Maximizing Charging Speed at Fast Chargers

[snstevens]

On a recent trip to Portland, OR I was having problems getting over 80KW charging at an Electrify America fast charger. To set the stage a bit --

• 2021 Taycan 4s with Plug & Charge enabled.
• "Battery-friendly Quick Charging" is not enabled.
• When charging at home on a L2 AC charger I limit the max charge to 85%.
• I try to charge at an Electrify America station once a week but usually stop at 85-90%

On my trip to Portland I stopped at various Electrify America charging stations just to test them out. I used the Taycan navigation system so that the car knew I was going to a charger and would potentially warm up the battery for maximum charging speed.

Regardless of whether I used a 150KW or 350KW charger, I only had charging speeds of 50KW-80KW. Pretty disappointed not to see 200KW on the 350KW charger, or 100KW on the 150KW charger.

I thought perhaps I needed to fully discharge the battery, so when I got home I ran the battery down to 5% SOC and warmed it to 85º prior to initiating charging. With that configuration the fastest speed I could achieve was 95KW on a 150KW fast charger. Is this the best I can get out of a 150KW charger?

In searching for information I came across some wording in the Porsche "Good to Know" app that says I should avoid doing DC charging all the time AND that I should also try to limit DC fast charging to 50KW most of the time. This didn't solve my problem - it just raised more questions for me.

If any of you can help I would be most grateful. My goals are these --

• Obtain the fastest rate of charge possible when I'm on a trip in the Taycan
• In addition to using a Profile for L2 AC charging that limits the max charge to 85%, are there any other recommendations for smart charging when I'm just running around town.

I've looked around the forum for answer to this, but came up dry. Any suggestions on how to up my high-speed charging game when traveling are appreciated.

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[W1NGE]

Doesn't sound like there is anything further you can do. It is possible that the EA units are throttling on their own rather than the car due to some invisible condition? Did you contact EA and ask their thoughts? Do you know of anyone else who gets faster charges from the same EA EVSE?

Generally, the speed is limited by the car if the battery isn't at optimum temp, battery save option is enabled, ambient air temp and battery's state of charge (SOC) at the start of the charging session. Beyond that then you've got to look at the infrastructure being used and if has temporary / permanent limitations placed on it.

Random final thought is to try a session without using Plug & Charge and pay via a different means - this might flush out if there is a hidden issue between Porsche & EA (or others).

 

[snstevens]

Doesn't sound like there is anything further you can do. It is possible that the EA units are throttling on their own rather than the car due to some invisible condition? Did you contact EA and ask their thoughts? Do you know of anyone else who gets faster charges from the same EA EVSE?

Generally, the speed is limited by the car if the battery isn't at optimum temp, battery save option is enabled, ambient air temp and battery's state of charge (SOC) at the start of the charging session. Beyond that then you've got to look at the infrastructure being used and if has temporary / permanent limitations placed on it.

Random final thought is to try a session without using Plug & Charge and pay via a different means - this might flush out if there is a hidden issue between Porsche & EA (or others).

I like the suggestion of disabling Plug & Charge to see if it behaves differently. I'll try that next time I charge and post the result.

Curious if you are able to get better rate of charge on your Taycan at a DC charging site, and what rate you get?

 

[W1NGE]

I like the suggestion of disabling Plug & Charge to see if it behaves differently. I'll try that next time I charge and post the result.

Curious if you are able to get better rate of charge on your Taycan at a DC charging site, and what rate you get?

I get 49kW from a 50kW but can't comment on anything higher as until recently there haven't been any near me - my nearest is 90 miles away.

 

[snstevens]

After further searching I found this post from @louv that answers 90% of my questions.

https://www.taycanforum.com/forum/t...my-taycan-charge-as-fast-as-i-want-it-to.779/

I'm still a bit puzzled as to why after using the Taycan Nav system to identify a charger 60 miles away, it didn't seem to precondition the battery, and I could only get 95KW rate of charging with SOC <50%. If anyone has insights please pass them along.

 

[arossti]

On the pedestal display of ElectrifyCanada stations (150kW and 350kW) the highest rate i have seen is 82kw, and the display also says this rate was ‘negotiated by the car’. I’d like to hear what you learn…

 

[gentley]

I am currently on a road trip from Vancouver, BC to Portland, OR. Earlier this evening I arrived at a 350 kW EA station at 9% SoC and 34 C battery with Plug & charge disabled (doesn’t seem to work for a Canadian car in the US..!). Charged to 71% in 15 mins with peak charging rate of 252kW (on the centre console). Was still getting over 100kW at 70% when I stopped the charge.

A warm battery and low SOC are the keys to a fast charging session.

Maybe a trip to the dealer..?

 

[snstevens]

I am currently on a road trip from Vancouver, BC to Portland, OR. Earlier this evening I arrived at a 350 kW EA station at 9% SoC and 34 C battery with Plug & charge disabled (doesn’t seem to work for a Canadian car in the US..!). Charged to 71% in 15 mins with peak charging rate of 252kW (on the centre console). Was still getting over 100kW at 70% when I stopped the charge.

A warm battery and low SOC are the keys to a fast charging session.

Maybe a trip to the dealer..?

Wow that sounds great! I think I’ll disable plug and charge and see if that helps.

