Battery charging

[Binhill1]

Will charging it when 40 percent left alter life of battery in the long term or
should I go for short run to take it down a bit more. Quite often find I use about 60 percent working out about 20 miles.

 

[MattyB]

Neither is necessary. As long as the battery is between 30-70% charged when leaving for any more than 24hrs and you store at around room temp you should be good for the largest number of cycles before significant capacity loss is a factor. Best would be to not charge at all after getting back from a ride that leaves 40% in it, then charge to full just before your next ride.

 

[Mikerb]

...agree...except I only charge to 100% if I am going on a long ride, otherwise I charge to c 80%. Regardless I charge to 100 % occasionally and leave overnight before use.

 

[Binhill1]

...agree...except I only charge to 100% if I am going on a long ride, otherwise I charge to c 80%. Regardless I charge to 100 % occasionally and leave overnight before use.

Ok it's just that I get out quite a lot so like it to be charged enough for a decent spin at 40 percent it would be a bit limiting for me , but was wary about charging it every time from that level.

 

[Russell]

I personally don't bother, I charge it back up to full after every ride. Nothing worse than wanting to go out on the bike only to find it has a flat battery.

 

[MattyB]

Ok it's just that I get out quite a lot so like it to be charged enough for a decent spin at 40 percent it would be a bit limiting for me, but was wary about charging it every time from that level.

The number of times you initiate a charge has no bearing on life - charging it 10 times in 10% increments is exactly the same as charging from fully flat to fully charged up once. Based on what you have stated about your usage pattern I would suggest you follow @Mikerb ‘s advice and charge to 70-80% each time after use if you want to maximise the cycle life.

 

[mtbross]

I heard it’s actually good to charge to 100% after every ride. Something about good for cells to have full charge. So that’s what I do. And it’s always ready to go.

 

[MattyB]

I heard it’s actually good to charge to 100% after every ride. Something about good for cells to have full charge. So that’s what I do. And it’s always ready to go.

No, that’s definitely incorrect (though EMBN have stated this on more than one occasion). Storage at elevated state of charge for extended periods will knacker your battery well before it reaches it’s maximum potential cycle life. 30-70% charge is where it needs to be if leaving for any longer than 24-48hrs between rides.

Lots of threads on this topic are available in the forum, have a gander...

Battery care/management - EMTB Forums
Loss in battery life - EMTB Forums
Battery Management - EMTB Forums

...and here's some external resources explaining the factors that influence cycle life, capacity degradation and power density over time...

How to Prolong Lithium-based Batteries - Battery University
Three Ways That Lithium Dendrites Grow

 

[wepn]

If you ask an electrical engineer that specialises in lithium battery technology, he would advise to charge to 80% or 100% before every ride - and charge to 40% or 50% for overnight or longer slumber.

 

[Mikerb]

There is no dispute that charging to 100% when full range is not likely to be needed is not the best way to prolong battery health. I think the confusion ...if there is any....is due to advice to fully charge before a ride to avoid range anxiety. If you know your ride will only use 50% then just charge to 80%. That also leaves 30% which is ideal for leaving the bike unused

 

[Binhill1]

There is no dispute that charging to 100% when full range is not likely to be needed is not the best way to prolong battery health. I think the confusion ...if there is any....is due to advice to fully charge before a ride to avoid range anxiety. If you know your ride will only use 50% then just charge to 80%. That also leaves 30% which is ideal for leaving the bike unused

Thanks folks some useful info from all comments. Going to look at the links put up know I won't understand half of it but has to be done.

 

[Mikerb]

All you really need to understand is that the final stage of charging is used by the BMS to balance the voltage in each cell. That is necessary occasionally but generates a lot of heat in some of the cells. I only charge to 100% the night before a long ride. For my normal rides of 2 or 3 hours I charge to about 80%.

 

[Binhill1]

All you really need to understand is that the final stage of charging is used by the BMS to balance the voltage in each cell. That is necessary occasionally but generates a lot of heat in some of the cells. I only charge to 100% the night before a long ride. For my normal rides of 2 or 3 hours I charge to about 80%.

So I've been out today 65 when i went out 15 percent left after ride so i will take it up to 70 tonight but intending a longer run Sunday so top it up tomorrow night or on Sunday morning.

 

[mtbross]

No, that’s definitely incorrect (though EMBN have stated this on more than one occasion). Storage at elevated state of charge for extended periods will knacker your battery well before it reaches it’s maximum potential cycle life. 30-70% charge is where it needs to be if leaving for any longer than 24-48hrs between rides.

