Battery charging, how often

[Andy-Mat]

Modern e-bike batteries come with a BMS that disconnects the charger once it is charged. So you really do not need to worry about having your charger connected to a timer unit.

If always true, nobody could measure their actual battery voltage at the charge socket, on the battery, as the BMS would prevent that.
Simples!
Of the few different e-bike batteries I have actually looked at myself, and when people here are asked to measure that voltage, most manage that, as the battery voltage was there to be measured.....I have always been able to measure battery voltage, did the BMS see my Multi Meter approaching or what?
But I am not saying ALL batteries/BMSs are made so.
Maybe some expensive batteries are made differently, but I have a cheap bike! And all the other bike batteries I could read the voltage when needed.

It could even be detrimental, as you don't know how out of balance the banks of cells are in your pack and it could take several hours to achieve balance, which is done at the end of a cycle. Only charging for a fixed time could prevent adequate time for balancing as no two charging cycles are the same.

The BMSs I have looked at, do not seem to rely on the charger for power for balancing, because if they did AND CURRENT WAS TAKEN FROM THE CHARGER, the charge LED would be RED, and not GREEN.
The Green LED is only switched on at a very low charge point! Below 3% of rated charge.
They simply use the higher voltage in one bank of cells (banks are unballanced, some are at a higher or lower voltage!) to feed a "low" bank, effectively reducing all banks to the state of the worst bank!
That is an old wives tale about the BMS using the charger, that too many believe wrongly.....
Just look very carefully at the graphic on that Battery University about Li-Ions and when charging is finished. At 3% of rated current..

Also, the damage is done if you leave the charger in an ON state, to the battery with the "Stage 4" Occasional topping charge!
You can see that graphic here, just in case you believe I made the graphic:-

Charging Lithium-Ion Batteries

Review simple guidelines for charging Lithium-based batteries and prolong battery life such as; a portable device should be turned off while charging and more.

batteryuniversity.com

Completely discharging a pack was done in the days of NiCd cells that used to suffer the memory effect. Lithium cells don't have a memory effect problem and deep cycling is never good for battery life, so avoid it.

You have this partly wrong, the lowest level that a NICAD or NMIH battery should be discharged to, if memory serves me correctly, is 1 volt!
Also, there are different schools of thought on this memory effect, you have to look around and pick the one you most believe in!

Memory: Myth or Fact? – Battery University

Discover if memory is myth or fact, and how to prevent and eliminate it

batteryuniversity.com

Or here:-

NiCd Battery Memory Effect » Electronics Notes

The memory effect associated with nickel cadmium or Nicad / NiCd batteries was a limiting factor in these cells: find out what it was and how to prevent it

www.electronics-notes.com

Where the original "finding" was:-
It was reputed that the effect was first noticed in satellites where the Sun was used when it was available, but the NiCd batteries were used when the satellite passed over the dark side of the Earth. Accordingly the batteries were repeatedly partially discharged and then immediately recharged again without experiencing a full discharge. Soon it was discovered that their overall capacity was reduced as they "remembered" the amount by which they were normally discharged.
In a Satellite, the batteries receive charge always at exactly the same point in the orbit, and it went at another same point in the orbit. That never happens on earth, as clouds alone change that for solar cells, but most charge from a mains that is more reliable than that!
But as NICADs are made differently since sometime in the 1990s, the memory effect has been for earthly uses, as good as not there anymore.
And even Satellites don't use NICADs anymore!
I trust that I have awakened your interest!
Andy

 

[WheezyRider]

A li-on battery fire is basically chemical, the electrolyte is highly flammable , there is very little lithium metal actually present .The potential energy contained in a charged battery contributes lots to maintaining the heat . A large amount of water does work in extinguishing , also inert material like sand, the key is to take the heat away to prevent re-ignition .

Throwing water on it is a bad idea. Sinking it in a large amount of water (eg pond, sea, lake, ocean) will indeed stop it dead. Your Lithium battery should not have reached the metallic Lithium stage anyway, that is not the plan!

The problem with over discharge is that the Battery management system requires power to work, and if there is no power at all it usually defaults to 'this battery is dead / unsafe / missing, and I'm not going to put any power into it'.

Sometimes that is too clever by half, but battery builders would much rather have it fail safe than the alternative .. apart from the fact they can then sell you a new one.

