40A Home Charger Went From 9.6kW to 3.4kW Max

[malogos]

I have a 40A, ChargePoint charger at home. It used to give my 23 Taycan a consistent 9.6kW, but after taking the car in for a couple recalls, I noticed that it now maxes out at 3.5kW.

Is that intentional? Is there a way to see how much power the car is requesting?

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[AutoX]

Not normal. Does your chargepoint show how many Volts your panel is supplying?

 

[malogos]

No, I only can set the charge limit (which is 40A).

Although looking into it, I found that the charger updated itself in the fall (which was coincidentally when I went in for the Taycan's check). And because it saves its own charging history, I see that the change from 9.6 to 3.5 actually occurred after that update.

 

[daveo4EV]

No, I only can set the charge limit (which is 40A).

Although looking into it, I found that the charger updated itself in the fall (which was coincidentally when I went in for the Taycan's check). And because it saves its own charging history, I see that the change from 9.6 to 3.5 actually occurred after that update.

it's defaulted to 50% - press the 50% buitton at the top of the unit to enable 100% charging…

or if your unit has a LCE screen find the settings and adjust the maximum amps back to 40 amps…

this is most likely a default setting which Porsche trotted out years ago when they were meltling NEMA 14-50 sockets due to the nominal operating temperature of their EVSE power supply cables

the reason for this and evolution of this are buried in this thread - see below…

https://www.taycanforum.com/forum/t...uide-to-the-porsche-evse-pmc-pmcc-pwcc.13886/

many Taycan owners opt'd for a high quality EVSE and no longer use their Porsche unit -YMMV.

 

[CrazyINP]

@daveo4EV I think he has charge point charger?

@malogos I would reset the charger and set it up again. It very well might be some auto settings after update. If that doesn't fix it, ping charge point

 

[daveo4EV]

@daveo4EV I think he has charge point charger?

@malogos I would reset the charger and set it up again. It very well might be some auto settings after update. If that doesn't fix it, ping charge point

a factory reset of the ChargePoing flex charger should return it to max power - please make sure your setting is appropriate for your breaker size and wire gauge.

there have been reports of ChargePoint flex chargers reverting to a lower AMP setting for no particular reason - this is easily fixed via the app based configuration tools for the ChargePoint flex charger - please see the chargePoint website for configuration instructions for your particular charger.

 

[malogos]

A charger reboot didn't do it, but a reset worked and it's back to normal ranges. Thanks, guys.

 

[tycanmt]

I have a 40A, ChargePoint charger at home. It used to give my 23 Taycan a consistent 9.6kW, but after taking the car in for a couple recalls, I noticed that it now maxes out at 3.5kW.

Is that intentional? Is there a way to see how much power the car is requesting?

At some point they made the default charge current 20A, presumably to avoid paying for people with sub standard wiring setting their homes on fire. You had to override that setting (I forget where). Perhaps the setting got reset to the default in the firmware update?

 

[malogos]

At some point they made the default charge current 20A, presumably to avoid paying for people with sub standard wiring setting their homes on fire. You had to override that setting (I forget where). Perhaps the setting got reset to the default in the firmware update?

It was set to 40A in the Charge Point app (Home > Charge Current Limit). I tried to change it to 16A (which I think is the default), but it didn't ever update... so something was up. The reset took care of it, though.

 

[JJToronto]

I have a 40A, ChargePoint charger at home. It used to give my 23 Taycan a consistent 9.6kW, but after taking the car in for a couple recalls, I noticed that it now maxes out at 3.5kW.

Is that intentional? Is there a way to see how much power the car is requesting?

I had the similar problem. My 2021 4S decided to stop accepting charge randomly one day. I have to plug it back and start all over. This could happen 5 times until it reach 100% on the same day. I took this in Porsche, they report back it was overheating. They reduced my 40 Amp charger to 30 Amp Charge rate. Later I found out this is a short term remedy, before I had problem with charging, I get 8.8kw charge speed, now I’m getting 7.2kw. The shop tech told me they did update the software, they have not done anything else, but they also informed me that they are not told what is in the software update. In translation, no idea how to get my charge rate back to the original speed. I checked with the Taycan manual. If you use a 40 Amp level 2 charger. You can get up to 11.2kw charge rate. They are still looking into this, a ticket to escalate to Germany, but it might takes weeks to months before they hear back. I’m kinda disappointed with Porsche that they can’t not fix the car still under warranty for 6 months now.

 

[AutoX]

I had the similar problem. My 2021 4S decided to stop accepting charge randomly one day. I have to plug it back and start all over. This could happen 5 times until it reach 100% on the same day. I took this in Porsche, they report back it was overheating. They reduced my 40 Amp charger to 30 Amp Charge rate. Later I found out this is a short term remedy, before I had problem with charging, I get 8.8kw charge speed, now I’m getting 7.2kw. The shop tech told me they did update the software, they have not done anything else, but they also informed me that they are not told what is in the software update. In translation, no idea how to get my charge rate back to the original speed. I checked with the Taycan manual. If you use a 40 Amp level 2 charger. You can get up to 11.2kw charge rate. They are still looking into this, a ticket to escalate to Germany, but it might takes weeks to months before they hear back. I’m kinda disappointed with Porsche that they can’t not fix the car still under warranty for 6 months now.

