Preconditioning a myth ?

[Petzi]

In some threads there is talk of “preconditioning” of the battery. This is certainly important in connection which navigation can be used (e.g. Waze). It is generally assumed that this is why you should use the Porsche navigation system, so that the battery is “prepared” for charging.

There is no possibility to start this “preconditioning” process manually. The car itself ensures that the battery is at operating temperature. Many people apparently believe that the battery should be “warmed up” especially at cold temperatures. The opposite seems to be the case. The battery should not be too hot, but it can be assumed that the system itself will take care of this.

Porsche Manual:
High-voltage battery care

If the battery reaches a temperature that is too high due to external influences, the battery is conditioned (cooled). Depending on the service life and battery charge, the temperature range for conditioning is reduced.

To reduce aging and wear of the high-voltage battery, observe the following measures:

• Charge the vehicle at temperatures between approx. –4 °F and approx. +86 °F.
• Avoid exposing the vehicle to temperatures above 86 °F for long periods of time, e.g. by parking it in direct sunlight.
• At ambient temperatures above 86 °F when parked: Connect the vehicle to the power supply after use. Charge the high-voltage battery with alternating current (AC) to a maximum battery charge of 80%.
• Especially before long journeys: Initiate the charging process via the Charging Planner and use the Departure function to charge with alternating current (AC).
• For daily use of the vehicle without long-distance journeys, set the battery charge to approximately 80%.
• If necessary, set the battery charge to 100% before long-distance trips.
• If the battery charge is below 5%, charge the high-voltage battery.

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[Yves]

With temps of 0C to 8C and driving around, DC fast charging will be slow without pre heating the battery … ideally the battery should be around 20 to 25C … such a shame there is no manual pre conditioning button, not even in the app … I have it in the BMW and when I know I will dc fast charge, I just kick off the pre conditioning in the app, making my iX charge faster then the Macan under these “winter” conditions.

 

[Petzi]

EIt is true that the exact parameters are not communicated by Porsche, but I believe that the optimum working temperature of the battery must also be the optimum charging temperature. The car will be programmed by default to reach the optimum working temperature of the battery. This means that you can charge the battery at any time during normal driving. Even if the outside temperature is very low, this can only become a problem - in the very rare case - if you park the car outside, start it and want to charge it immediately.

 

[Yves]

EIt is true that the exact parameters are not communicated by Porsche, but I believe that the optimum working temperature of the battery must also be the optimum charging temperature. The car will be programmed by default to reach the optimum working temperature of the battery. This means that you can charge the battery at any time during normal driving. Even if the outside temperature is very low, this can only become a problem - in the very rare case - if you park the car outside, start it and want to charge it immediately.

No the battery hardly warms up with normal driving … so I can drive the car for 30 minutes or more and maybe the temperature has gone up from 4C to 5C way to low to enable descent DC charging speeds … Also it takes a very long time to warm up the battery with a destination as fast charger, even a 30 minute drive will not get it to optimal charging temp … my iX with a 15 minute pre conditioning and a 10 minute drive to the charger, charges close to normal speed …

 

[SteveInKirkland]

I asked a Porsche engineer at a conference for the USA Dept of Energy how I could drive a Macan EV in Florida or Texas if exposing the vehicle to temperatures above 86 °F for long periods of time caused battery issues. His response was, "what fool told you that?"

His general advice for maintaining the battery was to (a) to maximize battery life, keep the state of charge at 50% if you used the car for less than 50 miles per day; (b) slow charge the vehicle at even slower than 9.6kW; (c) in cold weather, the Departures feature heats up the battery with an effect to increase range and increase charge rates at DC chargers; (d) higher levels of charge in the battery can result in higher performance for some systems (acceleration) and lower performance for other systems (regenerative breaking).

To me, I would feel more comfortable if we had observable test results with known environmental conditions to back up Internet lore. But I've found that Internet lore is one of the only sources of information about the car because Porsche is, effectively, silent.

 

[mikeright]

(c) in cold weather, the Departures feature heats up the battery with an effect to increase range and increase charge rates at DC chargers;

My car sleeps in an indoor garage.
No matter if use the departure feature or not. The battery is at the same temperature every morning: 15C, so below what Porsche says it is optimal to maximise the range.