A lot of water will eventually put it out. My main concern with the pond/lake/sea idea is that there are likely to be a lot of chemical nasties in these batteries and combustion products. Not good for the environment if they are then dispersed in such a way.

The amount of lithium present depends on state of charge. If you do get a lot of hydrogen produced, you could get a nasty explosion.

 

[ChuckingFeet]

Totally agree about the unwanted environmental effects , but sometimes needs must...

 

[Andy-Mat]

Please do not throw a burning lithium battery "in a pond" or even throw water on it. Lithium metal reacts vigorously with water to make hydrogen gas. Best to cover it in sand and stand well back.

You must tell that to the German Police and Fire departments, as they have experience of burning Tesla (an not just Tesla) electric car batteries, still burning and filling the atmosphere for miles around with toxic fumes, after 10 hours of burning!
Nowadays they bring a huge tank to the vehicle fire, usually an autobahn, place the tank near to the burning car, fill the tank for bowsers full of water, and use a crane to drop the burning wreck into the tank.
Then they twiddle their thumbs for an hour or so!
Here is a video from the Netherlands, that may help you:-

Or here:-

Or here this shows the big tank in use in Germany:-

Please tell me how the UK handles such car battery fires please?
Andy

 

[WheezyRider]

If always true, nobody could measure their actual battery voltage at the charge socket, on the battery, as the BMS would prevent that.
Simples!
Of the few different e-bike batteries I have actually looked at myself, and when people here are asked to measure that voltage, most manage that, as the battery voltage was there to be measured.....I have always been able to measure battery voltage, did the BMS see my Multi Meter approaching or what?
But I am not saying ALL batteries/BMSs are made so.
Maybe some expensive batteries are made differently, but I have a cheap bike! And all the other bike batteries I could read the voltage when needed.



The BMSs I have looked at, do not seem to rely on the charger for power for balancing, because if they did AND CURRENT WAS TAKEN FROM THE CHARGER, the charge LED would be RED, and not GREEN.
The Green LED is only switched on at a very low charge point! Below 3% of rated charge.
They simply use the higher voltage in one bank of cells (banks are unballanced, some are at a higher or lower voltage!) to feed a "low" bank, effectively reducing all banks to the state of the worst bank!
That is an old wives tale about the BMS using the charger, that too many believe wrongly.....
Just look very carefully at the graphic on that Battery University about Li-Ions and when charging is finished. At 3% of rated current..
View attachment 36621
Also, the damage is done if you leave the charger in an ON state, to the battery with the "Stage 4" Occasional topping charge!
You can see that graphic here, just in case you believe I made the graphic:-

Charging Lithium-Ion Batteries

Review simple guidelines for charging Lithium-based batteries and prolong battery life such as; a portable device should be turned off while charging and more.

batteryuniversity.com

You have this partly wrong, the lowest level that a NICAD or NMIH battery should be discharged to, if memory serves me correctly, is 1 volt!
Also, there are different schools of thought on this memory effect, you have to look around and pick the one you most believe in!

Memory: Myth or Fact? – Battery University

Discover if memory is myth or fact, and how to prevent and eliminate it

batteryuniversity.com

Or here:-

NiCd Battery Memory Effect » Electronics Notes

The memory effect associated with nickel cadmium or Nicad / NiCd batteries was a limiting factor in these cells: find out what it was and how to prevent it

www.electronics-notes.com

Where the original "finding" was:-
It was reputed that the effect was first noticed in satellites where the Sun was used when it was available, but the NiCd batteries were used when the satellite passed over the dark side of the Earth. Accordingly the batteries were repeatedly partially discharged and then immediately recharged again without experiencing a full discharge. Soon it was discovered that their overall capacity was reduced as they "remembered" the amount by which they were normally discharged.
In a Satellite, the batteries receive charge always at exactly the same point in the orbit, and it went at another same point in the orbit. That never happens on earth, as clouds alone change that for solar cells, but most charge from a mains that is more reliable than that!
But as NICADs are made differently since sometime in the 1990s, the memory effect has been for earthly uses, as good as not there anymore.
And even Satellites don't use NICADs anymore!
I trust that I have awakened your interest!
Andy

Just because you see a voltage across the BMS does not mean that you have direct access to the battery terminals. You need to look at current flow into the BMS. Inside the BMS there will be a blocking diode in series with the main battery output to prevent flow in the wrong direction. Another circuit will feed off from that to control the charging. When the BMS detects that the battery is full, that charging circuit is disconnected.

