Choice between DC rapid charge or AC fast charge

[i7fan]

In the UK at the Ecotricity public charge points there is a type 2 connector delivering AC fast charge (22 kW) and a CCS connector delivering DC rapid charge (50 kW). Obviously the latter is much faster. However, if time is not so important, would it be better for long term battery life to use the slower option?

 

[elptex]

No difference. Just charge it in whatever way is most convenient. You can find many reports and studies online that have now demonstrated that DC rapid charge is not really detrimental. BMW has given no specific guidance on charging because there isn't any to be had. Their only guidance is battery state if left unused for long periods of time.

Enjoy the car, you don't have to think/worry about it

 

[cove3]

Everything I've read says to use DC rapid charging sparingly. The e-Golf manual says to avoid consecutive uses of it, using Level 1 or 2 between. Given my understanding, I'm still puzzled by the cavalier use of Tesla's high speed charging stations, for example on cross country trips, as though DC charging should be the norm, not the exception.

I'm thinking Tesla could be headed for battery warranty problems down the road.

Ron

 

[elptex]

@above post ^

Read everything from the last 6 months. Anything prior to that is old news. Battery technology is both quickly evolving and misunderstood. Most recently, Nissan released information on the Leaf about DC quick charger, showing statistically no difference in battery life over a 3 year period between Leafs that charged exclusively via L2 and L3. And the Leaf doesn't have the active temperature management systems that the i3 does.

 

[mindmachine]

In the UK at the Ecotricity public charge points there is a type 2 connector delivering AC fast charge (22 kW) and a CCS connector delivering DC rapid charge (50 kW). Obviously the latter is much faster. However, if time is not so important, would it be better for long term battery life to use the slower option?

AC fast charge with type 2 connector will only charge at 7.4 kwh due to the fact that the on board chargers are limited to 7.4 kwh. There are two chargers rated at 3.6 kwh each, the MLE and KLE. The DC rapid charging is DC direct and does not need an on board conversion/charger from AC to DC and that is why you can charge faster with the DC. The DC rapid charger I believe is actually considered to be a Type 3 connector.

 

[WoodlandHills]

Everything I've read says to use DC rapid charging sparingly. The e-Golf manual says to avoid consecutive uses of it, using Level 1 or 2 between. Given my understanding, I'm still puzzled by the cavalier use of Tesla's high speed charging stations, for example on cross country trips, as though DC charging should be the norm, not the exception.

I'm thinking Tesla could be headed for battery warranty problems down the road.

Ron

I keep asking this, but you never answer: what EV do you own? And what does the eGolf manual instructions have to do with an i3? A Jetta and a M4 both use gasoline, but crossing the manuals won't tell you much useful about either car.......

 

[pdurham]

Though I'm by no means a battery expert, based on information online, there does appear to be growing evidence to the effect that DC rapid charging is not as harmful as once thought, or perhaps even not harmful at all, to long-term battery life. To be fair, there's also some evidence to the contrary. Bottom line: use DC charging when you're in a hurry but don't use it when there's plenty of time for level 1 or level 2. Simple.

 

[cove3]

Check my post. I have a US 2015 e-Golf, along with my two Series 5. What it has to do with the i3 is that both cars use similar nickel/cobalt/manganese module cell battery technology, so I would expect both companies to make the same recommendations for battery life.

Yet I find this not to be the case. BMW says keep plugged in at full charge when not using the car for extended periods and says nothing about DC charging, while VW says keep the car at 40-50% and avoid consecutive use of DC charging. I wrote VW asking what they considered to be extended....2 weeks, 1 month, 3 months?

As an aside, I did a Google on "does dc charging shorten battery life" While there were lots of hits, they all seem to refer to the same two studies that suggest little impact, although more so at 40K miles of driving than at 10K. Until more experience and studies accrue, I'd lean toward being conservative on the use of DC charging.

Ron

 

[WoodlandHills]

Check my post. I have a US 2015 e-Golf, along with my two Series 5. What it has to do with the i3 is that both cars use similar nickel/colbalt/manganese module cell battery technology, so I would expect both companies to make the same recommendations for battery life.

Yet I find this not to be the case. BMW says keep plugged in at full charge when not using the car for extended periods and says nothing about DC charging, while VW says keep the car at 40-50% and avoid consecutive use of DC charging.

As an aside, I did a Google on "does dc charging shorten battery life" While there were lots of hits, they all seem to refer to the same two studies that suggest little impact, although more so at 40K miles of driving than at 10K. Until more experience and studies accrue, I'd lean toward being conservative on the use of DC charging.

Ron

Ok, thanks for the clarification. Based on your posts I had thought you were an longtime EV owner with a well inormed point of view, but now I see you are as much of a newcomer to EVs as I am. I wanted to know how much value to place on your comments/trolling and you have cleared things up, thanks.

 

[i7fan]

AC fast charge with type 2 connector will only charge at 7.4 kwh due to the fact that the on board chargers are limited to 7.4 kwh. There are two chargers rated at 3.6 kwh each, the MLE and KLE. The DC rapid charging is DC direct and does not need an on board conversion/charger from AC to DC and that is why you can charge faster with the DC. The DC rapid charger I believe is actually considered to be a Type 3 connector.

That is good to know! Was wondering why 22 kW takes 3 to 4 hours while 50 kW takes less than 30 minutes.

What does MLE and KLE stand for?

The CCS connector is just a type 2 with two extra points afaik. Have not heard about it being called a type 3 connector.

 

[i7fan]

To the rest,
Thanks for your input. Guess I will take the slight risk in frequent usage of DC charge. So much more convenient. I live just a couple of miles from a charge point. Will treat it as my gas station! With free "gas" - until Ecotricity starts charging for its usage.

