[donald]

I reached a point of beginning to accept the Zoe's odd transmission noises. ( Zoe transmission noise, sounds bad, probably have to go... )

So I figured I'd better check out what it is like with charging, having not charged it yet (no need).

Firstly, they clearly haven't fixed all those high pitched noises during charging;

Still the high pitched noises at 10kHz and there is now also a steady whine at ~1500Hz.

Moving on to the charging.

After 7hr15min the car has gone from 4% to 89%.

Assuming the car has taken on 85% of 50kWh, that'd be 42.5kWh.

But after 7.25hrs it has consumed 53.7kWh. This makes the overall charging efficiency about 79%. If the battery were to actually be 52kWh (i.e. 85% of a usable 52kWh) that'd be a slightly better 82%, or if 48kWh usable, as seems more fitting, that'd be 76%.

All pretty bad numbers.

Why?

Well, I wasn't expecting that it'd run the AC on 7kW charging, for sure.

This causes the charge rate to cycle up and down between 6.4kW and 7.4kW at times.

A charge rate of 6.4kW x 7.25hrs = 46.4kWh, so if the car has taken on 42.5kWh then the actual battery efficiency is 91%, which is perfectly respectable. But it means the AC cooling has consumed 7.3kWh all on its own.

The ambient has been 12C overnight.

I guess because the battery is so dense, a much more voluminous lump of mass with smaller and fewer cooling routes possible for such a cell density, it has been designed to have almost continuous cooling at 7kW?

I can't say I noticed the battery cooling whilst it was discharging at considerably higher rates, though. Seems like overkill to me to extend its theoretical lifetime, and a pretty considerable cost to the user.

So, Zoe's charging efficiency is around 76% to 82%, and one possible interpretation is that about 15% of the total input gets spend on cooling alone.

(These numbers are based on the one charge I have made so far, which is in progress now.)

If the charger is dumping about 1.5kW into the car that doesn't end up in the battery, this sounds like it could escalate considerably if the car is charged in a hot garage, in summer. The hotter the garage gets, the more power the AC draws which then heats the garage up further. It's one thing to cool the car a lot to help the battery (to save warranty issues, but at the client's cost), but have they thought about what happens in a confined garage space?

 

[cah197]

If the charger is dumping about 1.5kW into the car that doesn't end up in the battery, this sounds like it could escalate considerably if the car is charged in a hot garage, in summer. The hotter the garage gets, the more power the AC draws which then heats the garage up further. It's one thing to cool the car a lot to help the battery (to save warranty issues, but at the client's cost), but have they thought about what happens in a confined garage space?

I did a full charge in my garage last night and haven’t noticed the ambient air being any warmer.

Have you handed the car back yet?

 

[MrMoonUK]

Your calculations are flawed, as the battery is bigger than 52kwh it’s probably nearer to 56kwh but no one knows what the buffer is yet! 4-89% is not 42.5kwh.

Charging is about 90% efficient at 7kw just like the last model as it’s exactly the same charging gear for AC. I very much doubt the battery cooling kicked in, you would hear it and at 7kw the only time on my old zoe I heard the cooking was after a long drive and an ambient of 30c.

the harmonic resonance is due to using the motor windings to covert AC to DC, again same as last model. Yes it’s weird and annoying but that’s what you get for buying a Renault Zoe, think of it as a unique feature 😂

as in your other thread the transmission noises are normal. You should hear my model X at foot to floor, windows open, if you hate the noises lol

 

[electricdriver]

Wow - that sounds pretty bad. I've done some (fairly limited) work on 7kW ac charging on my (otherwise embarrassingly inefficient) bloatmobile - biggest single charge was from 4% to 100% which should give a reasonable view of efficiency. The answer for this, and other, charges, is a relatively consistent 93%. Seems reasonable, I'd certainly feel aggrieved at anything much lower.

 

[MrMoonUK]

Wow - that sounds pretty bad. I've done some (fairly limited) work on 7kW ac charging on my (otherwise embarrassingly inefficient) bloatmobile - biggest single charge was from 4% to 100% which should give a reasonable view of efficiency. The answer for this, and other, charges, is a relatively consistent 93%. Seems reasonable, I'd certainly feel aggrieved at anything much lower.

It Sounds bad cos his maths is way off 😂

 

[cah197]

Your calculations are flawed, as the battery is bigger than 52kwh it’s probably nearer to 56kwh but no one knows what the buffer is yet! 4-89% is not 42.5kwh.

Well obviously you never charge up the ‘buffer’.

Current best calculations for usable (i.e. chargeable) capacity are just under 51 kWh, factoring in HVAC usage.

So 43.3 kWh.

@donald is referring to the fans running whilst charging, using additional power. I’m not sure if it’s the HVAC running.

 

[electricdriver]

It Sounds bad cos his maths is way off 😂

As @cah197 says - the buffer never gets charged / discharged in use, and the car doesn't report it. Don't think there's anything wrong with @donald's sums unless we've all misunderstood how the BMS handles capacity.

 

[donald]

I am just watching the power gauge now and it seems to float at just over 6.4kW then the power slowly increases by 100W or so, then another 100W, then a jump to 6.8kW then to 7.0kW, and then sometimes to 7.4kW. This is in the time frame of a few minutes.

I would tend to suspect there is a 100W or so of fan running all the time, perfectly expected, and if the exhaust temperature is high what I am seeing there is the AC cutting in to maintain the temp.

Based on that profile, I'd give a broad-brush estimate that the cooling overhead is around 300 to 500W, let's say 400W for an estimate.

