Possible battery/charger fault?

[Shane(NZ)]

Trek powerfly 500wh battery

So the last 3 or 4 times I have changed my battery overnight (always inside, battery removed)
It hasn't charged fully? Charger has stopped charging.
If I remove charger and plug back in it continues to charge again (approximately 30min more this morning) it never use to do this.
The charger gets warm as per normal battery does not.
I guess it's either faulty charger or battery or bms which is in battery.

Has anyone else had this problem?

Cheers Shane

 

[urastus]

After a ride, do you wait 30mins or so before charging? Or do you charge it straight away? I see you're from NZ - it must be getting cold there now . The video link might highlight a few possible causes.

 

[GrahamPaul]

After a ride, do you wait 30mins or so before charging? Or do you charge it straight away? I see you're from NZ - it must be getting cold there now . The video link might highlight a few possible causes.

One poor piece of advice given in that video is to keep a lithium battery topped up to 100%. This is just plain wrong, as described at length by "p c" in the first comment under the video.

You really do not want to be doing a 100% top up every time unless you are happy to buy a new battery every year or two.

As also given in the YouTube comment, the following link is highly recommended for understanding lithium batteries - whether used in your phone, laptop, ebike or electric car: Basic to Advanced Battery Information from Battery University

 

[GrahamPaul]

Trek powerfly 500wh battery

So the last 3 or 4 times I have changed my battery overnight (always inside, battery removed)
It hasn't charged fully? Charger has stopped charging.
If I remove charger and plug back in it continues to charge again (approximately 30min more this morning) it never use to do this.
The charger gets warm as per normal battery does not.
I guess it's either faulty charger or battery or bms which is in battery.

Has anyone else had this problem?

Cheers Shane

How old is your battery? It may be that charging it to 100% each and every time, your battery is now showing signs of deterioration.

How to Prolong Lithium-based Batteries - Battery University

 

[Shane(NZ)]

Normally over 1hr before charging after ride, takes 30min plus to drive home.
Thanks for the link, have seen that one.
About 17° today but is getting cooler.
I guess its doing something it didn't use to.

 

[urastus]

One poor piece of advice given in that video is to keep a lithium battery topped up to 100%. This is just plain wrong, as described at length by "p c" in the first comment under the video.

You really do not want to be doing a 100% top up every time unless you are happy to buy a new battery every year or two.

As also given in the YouTube comment, the following link is highly recommended for understanding lithium batteries - whether used in your phone, laptop, ebike or electric car: Basic to Advanced Battery Information from Battery University

OK, I didn't know that. Personally I only charge when I have to - eg 2 x 20km rides in eco, then charge. There were a couple of other points though, like the failure of some chargers when it gets to 0 degrees? And the 30min wait etc.

 

[urastus]

Normally over 1hr before charging after ride, takes 30min plus to drive home.
Thanks for the link, have seen that one.
About 17° today but is getting cooler.
I guess its doing something it didn't use to.

Awesome. Re the temp, I think he means you might have trouble if it is around zero degrees while you're charging.

 

[Shane(NZ)]

How old is your battery? It may be that charging it to 100% each and every time, your battery is now showing signs of deterioration.

How to Prolong Lithium-based Batteries - Battery University

I brought bike in july 2019 , done about 2,800km.
If the battery has degraded it still should charge up properly.
Thanks for the link, I'll have a read tonight.

 

[urastus]

One poor piece of advice given in that video is to keep a lithium battery topped up to 100%. This is just plain wrong, as described at length by "p c" in the first comment under the video.

You really do not want to be doing a 100% top up every time unless you are happy to buy a new battery every year or two.

As also given in the YouTube comment, the following link is highly recommended for understanding lithium batteries - whether used in your phone, laptop, ebike or electric car: Basic to Advanced Battery Information from Battery University

I read the article - it actually confirms what the dude said in the video. I think what you're referring to is storing the battery at 100% charge, which is damaging. The video actually says not to store the battery at 100%. After reading the article, the one change I will make is top up charging, rather than leaving it till I have around 1 bar left (what I currently do). It looks as though the best way to do this is top up charge before the ride ie don't leave it in a full state of charge from one weekend to the next. I may have it wrong though; I'd like to know if I have?

Actually, had to read some of it again to get my head around it. Ideally it is better not to fully charge the battery, period. I'm not sure how to achieve that - top up charge to 90 or 95%? Still open to any misunderstandings I might have; I'd like to do this right myself.

