low charging rate

[james]

Hi, new to ev's. I'm using public charging, usually turn up with 20 miles remaining. dc rapid charge about an hour, never acheived 80% charge. one time left for 1.5 hours and only added 30 miles range in total. tried ac rapid , left for 1hour 15mins and gained 45 miles. is it the car?

 

[teepee]

Welcome.
On ac rapid the MG will only charge at 7kw (20 - 30 miles) max per hour so not worth using that one. But on DC it should achieve up to 80 kw per hour depending on the charger.

 

[teepee]

In cold weather though it could be slower.

 

[james]

Hi, thanks for taking the time to respond. It looks like it is what it is then.

 

[teepee]

Which DC rapid chargers are you using?

Some of the older Polar chargers, although advertising 50 kw per hour, can sometimes only achieve about 20 kw per hour (60 ish miles or so)

 

[james]

Which DC rapid chargers are you using?

Some of the older Polar chargers, although advertising 50 kw per hour, can sometimes only achieve about 20 kw per hour (60 ish miles or so)

Hi it is a recent installation run by swarco econnect, 50kw dc and 45kw ac. On a side note, the third visit, I have had six sessions in total, I was hooked up to dc plug. I left it on charge and returned 50 mins later to find I had only gained 30 miles and that the plug would not release.

 

[teepee]

Mmm, doesn't sound too good. If your car is quite empty, a new installation should be getting up towards the advertised 50kw per hour (150 ish miles per hour) - less a bit for cold weather. Haven't used swarco before.

Although if I look back at all my 50kw rapid charging the best I've ever achievd was 37 kw per hour (Pod point and Polar) with an all time low of 14 kw per hour (Ecotricity)

 

[Jake]

Hi, new to ev's. I'm using public charging, usually turn up with 20 miles remaining. dc rapid charge about an hour, never acheived 80% charge. one time left for 1.5 hours and only added 30 miles range in total. tried ac rapid , left for 1hour 15mins and gained 45 miles. is it the car?

Are you sure which connector is which? 1hour 15mins on AC Type 2 will only get you about 35-40 miles at most. Using CCS (DC) connector from a range of 20 miles should add around 50+ miles in 20 mins or so at 36kWh rate and pro-rata up to 80% when the rate will start to tail off.

 

[Kithmo]

Are you sure which connector is which? 1hour 15mins on AC Type 2 will only get you about 35-40 miles at most. Using CCS (DC) connector from a range of 20 miles should add around 50+ miles in 20 mins or so at 36kWh rate and pro-rata up to 80% when the rate will start to tail off.

He'll only get 25-26 miles on AC at 7kWh in 1 hour 15 mins.

 

[Deleted member 2439]

Hi,

We tried using a couple of InstaVolt chargers today, one which was closest to us and then another which would be a cure for range anxiety on the way to/from our sons down south.

The experience was easy enough - with card swiped and charging then commencing. In both cases the car had about 40% charge - so we only charged for 10 mins or so it wasn’t needed and I couldn’t see the logic in filling up @ 35p per kWh as opposed to the 12.5 or so at home.

When we finished the first session the charge rate was only 21 kW, at the end of the second session an hour or so later the rate was 31kW. In both cases slower than the headline 50kW rate which should have been available. The temp was about 3 degrees c in each case, could this have been the reason for the slow charge rate possibl?

Also, in each case they took a £5.00 pre-auth from my card, with the end price being much less than that. I can see both pre-auths on line and I’m assuming/hoping that the final debited amount will be the lesser amount.

Any comments chaps?

Finally, my GOM when I got home from the round trip was 16 miles, so it looks like I actually needed those charges after all! The cars now happily filling it‘s boots on the Zappi at 7kW.

Thanks - Rob

 

[Deleted member 2439]

He'll only get 25-26 miles on AC at 7kWh in 1 hour 15 mins.

You mean 7kW, that’s the RATE of charge, 8.75 kWh would be the amount of energy extracted from a 7kW charger in 1h 15m.

Sorry if this sounds pedantic, it’s not supposed to, hopefully if we can get these units sorted out early in our EV ownership then that will keep the electrical engineers and pedants amongst us happy - as well as being accurate.

?

 

[Kithmo]

You mean 7kW, that’s the RATE of charge, 8.75 kWh would be the amount of energy extracted from a 7kW charger in 1h 15m.

Sorry if this sounds pedantic, it’s not supposed to, hopefully if we can get these units sorted out early in our EV ownership then that will keep the electrical engineers and pedants amongst us happy - as well as being accurate.

?

