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New Feature: Automatic Charge Threshold

Posted: Tue Jun 04, 2013 6:07 pm
by LoeSar
My wife and I take short trips(5-20 miles) to the store or kids activities. We don't use the charge timer because we might use 15 miles one day and use 50 miles another day. We just charge it when there is less than 28 miles left.

I propose having what I call an automatic charge threshold were i.e. if you have less than 15 miles or 10% SOC start charging to set maximum(80% or 100%). The values should be set by the user regardless of the charge timer setting. This would reduce the number of charge cycles and extend battery life also it would simplify the charge procedure and reduce user worry.

I see three solution levels 1. charger feature, 2. Carwings, 3. Car firmware.
1. A third-party solution where the evse determines when to charge
2. Another third-party solution where Carwings is used to remotely determine when to charge(probably the mostly problematic solution considering Carwings reliability.)
3. Car level solution; the best solution imo

Then when they have induction chargers there will be no need to worry about when to charge or about plugging it in.

Please give me your feedback and support if you like the idea or not!

Re: New Feature: Automatic Charge Threshold

Posted: Tue Jun 04, 2013 7:00 pm
by davewill
LoeSar wrote:... This would reduce the number of charge cycles and extend battery life also it would simplify the charge procedure and reduce user worry. ...
Charge cycles are not literally the number of times you charge the battery, but how much charging is done. Charging from 20% to 80% once is roughly equivalent to charging from 40% to 70% twice. Concentrating the charging into fewer sessions doesn't help. Your proposal does keep the average charge level lower, but if it causes people to discharge below 20% more often, it's no help at all.

Personally, I just charge to 80% any time I get the chance to plug in...unless I need to go to 100% for some reason.

Re: New Feature: Automatic Charge Threshold

Posted: Tue Jun 04, 2013 7:16 pm
by LoeSar
davewill wrote:Charge cycles are not literally the number of times you charge the battery, but how much charging is done. Charging from 20% to 80% once is roughly equivalent to charging from 40% to 70% twice. Concentrating the charging into fewer sessions doesn't help. Your proposal does keep the average charge level lower, but if it causes people to discharge below 20% more often, it's no help at all.

Personally, I just charge to 80% any time I get the chance to plug in...unless I need to go to 100% for some reason.
Yes, keeping a battery charged to 100% all the time reduces battery life; the piont I failed to make is lower soc increases battery life over time. Please explain why going below 20% is not good?

Re: New Feature: Automatic Charge Threshold

Posted: Tue Jun 04, 2013 9:42 pm
by LeftieBiker
It's become clear that early claims about lithium batteries, like the ones about NiMH and NiZn packs, were a bit exaggerated. While lithium packs tolerate going below 80% charge better than lead-acid batteries, it still shortens their life significantly. The Prius NiMH packs have done so amazingly well because the battery management system never lets them get to 100% charge, and doesn't let them fall below, IIRC, 30% - unless the car isn't run and it can't recharge them. So the best way to treat a Leaf battery pack is to keep it (roughly) between 25% and 85% charge. That doesn't necessarily mean that fast-charging it all the time to keep it in the optimum range is good either, though...

Re: New Feature: Automatic Charge Threshold

Posted: Wed Jul 03, 2013 5:28 pm
by JasonA
And Nissan doesn't allow the Leaf's pack to goto full 100% either. By defintion, a LiPo/LiOn cell is at 4.20v fully peaked/charged. The Leaf's BMS starts to cut off at 4.11 (too bad because there's ALOT of headroom and capacity left in that space)..

And on the bottom side, the low end on the scale is perfect for storage or long term sitting in the 3.8v range with 2 bars on the gauge.

I think having a "user adj" charge range is a great idea because it's NOT CONSIDERED a full cycle on the pack for those who want to drive 15-30 miles a day on flat areas.

This is why Tesla is sooo popular in that area. User adj battery charge points.

Longer battery life.

Re: New Feature: Automatic Charge Threshold

Posted: Wed Jul 03, 2013 5:45 pm
by adric22
LoeSar wrote:e having what I call an automatic charge threshold were i.e. if you have less than 15 miles or 10% SOC start charging to set maximum(80% or 100%). The values should be set by the user regardless of the charge timer setting. This would reduce the number of charge cycles and extend battery life also it would simplify the charge procedure and reduce user worry.
I'm failing to see what this "feature" will offer that the built-in charge timer doesn't offer. I set my charge timer to charge from 12:00am to 11:59pm. Essentially that means it will always start charging whenever I plug in the car, assuming it is less than 80% state of charge. That way I don't have to think about it, just plug it in. If I need to go further and I realize this a few hours ahead of time, I just walk out to the car and press the button on the dash that disables the charge timer, so the car begins to charge to 100%.

Granted, I think it would be nice if the 80% charge mode were made independent of the charge timers since it can be a bit confusing for some people. Actually, I wish they gave the user the ability to just pick a percentage, anything from around 50% to 100% in 5% intervals. For example, there are probably people who don't need 100% charge, but need just a hair more than 80%. Wouldn't it be nice to be able to set it to 85%, or 90%?

Re: New Feature: Automatic Charge Threshold

Posted: Wed Jul 03, 2013 8:54 pm
by LeftieBiker
adric22 wrote:
LoeSar wrote:e having what I call an automatic charge threshold were i.e. if you have less than 15 miles or 10% SOC start charging to set maximum(80% or 100%). The values should be set by the user regardless of the charge timer setting. This would reduce the number of charge cycles and extend battery life also it would simplify the charge procedure and reduce user worry.
I'm failing to see what this "feature" will offer that the built-in charge timer doesn't offer. I set my charge timer to charge from 12:00am to 11:59pm. Essentially that means it will always start charging whenever I plug in the car, assuming it is less than 80% state of charge. That way I don't have to think about it, just plug it in. If I need to go further and I realize this a few hours ahead of time, I just walk out to the car and press the button on the dash that disables the charge timer, so the car begins to charge to 100%.

Granted, I think it would be nice if the 80% charge mode were made independent of the charge timers since it can be a bit confusing for some people. Actually, I wish they gave the user the ability to just pick a percentage, anything from around 50% to 100% in 5% intervals. For example, there are probably people who don't need 100% charge, but need just a hair more than 80%. Wouldn't it be nice to be able to set it to 85%, or 90%?
Yes, that is the most common complaint about the charge settings.