RunningMan:

 

- ask anyone with a really worn out early gen Leaf.

 

Hi!

I think my future BEV selection will be limited to those with LFP batteries. I want to be able to 100% charge, every time I have time, I want minimum degradation and and I want maximum safety.

Am I wrong?

johno1234:

 

I think my future BEV selection will be limited to those with LFP batteries. I want to be able to 100% charge, every time I have time, I want minimum degradation and and I want maximum safety.

 

Am I wrong?

 

 

 

IMO, yes, it is wrong to be limited to LFP batteries only. You will very rarely get a chance to charge to 100% on a DC charger as last 20% take a long time and there is etiquette around EV chargers to only charge up to 80%. Depending on your charging habits at home and how long can you leave it on charge before you need to take the EV again, if it's not 100% charged then LFP calibration may suffer. Saying that modern BMS are great. 

There are hundreds and thousands of NMC battery EV's running on roads without catching fires. Quality of cells, BMS and EVSE plays a big part in catching fire with NMC. NMC has the benefit that you can charge up to 80% and should only be charged to 100% when planning a long trip few hours before hand. 

johno1234:

 

I think my future BEV selection will be limited to those with LFP batteries. I want to be able to 100% charge, every time I have time, I want minimum degradation and and I want maximum safety.

 

Am I wrong?

 

 

 

johno1234:

 

I think my future BEV selection will be limited to those with LFP batteries. I want to be able to 100% charge, every time I have time, I want minimum degradation and and I want maximum safety.

 

Am I wrong?

 

 

 

Personally, with current technology, I agree. The range available from LFP battery cars is perfectly adequate, and they tick all my other boxes: long life, low cost, free from elements that are rare or with potentially dubious human rights records. Something better will come along in future for sure. But for today, I'm with you: I would only buy an LFP car.

SaltyNZ:

 

Batman:

Above what kW charging would give battery damage?

Ie below what kW charging is happy for battery

 

 

 

It's not directly related to kW, it's related to C, which in turn relates kW to battery size. I seem to remember reading somewhere that around 0.2C was the optimum rate to balance quick charging (because while you're charging you're stressing the battery by running it in reverse, so you want that time to be short) against slow charging (because higher current stresses the battery more, and generates more heat which must be dispersed).

 

thanks, what is C ?

serious question. don't want to kill my battery ...

DS248:

 

Worth a quick read; eg. no, the power grid has not collapsed under the weight of ev charging, and no mass unemployment of gas station workers

 

In Norway, the Electric Vehicle Future Has Already Arrived

 

And worth noting at the end:  “We do see it as an opportunity,” Hakon Stiksrud, Circle K's head of global e-mobility, said of electric vehicles. “But if we are not capable of grasping those opportunities, it quickly becomes a threat.”

 

Norway funds their EV infrastructure with oil money, we haven't got oil money to burn

Batman:

 

thanks, what is C ?

It's the charge rate of a battery. C=1 means the battery charges to 100% in 1 hour i.e. a 100 kWh battery being charged at 100 kW.

If you charge that 100 kWh battery at C = 0.2 (so 20 kW) then it will take 5 hours.

So C depends on the battery capacity and the charger power, not just the charger power. Charging a 250 kWh battery at 50 kW is trivial, but push the same power into a 24 kWh battery (old Leaf) and things get interesting.

There's a few different notations used around the place though - C=0.2 is the same as C/5.

RunningMan:

 

Batman:

 

thanks, what is C ?

 

It's the charge rate of a battery. C=1 means the battery charges to 100% in 1 hour i.e. a 100 kWh battery being charged at 100 kW.

 

If you charge that 100 kWh battery at C = 0.2 (so 20 kW) then it will take 5 hours.

 

So C depends on the battery capacity and the charger power, not just the charger power. Charging a 250 kWh battery at 50 kW is trivial, but push the same power into a 24 kWh battery (old Leaf) and things get interesting.

 

There's a few different notations used around the place though - C=0.2 is the same as C/5.

 

thanks

so for now, C of 0.2 aka C/5 until i hear of something else

my leaf seems to charge at 0.1 or 1/10

SaltyNZ:

 

It's not directly related to kW, it's related to C, which in turn relates kW to battery size. I seem to remember reading somewhere that around 0.2C was the optimum rate to balance quick charging (because while you're charging you're stressing the battery by running it in reverse, so you want that time to be short) against slow charging (because higher current stresses the battery more, and generates more heat which must be dispersed).

 

wait ... that means 5 hours of waiting at the charging station!

Batman:

 

my leaf seems to charge at 0.1 or 1/10

 

On AC, but will be different on DC - closer to 1.

Batman:

 

wait ... that means 5 hours of waiting at the charging station!

 

Yep, that's exactly the point being made. Slower is better for long term longevity, but it's a balance with convenience.

Batman:

 

SaltyNZ:

 

It's not directly related to kW, it's related to C, which in turn relates kW to battery size. I seem to remember reading somewhere that around 0.2C was the optimum rate to balance quick charging (because while you're charging you're stressing the battery by running it in reverse, so you want that time to be short) against slow charging (because higher current stresses the battery more, and generates more heat which must be dispersed).

 

 

wait ... that means 5 hours of waiting at the charging station!

 

1/ You're not ever going to arrive at a charging opportunity at 0% SOC, unless you've seriously misjudged something in your charging plan.

2/ Unless you're planning on using AC charging opportunities (like the free ones at stores) your minimum charge rate is more likely to be 50kW.

Your home charging is most likely to be near 0.1C (7kW/70kWh) but charge time is typically overnight in that case so charge duration isn't really an issue.

So it sounds like, at least at this stage, electric vehicles aren't really that practical if you can't charge at home?

alasta:

 

So it sounds like, at least at this stage, electric vehicles aren't really that practical if you can't charge at home?

 

I believe so.

You lose a big chunk of the cost saving due to the inflated electricity price (those charging stations cost money to build and the owners expect a return on their investment). You don't want to be hanging around on them either so charge as fast as you can which is not ideal for the battery life. Home charging is the cheapest especially overnight when you can gently charge over 8 hours or so.

World BEV Sales Now 12% Of World Auto Sales