Battery monitor status indicator

[dannyboy413]

I have the 1.8 Hybrid Sol saloon, (top of the range in Ireland), and took delivery just as lock down was starting. I have to say that I am extremely pleased with the car but one thing puzzles me. The display showing how full the hybrid Battery is never shows full. The majority of the time it shows two or three 'empty' cells and quite often, if I try and force the car into electric vehicle mode, I get a message stating that there is not enough Battery power available. I do a 20 mile journey twice a day, Monday to Friday, plus other occasional journeys and the car will use the electric motor when necessary. Is what I am experiencing 'normal', or is the Battery not being charged as it should be?

[Catlover]

The computer system is programmed such that the Battery will never be full, nor will it ever be empty. It’s to protect the Battery, complete fill to empty apparently hurts the Battery and will shorten its life. Just let the computer do it’s job, relax, and enjoy the drive.

[dannyboy413]

Thanks for that Catlover. I hoped it was just the computer doing what it should, but nice to have it confirmed. And I certainly do enjoy the drive. 😀

[AndrueC]

It is unusual to see a fully charged Battery on the display. It usually varies between two or three bars of charge left at the bottom and one or two bars space free at the top. I've never seen a message saying that the Battery is not available - it just refuses to take over.

It's also worth considering that since all the energy in the Battery originally came from burning fuel and since the process of putting energy into and taking it out of the battery incurs losses it's probably not optimal to force electric running at every possible opportunity. The battery is best kept in reserve to take over from the ICE at low RPMs (urban driving or maintaining speed on a gentle downward slope). The losses from an ICE running at low RPMs will be greater than the losses from the battery/motor so overall you save energy.

This is why hybrids make great Taxis but are less 'spectacular' on the open road. They will generally beat the fuel economy of a petrol engine and with care can match that of a diesel but around town they are only beaten by a true EV.

[PeteB]

In fact, if the gauge ever shows all 8 bars lit, and it's continued receiving charge until the Battery will not accept any more (referred to as "Maxed out" - generally some time after the 8th bar lights up), the true State of Charge (SoC) is actually 'only' about 80% full.  If empty (no bars lit) it would still have about 40% SoC.  The gauge displays a 'window' of usable charge ranges that the Hybrid engineers deemed safe to allow.  This, along with managing rates of energy flow into and out of the Battery and cell temperatures is part of the 'secret' to the long life of the rechargeable Battery pack.  When the original Prius arrived in 1997, lots of doubters predicted masses of owners regularly spending a fortune buying replacement battery packs.

Here's a diagram showing the ranges of charge the relates to each bar of the gauge from an older Prius versions, but the principal remains on current models: 

 

A 2002 first generation Prius I once owned had some 70,000 miles on the clock before I experienced a true 'maxed out' condition for the very first time.  It was on a holiday in Scotland when I encountered some 5-6 mile long 1 in 5 (20%) gradient hills, and descending those saw the battery max out after 3-4 miles.  The original Prius didn't have an EV button (nor ECO or PWR for that matter) but when I reached level ground I found I could accelerate moderately briskly up to 60 mph on electric alone, as the system tried to use up some power to make room for any further 'free' regenerated energy that could be had.

The design philosophy appears to try to stay in the range of 2-6 bars lit.  Any lower and the engine works harder to add charge, any higher and it tries to use some charge up.  This is so that there's always enough energy to proved extra boost for acceleration or hills when needed, and nearly always enough room to receive regenerated energy from slowing or braking.

[dannyboy413]

Many thanks for the replies, the explanations given make sense.

Quote from AndrueC -

 "They will generally beat the fuel economy of a petrol engine and with care can match that of a diesel"

My last petrol engine car averaged about 38 mpg. My last car, a diesel, averaged 59 mpg and the Corolla, (using my own stat's), is doing 53.08 mpg after 14 weeks, so I am happy. 👍

[Rosgoe]

On my auris icon+ the engine never ever charges the Battery to full but using the brakes down a long steep hill will. Interestingly when the Battery meter showed full I could not switch it to ev mode it said ev mode not available until some of the change was used up.Don’t know if this will be the same on the corolla I am yet to find out as I haven’t got it yet!
i am wondering is it because the corolla batteries are lithium where as on the auris they are nickel metal hydride I think.

[Timmon]

The Corolla 1.8 and 2 ltr have different batteries. 1.8 is Li-ion , 2.0 is nickel-metal hydride. 

I have the 2.0 and it never shows full Battery driving locally. But on a trip to Devon last year I descended a long Devon hill, and it showed full and kept charging for 5 minutes under breaking.

 

[PeteB]

57 minutes ago, Rosgoe said:

...Interestingly when the battery meter showed full I could not switch it to ev mode it said ev mode not available until some of the change was used up...
i am wondering is it because the corolla batteries are lithium where as on the auris they are nickel metal hydride I think.

More likely because when you first tried the Battery was too hot for the software to allow selection of EV Mode.  The large amount of charge while descending a long, steep hill will have heated it up considerably.

[Rudy.]

On 7/9/2020 at 2:13 PM, Catlover said:

The computer system is programmed such that the Battery will never be full, nor will it ever be empty. It’s to protect the Battery, complete fill to empty apparently hurts the Battery and will shorten its life. Just let the computer do it’s job, relax, and enjoy the drive.

Hi. Thanks for clearing this up I have just bought a 2020 Toyota Corolla GR SPORT and first time owning a hybrid. I was baffled as to why the Battery never went up towards full, max I have had is 2 bars from top. So far love the ride it handles pot holes and smooth on the motorways too. 

[Woofwoof]

i have the 1.8 and it only shows full Battery when doing steep downhills tretches but at 1 point it got to a point where i felt the physical breaks engage