Battery Longevity

[Richard C.]

My Rav arrives this week, but I haven't been able to find definitive advice on how to baby the battery. Specifically, I drive few miles per day (usually 8-15 miles), so in my case, would it be preferable on the battery to only charge once every two or three days, or is it fine to plug in after each trip, no matter how small?

I know it's better to keep the battery in mid-range, between 25% -80% ... never going to either extreme, but was wondering if frequent charges - even twice or three times per day is better, or holding off and charging only every other day is best.

Thanks in advance for anyone who can give me wisdom!

 

[TonyWilliams]

Like any of these chemistry batteries, keeping the battery COOL and at 50% will give the longest life.

So, to answer your question would depend on the weather. In Phoenix, I would always have the car plugged (well, in the hot summer) so that the TMS will be powered. That generally means that the car will be charged to 80%.

I don't know of a way to leave it plugged in but not charge.

In moderate western Washington and Oregon, you don't need the TMS to protect the battery, so it will be easier to leave it closer to 50% unplugged for several days in a row.

The other extreme is temperatures below -20C (-4F) where I would leave the car plugged in so the cells won't freeze.

 

[palmer_md]

Like any of these chemistry batteries, keeping the battery COOL and at 50% will give the longest life.

So, to answer your question would depend on the weather. In Phoenix, I would always have the car plugged (well, in the hot summer) so that the TMS will be powered. That generally means that the car will be charged to 80%.

I don't know of a way to leave it plugged in but not charge.

In moderate western Washington and Oregon, you don't need the TMS to protect the battery, so it will be easier to leave it closer to 50% unplugged for several days in a row.

The other extreme is temperatures below -20C (-4F) where I would leave the car plugged in so the cells won't freeze.

+1 good answer.

 

[Jscifres]

I'm not going to abuse my battery if I can help it... but after 8+ years, what are the odds that a replacement battery would be an upgrade over the original when new?

 

[TonyWilliams]

I'm not going to abuse my battery if I can help it... but after 8+ years, what are the odds that a replacement battery would be an upgrade over the original when new?

These are "commodity" cells, sold by the BILLIONS (not exaggeration) of these annually. Used in common computers, phones, etc. They aren't going away in 8 years.

Our cars have 2900 mah cells. The larger 3100 cells are in the Model S. 4000 mah cells are almost ready to go.

All are in the cylindrical 18mm x 65mm "AA size" battery.

I expect at least double again in 8 years that will fit in the same box at the bottom of the Rav4. Some reprogramming and you will have 100kWh - 200kWh battery with 93.2kWh - 186.4 kWh useable.

It might take a bigger cooling system and charger!!!

 

[Dsinned]

As opposed to "charge immediate", would leaving your RAV4 EV set to a deferred, delayed start (scheduled) charging mode be a way to circumvent being plugged in, but not actively charging? I think it would. You just have to keep reprogramming the center condole (or via a Smart Phone) sufficiently ahead to thwart off "automatic" charging when plugged in at home. Simply not plugging in when the weather is moderate, would be your best bet because the TMS is not needed anyway.

Personally, I do not recharge (or plug in) until I drop into the teens on the GoM, unless I will be knowingly taking a double digit mileage trip before the next opportunity to recharge. Also, I try to stay away from extended charging as much as possible; only doing that once in a great while, as recommended by Toyota.

The main thing I worry about this time of year with the battery, is it getting too cold while parked overnight in my driveway. The OAT lately here has been flirting with freezing (32F). If I could, I would park it in a covered garage in such cold weather conditions, especially when it is raining (and certainly if it were snowing). Fortunately, I live in the SF Bay Area, where the thermometer hardly every goes below freezing in the Winter and seldom above 100F in the Summer, so I don't have to worry too much about potential degrradation taken by inclimate weather on my Li-ion battery pack.

 

[Richard C.]

@Dsinned - I agree, I think I will also refrain from charging until the range drops to 20 miles or so, then only charge up to 80 miles. Try to baby the battery as best I can. I can get away with it, since my driving needs is far less than probably most on this forum.

