Good practices for longer battery life

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raghu1111

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Joined
Mar 2, 2018
Messages
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I just bought 2017 SE rather than leasing. I love the car so far.

I am wondering if there are recommended charging practices for longer battery life. Please post a link here or tell us about your best practices. My Nissan Leaf had a setting where it can charge till 80% rather than 100%. I didn't see any setting like that for e-golf. I am not even sure charging only till 80% each time helps. I would not like to change my driving habits too much. The car handles well, and I wish drive it normally.
 
I have done extensive reading before I got my 2017. It seems that there are two distinct belief camps out there:

1) pay attention to the charge percentage (as you indicated) and charge to 80%, do not discharge below x% (usually 25 or 15).

2) VW has already taken care of this for you via the battery management. 100% are not really 100% and 0% are not really 0%. The protective margins for the battery are already respected in the system setup. Similar to a cell phone. So, don't worry, be happy, drive and charge as needed.

I tend to believe that camp #2 has it right.
 
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
 
cattlerepairman said:
I have done extensive reading before I got my 2017. It seems that there are two distinct belief camps out there:

1) pay attention to the charge percentage (as you indicated) and charge to 80%, do not discharge below x% (usually 25 or 15).

2) VW has already taken care of this for you via the battery management. 100% are not really 100% and 0% are not really 0%. The protective margins for the battery are already respected in the system setup. Similar to a cell phone. So, don't worry, be happy, drive and charge as needed.

I tend to believe that camp #2 has it right.

Camp #2 has it correct. VW engineers protect the battery from almost everything except DC Fast Charging, and they explicitly put in the owners manual that it will reduce battery life, and to Level 2 recharge fully every time after a DC Fast Charge. The purpose of Level 2 recharging is to make certain that the batteries A) get charged to where VW wants them when they consider it fully charged, and B) all the cells get an equalization charge. An Equlization charge is what maintains the battery life the longest for all the cells in the battery packs, the weakest ones, vs the strongest ones, due to manufacturing variances among battery cells.

In Summary, plug in overnight at home when you need a recharge, drive more, and worry less. Those are the instructions VW gives. Do this and it's unlikely you'll have battery problems under warranty. Try to avoid getting the "fuel tank" battery charge into the red zone, and charge up as soon as possible if it gets in that zone. Red zone, on any of the gauges, on a German car means stop driving and fix the problem. That includes the battery cells, don't go there... Red means STOP!
 
Thank you for the sound advice. I can imagine how #2 is what the car would be designed to support. Interesting to hear about 'equalization'.

One more clarification : I need only about 25% of the charge for daily commute. Do you suggest recharging to full each day (my work has level-2 charging & level 1 at home if needed) or charge once in 2 or 3 days (well before red zone)? From the description above, charging every day is just fine.
 
raghu1111 said:
Thank you for the sound advice. I can imagine how #2 is what the car would be designed to support. Interesting to hear about 'equalization'.

One more clarification : I need only about 25% of the charge for daily commute. Do you suggest recharging to full each day (my work has level-2 charging & level 1 at home if needed) or charge once in 2 or 3 days (well before red zone)? From the description above, charging every day is just fine.
Here's my recommendation: If you really truly only need 25% of the battery on a 2017 car (35kWh) then you can use the e-Manager to configure the car to only charge to 80% of the usable capacity. Then, it will drop to 50%-60% SOC during normal use and you can charge it every day like that. However, you should think about what kind of emergencies can come up in your life and make sure that the typical remaining charge is enough to handle those emergencies. I'm thinking of things like your kid gets hurt at school and you have to go pick them up, even if your spouse would normally handle that, it may still fall on you.
 
miimura said:
Here's my recommendation: If you really truly only need 25% of the battery on a 2017 car (35kWh) then you can use the e-Manager to configure the car to only charge to 80% of the usable capacity. Then, it will drop to 50%-60% SOC during normal use and you can charge it every day like that. However, you should think about what kind of emergencies can come up in your life and make sure that the typical remaining charge is enough to handle those emergencies. I'm thinking of things like your kid gets hurt at school and you have to go pick them up, even if your spouse would normally handle that, it may still fall on you.

