Charging, Charge State and Battery Longevity

M

Matt Evans

New Member
Hello Everyone,

I'm interested in optimizing my battery charging routine to maximize the life of the battery. Through the research I've done, it's my understanding that there are several significant variables that need to be considered in order to avoid undo degradation of lithium-ion cells.

The best practices for maintaining battery capacity are:
  1. Avoiding deep discharge, by not letting the battery drop below 30-40%.
  2. Not allowing the battery to hold a full charge for longer than 8hrs, preferably topping it off just before a long commute or road trip.
  3. Never charging a battery at extreme temperatures.
  4. Minimize the use of Type-3 chargers.
Assuming that these conditions should be reasonably achievable for most drivers most of the time. I'd like to discuss how best these can be achieved and to what extent Honda has taken any of these factors into consideration with their engineering.

So a few questions that come to mind,

  1. How accurately does the battery gauge reflect the actual charge state of the battery. I would assume that a full gauge would accurately reflect a 100% charge but, is the opposite true? When the gauge is reading at or near '0%', is the battery truly depleted or is there a buffer that Honda's software intentionally maintains? If so, how much?
  2. Is it possible to limit how much charge is delivered to the battery by setting an upper limit of say 80%?
  3. I understand that a thermal management system comes standard on the Canadian model. Is there a safeguard built into the software to prevent charging outside of a safe temperature range?
  4. If the car is plugged in but, not actively charging due to the charge schedule, will activating climate conditioning draw power directly from the battery?
  5. Finally, I've dug into the owner's manual that came with car but, it doesn't seem to clearly answer any of these questions for me. Does anyone know of any Honda resources that might go into more detail on these issues?
I look forward to hearing back from the community.

Thanks!
 
Here's one thread to get you started. There are others you may want to peruse too with a search on battery charging.

Since you've mentioned Type 3 chargers, which Clarity version do you have?

To summarize what I do; I just charge the car each time I'm done driving. I let the car's battery management system worry about the battery. ;)


https://www.insideevsforum.com/comm...ds/charge-strategy-for-max-battery-life.1154/
 
Matt Evans said:
1. Avoiding deep discharge, by not letting the battery drop below 30-40%.
Click to expand...
If you're driving a Clarity Electric, limiting your battery usage to 60% will result in a pretty restrictive 54-mile range. Honda's battery management systems already prevent completely discharging the Li-Ion battery pack--the full rated capacity of the battery is not actually available. The Clarity PHEV uses about 14 kWh of its 17 kWh battery.
 
Matt Evans said:
... research I've done ...
Click to expand...

Please provide footnotes/references.
Matt Evans said:
.... undo degradation of lithium-ion cells.
Click to expand...

I suspect we are all (myself included) more worried about this than we should be but are awaiting your references


Matt Evans said:
...Type-3 chargers.
Click to expand...

Ok. I’ll bite. What’s this and what Clarity’s use them?

Matt Evans said:
..
plugged in but, not actively charging due to the charge schedule, will activating climate conditioning draw power directly from the battery
Click to expand...

I can comment that even if you are not charging, you can’t start the climate conditioning if you are on a Type 1 charger (as documented).
 
Matt Evans said:
  1. How accurately does the battery gauge reflect the actual charge state of the battery. I would assume that a full gauge would accurately reflect a 100% charge but, is the opposite true? When the gauge is reading at or near '0%', is the battery truly depleted or is there a buffer that Honda's software intentionally maintains? If so, how much?
  2. Is it possible to limit how much charge is delivered to the battery by setting an upper limit of say 80%?
  3. I understand that a thermal management system comes standard on the Canadian model. Is there a safeguard built into the software to prevent charging outside of a safe temperature range?
  4. If the car is plugged in but, not actively charging due to the charge schedule, will activating climate conditioning draw power directly from the battery?
  5. Finally, I've dug into the owner's manual that came with car but, it doesn't seem to clearly answer any of these questions for me. Does anyone know of any Honda resources that might go into more detail on these issues?
I look forward to hearing back from the community.