As far as I am aware, BMS units generally start the balancing process when the constant current charger gets to 4.15V or thereabouts. For this to work, the BMS needs to be connected to the charger. Excess energy is sent to bleed off resistors, not to re-balance other cells.

If this isn't the case, I'd be happy for a BMS expert to tell me otherwise.

Yes I agree about the memory effect. It was never very clear in the first place, even with NiCds, but once the theory was out there, no one wanted to take the risk with what were expensive cells.

But, in any case, there is no reason to continue doing something that was for a completely different battery chemistry and technology.

 

[Andy-Mat]

they do produce hydrogen gas but if your lithium battery is burning, I reckon the pond's water will stop the fire in its track.

In the private sector, that is maybe the only way to save a house or people.....sad though for any wildlife!
Andy

 

[Andy-Mat]

Please do not throw a burning lithium battery "in a pond" or even throw water on it. Lithium metal reacts vigorously with water to make hydrogen gas. Best to cover it in sand and stand well back.

You misunderstand the situation completely. Li-ion cell fires are extremely dangerous, foams seem to just make them worse. I have posted some up to date information for you already here.
I would love to know how the UK Police handle such fires on the motorways of GB, if they do not do the same!
Andy

 

[RobN]

Nobody has mentioned taking the fish out of the pond before throwing your burning bike in..?

 

[Andy-Mat]

Just because you see a voltage across the BMS does not mean that you have direct access to the battery terminals. You need to look at current flow into the BMS. Inside the BMS there will be a blocking diode in series with the main battery output to prevent flow in the wrong direction. Another circuit will feed off from that to control the charging. When the BMS detects that the battery is full, that charging circuit is disconnected.

As far as I am aware, BMS units generally start the balancing process when the constant current charger gets to 4.15V or thereabouts. For this to work, the BMS needs to be connected to the charger. Excess energy is sent to bleed off resistors, not to re-balance other cells.

If this isn't the case, I'd be happy for a BMS expert to tell me otherwise.

Yes I agree about the memory effect. It was never very clear in the first place, even with NiCds, but once the theory was out there, no one wanted to take the risk with what were expensive cells.

But, in any case, there is no reason to continue doing something that was for a completely different battery chemistry and technology.

I have found, over many years, that Li-ion batteries simply do not like being connected to a charger, once the charge is complete.
I showed you a graphic and I explained it carefully why that is always a good idea, but apparently the graphic was in some way, possibly not understandable.
I cannot do more, if you are not understanding the graphic, sorry, that is your problem, as I find the BU graphic to be good, aqccurate, well drawn and very easy to understand!
Maybe you should take a long second look, to see if it sinks in.....
Andy

 

[ChuckingFeet]

Rather unnecessary to start insulting people on what has been a light-hearted thread .

 

[WheezyRider]

I have found, over many years, that Li-ion batteries simply do not like being connected to a charger, once the charge is complete.
I showed you a graphic and I explained it carefully why that is always a good idea, but apparently the graphic was in some way, possibly not understandable.
I cannot do more, if you are not understanding the graphic, sorry, that is your problem, as I find the BU graphic to be good, aqccurate, well drawn and very easy to understand!
Maybe you should take a long second look, to see if it sinks in.....
Andy

I think we'll just have to agree to disagree on how a BMS works.

This is interesting reading:

Life, death, and spontaneous combustion — here's why the debate about Tesla fires just got more fierce

A mysterious Tesla fire in a Shanghai parking lot has everyone talking about Tesla fires again. Business Insider dug into why the topic won't go away.

www.businessinsider.com

Read the bit about contamination with other metal during manufacture!

Makes you never want to get into an electric car. At least on a bike, the pack isn't that big, so if the worst happens it's unlikely to be such a problem. Of course, you really wouldn't want one of these charging in the house overnight.

The problem still remains with water, it takes heat away quite effectively, but it doesn't stop the reaction and you could get an explosion and likely re-ignition. EV battery fires are a serious problem and one people seem to be ignoring. Also, people want to have power walls in houses tied to the grid...