Thanks. I didn't see any setting to limit charging to 80%. Do you know where it is? I have lived with Nissan Leaf for 5 years (e-golf is replacing it).

120 miles is more than double current range of my leaf... so it is a luxury for me :). Leaf's battery lost 4 out of 12 bars, 33% degradation. We can always take a cab for emergencies from work since I live in a large metro area.
 
This link takes you to a video that goes through the e-manager settings. Hope it helps.

https://youtu.be/B7NpXhFHwlk
 
Does the e-Golf only truly level it's battery cells when touching a full 100% charge, or do they level during all L2 charging? When charging to a specific decile, like 70% or 80%? Is there harm in charging for a specific window of several hours each day, ending at a specific time and leaving the battery at a random SOC of, say, 68%?

I find VW's charging protocols abominable. Everything is either tied to charging immediately, or to a departure time. I'm self employed, so the idea of leaving at a specific time every day is foreign to me. Since the battery of the car is big enough that it is only on long trips that I want to charge towards the top of the battery, my ideal regular practice is to charge when power is cheap and clean. e.g. running from my solar array, or running from the 80% of my grid power that comes from a nuclear plant 50 miles away, which I can count on being all nuclear and no natural gas at night. My interest is in charging my e-Golf at a relatively gentle rate during those periods (say 13 amps and 240 volts), most typically from about 8 am to around noon or 1 pm, to minimize battery capacity loss. In my mind, anything close to a 70% reduction in range in 100,000 miles would constitute a horrible failure. In 81,000+ miles on my '13 Volt, my battery still charged to 4.036 volts in each cell in summer. Perhaps 1% range loss in four years and that many miles. Too small to measure with certainty. But I had to burn gas on long trips, so I switched to the '17 e-Golf, which allows me to do long trips without any gas at all, and that can charge at a full 30 amp L2 charging rate, and has the DC charging option.

My interest is in practicing charging during a specific window in time, to whatever level that achieves. Whether it's 74% or 82% doesn't really matter to me, since day to day I only use about 1/4 or 1/3 of my battery's capacity. I do not get net metering from my utility, so when I come back from long weekend trips I have an opportunity to drink up a substantial amount of my solar over two or three days, for example taking my battery from 28% to 64% the first day, 36% to 72% the second, 47% to 83% the third, and so on. Yet VW could not conceive on a circumstance where someone would simply want their car to stop charging wherever "off-peak" time ran out, and stop when power became more expensive or dirtier. Since I do not have a regular departure time, I just want to bank a reasonable amount of clean energy into it each day. It's rare I know in advance exactly when I'm going to leave.

All they had to do was offer a charging option to charge only during "off peak" rate hours. Without a departure time, their complex screens do not allow for such a protocol. Not without a burdensome amount of math every time one arrives home to set up charging for the next day. It's astounding to me they haven't, particularly given they do nothing to dispute that gentle charging tends to be easier on a battery, and charging to a lower peak voltage allows for more watt hours of throughput for a battery over its lifetime. Nor do they guarantee it won't matter. 30% range loss is a largely empty guarantee for anyone willing to do what's necessary to do better. I just don't buy Cattlerepairman's presumption that presumption #2 is correct in his hypothetical, particularly if it means I have to be the guinea pig.
 
VW guidelines for charging are given in the context of battery warranty, which is mandated by California. VW wants to sell you another car, not another battery, so if you want to keep the battery in top condition (and exceed the warranty guarantee), do NOT rely on VW software to do that.

For routine driving, don't charge above 80% SOC and don't discharge below 25% SOC. For occasional long trips, charge to 100% immediately before leaving and if the fuel gauge gets in the red zone, charge immediately. I don't think anyone who has commented here has any specific knowledge of how the e-Golf BMS balances cells.