I would like to know your true experience with that functionality and specially with the battery temperature.

Thanks all!

 

[Yves]

My car sleeps in an indoor garage.
No matter if use the departure feature or not. The battery is at the same temperature every morning: 15C, so below what Porsche says it is optimal to maximise the range.

I would like to know your true experience with that functionality and specially with the battery temperature.

Thanks all!

It just pre conditions the car, not the battery … as I already mentioned I have with the iX you have two buttons in the bmw app, one for cabin and one for battery pre conditioning …
On the other hand 15C is not bad, as far as I can tell the consumption rises noticable when below 10C …

 

[seabird]

My car sleeps in an indoor garage.
No matter if use the departure feature or not. The battery is at the same temperature every morning: 15C, so below what Porsche says it is optimal to maximise the range.

15C is not cold enough to need preheating. People place way too much importance on a relatively minor feature that is useful to a relatively small number of drivers.

The Porsche Macan has a 1200 pound lithium battery pack. Lithium batteries have a specific heat capacity around 0.5 BTU per pound per degree C. A preheating cycle designed to warm the battery by 10C would therefore require 6000 BTU or about 2kW at 100% efficiency. When factoring in coolant, pumps, insulation, wiring, and electronics that must also be heated and powered, we're close to 3kW. Which lines up, of course, with running a 5-6kW PTC heater for 30 minutes (i.e., a typical EV preconditioning cycle).

On the other hand, a DC fast charger, even at a modest 60kW initial speed in cold conditions, can produce the same heating power in just 3 minutes before starting to charge the battery (though in practice, it isn't literally 100% heat, switching to 100% charge, which is an oversimplification).

A preheating cycle, in other words, isn't doing all that much in the grand scheme. 1-5 minutes isn't nothing, but it's hardly worth worrying about.

 

[sor]

I’ve charged several different kinds of EVs, some sitting in snow for hours before charging, some in summer.

preconditioning does help get you closer to max speeds as soon as you plug in. Without it, the rate still ramps up quite well within 3-5 minutes.

My experience is that while it is not a myth, it is also not that important unless you’re in a race to charge and go, and under most non-extreme circumstances there isn’t a noticeable difference. The biggest difference I saw was after leaving a car at 10°F for six hours and then charging, where it took a few minutes to ramp.

 

[PrudentOcean]

Where the time savings matter most would be on a road trip where you arrive with a low SoC, but in that case the internal temperature of the battery pack would often be near the ideal temperature anyway. I see pre-conditioning as largely unnecessary.

 

[ColdCase]

I saved 35 minutes of my life today with preconditioning. What usually starts out a 75kWh charge rate and then drops off, today started out at 175 kWh and slowly dropped off to 140 . That could add up on a cross country trip.

When you only get 30 minutes free electricity at EA chargers, you can pretty much recharge without disconnecting and reconnecting if you start with a battery within the ideal temperature.

Otherwise not a big deal as I use overnight AC charging more routinely.

 

[sor]

My experience with no preconditioning is that it goes up steadily the first few minutes and meets the regular charging curve within a few minutes, not that it starts sub 100kw and goes down from there.

 

[seabird]

I saved 35 minutes of my life today with preconditioning.

There is a 0% chance this is true in North America in May. It's (1) not physically possible for your battery to have been cold enough to slow charging by any measurable amount anywhere in New England this week or (2) even if you did park in an industrial deep freezer for some reason, it's not possible for the preconditioning cycle to raise the battery temperature by enough to come anywhere close to doubling charge speed.

Reading the charging rate in the first 15 seconds of plugging in is not the way to base your time saving calculations.

 

[ColdCase]

These were max levels indicated over a period of minutes. Are you thinking EA has been playing with me at the three stations I use? Or perhaps my battery or control software is defective?

Its a small sample size, maybe a dozen charges. Just my observation that when I precondition and arrive at an indicated 30-40% SOC the charging rate is always significantly higher than when arriving at station with battery between 55 and 65F indicated.

I only used a shell station twice, the charging rates seemed to be a higher than EA, probably because the initial SOC was lower, but otherwise similar.

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