Hello All,
I always wondered how and when does the regenerative braking put back mileage/range back into the battery? I'm assuming it will do this when the car is turned off and the battery starts to settle? I say this because last night after a long trip, the range to empty was at 40 miles (Economy) and this morning when I turned the car on it jumped to 56 miles range to empty.
Any ideas if the regenerative braking actually adds range back into the battery?
@Wazzmania,
The phenomenon you discribed is absolutely normal. It is not due to regen as additive effect of regen occurs immediately. It is due to an automatic GOM correction due to change in your most recent driving conditions. It happens often but most people notice only when they have driven at high speed on the motorway then come off the motorway and drive for 10 to 15minutes at lower urban speeds before coming to a stop and also when the stop is prolonged and involves change in conditions such as temp rain etc.
Let me explain in detail.
Some people will claim GOM has a fixed formula of accumulated efficiency multiplied by battery capacity and will try to convince you that your GOM is malfunctioning because your GOM does not rally with your accumulated data. It is not true. Your GOM is working as it should. Using accumulated data makes GOMs completely inaccurate because what you did yesterday and the conditions in which you drove yesterday will never be the same as you will do today or the next day even if you are doing the same journey so GOMs do not use accumulated data.
The GOM is designed to try to accurately estimate how far you will travel with the charge you have remaining. GOM takes into account your current driving conditions. Because there is no way the GOM can know the future and where you intend to go and how you will drive and what the driving conditions will be is has to work out how to predict your current conditions. The electrotech and scientific community took some time to work out a method to give the most accurate GOM based on current conditions as distance traveled in an electric car depends on charge remaining and the rate of discharge of the battery both of which depend on so many factors other factors. After much scientific try and error the current self updating GOM system has generally been adopted.
It is based on the fact that the highest likely predictor of the conditions in which you will be driving in the next second is the conditions in which you where driving a second ago. So if there is data for a second ago we can use it to predict a second into the future.
This assumption remains relatively statistically significant but diverges slowly as the number of seconds increase. The more you increase the time and distance the lower the accuracy but if a relatively short time and distance is selected and the system is allowed to persistently update itself then a high accuracy is maintained. After much correlation and various forms of integration and calibration, GOM manufacturers selected various time and distance cut-offs.
Such "X" minutes and "Y" miles on which their GOM will be based. So your GOM uses data from only X minutes of your most recent journey(s) and or only Y miles of your most recent journey(s) to tell you how far you are likely to go assuming your continue to drive the same way you have been driving for said X minutes or Y miles. However because it is self updating it takes into account any changes as these changes occur. Self updating every sec or few secs and reacting to any change in the driving conditions makes the GOM super accurate. The exact value of X and Y is not published as it is usually a trade secret.
So what happend with your car is that you most likely were in a situation when your X and Y included your high speed motorway driving and or adverse conditions so your GOM showed a low figure. As you got nearer to your destination and stopped you were now in a situation where your X and Y now did not include your motorway driving and or adverse conditions and your battery temperature had changed from relatively high due to prolonged use to cool after standing idle so you got a big boost in your range.
The opposite effect also occurs. In such a case there is a significant drop in range after a short distance and time especially when you go on the motorway and drive above 70 - 80mph and or in adverse conditions. People however expect this and hence it is not surprising when it happens.
When you then subsequently slow down from 80 to 30 and now keep at 30 you will notice after an interval that the GOM figures will go up again or depending how far you have drive the decrease in range will look less than you anticipated.
Hope I have explained it well enough.
Unfortunately GOM is very accurate but complex to explain fully.
Most people do not understand it but it works provide you know that all it is tells you is that if you current condition prevail, you may be able to travel A miles with the amount of charge currently in you battery and if your driving conditions change after say 10 miles then the GOM will give you a new figure for your new driving conditions and thls figure is unlikely to be A minus 10 miles but rather what the GOM computer works out for the conditions you will be in at that moment.
Of course if it is a long motorway journey and all your driving conditions are uniform then the figure you get is more likely to be A minus 10 miles but if the conditions vary then so does the figure.
Apart from SOC, temperature, type of battery cooling, wind, road surface, rain, terrain / regen, speed, driving style etc all affect the GOM estimate of range and the system is designed such that as all these change the GOM figure also changes and self updates. The primitive GOMs will self update at least very minute and better ones few seconds.
