I don't think the normal depleted battery level is 20%

Hi,

I've now topped up the battery at a rapid charger (Ecotricity) twice. The first time the car showed 1 mile EV range remaining. The second time it also showed 1 mile EV range remaining but the engine started as I left the motorway???

The Ecotricity chargers show the car's battery level while charging and on both occasions the battery level was shown as 31% when the charging commenced.

I don't think this stacks up with the generally accepted 20% minimum battery level when the battery is normally depleted. I would have to say the normally depleted battery looks to be more like 30%. I see no reason to doubt the Ecotricity indication as it will only charge to 80% so it needs to know this number reliably to avoid damaging the battery.

Any experiences from anyone else? Anyone seen below 30% charge when they use a rapid charger?

Kind regards,
Mark

How does the rapid charger know the charge level of the battery? It has to be able to manage a wide range of cars that will have very different charging characteristics, so all it can do is to report the information it is receiving from the car. There's a world of difference between an Outlander PHEV with its small battery and a Tessla with the capacity to run a couple of hundred miles on a charge.

maby said:

How does the rapid charger know the charge level of the battery? It has to be able to manage a wide range of cars that will have very different charging characteristics, so all it can do is to report the information it is receiving from the car. There's a world of difference between an Outlander PHEV with its small battery and a Tessla with the capacity to run a couple of hundred miles on a charge.

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Hi,
When first plugged in it says "syncronising with the car". Then it pops up the existing car battery level and also shows the time it has been charging and the current amps being drawn.
I can only assume that the charger talks to the car and it passes the battery charge level.
Kind regards,
Mark

I suppose the cars we are talking about are almost new and must be designed with an expected service life of ten years or more - if they want the car to operate with a low battery threshold of 20% ten years from now, do they run it at 30% today?

I think the builder of the car is the more reliable source...

jaapv said:

I think the builder of the car is the more reliable source...

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Do they actually state the 20% level anywhere? They seem to be seriously lacking in publishing detailed technical information.
Kind regards,
Mark

On various articles on PHEV Li Ion car battery usage it states that the most efficient charge to retain in the battery (after initial EV stage) is between 20% and 35%.

The battery management system maintains this as it has been programmed by the car maker.

Also the same complex management system controls the mains charging cycle through it three stages;
A relatively quick Constant Current
then Transitional
And finally a quite slow Constant Voltage.

I think the complicated way in which this all works gives rise to the various confusing figures that appear in these forums.

You just have to trust Mitsubishi got it right

We should consider that new Li-ion batteries need to be conditioned , i.e. run through a number of cycles to attain their maximum capacity.

In addition to full cycling of the battery when new, to achieve full capacity, it is important to not leave a lithium battery in a fully discharged state for excessive time. Mitsubishi seem to have controlled the discharge and charge capacity levels with battery voltage limits. The driver ultimately will control the battery life with recharging and usage habits.

The remaining battery capacity left will be affected by the power consumption at that time, due to physical constraints within the battery chemistry. High power usage at the empty level will result in a more conservative battery cutOFF level. ie more capacity remaining.

My own PHEV has a usable capacity of around 10-11kWh based on the way my car is driven. 50% indicated battery capacity uses 5.5kWh to recharge to full. The battery in my PHEV is hopefully going to last way past warranty.

jaapv said:

We should consider that new Li-ion batteries need to be conditioned , i.e. run through a number of cycles to attain their maximum capacity.

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Li-Ion batteries do not need conditioning unlike some other batteries. Articles as below explain advantages etc of using this type.

Main disadvantages, include Lithium is very volatile, and is quite delicate if under or over charged. Heat build up in use, or charging, has to be carefully controlled. Therefore I think there is likely to be variable behaviour during use and charging.

As I say trust Mitsubishi and hope they have got the programming right.

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDIQFjAD&url=http%3A%2F%2Fpubs.its.ucdavis.edu%2Fdownload_pdf.php%3Fid%3D1169&ei=bsYjVJjzGYTkaLjIgvgI&usg=AFQjCNEvsPa7rskjQPIXfmllfOVkIzNosw&sig2=Wr91Lupos0136LlyccAUhg

The Ecotricity chargers show the car's battery level while charging and on both occasions the battery level was shown as 31% when the charging commenced.

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I've used them 3 times and my findings are consistent with yours.

I have been testing LYP chemistry batteries for 5 years now. These are a type of Lithium Ion battery like Lithium Iron Phosphate [ LFP ]. I have found the PHEV battery has been programmed to operate in a similar manner to the way I programmed my own BMS. Maintaining the optimum cell voltages for either maximum capacity, or maximum life is key. The Mitsubishi programming seems to be slated towards maximum life expectancy. I have no problem with this.