Gains from regen braking

[evcog]

Just charged my car to 80% then took a pleasent round trip journey to a beauty spot near to me in Somerset. I travelled 8.4 miles and my MG ZS EV Trophy Connect now shows 81%. A 1% gain in battery power is pretty good.
I useually travel in ECO when I can and always Regen level 3. Although this route was uphill all the way but obviously downhill on the way back. Average Mkw/hr was 3.9.

 

[schmiedel]

Yep, I have some routes here 3-4 miles downhill are enough to gain 1%, so it does make a difference, without regen these cars would be quite inefficient...

 

[rino1]

So drive 20 times and he's fully charged? If you returned to your starting position, it is impossible to gain energy. It would be a perpetuum mobile, which scientists are looking for for ages already. It would be surprising if saic found it lol

 

[schmiedel]

So drive 20 times and he's fully charged? If you returned to your starting position, it is impossible to gain energy. It would be a perpetuum mobile, which scientists are looking for for ages already. It would be surprising if saic found it lol

I don't see anyone claiming the car can drive creating energy, it is just some experiment to show the potential/importance of the regen braking. You could also test it by having ACC on in stop&go traffic for a few miles and then driving the same route without ACC...

 

[JimD]

Immediatley after a charge the battery indicator is often a bit out and goes up after a short drive. I see that a lot.

 

[Gadget Geek]

On an flat surfave, regenerative braking recovers around 60% to 70% of the kinetic energy, depending on the weight and speed of the vehicle (half the mass multiplied by the square of the velocity). Coasting however, only loses energy to friction of the wheel hubs and the tyres on the road so is more efficient over a longer distance.

So drive 20 times and he's fully charged? If you returned to your starting position, it is impossible to gain energy. It would be a perpetuum mobile, which scientists are looking for for ages already. It would be surprising if saic found it lol

Toyota found it though with their "self charging" hybrids.

 

[Tim Green]

But actual battery power recouped by regen is very small, just due to regen time compared to the power being used the rest of the time. Obviously on short journeys it is better, but as a total in normal use I'd be surprised if even 1% was recouped?

 

[Gadget Geek]

But actual battery power recouped by regen is very small, just due to regen time compared to the power being used the rest of the time. Obviously on short journeys it is better, but as a total in normal use I'd be surprised if even 1% was recouped?

I believe it's 12% overall.

 

[Tim Green]

12% would not be my experience, although it is difficult to quantify.
I just consider the time that power is being used, and at what level, compared with the odd 10-20% regen that one gets when slowing down.

 

[Gadget Geek]

Have a look at this Wikipedia page, the last section titled "Cars", gives the formula used to calculate the recuperation.

Regenerative braking - Wikipedia

en.wikipedia.org

Interesting stuff.

 

[Tim Green]

Yes, very interesting, and testing in the maths department.
However, the crucial figures I saw were 3% recoup out of town, and 14% in town.
I would suggest these are theoretical figures which would be much less in reality.
I think somewhere between 1 and 5% is more likely, but I am happy to be proved wrong. Regen does slow the car up nicely though!

 

[Tangoed Man]

I believe it's 12% overall.

From a reputable scientific source it is, at best, 5%. In other words, get up to your cruising speed and keep it there.

 

[Gadget Geek]

From a reputable scientific source it is, at best, 5%. In other words, get up to your cruising speed and keep it there.

Can you supply that reputable scientific source please. I'd like to have a read.

 

[pollenface]

I've gone from 50% to 51% while slowing down from 100kph for a red light.

 

[Tim Green]

You must have good eyesight!

 

[Tangoed Man]

I've gone from 50% to 51% while slowing down from 100kph for a red light.

Yes, but had you kept going at 100kph your overall energy consumption would have been less!

 

[Gadget Geek]

Yes, but had you kept going at 100kph your overall energy consumption would have been less!

True, but his car might have been a right-off if he'd run the red light.

 

[johnb80]

But actual battery power recouped by regen is very small, just due to regen time compared to the power being used the rest of the time. Obviously on short journeys it is better, but as a total in normal use I'd be surprised if even 1% was recouped?

It's impossible to generalise like this, I'm sure it will be a good bit more than 1% though. Consider a journey thats free flowing mainlu dual carriageway and motorways. The legth of time regenning would be minimal therefore the % figure would be very low, probably 1% or worse. Now consider driving in bumper to bumper stop / start traffic, it would probably be regenning a substantial amount time, the % figure would be much higher.

 

[Gadget Geek]

Now consider driving in bumper to bumper stop / start traffic, it would probably be regenning a substantial amount time, the % figure would be much higher.

It would be recuperating small amounts of energy more often, but would also be using a lot more energy to pull away again, so there would be a net loss, making the % lower. As Scotty was fond of saying, "yer canna change the laws of physics".

 

[johnb80]

It would be recuperating small amounts of energy more often, but would also be using a lot more energy to pull away again, so there would be a net loss, making the % lower. As Scotty was fond of saying, "yer canna change the laws of physics".

Absolutely, I'm fully aware of that, just working on a system of adding an alternator to the wheel of the car to charge the battery as I drive

I was merely showing by example how the % figure would vary dramatically with 2 different styles of journey