Thanks!
Click to expand...
Hi Matt, welcome to the board! I'm going to assume since you're talking about Level 3 charging that you are referring to the EV Clarity. There seems to be more PHEV than EV owners on this board (at least the PHEV owners are more vocal), so it's nice to have an EV voice to add to the discussion.

1. The battery gauge in the dash is accurate. When you reach '0' indicated EV range two bars remain in the gauge, which is the buffer that Honda engineered into the car for battery longevity and to maintain HV capacity.
2. The car has a charge timer function, but no charge capacity limit, unfortunately. I manage this manually by utilizing the charge timer on my OpenEVSE, which is significantly easier to set and modify than the Clarity's built-in charge timer. I have a pretty good sense now of how long I need to charge from what battery SOC to reach about 90% or so in the morning just before I leave for work.
3. I've heard some owners indicating this week that they had problems trying to do a 3rd DCFC in one day. This is in So Cal, where we've been experiencing 110+ degree temperatures. So I believe there is some kind of thermal safeguard when the battery is at thermal extremes (both extreme high and low).
4. I've not tried using remote pre-conditioning while the car is plugged in, so I'm hoping others can comment on this.
5. The full owner's manual (not the abridged version that came with the car) is available to view and download here (2018 EV link). You can also request a free hard copy of it within 6 months of purchase/lease.
 
I just saw this more relevant thread after responding to another. This is what I wrote:

This is a bit of an aside of the thread but it seems that Tesla's recommendation to charge the car to 80% for everyday driving should apply to the Clarity too. I know for a fact that Tesla's battery management system keeps an upper buffer when the system stops charging because they can extend the EV range through an over-the-air update for emergencies. The 80% recommendation correlates to research on Li ion batteries to keep the charge around 50% for maximum battery longevity. The worst thing you can do for longevity is to fully charge and fully discharge between cycles (heat is a bigger killer but that's harder to control). For devices like laptops, it's always recommended to charge them frequently but not fully and never allow them to deplete if possible. Based on that, I've been been charging my Clarity to 80-85% for everyday use and rarely allowing it to drop below 40% except during road trips. I know this won't work for many but I do multiple short drives (5-15 miles each) each day so I just charge between each run.
 
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My understanding is the Honda Clarity uses Japanese Blue Energy Lithium Ion battery packs. A lithium ion battery is considered fully charged when the voltage reaches 4.2 volts. Blue Energy suggests their battery packs only be charged to 3.6 volts or 85% of a fully charged LI battery. I assume Honda followed that logic which would greatly extend the life of the LI batteries. Here is a statement from the Blue Energy web site:

　The battery is 17% lighter and 7% smaller than conventional products but offer equivalent or more capacity and output performance as well as durability/safety performance.
● Excellent output performance in the wide range of temperature.
● Long durable performance with 50,000cycle or more and 10 years or more.
● Voltage characteristic which can detect condition with ease from initial phase till the end of durability test.
● Environmentally resistant performance and resistant safety which is suitable for mounting to the vehicle.

I think Hondas computer takes care of the LI batteries so I don't worry about it.
 
Wow, this certainly clears up a lot of my questions. Thanks!

Unfortunately I haven't had the opportunity to drive my new Clarity PHEV for more than a couple hours, as I picked it up on my way to the airport before leaving for work. I really can't wait to get back and familiarize myself more with it.

It's clear from some of the responses that Type-3 chargers don't function with the Clarity PHEV, I suppose I was a little unclear on this :)

Then again, the first charging station I drove up to was a Tesla one. I had a short chat with a friendly gentleman who was charging his model X and, he explained the proprietary nature of Tesla chargers to me. He was also very interested in what the heck I was driving lol

Even in the few short hours I had with my new Clarity I got more than few curious looks and several people coming up to ask about it.
 
