Leary of the passive heating/cooling approach

[Sudaval]

All:
I am considering buying a used 2016 eGolf partly because it's roomier -- and may possibly be better supported -- than the Fiat 500e cars I've been leasing since 2013. I have to lug a big, active dog around, so roominess counts.
I have a lot of concern over this "passive" system. Fiat heats and more importantly cools its batteries with a liquid system. This "passive" approach sounds too similar to the Leaf misadventures that lead to catastrophic battery degradation.
It mystifies me that I read so little about temperature-related degradation in this or related forums. Can anybody inform and reassure me? Reassurance would involve lots of well-documented examples as to why I shouldn't worry about this.
I'm especially leery when I read stuff like this on other eGolf forums:

SE has a standard resistive heater only which will cut range by about 40% when activated. Combine that will lithium batteries producing less power at low temperatures and it quickly chains the e-Golf down to a much shorter range. The SEL Premium comes with the heat pump as standard which apparently will move heat from the drivetrain to the cabin (via some sort of magic, for all the information I can find about the specific implementation in the e-Golf) without firing up the resistive heater, and in that case its pretty similar to running the AC. Of course, if you're in a cold climate the heat pump probably won't cut it in frigid temperatures, but for 'standard' chilly weather its great and quite efficient. Also, the heated seats are extremely efficient and mean you can get away without running the heat in a wider range of temperatures than you would expect. Preheating/precooling the car while plugged in before you leave makes a BIG range difference in the more extreme weather conditions. Likewise a pop in windshield reflector in summer. Seriously.

The coolant in the e-Golf is used to cool the motor and power electronics.
The e-Golf traction battery is passively cooled. There is no active cooling at all.
Thanks in advance.

Maybe I'm missing something, and if so, I'd be relieved to hear it.
Thanks in advance for any thoughts.

 

[f1geek]

Nissan Leaf has crap battery chemistry and BMS that does not let you explicitly set max charge SoC. You should keep battery between 80% to 20% most of the time and especially in summer above 90F. Even Tesla does not recommend charging to 100% all the time. Leaf has no charge limit setting. VW 24.2 kWh pack is from Panasonic and 35.8 kWh pack is from Samsung SDI. These companies are good at battery chemistry - Panasonic makes cells
For Tesla, fir example. Nissan makes own cells and is not good at electrochemistry, as evidenced by Leaf pack degradation. If there was a lot of deg in e-Golfs I bet the internet would be full of reports. Yes, liquid cooling is the best, but every design is a compromise and by not including it VW saved weight and complexity but I agree it is not as good for pack. If you live somewhere super hot, a liquid cooled pack is better.

 

[Sudaval]

Thanks for the information. Can you let me know what restricting the charge capacity as you’ve suggested does to range in terms of mileage? I don’t make many long trips, but I do have one weekly trip of about 70 miles round trip with no guarantee of a charge in the middle. Also, LA had several very hot spells over recent summers, in the 100s, and those can be expected to worsen. That doesn’t sound good for the eGolf, correct?

 

[f1geek]

How you treat a lithium ion battery determines how many charge cycles you can get out of the pack before you see significant degradation (automakers tend to agree on 30% loss of capacity as making battery "unusable" - but the user may not consider this a significant problem, depending on the initial range offered by the given pack). Lots of scientific labs have done studies on battery cycling at high temps and different starting and ending SoC. In general, if you routinely cycle the pack 0 to 100%, and at high temps (40 C to 50 C), you will hit the 30% deg in about 300 to 500 cycles. If you cycle 20 to 80%, you will get more like 4000 to 6000 cycles. I am generalizing a bit here, as these numbers are very dependent on battery chemistry. These published tests generally are at elevated pack temps, so are probably worst case. Additionally, the e-Golf BMS does not let you access all the capacity, so there is a buffer at top and bottom to prevent you from really cycling from 0 to 100%, and the e-golf BMS will limit power available or charging speed if the pack gets too hot. Regardless, keeping any well made (not so sure about Leaf) battery pack between 20 to 80% routinely will provide you with at least 100,000 to 150,000 miles of use before you hit the 30% deg (Tesla Model 3's are probably good for 500,000 miles, but Tesla is the best), if not more.

