New to Prius Prime - Battery Questions

Discussion in 'Prime Plug-in Charging' started by route246, Jun 23, 2020.

  1. route246

    route246 Member

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    I'm new to the Prime but this is my 4th Prius so I'm not new to the brand or the car. That said, I have been relentlessly holding off buying a plug-in or full EV because the pending battery technology breakthrough (low-valence nano-fractal peace dividend electrode substrate technology) we are all waiting for hasn't happened yet. Back in 2010 I guessed it would have broken through by 2015 or so but we're still waiting. I avoided lithium-ion for safety reasons (they tend to overheat easily when under high discharge rate or worse get shorted) and lack of wide climate and temperature range performance, but the temptation this year to get a 2020 Prime got the best of me so I sold my 2014 to a friend and got one. No regrets, no remorse. The car is everything I expected.

    That said, I have read everything in these forums that I could regarding traction battery hygiene and I see a lot of vagueness and inference but no real definitive scientific opinion based on research into the chemistry and physics of keeping lithium-ion batteries healthy. Is there any basic research published? I am sure there are patent filings and scientific papers out there but I haven't had time to search for them.

    There are some common sense ideas that can be safely inferred like avoiding cold and heat when possible but very little research-based opinion regarding charge/discharge speed, optimal capacity management and general sound guidelines which are backed by research and science.

    One thing that I'm curious about is Level 1 vs Level 2 charging. I currently use L-1 at home and L-2 where I can get it for free. My intuition tells me that -L1 is less stressful but others here have said L-2 is not a problem. I know for a fact that L-2 generates more heat than L-1 which cannot be a good thing. With shelter-in-place orders here in NorCal I haven't had much opportunity to commute to work or take the car on the road (spare tire arriving in a few days from eBay, thanks to forum articles here about which tire size to order, etc.) but I have driven quite a bit locally here and getting 34-38 miles on a charge (I have experience hypermiling my previous 2014 Prius to 74MPH for a full tank). I don't see a need to invest adding a 50A circuit since I'm plenty comfortable using gas if necessary (I don't think I've spent more than a few miles out of 600 total in hybrid mode, BTW). I really don't see the need if the L-2 charger is going to degrade the batteries, even minimally, over the life of the car. Will it degrade the batteries more than L-1 would?

    Anyway, thank you for the wonderful forums. I've learned a lot here.
     
  2. ColoradoBoo

    ColoradoBoo New Member

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    Yes it's interesting to hear of the new technologies and things they are working on. Aren't you stoked for the hydrogen engine Toyota has been working on???

    Concerning the batteries and temperatures, in 2005 a co-worker moved from Colorado Springs to Fort Greely Alaska and he drove his Prius up there. Fort Greely can hit -60 so I asked him what mods his did for the arctic weather and he said he had the dealer put in a block heater, radiator heater, and they have a small electric heating blanket that you put around the battery. That winter, I kept asking him how the Prius was doing and he said great....always started and seemed to be functioning normally. He did say it takes a long time to heat up but at those temps that's true of just about all 4-cylinder cars....even Tundras take quite a while to warm up at -60. (I worked a year up there in 2008)
     
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  3. bisco

    bisco cookie crumbler

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    toyota has taken care of all that, no worries. best you can do is keep the cooling system clean. L1 and L2 are not significantly different.
    you can drive like me, a little old lady. toyota plugs have proven to be very durable.
     
  4. route246

    route246 Member

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    Thanks. I drive my daily driver like an old grandmother. I have a 400HP Focus RS on the weekends and drive like a madman. I lead two lives, driver wise. LOL.
     
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  5. Salamander_King

    Salamander_King Senior Member

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    When you find it please post it here. I probably won't understand most of them, but someone here will. For me, battery maintenance and longevity are more of art than science. You will find a lot of antidotal claims on "did this and the battery lasted this long" or "didn't do this but the battery still lasted this long". I just think there isn't any simple answer.
     
  6. route246

    route246 Member

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    I tend to agree with you in full. Inference can be less than optimal, especially when scientific method is not applied to something like battery life which requires it. I'll start doing some searches to see what comes out.
     
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  7. Hicksite

    Hicksite Junior Member

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    There’s an interesting (to me at least) article on battery life and contributing factors at: geotab.com/blog/ev-battery-health/
     
  8. route246

    route246 Member

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    Excellent article. This is the type of data I was looking for. There is quite a bit of generalization but it is backed up by data.
     
  9. jerrymildred

    jerrymildred Senior Member

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    I've already pointed this out in several other threads where people got concerned about L2 charging. It takes two hours at L2 to go from 0% EV to 100%. If you're driving and put the car in charge mode, it'll go from 0% to 80% in about 30 minutes. That's almost four times the charge rate of L2.

    And, if I drive 60 mph in EV, I'll go from 100% SOC to 0% in way under 30 minutes. Last summer, in Colorado, I went from 10% SOC to 98% SOC in maybe 20-30 minutes going down a long steep grade. The ICE came on at 98% and my guess was that the battery was getting warm so it stopped charging. So L2 is nuthin'.

