2022 625 Battery Rapid Discharge from 10%

[pwiles1968]

I have a Reign E+3, on a few occasions i have run the battery to or close to dead and have noticed something, I Use A Garmin with accurate % readout, but from about 10% the battery seems to deplete quite quickly about twice as fast as it does through the rest of the battery charge.

I have done ride up at a couple of bike parks and get very consistent battery use for the ride up but when i hit 10% from 10 to 5% comes quite quickly then at 3 or s it goes into minimum power mode. First time it happened i thought that it was just me but I have had it happen a couple of times now.

Anyone else experienced anything similar with a Giant Battery.

 

[Kiwi Giant]

This is the typical characteristic of a Lithium-Ion battery. Discharge is not linear below 20%. Discharge will increase from 20% to 10% and then rapidly drop off from 10%. Both my 500Wh & 800Wh do exactly the same thing. A discharge graph of a Lithium-Ion battery cell looks like this:

 

[pwiles1968]

This is the typical characteristic of a Lithium-Ion battery. Discharge is not linear below 20%. Discharge will increase from 20% to 10% and then rapidly drop off from 10%. Both my 500Wh & 800Wh do exactly the same thing. A discharge graph of a Lithium-Ion battery cell looks like this:

View attachment 98907

Surely the reported % is not the actual SOC of the battery but should be useable % remaining ? I thought it would be like driving a car empty you still have an amount of fuel left in the tank you just do not use it.

If that is the case i can work with it I treat 10% as empty but giant should really do this in software

 

[Nicho]

I have a Giant trance 2019 and the battery always drops much faster below 20%.
I was told by Giant via my LBS that every few charges I should run the battery down as close to empty as I can get it, then charge it up to 100%, because if this isn't done the battery's health will suffer.
Last week I did this and found it dropped quickly between 10% and 2% in about 5 miles, and then stayed at 2% for another 2 miles and then the motor switched off when it showed 1%.
Battery % readings were from my Garmin.

 

[Planemo]

I do get you, but as you say I think you will just have to work with it I'm afraid.

It all depends how low Giant set their min voltage. Most bike companies will screw it as low as possible to obtain the max Wh to look good in the specs. If say it's 3v per cell it ain't much good to man nor dog because between about 3.4v and 3v theres bugger all juice left in reality as Kiwi's post shows.

On my electric unicycle the shut off is 3.3v so it's a little more linear and does in fact read pretty accurately. That said, the manufacturers don't have much option because if you are riding one at 3v you are milliseconds away from a faceplant/broken shoulder so they have to err a little on the side of caution. Obviously with bikes it's not really an issue if the power fails at any time.

 

[Kiwi Giant]

You would think so, but basically the % remaining is just a derivative of the battery voltage. As you say, nowadays I treat 20% as the "red light warning" and 10% as the "end of the road". Typically, if I'm lucky and depending on terrain I can only hope to get another km or two at 10%. On a hill it will drop alarmingly below 10% and a complete drop-off in 100m under 5%.

 

[emtbeast]

Kiwi Giant is on the point here.
Good to see people are using my posts to educate others about battery tech, that's what I was hoping when posting...and happy to see the forum working in a good way...cause some forums are just full off...

By my measurements basically the last 13% of the battery the consumption is ~77Wh/100m altitude gained vs the average of 33Wh/100m...so actually more than double.

I personally wouldn't deplete the battery below 10% unless really really really necessary. If that is the case you need to charge it back up to a least 60% right after the ride, not the next day, few days after...you get the picture...because otherwise you risk battery health damage and capacity decrease. ✌

 

[pwiles1968]

Kiwi Giant is on the point here.
Good to see people are using my posts to educate others about battery tech, that's what I was hoping when posting...and happy to see the forum working in a good way...cause some forums are just full off...

By my measurements basically the last 13% of the battery the consumption is ~77Wh/100m altitude gained vs the average of 33Wh/100m...so actually more than double.

I personally wouldn't deplete the battery below 10% unless really really really necessary. If that is the case you need to charge it back up to a least 60% right after the ride, not the next day, few days after...you get the picture...because otherwise you risk battery health damage and capacity decrease. ✌

I always recharge bike to 60% ASAP and leave it at 60 till before i ride, I sort of know what battery discharge profiles look like, but I would expect a bike manufacturer to know a lot better and you think they would be able to program the reported level to match a discharge curve so you can get an accurate estimate of range.

I asked Giant UK and they said talk to my dealer who said that what I am seeing is not normal, bike is actually in a dealer now undergoing diagnostic checks .

 

[emtbeast]

I always recharge bike to 60% ASAP and leave it at 60 till before i ride, I sort of know what battery discharge profiles look like, but I would expect a bike manufacturer to know a lot better and you think they would be able to program the reported level to match a discharge curve so you can get an accurate estimate of range.