Lots of threads on this topic are available in the forum, have a gander...

Battery care/management - EMTB Forums
Loss in battery life - EMTB Forums
Battery Management - EMTB Forums

...and here's some external resources explaining the factors that influence cycle life, capacity degradation and power density over time...

How to Prolong Lithium-based Batteries - Battery University
Three Ways That Lithium Dendrites Grow

Good to know! Thanks!

 

[Pukmeister]

There is no dispute that charging to 100% when full range is not likely to be needed is not the best way to prolong battery health. I think the confusion ...if there is any....is due to advice to fully charge before a ride to avoid range anxiety. If you know your ride will only use 50% then just charge to 80%. That also leaves 30% which is ideal for leaving the bike unused

The mass of the electrons is almost zero, why are you only charging to 80 %, is it to save weight ??

Fully charge before a planned ride, have no range anxiety, use 50% on the ride, store at 50% afterwards until the next recharge:near perfect.

 

[mtbross]

I have never stored my batteries (road or mtn e-bikes) at 50% for long. Just charge them up so they are ready to go, which is usually never more than two days, max three before used again. So I was curious if I was hurting the battery. Not sure about the different brands, but Rocky Mountain people said:

----------------------------------------
In general, Lithium Ion batteries will last the longest with smaller cycles.
For example, 200 half cycles, will put slightly less stress on the cells than 100 full cycles.
This effect is quite marginal however.

Our system is designed to keep the battery within its safe parameters at both full and empty. At the top end, our charger regulates the current to allow the maximum amount of energy per cell, without over charging. At the bottom end the motor controller is dictating the cutoff or where ‘empty’ is, and rolling off motor current accordingly to keep the cells safe.

Another note would be regarding temperature. Sustained high current draw at high temperature could shorten the life of the cells (ie hill repeats in the dessert), however the battery’s internal management system has a temperature failsafe to stop the battery from supplying current if it is too hot.

It doesn’t hurt to keep the battery fully charged, and is far more convenient to have a full bike ready to ride. If the battery is left for months on end without use, then a top up charge is a good idea.
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So, for me, I just don't have the mental bandwidth to be closely monitoring where my battery is, and when I should or shouldn't charge it. I'll just continue to charge it either after a ride, or a few hours before.

For what it's worth, I've been charging the battery on my Giant Road-E bike after every ride for over 1 1/2 yrs, and the battery health via the app says 99%.

 

[MattyB]

...Not sure about the different brands, but Rocky Mountain people said:

----------------------------------------
In general, Lithium Ion batteries will last the longest with smaller cycles.
For example, 200 half cycles, will put slightly less stress on the cells than 100 full cycles.
This effect is quite marginal however.

Our system is designed to keep the battery within its safe parameters at both full and empty. At the top end, our charger regulates the current to allow the maximum amount of energy per cell, without over charging. At the bottom end the motor controller is dictating the cutoff or where ‘empty’ is, and rolling off motor current accordingly to keep the cells safe.

Another note would be regarding temperature. Sustained high current draw at high temperature could shorten the life of the cells (ie hill repeats in the dessert), however the battery’s internal management system has a temperature failsafe to stop the battery from supplying current if it is too hot.

It doesn’t hurt to keep the battery fully charged, and is far more convenient to have a full bike ready to ride. If the battery is left for months on end without use, then a top up charge is a good idea.
-------------------------------------------------

They were doing so well until they got to the end...

Huge amounts of research has been done into degradation over time and in use for Lithium chemistry cells. It has been shown many times that prolonged storage at elevated SOC (normally considered to be anything over 80%, or 4V/cell) does cause premature aging in Li packs, reducing cycle life, capacity and the ability to deliver higher currents (often referred to as power density). Of course they could in theory only be charging to 4V/cell to increase life, but by doing so they would be leaving a lot of capacity on the table. Given they are claiming some of the biggest capacity batteries around (674Wh in the Altitude Powerplay) that seems rather unlikely. Anyone know the cell configuration and type on their batteries? If we knew that we would know the theoretical maximum capacity.

For what it's worth, I've been charging the battery on my Giant Road-E bike after every ride for over 1 1/2 yrs, and the battery health via the app says 99%.

Whilst battery health figures can enable rough comparison of packs of the same type from the same manufacturer, their absolute values are of little use since we have no idea how they are calculated. The only way to tell if a battery is truly healthy is to conduct a number of controlled tests on it, which normal involve a full charge/discharge cycle.