    Toyota doesn't want your car to break, so they went way out of their way to make sure you can use it normally. Also note that in Japan, you can get it with CHAdeMO charging which is more amps than a typical house can provide.
     
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  10. route246

    route246 Member

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    I'm new to Prime and EV, less than a month new, but I have been reading up on the battery topic for a long time. I'm not really concerned as much as just curious about best practices based on scientific research vs anecdotal or inferred opinion.

    The only exception I take to inferred opinions regarding charge rates, ambient temperature and capacity guidelines based on logical thinking is that batteries, especially lithium-based ones have non-linear behavior in state-of-charge and wear and charge/discharge characteristics.

    Here are some points I ponder with respect to this subject.
    • EV vehicles use an array of 18650 cylindrical cells. The capacity is determined by the number of 18650 cells. One point lost is the number of cells also determines the amount of charge and discharge current that is loaded to each individual cell. Tesla uses a huge array of cells for the Model S and enables and disables them according to the feature you pay for when you buy the car. Lower range means lower capacity allowed but it is for the same number of cells for the same SOC capacity. It sounds counter-intuitive but if I owned a Tesla I would try to find the S-model 60 (lowest, I think) because it is going to have the best conditioned battery. Again, this is just a logical inference, perhaps a misguided inference.
    • Discharge and charge rates are independent in terms of battery wear. There is much conventional wisdom inference that they are the same. It could be valid, no dispute of this. I would just like to read some scientific reasoning to back up this inference.
    • L1 and L2 are arbitrary standards based on input current limits but as I understand things the charge control unit in the car determines the actual charge current and resulting charge rate. As I understand things charge rates are very non-linear based on the overall SOC. Again, a lot of inference here but it is short on data.
    • I bring up linearity and equivalence because much inference is based on it. I just found the batteryuniversity website and it has a wealth of scientific data and reasoning which I am digesting now. It is overwhelming, BTW.
    • Lastly, I hope this doesn't evolve into something like this thread: Full state of charge vs 80% | PriusChat which I found informative and amusing but very difficult to pull wheat from chaff. I remember lurking in this thread when it happened and I learned a lot but there were too many hard feelings and gotcha's for my taste.
     
  11. bisco

    bisco cookie crumbler

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    probably better off in the technical section
     
  12. Hicksite

    Hicksite Junior Member

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    In the article on geotab.com to which I provided a link, the data showed an observable but not significant difference in the effect on battery health for L1 vs L2 charging, but a significantly more negative effect for DCFC charging, due to relatively high currents and temperatures. I wonder if driving in charge mode has a similar effect? I have never seen a need to use charge mode, but I know others sometimes use it.
     
  13. jerrymildred

    jerrymildred Senior Member

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    I have experimented with charge mode, but I don't use it either. Too inefficient.
     
  14. Hicksite

    Hicksite Junior Member

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    Yeah, I thought so too!
     
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  15. Fuel Miser

    Fuel Miser Junior Member

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    I use Charge mode quite frequently. So far it hasn't really affected my range in any measurable way. Mind you I don't have access to a plug at the apartment building just yet. I typically also don't fully run from 0 to 80 using Charge mode. I would say from 30%-70% when I'm driving at an optimal 45 - 50 MPH ( 70 - 80 KM/h ) as it charges the fastest (most efficient) at these speeds. I charge at work on their Lvl 2 from time to time unless its like 95 degrees out. I will typically go 640miles before I need to fill with 1/4 tank gas left.
     
  16. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    From what I understand, one has to practically be an electrical engineer to know when CHARGE mode is a win. I think that there are only a few very specific cases where one comes out ahead using it; it is almost always more efficient to just let the car mange things itself in hybrid mode if you cannot charge from an outlet.
     
  17. Salamander_King

    Salamander_King Senior Member

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    I think you are correct in terms of the energy efficiency. But I am wondering what about economic of the CHG mode. I am paying ~40% more on electricity compared to gasoline for the same distance. If I use gasoline to charge the traction battery, would it be cheaper than charging from the wall?
     
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  18. jerrymildred

    jerrymildred Senior Member

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    I think in your case charge mode would be cheaper than from the wall, but most likely not cheaper than just leaving it in HV. At speeds where the engine can economically charge the battery, it does that anyway and switches back & forth every couple miles from EV to HV and back.
     
    #18 jerrymildred, Jul 24, 2020
    Last edited: Jul 24, 2020
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  19. Salamander_King

    Salamander_King Senior Member

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    Yeah, that's the thing. HV mode is already so efficient, using the CHG to drive later on EV mode probably use more gas than just driving HV mode to go the same distance. That's why I am using HV mode to charge my battery to get the maximum amount of EV efficiency.. Right now, I am hovering around 20miles/kWh on EV mode, but this is with a lot of help from gasoline engine on HV mode.
     
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  20. Tideland Prius

    Tideland Prius Moderator of the North
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    Agree with the last four messages.

    One thing you might wanna use CHG mode for is for Remote A/C. It won’t work if you’re in HV mode so if you want to pre-cool the cabin, it’ll cost you a bit of fuel ahead of time.
     
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