I asked Giant UK and they said talk to my dealer who said that what I am seeing is not normal, bike is actually in a dealer now undergoing diagnostic checks .

I know what you mean, but I haven't seen an ebike manufacturer that does that on their systems.

Probably u and I know the reason for it, as that would require to lower the Wh specifications of their batteries...or extra software development wich costs and probably isn't a big deal to do but as probably the majority of ebike riders don't care about this it's obviously not a concern for the companies.

You won't get anything from a dealer diagnostics...just stats of your riding modes and a few other stats and firmware numbers. This kind of battery behavior is normal, especially with Giant ebikes...my buddy has the 2020 Rein E and has the same behavior.

Edit:
Oh and what I think about ebike dealers...from experience...even if they have good knowledge of mtbs...the ebike world is a completely different world and mostly(for now) the staff is mostly uneducated and have a serious lack of knowledge to help the customers.
So they usually pop the bike to diagnostics find nothing and say it's fine.
The problem is that sometimes they are right but sometimes when diagnostics doesn't show a flaw they aren't right because they are not educated/experienced enough.

I myself when buying an ebike already deduct 15% from the stated battery Spec and that's basically the real useable capacity of it.

 

[Kingerz]

The Giant manual that comes with the bikes recommends a full discharge periodically to increase battery life.

 

[emtbeast]

The Giant manual that comes with the bikes recommends a full discharge periodically to increase battery life.

True it does, well I personally don't practice that as I know a bit about battery tech and know that when a battery starts discharging exponentially it's on the limit of safe for battery health. Basically what I do and it's enough to discharge it to min ~10% while riding and then charge it back up to 100% and If you do that periodically it's better than discharging to 0% and back to 100%.
Lithium Ion batteries aren't like old NimH that had a memory effect, and you had to discharge them to 0% otherwise the battery thought the 0 was at where you started charging them back up.

 

[Planemo]

True it does, well I personally don't practice that as I know a bit about battery tech and know that when a battery starts discharging exponentially it's on the limit of safe for battery health. Basically what I do and it's enough to discharge it to min ~10% while riding and then charge it back up to 100% and I you do that periodically it's better than discharging to 0% and back to 100%.
Lithium Ion batteries aren't like old NimH that had a memory effect, and you had to discharge them to 0% otherwise the battery thought the 0 was at where you started charging them back up.

Totally agree. Running a Li-Ion (or Li-Po for that matter) down to nothing does zero to increase battery life and in fact stresses the cells. Minimum 10% for me too. I have no idea why Giant would recommend otherwise. A Li-Ion is a Li-Ion, they aren't using some weird cell tech.

I've run Li-Po packs down to zero in the past and they were always the ones that puffed up first, many months before the packs that were only taken down to around 10%. Same make, model etc of pack.

 

[Kingerz]

Totally agree. Running a Li-Ion (or Li-Po for that matter) down to nothing does zero to increase battery life and in fact stresses the cells. Minimum 10% for me too. I have no idea why Giant would recommend otherwise. A Li-Ion is a Li-Ion, they aren't using some weird cell tech.

I've run Li-Po packs down to zero in the past and they were always the ones that puffed up first, many months before the packs that were only taken down to around 10%. Same make, model etc of pack.

Well, you could be right since most things written about batteries contradict each other, except that the manual is very specific and surely it is based on the technology from Panasonic that makes the product?
I notice that much of the manual is about other bikes (no lights on the Trance) but still, it is no wonder people don't know what to do.

 

[Planemo]

Yeah it's weird why Giant are saying that. The only potential upside of fully discharging a pack would be to maybe help the system calibrate it's ongoing range estimates. But as I don't really care about that (relatively to battery longevity) I won't be taking my pack down to 0%. And it certainly doesn't give that info to do so in my Haibike manual either.

Do whatever you are comfortable with, it's all largely moot really as most people won't keep their ebikes for long enough to really worry about it. But mines a keeper so I will treat the pack as is commonly understood practice for Li-Ion's.

 

[jonmat]

I have a Reign E+3, on a few occasions i have run the battery to or close to dead and have noticed something, I Use A Garmin with accurate % readout, but from about 10% the battery seems to deplete quite quickly about twice as fast as it does through the rest of the battery charge.

I have done ride up at a couple of bike parks and get very consistent battery use for the ride up but when i hit 10% from 10 to 5% comes quite quickly then at 3 or s it goes into minimum power mode. First time it happened i thought that it was just me but I have had it happen a couple of times now.

Anyone else experienced anything similar with a Giant Battery.

I don't know who makes the battery for your bike, however I have had similar experience with Shimano batteries. You get down to two bars and think you have 30% left and three or four miles later, it's flat and dead. Bosch batteries tend not to be like that, if you have a couple of bars lit on the indicator then you still have plenty of juice to get you home.