See attached. Reached out to an old buddy from college a while back. Turns out his company is a member organization of SAE. Here is the entire write up on
"Integrated Cooling System for Underfloor High Voltage Devices in PHEV" from Honda R&D which talks about cooling of the battery and battery system for the Clarity PHEV and Electric. To clear up some misconceptions, cooling of the battery does not involve any air conditioned air. It's basically a separate radiator system that works to bring the temperature down x degrees versus ambient. If ambient - x degrees does not fall within the target battery temperature (y), then a valve switches so that the hotter fluid bypasses the battery and the battery's thermal resistance and heat rejection is all that is left to dissipate heat from the battery. With that new information, I amend an earlier recommendation of "charge the battery as soon as you get home". The goal (y) is to keep the battery between 77 and 95 degrees. Therefore for us folk in the southern portions of the US, it is best to charge in the middle of the night as the battery temp will rise during charging.
 

Attachments

8 year, 100,000 mile warranty.
https://automobiles.honda.com/clarity-electric/landing-pages/clarity-faq#battery-last

So that is prolly on the bottom on the bell curve, so for normal folks who pay no attention it will probably last 10 years or so. For people who obsess about the battery and baby it and try to extend the life in a manual fashion like myself, it will probably last 10 years plus an extra 3 weeks, 4 days and 17 hours. :) :)

No one knows the cost right now but it is probably a pretty penny. I had an 06 Honda Civic Hybrid that needed a new IMA battery in 2012. Was able to talk them down from $3,000 to $1,200. I wouldn't be surprised if the Clarity battery would be 3 to 5 times that.
 
Matt Evans said:
Hello Everyone,

I'm interested in optimizing my battery charging routine to maximize the life of the battery. Through the research I've done, it's my understanding that there are several significant variables that need to be considered in order to avoid undo degradation of lithium-ion cells.

The best practices for maintaining battery capacity are:
  1. Avoiding deep discharge, by not letting the battery drop below 30-40%.
  2. Not allowing the battery to hold a full charge for longer than 8hrs, preferably topping it off just before a long commute or road trip.
  3. Never charging a battery at extreme temperatures.
  4. Minimize the use of Type-3 chargers.
Assuming that these conditions should be reasonably achievable for most drivers most of the time. I'd like to discuss how best these can be achieved and to what extent Honda has taken any of these factors into consideration with their engineering.

So a few questions that come to mind,

  1. How accurately does the battery gauge reflect the actual charge state of the battery. I would assume that a full gauge would accurately reflect a 100% charge but, is the opposite true? When the gauge is reading at or near '0%', is the battery truly depleted or is there a buffer that Honda's software intentionally maintains? If so, how much?
  2. Is it possible to limit how much charge is delivered to the battery by setting an upper limit of say 80%?
  3. I understand that a thermal management system comes standard on the Canadian model. Is there a safeguard built into the software to prevent charging outside of a safe temperature range?
  4. If the car is plugged in but, not actively charging due to the charge schedule, will activating climate conditioning draw power directly from the battery?
  5. Finally, I've dug into the owner's manual that came with car but, it doesn't seem to clearly answer any of these questions for me. Does anyone know of any Honda resources that might go into more detail on these issues?
I look forward to hearing back from the community.

Thanks!
Click to expand...
It may be better to use the hell out of it and let honda replace it in warranty...haha. Just saying that you could squeeze an extra year out of your battery by being extra thoughtful and have it go out just after the warranty expires. If you just enjoy the car and make it work a little harder, the battery could fail just before the warranty expires. The battery has an expected rate of degeneration. If it falls below that level while under warranty, honda will replace it.
 
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neal adkins said:
It may be better to use the hell out of it and let honda replace it in warranty...haha. Just saying that you could squeeze an extra year out of your battery by being extra thoughtful and have it go out just after the warranty expires. If you just enjoy the car and make it work a little harder, the battery could fail just before the warranty expires. The battery has an expected rate of degeneration. If it falls below that level while under warranty, honda will replace it.
Click to expand...

Unfortunately what we saw from Honda's documentation is that the battery (combined Pack A and B) would have to fall to 25% of original capacity before Honda would declare it defective - that is a fully charged battery would have to provide less than 12 miles of range.
https://insideevsforum.com/community/index.php?attachments/p144a-battery-pack-deteriation-pdf.1359/
in
https://insideevsforum.com/communit...rge-strategy-for-max-battery-life.1154/page-2
 
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