goes my theory of intermittent charging.

 

[urastus]

Sheesh! Just eyeballed my charger - it is only 1.8amp output. I'm no sparky, but I haven't heard that number mentioned before. I have an e8000 motor; the charger is an E6002. I assumed there was just one charger, but europe and US / Canada have different chargers. You can check the relevant links - look to the specs then hit the down arrow. My one is different - shimano's spiel about charging times relates to Europe / US models, but not the model that I have - times are totally different. 6.5hrs to 80%, 7.5hrs to full charge. I'm actually quite happy with this; I'd rather have a slow charge. Bugger shimano and their advertising though - I was about to start troubleshooting. I was wondering if I had a swollen battery or a dodgy charger. So unless any aussies are contributing here, I'm on my own. A big thankyou to Oldgoat for doing that research. Interesting to note that for mine, supposedly, 6.5hrs to 80%, and only one more hour to full! With these figures it works out to about 5min for each % up to 80%. Then 3min for each % of the last 20%. That's back to front to how your batteries charge. I'm guessing there must be some intelligence that controls the different methods of charge in the chargers: yours are fast up to 80%, then slow for the last 20%; mine is slow up to 80% then fast for the last 20%. Of course, I can't assume that all is linear up to 80% either. I can confirm the charger is black, and that my bike is an awesome red and flat black

My apologies to steve sordy who asked what charger and battery I was using early on in the piece. My search at the time just pointed to the one charger, and two battery capacities (504 and 418). I came across the different chargers via a search outside of shimano - my charger actually shows up in the e5000 accessories (check out the address in the link); from there I learned how to navigate the e8000 series.

 

[Flatslide]

Even though my bike is 48V, the charge experience is the same (just faster). If I access the app while charging, the charger is pushing 4.9A continuously all the way to about 80% equivalent at 52V. The app will show the battery at 100% during this (because the battery % is voltage related and the charger is outputting 52V). If I unplug while at about 80% (based on my experience with charging time), the voltage and related % reading will drop slowly until the voltage is around 51V. This is 80% +/-. The RM battery is full at 54.2V and flat at 43V. I ran it flat last week to calibrate the BMS. I think the constant part-charging over 10 months caused the BMS to behave like it had the upper and lower voltage limits out of whack. From a full charge, the display would show the battery rapidly decreasing in available energy as the iWoc lights were changing colour much sooner than had been normal. The battery had still had the capacity, but the display was showing 15% for miles and miles after dropping there very quickly. A short 100m steep climb at 60% assist in 1st would make the display show a loss of 25% capacity lol. I rode it until it switched off. I left it an hour after which it still wouldn't switch on, plugged it in, waited a couple of minutes, switched it on and took this screenshot:


A full charge took 2hrs 50mins when the charger switched off.


Flat to 80% takes 1hr 40min, then 1 hr 10mins extra for the final 20%.

After a full cycle the battery and display are back in sync.

 

[urastus]

flatslide: yes, it looks as though the majority of ebike batteries and chargers work like that. For the model charger that I have though, shimano gives a different scenario - they're either wrong or there is some intelligence built in somewhere. I will plan my future charging times based on their figures, which are the only ones that come close to making sense with what I've found. ie 5min per % up to 80%. I'm feeling more optimistic that this will be right for up to 80%, which is really what this thread here is concerned with For example, there is no problem at all charging to 100%, whether it is one hour or two hours, I just unplug when all the lights are off. When I next ride with a friend, I shall test the timing of that last 20%.