2016 e-Golf brand new EPA range is 85 miles. If you need to depend on that 70 mile (I am assuming high speed, but maybe in LA traffic prevents high speed?) trip for 100,000 miles, I can't give you a good answer. I don't think you would have any issues with the 2017 or newer e-Golf with 35.8kWh pack, but 24.2 kWh may be on the edge for your use case, since you need to routinely use almost full range in hot temps (means a lot of 100% charging). Best of luck.

 

[f1geek]

I should add that while the EPA range of a 24.2 kWh e-Golf is 85 miles, you achieve a much higher range if you drive efficiently. When I had my 2015 SEL, I hardly ever saw 85 miles for around the town driving - I could usually get at least 100 to 105 miles if I drove 100% to ~10% SoC, not that I did it very often. In the winter in the SF Bay Area I could expect about 70-80 miles on the highway (heat on, Eco mode), until I had to stop to charge. For a once every two month 90 mile drive, I used to stop at about 50 miles for a 30 minute 21 kW DCFC to make the trip low stress.

 

[Sudaval]

This is helpful. A few more questions:

* I almost certainly won’t be able to afford the used SELs, from what I’ve seen so far. So that means the more power-consuming heater, for one thing. But I was astonished at the 40% drop in range quoted above for driving with the heater on. I don’t want to be talked out of bad news — I’d rather have the facts — but Jeeze. 40%? I wouldn’t use the heater much, but on my 500es, range loss was about the same whether I used the heater, ac, or just the blower. Is that the case with eGolf, too? Typically with the 500e, using those things might cost me about 10% of my range.

* I believe I saw a question on the forum about what CPO means in California, and specifically what it means with respect to battery condition, but I don’t recall seeing an answer. Is there a quick and trustworthy way to find out about a battery’s charging history and prospects for continued service at the dealership or at a mechanic’s shop?

* What I’ve read about what fast charging can do to a battery spooks me. I probably wouldn’t do it at all, but I’d like to hear more about your and others’ experience.

Thanks.

 

[f1geek]

Any EV will lose range due to: driving at highway speeds, cold ambient temperatures (battery chemistry holds less energy at cold temps), heater usage in cold ambient temps, and certainly a heat pump uses less energy to heat cabin than resistive heating. For around town to get 110 miles, my speeds rarely go above 35mph, I don't use heat or A/C and the weather is warm. My highway trips are usually in winter (40-50 F), high speed, and I had heat turned on. Two very different use cases and range loss is not solely due to turning on heater. I would say all other factors being equal, turning on the heat in my SEL probably caused a ~10% cut in range. Seat heaters only use about 1% of range.

Best way to find out range is to charge the car to full and drive it down to 10%. Otherwise you need to know how to use the OBD dongle and software. I know nothing about Certified e-Golf warranty.

This is the direct quote from the owner's manual:

"Battery capacity will decrease if you frequently and consecutively charge your vehicle at a DC charging station. Therefore, always alternate high-voltage charging (DC fast charging) and low-voltage charging. For example, you can charge your vehicle overnight at an AC charging station or use an AC wallbox if the vehicle was charged at a DC charging station during the day."

If fast charge infrequently, and don't do it several times in a single trip, the effect on the pack will be minimal. I take one or two 250 mile trips a year so I need to fast charge on the way. Other than that, I typically L2 charge. VW says this because fast charging heats up the pack (joule heating) and high temperatures cause damage. If you fast charge in cold weather, the pack will cool off a lot more quickly than in hot summer weather.

Even Tesla will permanently throttle the Supercharger speed on certain Model S cars because the owner's fast charged them too much, so this is not unique to the e-Golf.

There is misinformation on this forum with incorrect wording that will scare you because the manual has been misinterpreted. The e-golf is designed for long trips and VW included a DCFC port (initially it was optional) to enable long journeys. If the VW engineers really wanted to prevent DCFC use, they could have done what Fiat did with the 500e and not made DCFC an option.

 

[JoulesThief]

I've owned a lot of VW models, over the years. I currently own two other VW's, both TDI's, that are much more comfortable on long distance trips than my 2015 e-Golf SEL that I've owned 4 years.

My e-Golf has very stiff suspension. The seats are "leatherette" and nowhere near as comfortable as my two other VW's. I have no problem in my TDI's doing 70 mph or more to keep up, barely with the flow of traffic, on interstates, for hours, in comfort. Like 600 to 700 miles between any stops if your stomach and bladder could handle it.

One hour in the rough riding e-Golf on California freeways at 70 mph and I'd be ready to charge again immediately. Problem is finding public charging locations every 70 miles that are RELIABLE, or not broken down, or having to wait in line to use it.