I think you need to use a 48amp charger to get 11kw rate. You'll only get 8kw rate with a 40amp charger

 

[daveo4EV]

I think you need to use a 48amp charger to get 11kw rate. You'll only get 8kw rate with a 40amp charger

yes you need a 48 amp EVSE on a 60 amp breaker in North American to provide 11 kW charge rate - however Porsche has been neutering their EV's to only support 9.6 kW max charge rate in North America…

the Macan EV is max 9.6 kW
Taycan gen-1 is 11 kW - or 9.6 kW depending on software updates
Taycan gen-1.2 is 11 kW or 9.6 kW depending on software updates

YMMV.

 

[JJToronto]

I think you need to use a 48amp charger to get 11kw rate. You'll only get 8kw rate with a 40amp charger

I used to get 8.8kW before the software upgrade. This is our 2nd Taycan too.

 

[daveo4EV]

I used to get 8.8kW before the software upgrade. This is our 2nd Taycan too.

historically the Taycan shows the charge rate actually "hitting" the battery not the "raw" power coming from the EVSE - 8.8 kW is about right for a "raw" power feed of 9.6 kW…

this is inline with expected overhead/losses for converting AC/DC power to charge the battery and losses to run the vehicle's electronics during the charging process…

8.8 kW makes perfect since with a 9.6 kW "raw" feed…

 

[daveo4EV]

to demystify this stuff - the math is simple

the formula is:

watts = volts * amps

for simplicity sake we'll normalize voltage to 240 volts

that leads to the following table of "common" circuit breaker sizes - and "raw" watts/kW's capacity

Volts	Amps	Watts / (kWs)
240	30	7,200 (7.2)
240	40	9,600 (9.6)
240	50	12,000 (12)
240	60	14,400 (14.4)
240	100	24,000 (24)

however EV chargers called EVSE's (Electric Vehicle Supply Equipment) are considered "continuous use" devices - and therefore the the 240V's circuit has to be derated to 80% of raw capacity to allow for safe operation over hours and hours of continue use charging a 100 kWh battery…so the table below documents the EVSE "raw" capacity for a given circuit breaker

Breaker Size (amps)	80% Capacity (amps)	EVSE raw output watts (kWs)
30	24	5,760 (5.76)
40	32	7,680 (7.68)
50	40	9,600 (9.6)
60	48	11,520 (11.52)
100	80	19,200 (19.2)

• EVSE's on circuit sizes of 50 amps or smaller can be mobile/plug-based or hardwired…
• EVSE's on circuit sized greater than 50 amps _MUST_ be hardwired - mobile plug-based EVSE's are not allowed by north American building codes.

Some EV's show the "raw" power being fed to the vehicle in their in car interface, and some EV's (Taycan for example) show the "effective" power rate that is actually charging the battery. A 10% loss from raw power to effective battery charge rate is normal and expected as part of any normal charging process - industry standard equipment loses about 10% of the raw power feed to AC/DC conversion + other overheads while charging your battery - this is expected, required, and completely normal.

* - it should be noted that North American grid voltage is not strictly 240V - normal variations happen by region, weather, time of day, grid loads, etc… nominal variation is expected/allowed by ANSI standard - so voltage for your home may be as low as 228 volts or as high as 252 volts - this is consider "normal" by most Power providers and expected. If your home's voltage is outside these specifications you can work with your grid provider to have them update your home's feed to be "with in specification" - YMMV with different regional gird providers, but if your voltage falls inside the nominal +/- 5% most grid providers will consider that normal and not provide any adjustments.

1. The Standard: Under ANSI C84.1, the national standard for North American residential electrical service, the Range A service tolerance for a 240V nominal system is +/- 5%. This means any voltage between 228V and 252V is officially in spec. Any consumer product sold for the North American market—especially a premium EV—is legally expected to operate within this standard window.

therefore the "raw" watts provided by any given EVSE is directly affected by the actual voltage being supplied to your home from the grid - a 5% +/- variation in "raw" watts/kWs is therefore normal, expected.

** - voltage drops also as a function of wire gauge and length from the power source - voltage is measured where it enters your home - and expected to be within ANSI tolerances "at your meter or home entry point" - however depending on wire materials, length, thickness/gauge, and sub panels, and circuit breakers voltage may drop significantly between where power enters your home and your EVSE, also other appliances in operation at the same time as your EVSE can also cause a voltage drop between what voltage is "entering" your home and your EVSE is providing.

*** - all this is to say the table's present above are calculated based on a "ideal/aspirational" 240 volts - real world conditions allow for a 5% +/- variance from that ideal and watts and kW's being provided to your EV vehicle will also therefore be variable from the ideal numbers presented above. Most EV's don't care and simply operate with a wide variance in actual voltage/watts/amps and monitor the battery until it reaches the target SOC% in terms of kWh's provided by the charging session.

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