As Tony acknowledged, the Pacific Northwest has fairly moderate weather, rarely going below freezing or above 90. My Rav will be in an enclosed garage, so cold won't be too much of an issue, although in the summer, the garage can get pretty warm. Maybe keep the Rav plugged in with the 110 charger on those days. Does that sound like a good idea?

 

[Dsinned]

Richard, yes, I think that should be a good plan for you. Another factor here is the "rate" of charging. Generally speaking, the slower the rate of charge, the better for the long term health of the battery. On the 120V OEM charger, this would almost be like "trickle charging" a battery, which is to say, only to keep it from discharging while not in use. That's not quite the case here at 120V when the charging current will be 12A.

In your situation, it sounds like taking a round trip of 100 miles or so, will seldom be the case - same for me. I think minimizing the frequency of recharging and keeping to a regimen of minimal use of faster charging rates, can only help prolong battery life. I plan to own the car for at least ten years, otherwise this would not be of any real concern.

The reduced delta T by charging at 240V 40A vs. 240V 32A (in my case), is not that significant; maybe an hour less in duration. I usually have ample time to spare by recharging after midnight, completing by early morning before I will need to drive somewhere that day. Only doing this one or two times per week, should all that is actually necessary. My RAV4 EV will only accumulate 50 to 75 miles per week of typical driving, so I don't need to recharge every day by any means. However, I might need to do an extended charge once every few months, due to a longer than usual trip planned somewhere.

It may seem a bit paranoid, but the battery on this car is going to receive way more TLC than is really necessary from owners like us. :mrgreen:

 

[Dsinned]

These are "commodity" cells, sold by the BILLIONS (not exaggeration) of these annually. Used in common computers, phones, etc. They aren't going away in 8 years.

Our cars have 2900 mah cells. The larger 3100 cells are in the Model S. 4000 mah cells are almost ready to go.

All are in the cylindrical 18mm x 65mm "AA size" battery.

I expect at least double again in 8 years that will fit in the same box at the bottom of the Rav4. Some reprogramming and you will have 100kWh - 200kWh battery with 93.2kWh - 186.4 kWh useable.

It might take a bigger cooling system and charger!!!

I think you may be right Tony, in which case, these cars will be even BETTER by the end of the decade, which is more than anyone can say about most ICE cars. Just imagine, a 2012 RAV4 EV in the year 2020 may have a replacment battery with a range of 200 or maybe even 300 miles, and may cost no more than a few thousand dollars. The removal of the original battery and installation of the new and improved one will probably cost more than the battery itself! :mrgreen:

 

[locman]

The Nissan LEAF(I also own a LEAF) user's manual states that one way to prolong battery life is to avoid charging while the battery is hot(ie. immediately after driving)
I could not find this recommendation in the RAV4 manual. Does this mean I can ignore this recommendation for the RAV4? And this is thanks to the fact that the RAV has active cooling and overall superior battery technology?

-locman

 

[TonyWilliams]

The Nissan LEAF(I also own a LEAF) user's manual states that one way to prolong battery life is to avoid charging while the battery is hot(ie. immediately after driving)
I could not find this recommendation in the RAV4 manual. Does this mean I can ignore this recommendation for the RAV4? And this is thanks to the fact that the RAV has active cooling and overall superior battery technology?

-locman

There's also nothing about long term battery storage in the Toyota manual, either. No, please don't charge a hot battery, period. But, normally, the TMS will have the battery at the proper temperature while driving and charging. However, just leaving the Rav4 sitting out on a hot Phoenix parking lot in the summer might have some really, really hot cells... just like a LEAF.

You can "precondition" the cabin and the battery**** before you motor off or charge. That should heat up or cool down both as required. If you are driving and need a charge, have at it. Obviously, the batteries are already at the ideal temperature.

This is different than a LEAF because there is no cooling system at all on the battery, not even an internal recirculation fan that the prototypes had.


****I presume this to be the case, which is the same as Tesla who made the battery

 

[jspearman]

Definitely won't be charging our RAV mid-summer out in the wild. Short range of Leaf necessitated this, but I will do all my charging after midnight this summer. I'm convinced our Leaf met an early end because of the midday summer charging, which was always done right after driving because we didn't have time to wait. Really want a fix for charge timer issue before summer.