 

[psquare]

But how many miles to get on and off the motorway?

Most of them are along M40 and M1 in your part of the world. I think there are some at Ikeas though.

 

[nowtta60]

I'm making sure EV owners get this right, so for the record...

Charging rate is measured in kW (small k capital W)

Charge amount is measures in kWh. If it were fuel then kWh is your litres or gallons and kW is how long it takes to fill the tank i.e the pump speed.

On an i3 AC max charge rate is 7.2kW on the type 2 socket or 50kW on DC CCS unit.

The i3 only draws power from 1 of the 3 phases available on the AC fast chargers. Really only useful for destination charging (going shopping, work, staying in a hotel). Though occasionally if its the only thing available it will get you a few extra miles. Thinks its 3-4 hours to fill the i3 from empty on the 7.2kW rate. 20 minutes to get 80% on CCS - but about an hour to fill as it has to slow down at the end to keep temperatures down as the battery resistance goes up.

The DC is for when you are on a journey and only want to nip to the loo, eat a burger and grab a fresh coffee. By the time that's done your battery should be back at 80%.

I wouldn't plan on using it as your main "free" charger.
a) your time is worth something
b) they don't work all the time. Reading on here it sound like a 50% success rate - though we probably only get to hear the bad news.
c) They "might" prematurely age your battery. No one will know for sure till about 3-4 years from now with hihg mileage users. If it needs replacing sooner than later then it isn't free ...circa £10,000 for a new set of modules at current prices.

One thing I've been doing tonight is finding out where all the 7kW chargers are in places I usually vist. Look on http://chargeyourcar.org.uk/ev-driver/join/ is a good start. Some places have free parking as well as free charging. Though most by me are in pay public car parks - at least the charging is free. So I'm still better off than with my ICE.

If you can find a 7kW unit in your local town centre - or a town nearby and don't do many miles - I'd recommend that instead of going out your way just to use a CCS.

 

[i7fan]

...
I wouldn't plan on using it as your main "free" charger.
a) your time is worth something
b) they don't work all the time. Reading on here it sound like a 50% success rate - though we probably only get to hear the bad news.
c) They "might" prematurely age your battery. No one will know for sure till about 3-4 years from now with hihg mileage users. If it needs replacing sooner than later then it isn't free ...circa £10,000 for a new set of modules at current prices.

a) a top-up with DC charge will not take much more time than filling my current 70 litres tank
b) will report on my experience in the future
c) there is that 8 years warranty to fall back on

One thing I've been doing tonight is finding out where all the 7kW chargers are in places I usually vist. Look on http://chargeyourcar.org.uk/ev-driver/join/ is a good start. Some places have free parking as well as free charging. Though most by me are in pay public car parks - at least the charging is free. So I'm still better off than with my ICE.

If you can find a 7kW unit in your local town centre - or a town nearby and don't do many miles - I'd recommend that instead of going out your way just to use a CCS.

Perhaps you missed my remark that an Ecotricity charge point is just 2 miles away from my house. I can pop over in 5 minutes, plug in for 15 minutes, read a few pages of my latest novel (or check my email, or browse a forum or two, etc) and be back home in another 5 minutes.

 

[jackt]

Whilst you can use DC as much as you like (and suffer negligible degradation over the norm at least according to current research / real world usage) you should also periodically use a L2/slow charger.

When rapid charging it just dumps as much kWh as quickly as possible it does not balance the pack, thats why you only get to ~90% and if you restart the session it takes much longer for the last 10%.

My favourite analogy being DC fast charging is like drinking water from a Fire Trucks hose, it hydrates you yes but its not all that pleasant.

I don't have DC charging on my i3 but I do have it on the PHEV - it prompts you sometimes to "Service EV Components" after being left at low charge for an extended period and rapid charging - as its detected a cell imbalance, cell imbalances are bad for your pack as to work most efficiently you need to draw power uniformly across all cells.

 

[mindmachine]

Whilst you can use DC as much as you like (and suffer negligible degradation over the norm at least according to current research / real world usage) you should also periodically use a L2/slow charger.

When rapid charging it just dumps as much kWh as quickly as possible it does not balance the pack, thats why you only get to ~90% and if you restart the session it takes much longer for the last 10%.

My favourite analogy being DC fast charging is like drinking water from a Fire Trucks hose, it hydrates you yes but its not all that pleasant.

I compare it to pouring a 12 oz beer into a 12 oz glass. The faster you pour the more foam you get and the less beer will actually fit in to the glass.

 

[jackt]

@mindmachine I like that one two, I might nick it off you but make it British

 

[mindmachine]

@mindmachine I like that one two, I might nick it off you but make it British

I thought about that but thought you might like using the p (pint) analogy yourself. LOL

 

[jadnashuanh]

While you can get the stated 80% in around 20-minutes (depending on temp, capacity of the CCS unit, and where you started from), if you want it full, it will take nearly an hour to top it off. It slows down considerably after it reaches a certain point. IOW, using a level 2 unit at 7+kw/hr is likely to get it topped off about as fast as leaving it on a CCS unit above that 80% mark.

 

[RJSATLBA]

While you can get the stated 80% in around 20-minutes (depending on temp, capacity of the CCS unit, and where you started from), if you want it full, it will take nearly an hour to top it off. It slows down considerably after it reaches a certain point. IOW, using a level 2 unit at 7+kw/hr is likely to get it topped off about as fast as leaving it on a CCS unit above that 80% mark.

I was expecting that it would be impractical to get more than 80% from en route use of a CCS but have found that by the time I get back to the car after a tea or coffee it is often closer to 90% (and almost invariably 5% more than iRemote showed!). So it seems that a CCS is still charging pretty quickly between 80 and 90%, even though it may be slowing.