 

[GrahamPaul]

I read the article - it actually confirms what the dude said in the video. I think what you're referring to is storing the battery at 100% charge, which is damaging. The video actually says not to store the battery at 100%. After reading the article, the one change I will make is top up charging, rather than leaving it till I have around 1 bar left (what I currently do). It looks as though the best way to do this is top up charge before the ride ie don't leave it in a full state of charge from one weekend to the next. I may have it wrong though; I'd like to know if I have?

Actually, had to read some of it again to get my head around it. Ideally it is better not to fully charge the battery, period. I'm not sure how to achieve that - top up charge to 90 or 95%? Still open to any misunderstandings I might have; I'd like to do this right myself.

That's a common misunderstanding. The article is not referring to storing the battery but to how the battery is degraded by charging to 100%. Here is a useful diagram from heavy duty electric car research to really show the difference in total charge cycles. (Note that "total charge cycles" refers to the amount of times that a battery is fully charged and then discharged, and not to how many times you put it on charge for a partial top-up. It is the summation of all of those partial times of charge and discharge).

As you can see, you get about 3 times more useful life out of a battery by only ever charging it to 80%.

Somewhere or other, I've got a diagram for partial charges of ebike batteries which demonstrates the same thing, but can't for the life of me lay my hands on it at the moment.

 

[urastus]

That's a common misunderstanding. The article is not referring to storing the battery but to how the battery is degraded by charging to 100%. Here is a useful diagram from heavy duty electric car research to really show the difference in total charge cycles. (Note that "total charge cycles" refers to the amount of times that a battery is fully charged and then discharged, and not to how many times you put it on charge for a partial top-up. It is the summation of all of those partial times of charge and discharge).

As you can see, you get about 3 times more useful life out of a battery by only ever charging it to 80%.

Somewhere or other, I've got a diagram for partial charges of ebike batteries which demonstrates the same thing, but can't for the life of me lay my hands on it at the moment.

Awesome, yes I finally understood that, thankyou for confirming it. The problem looks like how to charge it to 80 or 90%. It also looks like the length of time that the battery remains in a fully charged state is an issue. At this point I'm thinking charge after every ride but just before a ride. Re the partial charges of ebike batteries - your article actually describes this too. There's a Depth of Discharge graph - basically showing that top up charges (preferably to 80% or so) will give you many more cycles than charging from a fully flat or nearly flat battery - I've been doing the latter (well from 1-2 bars out of 5 bars).

 

[GrahamPaul]

Awesome, yes I finally understood that, thankyou for confirming it. The problem looks like how to charge it to 80 or 90%. It also looks like the length of time that the battery remains in a fully charged state is an issue. At this point I'm thinking charge after every ride but just before a ride.

I went through that same quandary. I now charge before my ride to just over 80% (unless I'm doing a big ride, then it goes all the way to 100%). Why just over 80%? Because the Bosch Powertube has 5 lights and I only know that I've got to 80% when the 5th one starts flashing.

I usually finish my rides with around 20-40% remaining (2 bars showing), so alway have to charge. I can't face the 2.2km at 10% climb to get home without some help.

 

[urastus]

I went through that same quandary. I now charge before my ride to just over 80% (unless I'm doing a big ride, then it goes all the way to 100%). Why just over 80%? Because the Bosch Powertube has 5 lights and I only know that I've got to 80% when the 5th one starts flashing.

I usually finish my rides with around 20-40% remaining (2 bars showing), so alway have to charge. I can't face the 2.2km at 10% climb to get home without some help.

Yeah, I have no such thing Maybe I have? I'll look while it's charging next time. It's shimano, the power comes on while it's charging. I don't think it shows the bars though (pretty sure it doesn't). My only other option would be pretty random guess work using a timer Unless there is some other gizmo available but I imagine that would have to fit between the charger and the bike / battery. Thanks for your patience Graham.

 

[urastus]

If anyone is interested I found this charger - prohibitively expensive for me. Saw a video where a bike shop has one, which would make sense. It can charge all sorts of batteries but you need to buy the right lead for it. This can be programmed to charge slow and up to 80%, or whatever percentage you want (70% for storage?). I will buy an outlet timer though, and play with that. Very cheap and many uses.

 

[GrahamPaul]

If anyone is interested I found this charger - prohibitively expensive for me. Saw a video where a bike shop has one, which would make sense. It can charge all sorts of batteries but you need to buy the right lead for it. This can be programmed to charge slow and up to 80%, or whatever percentage you want (70% for storage?). I will buy an outlet timer though, and play with that. Very cheap and many uses.

That charger is very popular with the self-build crowd who build their bikes with massive batteries. It's a great way to ensure they don't burn the neighbourhood down