I would never consider an e-Golf as suitable for long distance trips, in comfort or in time, if your spare time is of value to you. Not yet, at least. The 2016 SE does not have fast charging as a feature, but it is a $1200 option. 3.6 kWh charge rate is it's max recharging rate. VW sold and lease a LOT of those models in 2016.

YMMV, I have other options for taking on long distance drives. Having owned my e-Golf 4 years, I don't even consider it for anything except around the city trip in stop light and stop sign road and Blvd driving, because that's what it really does the best... using it's regenerating capabilities, instead of brakes, and not wasting energy idling stopped, in traffic, using energy doing absolutely nothing.

The e-Golf has a very heavy, really small "fuel tank" for doing long distance. IMHO, long distance with this model electric car isn't worth my time. YMMV, I don't enjoy waiting to drive while my battery recharges. Therefore, I charge at home at my convenience, in the garage, and do whatever I can to avoid public EVSE chargers.

The most major irritating feature to me on long trips is all the time and mileage wasted driving out of your way to get to a charging facility, then back on your route. In my e-Golf, it really cuts into the range and efficiency of getting to your destination in a timely manner. Having to get off of freeways and highways to get on surface streets and traffic to get a recharge really isn't very efficient or convenient, regardless of what anyone else says here. If your spare time is worth money, wasting time charging at a public EVSE becomes expensive in more ways than one.

 

[f1geek]

Just to add some more info from my ~60 mph highway drive this morning at 39 F ambient temp. When I turned on the heat set to 72 F (driving in Eco mode), my range dropped from 104 miles to 95 miles - so that's a 9% loss in range. My car has the heat pump.

I think a good general rule is to buy a car with a range that is 1.5 times your typical long trip. Since you will be making a 70 mile trip 52 weeks a year, I would say that you would be better served by a ~110 mile battery pack so you don't need to worry about range.

I really enjoy stopping to charge on my rare long trip because after 1.5 to 2 hours, I probably need to pee and also I love to take 30 to 45 minute walks. The charging infrastructure is getting better every day in CA and I see even EVgo is now putting in locations with 4 or more charging stations. I have never needed to wait for someone to finish charging in the 5 years I have been taking long EV journeys. Once someone ICED a station, but I didn't let that stop me from getting a DCFC - I just parked my car to block the offending vehicle (while I charged) and then security kindly provided a parking ticket. I may take a trip to the snow this winter and would gladly take my e-Golf if I were the only driver. My daughter wants to have experience driving in the snow and will probably accompany me so I would much rather take the 20 year old beater (which already has dents) she drives so the e-Golf doesn't need to go to the body shop.

 

[cctop]

I think a good general rule is to buy a car with a range that is 1.5 times your typical long trip. Since you will be making a 70 mile trip 52 weeks a year, I would say that you would be better served by a ~110 mile battery pack so you don't need to worry about range.

I'll say it in stronger terms than f1geek did:

If you commonly have a 70-mile trip without the possibility of recharging, do not get a 2015 or 2016 e-Golf.

There are many variables that can reduce your range, the most common ones being cold weather and highway speeds.

Model years 2017 and later have a larger battery, so you'll be fine with them.

 

[user 2305]

I'm a little confused by this thread as there seems to be a conflation of two totally different subjects:

1: Battery cooling - ie, whether or not the eGolf's passive battery cooling system has any drawbacks to battery life/performance
2. Cabin climate control - ie, to what extent using the cabin heater reduces range

I don't know a lot about the first topic, but I'm not aware of many issues/problems related to it.

For the second topic, like any EV, using the cabin heater will reduce range a bit. So does cold weather. Things to factor in when deciding on how much range you need in an EV.

Note: the quote in the original post related to resistance vs. heat pump is related to cabin climate control and has nothing to do with active vs. passive battery cooling.

