Battery charging and regenerative braking

[Romeo]

I kept getting a low battery warning on my Disco Sport MY17, even though a voltmeter said ok and sat steadily at 14.7 (a bit high?) whenever the engine was running. Off to dealer who did a software update (welcome to 21st century battery management). No more warning, but now the voltage sits at 13.2 (a bit low?) EXCEPT when the car decelerates, when it rises to almost 15volts. Dealer man says this is absolutely correct, and that the car uses regenerative braking (dumping energy into the battery) when decelerating.
does all this sound kosher? 13.2 volts? And regenerative braking? I would have expected to have seen a mention of this in the brochures or ads.
does anyone have any more info on this?

romeo

[Old Farang]

I have no idea about your particular car, but the theory is explained as follows. Regenerative braking in itself is just about as old as electricity, but earlier systems were more of a "dynamic braking" method where a large resistor was shunted across the motor as switching caused the motor to act as a generator, and the energy was simply converted into heat in the resistor. Modern electronics of course make the process simple, and the "saved" energy useful. (used in F1 cars now)

https://www.12voltplanet.co.uk/user/downloads/Smart%20alternators%20&%20regenerative%20braking%20info.pdf

[Cambo_oldjaguar]

The dealer is feeding you lines.

Unless your car is a hybrid? Which I'm 99% sure it isn't.

The "smart charging" is nothing new, been around for at least 10 years, the Freelander2 had it, the alternator varies the output voltage depending on driving conditions.

But only hybrids have regenerative braking.

https://uploads.tapatalk-cdn.com/20180811/f057c71236f0fdb9b3a9b3d4ce27568a.jpg

I drove this one today, you can literally feel when it starts to charge during deceleration, it's like someone steps on the brakes.

[drivesafe]

Hi Romeo and Old Farang, as Cambodia posted, the use of the term Regenerative Braking is a misnomer and while every one uses this term, it is incorrect for describing the charging operation in new vehicles.

It should be called KINETIC Charging and is based on whether the ACCELORATOR PEDAL is pressed or not.

It has absolutely nothing to do with braking.

I will post up info in my Auto Electrical thread shortly.

On-Line auto electrical info (https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info.html)


BTW Old Farang, don't put too much faith in that crap Charles Sterling puts out.

I use Sterling gear as it is, as far as I am concerned, the best of the best, but he has a tendency to use porkies to sell his gear.

That link you have is a perfect example.

He is using a Ford as the test vehicle, and while Ford does have the worst alternator charging algorithms, but Ford allows the owner to have these turned off so the alternator runs at a constant 14.4v all the time, and this is a perfect charging voltage.

By turning off the charging algorithms, you have no need for any of Charles's gear, but he forgets to tell anyone about this fact.

There is lots of other misinformation in that link as well.

[Old Farang]

BTW Old Farang, don't put too much faith in that crap Charles Sterling puts out.
No idea who he is, or his agenda. Just trying to help the OP. And also no idea about new car systems, but have been responsible for maintaining both dynamic and regenerative braking systems for about the last 50 years.

[drover81]

I thought the new cars have an smart alternators. The alternators vary output when the battery voltage is low and when the car is 'braking' - hence the use of the term 'regenerative'.

Considering how all other cars are, it's a sales pitch at best.

Curios to see if the variable output extends the life of the battery though.

[drivesafe]

Hi again folks and to save multiple postings of the same subject, I have posted up some details about Regenerative Braking, or the lack of it, in my auto electrical thread.

Here is a link to it.

https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info-9.html#post2832814

[goingbush]

This is regenerative braking .




https://youtu.be/8Dy28Fg28bg

Testing the Regen braking mod. Not much of a hill but the only one in battery range . The braking from 60 was regenerative only (no foot brake) . The descent control was on max then i decreased regen level with dash potentiometer & then max again. Works well , this was 3rd gear high range.

[Romeo]

Thanks for the replies, guys. I guess the term “regenerative braking “ is relative - a small battery in a non electric car can only absorb a small amount of energy, whereas a big battery in an electric vehicle....nice video, topictoaster
and thanks for your input, drive safe. I know a little more about intelligent BMS now.