If you want to charge only during certain times, set up the charge timer to only charge "off peak" at your preferred times. Also, set the maximum charge % to whatever value you want. If you need to charge immediately, just press the immediate charge button.

As far as 13A vs 30A, with a 35.8 kWh battery, charging at 240V, 30A is only 0.2C, so I am skeptical that you would do any damage at that charge rate, based on experimental data that correlates C rate with degradation. Of course, if you want to be really conservative, charge at 13A.
 
Thanks. I had such good luck charging at 0.1C on my '13 Volt that I'm inclined to stick with that. It also allows me to be sure I'm shaving the maximal amount of kWhs from my solar array. That produces at a typical bell curve shape from about 8 am to 1 pm, so I can be sure I'm drawing entirely and only from that if I charge at 3.1 kWs for several hours in the middle. A higher rate would mean grid power for the slightest cloud, and long stretches where the car was done charging.

A good chunk of my frustration comes from my charging experience after my return from my last trip. I set it to charge from 8 am to 12:30 pm at 3.1 kWs, but made the mistake of setting the limit at 80%. The battery was at 25% when I got back, so it started charging at about 6:30 am to make sure it hit 80% by 12:30 pm, even though that was outside my off-peak setting. So I payed retail for the extra amount, and I had to sell more of my production the following day at 3 cents a kWh, rather than put it into my car. If my utility doesn't want my power, I'd rather keep it for myself. Next time I'll spend the minute or two to do the math and set a more appropriate limit.

GM has three charging modes- immediate, departure time, and off-peak. And you can prioritize off peak and allow peak, or allow only off-peak. I'm amazed VW's engineers left that out entirely. GM's set up is simpler, and more functional.
 
Have you in the e-Manager created a Charging Location with the off peak hours and then assigned it to a Departure time?
 
Thank you for the video. That was very useful. So the maximum charge setting is inside each 'location'. The car manual is very big and I am still skimming through it. I wish VW has small help bulbs on the system (similar to digital cameras). Also there does not seem to be any soft copy of the manual available.

SocaleGolf said:
This link takes you to a video that goes through the e-manager settings. Hope it helps.

Code:
https://youtu.be/B7NpXhFHwlk
 
The manual is huge, confusing much of the time, and poorly laid out. In the 2017 manual the Start Engine procedure is on page 212. Maybe the wanted to make sure you read everything before that.

I did find a 2015 online copy https://carmanuals2.com/get/volkswagen-e-golf-2015-owner-s-manual-88312

When I contacted VW Chat regarding an online or pdf version I was told " there is not a timeframe on when one would be available, regretfully." So I am not holding my brief on this one. Glad you find the video helpful.
 
SocaleGolf said:
Have you in the e-Manager created a Charging Location with the off peak hours and then assigned it to a Departure time?

Absolutely. That's where most of my frustration stems from. The departure time, the limit setting, and the off peak hours fight with each other. There's no way to get them into full agreement. And the math to get them even close is completely unnecessarily burdensome. The protocols should simply ask you to prioritize which ones should rule.
 
EdWNorris said:
SocaleGolf said:
Have you in the e-Manager created a Charging Location with the off peak hours and then assigned it to a Departure time?

Absolutely. That's where most of my frustration stems from. The departure time, the limit setting, and the off peak hours fight with each other. There's no way to get them into full agreement. And the math to get them even close is completely unnecessarily burdensome. The protocols should simply ask you to prioritize which ones should rule.
The only way I found for the system to work predictably on my 2015, back in 2015, was to disable the Off-Peak function. That leaves simple departure time math based on SOC and EVSE voltage and amperage. When I tested it in detail back then, I found that the 240V 30 amp charging finished within +/- 5 minutes of the departure time and the provided 120V charge cord finished about 30 minutes late after running for 10 hours.
 
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