This "80% Rule"

[Wesley2024]

I am new to this EV world having only owned my RX 450h+ for a few months. I am really enjoying the car and love having the added ability to add 37 to 40 miles of EV driving. However, I am now reading regular articles that say an EV Battery should only be charged to  80%, as charging to 100%"will dramatically reduce Battery Life" If this is the case then the range of the vehicle will obviously drop accordingly. So the EV range on the RX is actually 30 to 32 miles. Likewise for full EV vehicles the stated range will be much less. I don't need to charge up every night, perhaps a couple of times a week. Do I really need to pay attention to this recommendation?  Would appreciate the views of other PHEV owners.

[RONNIE W HODGEKINSON]

39 minutes ago, Wesley2024 said:

I am new to this EV world having only owned my RX 450h+ for a few months. I am really enjoying the car and love having the added ability to add 37 to 40 miles of EV driving. However, I am now reading regular articles that say an EV battery should only be charged to  80%, as charging to 100%"will dramatically reduce battery Life" If this is the case then the range of the vehicle will obviously drop accordingly. So the EV range on the RX is actually 30 to 32 miles. Likewise for full EV vehicles the stated range will be much less. I don't need to charge up every night, perhaps a couple of times a week. Do I really need to pay attention to this recommendation?  Would appreciate the views of other PHEV owners.

Never Known an EV lexus to Charge 100% Computer Dynamic Controls Ensures this does Not Happen To protect The Battery As far as i am Aware...Cheers

[Linas.P]

1 hour ago, Wesley2024 said:

I am new to this EV world having only owned my RX 450h+ for a few months. I am really enjoying the car and love having the added ability to add 37 to 40 miles of EV driving. However, I am now reading regular articles that say an EV battery should only be charged to  80%, as charging to 100%"will dramatically reduce battery Life" If this is the case then the range of the vehicle will obviously drop accordingly. So the EV range on the RX is actually 30 to 32 miles. Likewise for full EV vehicles the stated range will be much less. I don't need to charge up every night, perhaps a couple of times a week. Do I really need to pay attention to this recommendation?  Would appreciate the views of other PHEV owners.

Luckily you don't have (B)EV, RX450h+ is PHEV and the shortfalls that apply to BEVs do not apply to your car. There are few misconceptions here - first even modern BEVs don't use 100% Battery, so what hurts them is not 100% charge but "fast DC" charging. Your car is not capable of "fast DC" charging so you don't need to worry about it (the Lexus "fast" charging is 6.6KW AC, fast DC would be something like 150-500KW DC). Either way - this recommendation you mentioned applies to BEVs not PHEVs.

The car itself will manage the Battery charging, you can plug it in without worry to degrade the Battery QUICKER, it will degrade, all batteries do degrade, but it being PHEV first of all it is not as critical for the usability of the car and secondly it won't degrade as much. Lexus PHEVs have a lot of spare capacity in Battery, so realistically it is never 100% charged, nor 100% discharged (same like BEV, but PHEV it is just easier to manage as you have ICE back-up at all times). So for example even if you charge it to what looks like 100%, the car Battery still has probably 20% of capacity left, because it still needs to have some space for regen braking etc. Likewise if you Battery runs low, it just going to switch on ICE automatically to maintain the minimal charge and operation of all systems.

With PHEV you really don't need to worry about overcharging you Battery or degradation of it. Again as I said - all batteries degrades with time and eventually your Battery will also degrade, but in practice it is almost irrelevant, you probably won't even notice significant degradation in first 5 or even 10 years. I guess the more you use the EV mode on your car, the quicker it will degrade (batteries degrade with charge cycles), but again - that is inevitable part of using the car, by doing it you don't hurt the car more.

[Wesley2024]

Thank you very much for your replies. Extremely helpful. I can now relax and enjoy the car!!

[Ken R]

I have had a NX450h+ and now have a RX450h+  and regularly charge the Battery. As explained by Linas.P you can charge with confidence!

Best that I get from the Battery in pure EV mode is 51 miles (summer months) but as you say c40 miles is available at this time of year. Superb car - enjoy yours!

 

[Wesley2024]

Hi Ken. Interested that you are getting over 50 miles of EV. My charge has gradually increased on the App to 40 but the car info screen only shows 37 max. Is your car actually displaying 50+ or is that what you have calculated the mileage after use?

Yes, I agree it is a super car!

[Ken R]

Hi Christopher

Display has shown 51 in the past. Today it was indicating 48 but given the temperature I expect to get around 42 miles. I have found that the ev range displayed is generally optimistic.

[brendangeorge]

The car's Battery management system will take of charging it and balancing the cells.  Charging to 100% will not impact the Battery life and is needed to make sure the cells are balanced.  The system will take care of that.  If you managed to discharge the traction Battery until it is flat you will be in bad shape because you need it to start the car.
EV batteries are affected by temperature - Tesla worked this out and go the great lengths to control their Battery temps - heat pumps for cooling (not just fans these days) and heating.
The 80% charge issue is important to note because it is very bad to over charge these type of Battery so a BMS takes care of it.  You can fast charge a Battery between 20% and 80% - at 80% the system slows down and has to balance the cells.  Most people with EVs who use fast charges on the road stop at 80% because of the time to get to 100% from 80%.  However, follow the instructions provided by the manufacturer and you will be fine.
There is a lot of fun stuff talked about batteries.

This may help to illustrate what a BMS does - it is not my car but Solar energy system.

The blue lines are the 4 batteries charging - they go at full rate until 90% and then slow down an balance out to 100%  We could so with some Sunshine 🙂

 

[Scotlex]

Some good information here. Thanks.

I always charge to 100%.