LR battery efficiency.

[AndyL61]

I have a Trophy and being tight try to get the most out of my quids worth of kWh. The NMC battery is more energy dense the higher the SOC. So you get more m/kWh the higher the SOC. So for the best m/kWh use the top end of the SOC and recharge before it gets low (less than 50%). Biggest problem with this is if you only charge to 80% for battery health you are charging a lot more often. Told you I was tight !

 

[Derek25]

I have a Trophy and being tight try to get the most out of my quids worth of kWh. The NMC battery is more energy dense the higher the SOC. So you get more m/kWh the higher the SOC. So for the best m/kWh use the top end of the SOC and recharge before it gets low (less than 50%). Biggest problem with this is if you only charge to 80% for battery health you are charging a lot more often. Told you I was tight !

Where's the evidence for getting more miles/kWh at different states of charge?

 

[johnb80]

I have a Trophy and being tight try to get the most out of my quids worth of kWh. The NMC battery is more energy dense the higher the SOC. So you get more m/kWh the higher the SOC. So for the best m/kWh use the top end of the SOC and recharge before it gets low (less than 50%). Biggest problem with this is if you only charge to 80% for battery health you are charging a lot more often. Told you I was tight !

If youre really tight you should be aware that a fully charged battery is heavier !

 

[AndyL61]

Where's the evidence for getting more miles/kWh at different states of charge?

It's more energy dense at higher SOC, it's a characteristic of the battery chemistry.

 

[GaryMG4]

Id have thought that 1kwh would give you a certain number of miles regardless of the SOC. I'd also suggest that you will spend more time on charge if you charge to 100% all the time as the rate really slows down at that level. I do believe that a 50% SOC is less than 50% of the actual capacity.

 

[AndyL61]

Id have thought that 1kwh would give you a certain number of miles regardless of the SOC. I'd also suggest that you will spend more time on charge if you charge to 100% all the time as the rate really slows down at that level. I do believe that a 50% SOC is less than 50% of the actual capacity.

It only slows down on a rapid CCS , on a home EVSE it is slow anyway.

 

[Themist0]

At 2.5p per mile (overnight on intelligent octopus) then I’m not worried about saving a few pence each journey, especially coming from a landy disco at 25p per mile (not to mention the £695 car tax)…

 

[AndyL61]

Yeah that's a fair point. I'm on standard 30p /Kw.

 

[Jomarkh]

At 2.5p per KWh (overnight on intelligent octopus) then I’m not worried about saving a few pence each journey, especially coming from a landy disco at 25p per mile (not to mention the £695 car tax)…

What part of the UK are you in to get IO at 2.5p/kWh?

 

[Rolfe]

No, me neither.

 

[johnb80]

At 2.5p per KWh (overnight on intelligent octopus) then I’m not worried about saving a few pence each journey, especially coming from a landy disco at 25p per mile (not to mention the £695 car tax)…

I think you will find it's 7.5p per kWh surely?

 

[Derek25]

It's more energy dense at higher SOC, it's a characteristic of the battery chemistry.

Where's the evidence that more energy density gives you more miles/kWh?

 

[Themist0]

What part of the UK are you in to get IO at 2.5p/kWh?

Sorry I meant 2.5 p per mile.. on 7.5p taffiff overnight.. I’ll correct it

I think you will find it's 7.5p per kWh surely?

Correct and stop calling me Shirley

 

[AndyL61]

Where's the evidence that more energy density gives you more miles/kWh?

Well I've noticed it myself and also a YouTube video of range test at 70 mph confirmed that the top 50% returned more miles than the last 50% . It makes sense because the voltage reduces as the SOC reduces with NMC batteries .

 

[GaryMG4]

I think you'll find that the relationship between SOC and kwh is not linear. So it would take say 25kwh to get from 0 to 50% and 35kwh to get from 50 to 100%.

 

[johnb80]

Well I've noticed it myself and also a YouTube video of range test at 70 mph confirmed that the top 50% returned more miles than the last 50% . It makes sense because the voltage reduces as the SOC reduces with NMC batteries .

Doing a very quick calculation based on voltage to charge, the bottom 50% has 14% less storage in it in terms of kWh.

 

[johnb80]

It only slows down on a rapid CCS , on a home EVSE it is slow anyway.

Whilst it is slower, it does also slow down dramatically as you approach full charge

 

[Derek25]

Well I've noticed it myself and also a YouTube video of range test at 70 mph confirmed that the top 50% returned more miles than the last 50% . It makes sense because the voltage reduces as the SOC reduces with NMC batteries .

1 kWh is1 kWh whatever the density of the battery. What you're seeing is probably variations in the battery management system's reading of the battery's capacity.

 

[johnb80]

1 kWh is1 kWh whatever the density of the battery. What you're seeing is probably variations in the battery management system's reading of the battery's capacity.

This is true BUT batteries arent rated in kWh they have Amp/Hr capacities. The voltage between fully charged and 0% drops significantly so the lower half has a lower terminal voltage average than the upper half. This of course means that the average voltage is lower in the bottom 50% of it's amp hr capacity and therefore the KWh storage is also lower.

 

[siteguru]

The SE SR has an LFP pack which maintains a fairly constant voltage across most of the capacity range. Therefore I'd assume that the energy density of the SR is much more uniform.