Battery heat meter and 30kw leaf

BoatMad

KCross wrote: »

Not true. I saw mine go to 9!

so much for the internet, at 9 the charging rate must have been very seriously reduced

KCross

BoatMad wrote: »

so much for the internet, at 9 the charging rate must have been very seriously reduced

On the contrary it was quite quick! You're not having a good day BoatMad!

9 bars isnt in the red so, I'd say, the BMS didnt kick in.

I charged from 7->81% in 25mins adding 18.2 kWh's and during that time the bars went from 7->9. Thats quick for a 24kWh LEAF.

I'd imagine the BMS kicks in when you hit the red.

BoatMad

KCross wrote: »

On the contrary it was quite quick! You're not having a good day BoatMad!

9 bars isnt in the red so, I'd say, the BMS didnt kick in.

I charged from 7->81% in 25mins adding 18.2 kWh's and during that time the bars went from 7->9. Thats quick for a 24kWh LEAF.

I'd imagine the BMS kicks in when you hit the red.

intersting , the manual says that reductions in charging occur from bars onwards

when you had 9 bars, did it reduce when driving

KCross

BoatMad wrote: »

intersting , the manual says that reductions in charging occur from bars onwards

when you had 9 bars, did it reduce when driving

It did. It went back to 8 bars.

Upto that point I was on motorway and driving at 75mph. The last leg of the journey was minor roads so I was hitting small towns and stuck behind trucks etc.

BoatMad

KCross wrote: »

It did. It went back to 8 bars.

Upto that point I was on motorway and driving at 75mph. The last leg of the journey was minor roads so I was hitting small towns and stuck behind trucks etc.

Interesting I went back to the comment about limiting to 8 bars, it was specifically made in relation to the 30 Kwh

KCross

BoatMad wrote: »

Interesting I went back to the comment about limiting to 8 bars, it was specifically made in relation to the 30 Kwh

Where was that comment.... in the manual or SpeakEV?

I think all my manual said was that the BMS would kick in when it got to the red and that it would reduce rapid charging rate and would eventually go to turtle mode to save the battery.

On the long multiple rapid charges I've had I never got into the red but I was one short of it.

BoatMad

KCross wrote: »

Where was that comment.... in the manual or SpeakEV?

I think all my manual said was that the BMS would kick in when it got to the red and that it would reduce rapid charging rate and would eventually go to turtle mode to save the battery.

On the long multiple rapid charges I've had I never got into the red but I was one short of it.

The manual says reductions in charge rate occur from 8 bars onwards ( and below 4 bars ) ,

The fact they have to reduce current says it all really.

If it was cooled they wouldn't have to do this. Bad engineering.

BoatMad

Deleted User wrote: »

The fact they have to reduce current says it all really.

If it was cooled they wouldn't have to do this. Bad engineering.

Its not bad engineering , its a tradeoff between operating envelopes and costs

that all, its actually an example of " good " engineering

bad engineering would be to do nothing as battery temp climbs

KCross

BoatMad wrote: »

The manual says reductions in charge rate occur from 8 bars onwards ( and below 4 bars ) ,

The text must have been updated as my manual just talks about the red bars, no mention of bar 8

I suppose the 30kWh does have an updated BMS so the behaviour might be different for you and hence the updated text.

No, good engineering is cooling the pack, not cooling it is a bad management decision not a good engineering decision.

I bet they thought most people who would buy the leaf would never drive half the miles many are doing and wouldn't be an issue.

yqtwqxqm

Im convinced reading some of these threads that some people think an EV is a horse and not a machine

Dardania

BoatMad wrote: »

Its not bad engineering , its a tradeoff between operating envelopes and costs

that all, its actually an example of " good " engineering

bad engineering would be to do nothing as battery temp climbs

A cooling system would add weight. It's all a trade off

KCross

Deleted User wrote: »

No, good engineering is cooling the pack, not cooling it is a bad management decision not a good engineering decision.

I bet they thought most people who would buy the leaf would never drive half the miles many are doing and wouldn't be an issue.

The problem is you are not quoting any facts or figures to back that up.

If Nissan are replacing a high percentage of their batteries I'd agree with you. Do you have details of their failure rate?

Of the few hundred thousand they have sold to date how many failed due to lack of cooling?

If you can't quote those figures you are just making it up.

If it were a major issue they wouldn't have increased the battery warranty from 5 to 8 years with the 30kWh battery.

Just look up the effects of heat on lithium batteries, Nissan don't have a magic battery.

Nissan won't release any figures to battery replacements, there are many leaf owners in the U.S with reduced capacity and expect to be out of warranty before it's at the point they're allowed claim. Some Mk I Leaf owners here have lost 1 bar after only 60 K Kms.

Do your own research about heat effects on Lithium batteries.

Boat_Mad will dispute it all as rubbish.

I expect if heat had no effect on the battery that Nissan wouldn't bother to cool the Env 200 battery.