 

[f1geek]

Let's begin with the word "range". When we are talking about a car's or battery pack's range, we are talking about the EPA range. The EPA range is a number assigned by the US EPA based on a specific test cycle for EVs. The EPA keeps the car in the default setting and runs it through a proscribed range of speeds and simulated terrain, typically in a lab in Ann Arbor, MI. The ambient temperature for this test is 77°F ± 9°F. Since the automatic settings for the e-Golf are Normal Mode, D Mode, and auto climate control set at 72 F, these are the settings that provide us with a reference for the range of, for example, 125 miles for the 2017 e-Golf base model. The EPA does not test all trim levels, necessarily. All gas and diesel cars lose efficiency (and therefore range on a full tank of fuel) in the winter because they are less efficient and potentially also because fuel blends are different in the winter to help reduce smog. All EVs lose range in the winter because battery chemistry can't provide as much available energy as compared to 77 F and also due to additional energy needed to heat up drivetrain components, including the battery, for those cars that are able to heat these components. Also, any aerodynamic effects due to cold or warm air effect all cars somewhat similarly, though I suspect EVs can be more aerodynamic because they don't have hot spots that may upset the smooth flow of air around the car. EVs lose more range than gas or diesel cars in the winter because most of the energy in petroleum fuel is wasted as heat (gas cars extract about 26 to 28% of the energy in gasoline for motion- the rest is wasted, while EVs are about 95% efficient in converting chemical energy into forward motion) and in the winter, this waste heat is really good at heating the car. In an EV, there is very little waste heat, so most of the heating is provided by more battery energy usage.

Heat pumps use much less battery energy to heat the cabin as compared to resistive heaters, so my car and SEL cars with the heat pump are more efficient (and get more range) in winter temperatures.

In warm weather, I turn off the heat or A/C, drive in Eco mode and drive gently, and I am typically able to get at least 140 miles (on the highway) or 160 miles (on local roads) on a full charge. In colder weather, I typically am able to get about 120 miles of range driving locally.

In any weather, if you use more energy than the EPA did in the official test cycle, you will get less than the EPA range. In any weather, if you are able to use less energy than the EPA did, you will get more than the EPA range. Of course, if the battery making available significantly less energy due to very cold weather, say below freezing, you will may not be able to match the EPA range even if you shut off the heat - because the e-Golf pack has no active heating, even pre-conditioning the car probably has a minimal effect on the pack temperature even though it will warm the cabin, thus the range will still be less than at 77 F.

Ok. The last paragraph does mix battery performance a bit with cabin heating, but when it gets cold and you decide to use the heat, range drops due to both of these factors.

As to battery longevity: the cold weather has no impact on battery longevity. While the battery won't hold as much energy when cold, if you warm up the battery to 77 F, it will perform like it did in the EPA test. Heat is what is bad for lithium ion batteries, and especially when the cells are fully charged. 100% SoC in winter is much less harmful than 100% SoC in 95 F or higher temps, if your pack can't be cooled by a BMS controlled cooling system. If I had a Tesla I would not worry about hot temps because the Tesla BMS keeps the pack temperature under control, even when not plugged into power. In the e-Golf the owner has to pay attention so as to extend the pack longevity.

I hope this all makes sense.

 

[JoulesThief]

I've always read that there's about a 16 to 17% loss of power from the motor or engine output shaft, through the transmission gears and drivetrain, to the wheels. How did you come to the 5% loss?

 

[user 2305]

That makes excellent sense

The original poster refers to passive cooling and also the Nissan Leaf, which like the eGolf, uses passive battery cooling. Some EVs such as the Chevy Bolt and Teslas use an active battery cooling system (where liquid coolant is circulated to cool the battery instead of air). These are systems which regulate the temperature of the car's battery, but not the passenger cabin.

I'm not sure which is better. Perhaps for larger batteries, an active cooling system is more important.

So with all the talk in this thread about cabin heat (resistance/heat pump) and range, I wanted to call out that the battery cooling system is a wholly different topic (and make sure the original poster understands that distinction).

 

[f1geek]

For battery longevity, active liquid cooling is the best. The battery can be kept in an optimal temperature window during high speed driving, DCFC sessions and high ambient temps. All the e-Golf and Leaf BMS can do is cut power usage or slow charge rate, and even then battery temps may get up to damaging levels under extreme conditions.

Active cooling systems are more complex, cost more, weigh more, take up more room, and use energy to operate, but I think the benefit of preserving cell longevity and also enabling high speed charging and improved cold and hot weather performance (when pack can be pre-heated or pre-cooled) are worth it, especially if buying a used EV operated for years in a hot climate.

I think it is really smart that when you put a Tesla Model 3 Performance into track mode, the battery pack cooling system is set to maximum cooling to condition the pack for the high heat generation that will accompany high speed driving and heavy regen braking. Not that I can afford that car, but I admire the engineering.