So, over 7.25hrs that'd be, say, 3kWh so the total 'battery charge in' would be 50.7kW for an effective usable charge of 42.5kW. That'd be ~85% efficiency into the battery cells, which is about what the Kia Soul achieves.

So I think I am concluding about 85% cell-charging efficiency and 400~500W cooling.

This is assuming 50kWh usable and the SOC gauge is linear.

 

[donald]

It Sounds bad cos his maths is way off 😂

Iz a Diophantine equation, innit, so you might be right.

 

[cah197]

On my 6 hour drive I worked out that HVAC could be using up to 4.5 kWh. So it’s likely that on a single charge session the cooling system could be using quite a bit of power.

 

[donald]

Your calculations are flawed, as the battery is bigger than 52kwh it’s probably nearer to 56kwh but no one knows what the buffer is yet! 4-89% is not 42.5kwh.

I am not calculating a buffer, and the SOC meter doesn't show a buffer. What is the buffer got to do with it?

My stated assumption is that 0% to 100% is 50kWh usable. My sample charge was 85% of that.

Charging is about 90% efficient at 7kw just like the last model

You show me your numbers, I've shown you mine.

the harmonic resonance is due to using the motor windings to covert AC to DC, again same as last model. Yes it’s weird and annoying but that’s what you get for buying a Renault Zoe, think of it as a unique feature 😂

I know what it is, you'd imagine they might have made improvements?

as in your other thread the transmission noises are normal. You should hear my model X at foot to floor, windows open, if you hate the noises lol

They are not remotely normal.

These are not noises that occur under load, as you suggest there. They are a second set of gear noises, in addition to the usual reduction box noises, but only occur around 0kW. Above 10kW or so they are never heard.

It is gear lash on a high speed gear. I know exactly what it is (to 95% confidence).

 

[donald]

Balancing took around 20 minutes after dropping from max power, which is pretty normal for Renault/Nissan in my experience.

(FWIW, I never saw any cell balancing in the Soul, it'd drop from 6.2kW to 5.5kW for 2 or 3 minute, then straight to 0kW.)

Total energy consumed to go from 4% to 100%; 63.2kWh. About 76% efficiency assuming that charge has made 48kWh (96% x 50kWh) available to me for use.

 

[srichards]

It's annoying they haven't sorted out the high pitched squealing . It's so nice having the Leaf that is silent and isn't making half the things in the house squeal along.

 

[proddick]

My stated assumption is that 0% to 100% is 50kWh usable

From the Norwegian winter test we know that there is quite a bit left at 0%. Even in winter they drove 30km after it got to zero. Probably do 50km in summer!

 

[donald]

From the Norwegian winter test we know that there is quite a bit left at 0%. Even in winter they drove 30km after it got to zero. Probably do 50km in summer!

But that is not part of the 50kWh usable I am assuming 0 to 100%.

The only question is the total usable capacity 0 to 100%.

It doesn't matter what is below 0% if I neither use it nor recharge it.

 

[proddick]

But that is not part of the 50kWh usable I am assuming 0 to 100%.

But 0% to 100% isn't 50kWh, it is quite a bit less. Usable capacity is to empty - when car stops and Norwegian report measured it at 51KWh.

 

[cah197]

But 0% to 100% isn't 50kWh, it is quite a bit less. Usable capacity is to empty - when car stops and Norwegian report measured it at 51KWh.

Bear in mind the HVAC usage isn’t included in the cars consumption estimate, so it will underestimate in cold weather. This is what caught me out as the HVAC can use quite a bit of power over the range of the car.

Although I haven’t done a full range test in warm weather with HVAC off all the way, initial indication is it has got 50.9 kWh usable to 0% SOC with another 1 kWh of reserve till it dies. Which would equate to 52 kWh usable.

 

[donald]

But 0% to 100% isn't 50kWh, it is quite a bit less. Usable capacity is to empty - when car stops and Norwegian report measured it at 51KWh.

Less makes the figures even worse.

If it is 46kWh from 0% to 100%, then the efficiency drops further to (46 * 0.96)/63.2 = 69%

I don't want to imagine the car is that badly inefficient. Please don't tell me that, I would be even less inclined to keep it.

 

[BogieMan]

How have you measured the energy ?

The BMS is managing the battery and there must be some kind of learning that goes on in the first few charges and discharges as the BMS gets to know the battery characteristics.
The BMS also has to decide on the battery SOC, it is all algorithms. There is also balancing that is wasteful which may be greater on first charge.
Effectively you're very reliant on what the car BMS tells you.

Simplistically you can measure or estimate the energy that goes into the car and how many miles it goes, but everything else is plucked from the BMS.

Even with mileage you are dependant on the odometer accuracy.
I ran many Montegos, petrol and diesel, and the diesel mpg was amazing. However, after some months I did notice the mileage to work was about 2 miles further in the diesel compared to the petrol. I reckon that crafty Austin Rover jigged their odometers in the diesel to over read so when you did the mpg calculations you were overjoyed !

 

[proddick]

Less makes the figures even worse.

If it is 46kWh from 0% to 100%, then the efficiency drops further to (46 * 0.96)/63.2 = 69%

I don't want to imagine the car is that badly inefficient. Please don't tell me that, I would be even less inclined to keep it.

Yeah sorry about that. I doubt the ZE50 is much different to earlier models as the approach used to charge hasn't changed. The attached report is where I found just how dreadful a Zoe is on the granny charger and why people really, really shouldn't use it as a regular means of charging. It doesn't list 32A single phase, but I guess similar to 3 phase at 65%