I bet the current 24 Kwh improvement is more down to the current capability or C rate and higher cycling ability than heat resistance , so changes like that alone will improve battery life but doesn't mean it's less sensitive to heat.

KCross

Deleted User wrote: »

Just look up the effects of heat on lithium batteries, Nissan don't have a magic battery.

Nissan won't release any figures to battery replacements, there are many leaf owners in the U.S with reduced capacity and expect to be out of warranty before it's at the point they're allowed claim. Some Mk I Leaf owners here have lost 1 bar after only 60 K Kms.

Do your own research about heat effects on Lithium batteries.

Boat_Mad will dispute it all as rubbish.

I expect if heat had no effect on the battery that Nissan wouldn't bother to cool the Env 200 battery.

I bet the current 24 Kwh improvement is more down to the current capability or C rate and higher cycling ability than heat resistance , so changes like that alone will improve battery life but doesn't mean it's less sensitive to heat.

I'm not going to put myself forward as a battery expert but it seems you are taking some anecdotal evidence and attributing heat and lack of cooling as the sole cause without anything concrete to back it up. That makes me skeptical.

Maybe your right but without evidence it's just a theory.

The reason for the env200 cooling is obvious enough and already explained. Heat is a problem for Li, no argument from me there, and is dealt with in the LEAF by the BMS. The van needs more cooling and so it was added. That doesn't mean that the LEAF needs it.

As I said, if Nissan know there is a problem with lack of cooling in the LEAF why didn't they just add it. Why did they increase the warranty. Those are not the actions of a company covering things up.

Either they know more than you or they are stupid!

KCross

KCross wrote: »

I'm not going to put myself forward as a battery expert but it seems you are taking some anecdotal evidence and attributing heat and lack of cooling as the sole cause without anything concrete to back it up. That makes me skeptical.

Maybe your right but without evidence it's just a theory.

The reason for the env200 cooling is obvious enough and already explained. Heat is a problem for Li, no argument from me there, and is dealt with in the LEAF by the BMS. The van needs more cooling and so it was added. That doesn't mean that the LEAF needs it.

As I said, if Nissan know there is a problem with lack of cooling in the LEAF why didn't they just add it. Why did they increase the warranty. Those are not the actions of a company covering things up.

Either they know more than you or they are stupid!

Same battery in the van as in the Leaf, if heat was't an issue they wouldn't have gone to the trouble of cooling it but they did because they designed the chassis to accommodate the extra bulk of the cooling system, this isn't possible in the Leaf at this stage in it's production cycle. So they learned from the data coming in from the Leaf and it was a good idea to design the van from the start to have thermal management of the battery. (a good engineering decision)

The warranty was extended on the 30 Kwh, probably because it's a different chemistry and probably less prone to the effects of heating or they extended the cycle life so that any degradation from the effects of heating would be less noticeable (masked), the extra cycling life would extend the life of the battery alone. And saying this it's still not good practice to restrict fast charger output to prevent thermal runaway !

KCross

Deleted User wrote: »

Same battery in the van as in the Leaf, if heat was't an issue they wouldn't have gone to the trouble of cooling it but they did because they designed the chassis to accommodate the extra bulk of the cooling system, this isn't possible in the Leaf at this stage in it's production cycle. So they learned from the data coming in from the Leaf and it was a good idea to design the van from the start to have thermal management of the battery. (a good engineering decision)

The warranty was extended on the 30 Kwh, probably because it's a different chemistry and probably less prone to the effects of heating or they extended the cycle life so that any degradation from the effects of heating would be less noticeable (masked), the extra cycling life would extend the life of the battery alone. And saying this it's still not good practice to restrict fast charger output to prevent thermal runaway !

Unfortunately every word of that is just conjecture.

I wont disagree with your theories but I wont agree with them either because there is no substance behind them.

It just seems to me that a "normal" LEAF driver would rarely get the car into the red zone through everyday use. That being the case why would you need to add to the expense of the car by adding cooling?

Think about it... lets say they add the cooling... your car rarely, if ever, hits the red zone and so the cooling never kicks in.... what use was the cooling in that case and you have increased the car weight and price!

I drove the car across England and Wales in one day with multiple charges at full motorway speeds and I did not hit the red zone. Possible if I did one more rapid charge it would have hit red but thats an extreme case and not a "normal" day for a LEAF driver and the BMS would have protected the battery anyway.

A van driver would easily do 4+ rapid charges in a day and hence it needs the cooling. These are just simple basic observations that go against your conjecture. You seem to just make things up and put them out there as fact.

Yep , just making it up for a laugh................

Speaking of cooling, they also should have a battery heater to maintain the battery to an efficient level for charging and range, like most other EV makers but they couldn't do that because they can't cool it lol

KCross

Deleted User wrote: »

Yep , just making it up for a laugh................

Speaking of cooling, they also should have a battery heater to maintain the battery to an efficient level for charging and range, like most other EV makers but they couldn't do that because they can't cool it lol

Another trade off. The car is for the mass market so the costs have to be kept down.