 

[wemct]

I am currently on a road trip from Vancouver, BC to Portland, OR. Earlier this evening I arrived at a 350 kW EA station at 9% SoC and 34 C battery with Plug & charge disabled (doesn’t seem to work for a Canadian car in the US..!). Charged to 71% in 15 mins with peak charging rate of 252kW (on the centre console). Was still getting over 100kW at 70% when I stopped the charge.

A warm battery and low SOC are the keys to a fast charging session.

Maybe a trip to the dealer..?

I totally agree that a preconditioned battery and low SOC are necessary to get the super fast charging rates. Today was one of those great sessions. I hit 260kW and was still above 200kW at 55% SOC. I was at the same station the day before and peaked at 158kW (no preconditioning).

 

[daveo4EV]

a consideration is that all charge rates are “maximum” rates under “ideal” conditions - slow charge rates can be due to a large/vast/hidden number of factors largely outside the control of the vehicle owner or manufacturer…

but it also must be considered that the local charging hardware may be “slowing” the charge rate due to rate limiting at the charging station from the power company

150 kW and 270 kW is a _LOT_ of power - and the local power feeds may be “asking” the stations to slow down to avoid overloading the local grid…

also heavily used stations can also rate limit if they’ve been running hard and long before you arrive and they may slow down power delivery for thermal management

bottom line - there are a large number of variables that go into charge rate for any given session and neither the vehicle _OR_ the charging station will show you enough information about all those variables as to what variable is causing a charge session to be be slower than expected:

another example: 150 kW charging cables are liquid cooled - the fast charge rate can only be delivered over a cable that is demonstrating effective cooling - the coolant circulating in the cable is temperature measured - and if the charging unit “sees” the temperature of the coolant is “too” high it will limit the charge rate to avoid overheating the cable…

there are a very large number of variables in effective fast charging - and you need _ALL_ the data (which is not shown to us as normal consumers) to determine why any one charging session is being throttled.

 

[daveo4EV]

another reason your charge session might be slow…

billing - commercial power is billed based on “demand” loads - and demand loads are very very expensive - EA has daily limits on their quota for demand loads for power meters at their sites - they may throttle charge rates to manage their daily billing quota’s - knowning they have already services a large number of vehicles in a given day - they man engage in cost management and limit their high demand loads to avoid costs they would otherwise incur to delivery you your best possible charge rate…

as I said there are a large number of variables that go into a given session’s charge rate - and we lack visibility to nearly _ALL_ of them - so there is NO way to know WHY a particluar session yielded the charge rate it demonstratred - it may having NOTHING do to do with you _OR_ your car - you simply can’t know.

 

[daveo4EV]

EA tech’s confirmed for me the week following thankgiving at the Aptos, CA EA station - I met and talked to them while they commissioned the 4 stations there - write on that coming soon…

there are batteries at most EA sites - the batteries server AT LEAST two purposes…

1. demand mitigation during “peak hours” so that they can not pull as much power during expensive time periods
2. demand delivery to meet high charge rates that exceed the actual delivery rate of the “power grid feed” to the AC/DC converters on site

_IF_ the local site’s batteries are depleted - you may suffer reduced charging rates because the “grid feed” can’t actually deliver the amount of power your vehicle is requesting - the local batteries can “boost” local charge rates to current flows that exceed the actual ‘feed rate’ from the local power transformers - this is great - until the batteries are “empty” and then you are stuck running at the maximum rate of the power-grids actual feed rate…

think of it like water

1. feed from the water company can delivery 100 gallons per second
2. install a water “tank” - a reservoir to hold water locally
3. store 1000 gallons in the reservoir
4. pull up a car that can take “200“ gallons a second (100 gallons more than the “feed” can provide
5. the reservoir can “match” the 200 gallons a second demand until it’s empty - at which point your car will be restricted to the maximum rate of the “feed” which is 100 gallons per second…
6. you car will suck the local reservoir dry in 5 seconds, and then be throttled down to 100 gallons per-second for the remainder of the “fill” session - the rate of the actual feed from the water company…

your charge session may be slow because the onsite batteries are “empty” having serviced other vehicles prior to your arrival and not had time to top back up before you arrived…

or it may be slow because your site does not yet have onsite batteries which are required to deliver max rates of charge - like the current Aptos, CA EA site, 4 stalls, infrastructure for batteries - no batteries on site yet due to world wide supply crisis - tech’s estimated 5-7 months before they are delivered and installed - until then site is capacity limited to the raw “feed rate” from PG&E - this site apparently has a “raw” feed rate of 250 kW from PG&E - but there are 4 150 kW stalls - well you’re only going to get 150 kW if you’re the only vehicle charging…if there are 3 cars charging there is only 250 kW available to feed the 3 cars - or 80 kW split evening - but because of tapering it’s variable through the charging session…if my Taycan is onlly pully 40 kw at 90% SOC - that leaves 210 kW from the other 3 stalls…

you get the idea - this stuff is _COMPLEX_ - and again as to why you ever get any particular charge rate at any particluar point in time in a particluar location depends on a number of factors _INCLUDING_ recent use prior to your arrival…

 

[Klepper]

I totally agree that a preconditioned battery and low SOC are necessary to get the super fast charging rates. Today was one of those great sessions. I hit 260kW and was still above 200kW at 55% SOC. I was at the same station the day before and peaked at 158kW (no preconditioning).

I had a similar experience this weekend. I hit 257kW at a low SOC and I had the battery pre-conditioned on arrival (I had set the charger as the destination in the Nav).

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