Maybe the UK do the same as the US fire department recommend tackling an EV fire:

You ought to ask them.

LiFePO batteries are supposed to be a lot safer. I wonder how safe...

 

[PP100]

Elon Musk has just announced his new battery fire fighting device. I am sure nothing can go wrong.

 

[flecc]

Please tell me how the UK handles such car battery fires please?

General Motors, Nissan and Tesla have published a guide for firefighters and first responders to properly handle a crashed electric-drive vehicle and safely disable its battery and other high voltage systems.

These fires are extremely rare and the very few that occur are almost entirely in Tesla and a few related cars used by some US taxi companies.

Here in the UK the dominant selling car has been the Nissan Leaf which has a worldwide record of never having a traction battery fire in any of the over a third of a million produced. One Leaf in Texas did have a fire, but it was caused by the car's ordinary lead acid battery side under the bonnet which powers the usual car ancillaries just like any ic car. The underfloor lithium traction battery was unaffected.

There has only been one e-car traction battery fire in the UK, a Tesla model S from 2017 burning out in Chester, England on November 12th 2019. We have over 20,000 of these S models on the UK's roads with a very large nationwide Tesla charging network, and their model 3 has now sold over 6000 here.

Internationally e-cars have suffered far lower fire rates than ic cars by a huge margin. It should also be considered that these e-car batteries are now also used in home Powerwalls in conjunction with solar panels and the grid electricity with no fire problems. Indeed this is where Tesla and Nissan traction batteries will be going here at the end of warranty life of 75% capacity remaining to be useful for many more years.

The risk of e-car fires occurring has been grossly over exaggerated, as said they are extremely rare and mainly confined to the Tesla model S, their first attempt at a passenger carrying car nearly a decade ago. They've made many design changes, particularly to their batteries and they now make all their own cells to ensure the highest standards.
.

 

[flecc]

Rather unnecessary to start insulting people on what has been a light-hearted thread .

It's what Andy-Mat seems to like doing if others do not agree with his stranger notions, especially about batteries and e-cars.
.

 

[flecc]

EV battery fires are a serious problem and one people seem to be ignoring. Also, people want to have power walls in houses tied to the grid...

EV battery fires are not a serious problem, see this link.

And there were over 50,000 home powerwalls already installed by July 2019 using these Tesla car batteries in solar panel and grid installations with no news about fires.

Just as with every new technology, there's far too much scaremongering on this whole subject, the media stirring it up as usual.
.

 

[WheezyRider]

EV battery fires are not a serious problem, see this link.

And there were over 50,000 home powerwalls already installed by July 2019 using these Tesla car batteries in solar panel and grid installations with no news about fires.

Just as with every new technology, there's far too much scaremongering on this whole subject, the media stirring it up as usual.
.

I hope you are right

Does anyone know why the Nissan Leaf has a better record than Tesla? Did Tesla cut corners in the early days in the rush to get a product to the market?

The problem is when one does catch fire, what is the best way to put it out?

Also, for us e-bikers, who might have packs made of cells of unknown origin, what is the best procedure for dealing with a pack fire, should the worst happen?

 

[Amoto65]

Rather unnecessary to start insulting people on what has been a light-hearted thread .

Par for the course I am afraid from certain people on here if you have an opposing view, best way is to ignore them and let them rant away.

 

[Nealh]

Just as with every new technology, there's far too much scaremongering on this whole subject, the media stirring it up as usual.
.

And Andy.

 

[Nealh]

I hope you are right

Does anyone know why the Nissan Leaf has a better record than Tesla? Did Tesla cut corners in the early days in the rush to get a product to the market?

The problem is when one does catch fire, what is the best way to put it out?

Also, for us e-bikers, who might have packs made of cells of unknown origin, what is the best procedure for dealing with a pack fire, should the worst happen?

Runaway.

 

[Andy-Mat]

It's what Andy-Mat seems to like doing if others do not agree with his stranger notions, especially about batteries and e-cars.
.

I have been on the receiving end of some very rude comments, far too many times here, perhaps if they had followed yours and someone else's "new advice", things might have developed in a different manner....
And what I said was far less rude than some others here have said....
Andy