As I understand it, the LEAF can be bought with a battery heater for the very cold climates.

I think we agree that if they had heating and cooling it would be more efficient. The issue is that that efficiency costs money and increases the cost of the car. Not enough people are buying it now so increasing the costs isnt going to help.

Your cooling might come with the larger batteries... although a larger battery would mean less rapid charging so maybe cooling wont be required there either? We'll see what the engineers think!

Those engineers reputation has been already damaged by first stating the battery needed no cooling in all climates to then having to replace several batteries even Elon Musk said that was a mistake.

The larger battery that was demonstrated also has no form of cooling. And I would assume the battery is being tested already.

This battery may not get nearly as warm through driving and fast charging because the battery will have much more Kwh and will naturally be capable of pulling much larger currents and taking them too which would greatly reduce heating so this battery might actually not need cooling at all simply because it may not warm up enough however, the battery will most likely be capable of fast charging at 100+ Kw due to this natural ability to take much larger currents and charging at this power level might cause it to heat up but at 45 Kw probably not.

All leafs from the updated July + 2013 built have a battery heater which turns on at -17 and off at -10 deg C to prevent permanent damage to the battery, just like in the red zone it limited fast charge power so the battery won't reach thermal runaway and kill it. But normally the battery shouldn't be allowed near these levels of extremes in the first place.

Cost was a limiting factor in the Leafs design but reputation is also important, compromises had to be made and I'm not saying the Leaf is a bad car , it certainly isn't and I love it. Gen II will be a lot better.

BoatMad

Deleted User wrote: »

No, good engineering is cooling the pack, not cooling it is a bad management decision not a good engineering decision.

I bet they thought most people who would buy the leaf would never drive half the miles many are doing and wouldn't be an issue.

You persist in presenting opinions that are simple statements without any backup logic or facts

FACT 1 . IN normal driving and slow charging nissan battery remains in a reasonable static state as regards temperature, the passive cooling copes with heat generated from discharge

This clearly works, in the vast majority of situations , except certain " edge " cases , where ambients are very high


FACT 2 : There is heat gain while DCQC occurs , There are no statistically relevant or verified data to correlate thermal cycling with abnormal degradation for Nissan batteries . We simply have no real data

FACT3: we know the BMS throttles DCQC charging to control heat gain

The evidence is some very good engineering is being practiced . Nissan clearly feel that the operating envelope of the Leaf is within the cooling ability of the passive system.

There is no evidence to suggest anything otherwise . If such evidence in time appears and is consistent and quantitive and shows there is a problem , leading to abnormal degradation, that I shall be quite happy to agree that Nissan goofed.

At this juncture there is no such evidence

Give me a Bucket, I want to puke after reading that, and to think I was called a Nissan leaf fan boy in the regular motors section !

yqtwqxqm

Well heres one for you.
I had the car on a fast charge yesterday. Went from 11% to 85%.
At 65% the battery heat bars actually went down from 6 to 5.
And it was a proper fast charger too. Not one of those dreadfully slow fast chargers like the one at Glasnevin.

BoatMad

I can add can add sone more experiences

On Saturday I went Waterford cork , Waterford , wexford, Gorey

It was a warn day , car was slow charged first. 5 bars by cork , two bars added at FCP cork, and two bars added at Nissan dungsrvan

But driving at 90 kmph , this was down to 7 bars by Waterford and 6 bars by wexford

This suggests that certainly in Irish typical ambient the passive cooling works quite well. The battery doesn't stay at elevated temperatures for two long.

When I checked in Waterford the battery temp bars only reduced down to 7 on switch off /switch on and not while driving

KCross

BoatMad wrote: »

I can add can add sone more experiences

On Saturday I went Waterford cork , Waterford , wexford, Gorey

It was a warn day , car was slow charged first. 5 bars by cork , two bars added at FCP cork, and two bars added at Nissan dungsrvan

But driving at 90 kmph , this was down to 7 bars by Waterford and 6 bars by wexford

This suggests that certainly in Irish typical ambient the passive cooling works quite well. The battery doesn't stay at elevated temperatures for two long.

When I checked in Waterford the battery temp bars only reduced down to 7 on switch off /switch on and not while driving

As a matter of interest, as you drive does the air flow directly over/under/around the battery or is it insulated and just giving off heat into the atmosphere? Or do you know?

i.e. How does the passive cooling actually work?

BoatMad

KCross wrote: »

As a matter of interest, as you drive does the air flow directly over/under/around the battery or is it insulated and just giving off heat into the atmosphere? Or do you know?

i.e. How does the passive cooling actually work?

From the you tube video it's just passive air flow around the bottom of the pack

BoatMad

Well generated 9 bars today after fcping in Carlow , had been driving like a bit of a lunatic up to then. So I'd say thermal lag caused some extra heat buildup while charging

Went back to 7 as I drove more sedately after !!!