 

[snoltor]

Tony, I saw one of your posts a couple of days ago about how under ideal conditions the battery should be kept at 50% charge. I'm still in my first week of ownership and working out my charging schedule. At this point I could charge at work and top off the battery everyday... but from your advice it sounds like perhaps I shouldn't do that on days when I don't need the full range of the battery. Are there any sites you can point me to for reading up more on those sorts of issues? Thanks again for your advice.

Steve

There's also nothing about long term battery storage in the Toyota manual, either.

 

[TonyWilliams]

Tony, I saw one of your posts a couple of days ago about how under ideal conditions the battery should be kept at 50% charge. I'm still in my first week of ownership and working out my charging schedule. At this point I could charge at work and top off the battery everyday... but from your advice it sounds like perhaps I shouldn't do that on days when I don't need the full range of the battery. Are there any sites you can point me to for reading up more on those sorts of issues? Thanks again for your advice.

Steve

There's also nothing about long term battery storage in the Toyota manual, either.

Well, there's really nothing other than drab, technical papers out there to go by. Panasonic probably has some good data on their website (our Rav4 battery cells are 18650's built by Panasonic). We've been talking about this for years on the Nissan LEAF site, and I've personally been involved in testing cars that didn't handle the heat so well.

You'll note, Tesla just today pushed out a new change to the Model S where you can now select 50% charge level !!! Perfect for long term storage with the car left plugged in (that we will likely never get in the Rav4).

 

[n3ckf]

Just getting used to this car...

however my drive to work is < 1/4 the range of the car, so i plan to charge at work *only* most of the time. We have a lot of Level 2 30A chargers at work and they cost nothing to use. This is *better* than free gas...

But i'll leave it uncharged at night for awhile since on those rare occasions when i need more range, i could top it off at night in the garage @ 120V (I dont own my garage, so i cant install a charger here). About 7 hours of 120V charge replaces what it takes me to get to work (or back).

 

[cwerdna]

^^^
Yep. I know someone w/a BMW ActiveE who "reverse charges" (former Leafer). He gets free L2 charging at work and I believe occasionally does L1 charging at home.

Installing a L2 EVSE at home was crazy expensive due to the amount electrical work needed. So, he didn't do that.

 

[snoltor]

Well since I'm in biology research I'm used to drab boring technical papers! Still learning lots, found a paper yesterday posted on one of the forums.... also been reading posts on the Tesla forum. By the way, the Rav4 EV does have the same battery that Tesla originally offered, or was going to offer with the base Model S, right? Especially in terms of the type of lithium battery used.
I'm finding this website useful for getting up to speed on battery basics:
http://batteryuniversity.com/learn/

Well, there's really nothing other than drab, technical papers out there to go by. Panasonic probably has some good data on their website

 

[RAV4Elly]

When plugged in doesn't the cars computer dictate how best to charge the battery? I leave my car plugged in when I am home. I use the 40 amp leviton charger.

 

[Vach]

There's also nothing about long term battery storage in the Toyota manual, either. No, please don't charge a hot battery, period.

I'm not sure if they have updated these manuals recently, but I found some minor stuff referring to this in the manual on the website:
http://www.toyota.com/t3Portal/document/om/OM42838U/pdf/sec_01-03.pdf

Page 80 to 81, although they don't get really specific on the storage and mention other storage tidbits throughout the chapter. It's like they want you to go fishing for it or something.

 

[waidy]

There's also nothing about long term battery storage in the Toyota manual, either. No, please don't charge a hot battery, period.

I'm not sure if they have updated these manuals recently, but I found some minor stuff referring to this in the manual on the website:
http://www.toyota.com/t3Portal/document/om/OM42838U/pdf/sec_01-03.pdf

Page 80 to 81, although they don't get really specific on the storage and mention other storage tidbits throughout the chapter. It's like they want you to go fishing for it or something.

Thanks for the pointer. This is interesting: On page 80, it said "Pre-climate operations will occur while the amount of charge remaining in the traction battery is more than 50% at the time pre-climate operations begin. " Do they means 50% of 16 bars or 50% of the 16 bars + the 4 hidden bars? Technically, SOC should be referred as the percentage of charge of a complete pack which is not 41.8 kWh but 50+ kWh.