I'm just basing my figures on actual real world experience of charging at Tescos 7kWh chargers.
I get about 20 miles/hour, so 1.25hrs x 20miles = 25miles no miles/kw theory involved.
It might stretch to 27-28 miles in warm weather when it goes up to about 22 miles/hour.

 

[Noraf142]

Any comments chaps?

Thanks - Rob

If the first rapid is close by in driving time, the battery pack might not have come up to ideal temperature, witch will result in slower charge while it heats up.

Outside temperature does affect charging rates.

 

[Jake]

I'm just basing my figures on actual real world experience of charging at Tescos 7kWh chargers.
I get about 20 miles/hour, so 1.25hrs x 20miles = 25miles no miles/kw theory involved.
It might stretch to 27-28 miles in warm weather when it goes up to about 22 miles/hour.

My average miles/kW = 4.2 . As Lincs Robert pointed out 1.25 hours charging at a rate of 7kW/hour = 8.75kW gained. 8.75 x 4.2 = 36.75 miles which is what I based my statement of "35-40 miles at most".

 

[james]

Date	Duration	Site	Type	Status	kWh	Cost
2020-12-28 10:35:25	1:13:19	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	8.46	£2.54
2020-12-18 11:13:32	0:47:43	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	27.01	£8.10
2020-12-11 10:30:58	0:47:45	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	28.36	£8.51
2020-12-02 10:14:02	0:00:00	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	12.93	£3.88
2020-11-16 13:40:49	0:50:41	Marketplace Car Park Swaffham - Norfolk	Rapid	Paid	31.08	£9.32
2020-11-03 13:53:54	0:45:14	Marketplace Car Park Swaffham - Norfolk	Rapid	Paid	22.53	£6.76

 

[Deleted member 2439]

If the first rapid is close by in driving time, the battery pack might not have come up to ideal temperature, witch will result in slower charge while it heats up.

Outside temperature does affect charging rates.

It was a 30 min drive away .......

 

[Jake]

Date	Duration	Site	Type	Status	kWh	Cost
2020-12-28 10:35:25	1:13:19	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	8.46	£2.54
2020-12-18 11:13:32	0:47:43	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	27.01	£8.10
2020-12-11 10:30:58	0:47:45	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	28.36	£8.51
2020-12-02 10:14:02	0:00:00	Marketplace Car Park Swaffham - Norfolk	Rapid	Unpaid	12.93	£3.88
2020-11-16 13:40:49	0:50:41	Marketplace Car Park Swaffham - Norfolk	Rapid	Paid	31.08	£9.32
2020-11-03 13:53:54	0:45:14	Marketplace Car Park Swaffham - Norfolk	Rapid	Paid	22.53	£6.76

Up until 28th December looks like you were getting 30-36kW/hour charge rate. Could it be on the 28th it stopped charging after 15 minutes?

 

[Deleted member 2439]

I'm just basing my figures on actual real world experience of charging at Tescos 7kWh chargers.
I get about 20 miles/hour, so 1.25hrs x 20miles = 25miles no miles/kw theory involved.
It might stretch to 27-28 miles in warm weather when it goes up to about 22 miles/hour.

Hi, my point is being missed.

Tesco’s charger are 7kW chargers, not 7kWh chargers.
A kW is not the same thing as a kWh. That is the point I’m making, which, from an engineering or energy perspective is a key distinction.
A kW is a unit of power, a kWh is a unit of energy. I agree with the numerical aspect of your comments, but disagree with the units being quoted - for the reasons explained.

It’s a simple and innocent enough error, but on an EV forum we need to be getting these things correct - it’s the sort of error akin to people talking about their broadband speeds in MegaBytes per second - WRONG, it’s megabits per second.
My motivation here is not to tease, simply to point out that electrical engineering terms are being incorrectly applied.

Cheers - Rob

 

[Deleted member 2439]

My average miles/kW = 4.2 . As Lincs Robert pointed out 1.25 hours charging at a rate of 7kW/hour = 8.75kW gained. 8.75 x 4.2 = 36.75 miles which is what I based my statement of "35-40 miles at most".

That’s a really good rate, how long is that over? Ours is barely at 3, mind you, we have only had the car a week and had the heater on max every time it’s been used as the outside temp has barely risen above 3 degrees ?

 

[Jake]

That’s a really good rate, how long is that over? Ours is barely at 3, mind you, we have only had the car a week and had the heater on max every time it’s been used as the outside temp has barely risen above 3 degrees ?

4.2 was the average for the last 200 miles or so whilst using some of Mark H techniques to achieve a better miles/kW. I won't be driving that efficiently now the temperature has dropped. My overall average from new is 3.9 over 1800 miles.