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-   -   Mahindra Reva e2o : Official Review (https://www.team-bhp.com/forum/official-new-car-reviews/134857-mahindra-reva-e2o-official-review-20.html)

I have a E2O with 80km range battery.
I have no issues with the range. My daily commute is 20Kms and by the time I reach back home I will still be left with 60Km range after a full charge. This is with heavy traffic along Bannerghatta road and BTM layout with AC on.

I make full use of the regenerative braking and this helps a lot.

On my client visits to whitefield (usually over afternoon), I regularly gain a KM or two just with regenerative braking on those wide roads and flyovers.

I agree that the charge will be leaked once the charging is shutdown. I make it a point to start charging the car at midnight and make sure I have the full charge (well almost) by the time I start in the morning.


This again depends on the driving pattern even with the AC turned on. While turning on the AC will reduce the range, in my case I only see it around 10% reduction of the entire range. I usually drive sedately at a speed of 40 - 60 kms. However I observed that using the heater in the cold mornings will reduce the range drastically when compared to the cooling.

I doubt if this can have any impact on the efficiency. The charge levelling will only make sure that all the cells are equally charged and I am not sure whether the slightest discharge creates any imbalance between the cells that could impact the efficiency. May be experts can provide more insight on this.

From the daily use and with our driving style (driven by me and my wife), we get an average of 70 Kms with the AC turned on. That should get you at least and average of 100 Kms for the full range. Did you get to try a full range test in a single day? The last time I tried, I drove for almost 73 Kms and still has 7% charge left.

hmm... Interesting... Should try to do a full charge to 10% depletion test on the weekend...


But, how did you determine the 60km range left? Using DTE?

What is your SOC after 20km run? You can make crude calculation on how much battery depletes on the basis of SOC, and that differs from DTE, because I am not sure DTE is accurate...



So, do you have 80km battery as well??

I use the DTE to determine the range and it is quite accurate. The SOC after driving 19.6Kms today is 78% and the DTE is indicating 60KMs. This is with 100% AC and in 'F' mode.

Also keep in mind that, once the SOC falls below 20%, the car will go into Energy saving mode and it will restrict acceleration to conserve range.
The car will shut down AC once the charge level drops below 10%.

Reva engineers have informed that they have driven 122Kms in the 100Km range E2O on their test cars and around 158Kms in the 120Kms range E2O.

The maximum I have driven in a day is 82.3Kms with 6% charge remaining and a range of 4Kms. This was done after driving in heavy bumper to bumper traffic, a drive to visit a client in whitefield and a shopping trip to nearby market.

Oh man. That's super efficient. Were you the only person in the car? Regenerative braking plays a big role in getting the additonal range. I got used to it so much these days that even at the slightest chance I unintentionally take my foot off the accelerator and an obvious thing that I do on down hill.

Yes. I got the 80Km range one as the 1.3L discount is appliable only for the 80km range batteries then. But the car came with all the other features of the T2 model.

For most of the drive, I was alone except for around 30Kms. I always ensure to coast to a stop than apply brakes.
The regenerative braking can generate good amount of energy if the speeds are above 50Kmph. It is fun to see the range and SOC going up due to regenerative braking. clap:

you mean to say, you allow the car to slow/stop itself instead of applying hard brake ? Does it generate more energy ?
I was in the assumption that "more brakes.. more power gets generated" :)

Kindly confirm, I shall try that way.

Prem.

You are right, more the brake pressure, more energy is generated. But you will also be stopping quicker and the regen duration is shorter.
If you are coasting to a stop, the car will regen for a longer duration and it will not consume any power since there is no throttle input.
The car stops regenerating below the speeds of 10Kmph.

I don't always coast to a stop, I generally coast while stopping only if there is little or no traffic in front and behind the car.

Im not sure how these regeneration system work, but in theory at least it should not make any difference whether you brake hard or gradually. What you are doing is converting kinetic energy to electrical energy. (Or some other form of static energy, e.g. Pressure, flywheel ). The kinetic energy is depended on the mass (fixed) and speed. (E= 1/2MV(2)). So it is really only your speed that determines how much energy you regenerate, not the amount of brake pressure and or deceleration rate.

Without really understanding these system i can well imagine that below a certain speed in practice it becomes impossible to generate energy. Come to think of it, incase of a flywheel I can even imagine that braking gradually is more efficient from a regeneration point of view than hard braking. Due to the inertia of the flywheel you can only spool it up so quickly.

Jeroen

As far as I understand, it depends on the amount of pressure applied on the brakes. Along with regenerative braking, these vehicles also have conventional brake pads.
Depending on the pressure applied, the ecu decides whether to apply only regen brakes or to apply conventional brakes. High pressure on brakes would mean, it is the brake pads that are doing the braking, loosing most energy as heat. Coasting or slow braking will involve very less brake pad usage and more energy is restored back to batteries.
This is what i understood while reading some docs about Toyota Prius. I could be wrong.

I stand corrected, the regenerative braking is dependent on speed.
Thanks for the explanation.

Heard from the technician at Mahindra reva that they are working on a 4 door vehicle with a range of 180Kms. Possible launch will be in 2016.
They are also planning for quick charge stations in between major cities just like Tesla.

They are working on a Verito EV version. I thought it'd only be ready to sell in 2017...

In any case, there are many things for Mahindra-Reva to fix.

1. They currently use an excide supplied chinese Lithium-Ion cell. It is not even known who is the actual manufacturer. They need to shift to a good japanese supplier like Panasonic, who have batteries that are sure to last 8-10years.

Since, they are charging Rs.1.8Lakhs for battery, the per Kwh battery works out to about Rs.17,000 (approx. US$275/kwh). In reality, this is more than what the battery replacement in US costs!

Nissan Leaf, which has 24Kwh battery, replaces entire battery for only US$5,500 (Rs 3,41,000), which is less than the price of the chinese batteries that Mahindra is providing.

Since India does not have any import duty on EV batteries, the only explanation I could think of - economy of scale. I am sure Nissan buys these batteries in far higher quantities than Mahindra.

but, yet - it is better to move to a reliable battery that will have 8year/100,000 kind of life.


2. Mahindra should target a product towards the rich (like tesla did). it should make it a life style product.

In India making a cheap car doesn't necessarily pay! Tata nano is an example. While E2O has a purpose, I think Mahindra would do well to build a plush EV that sells for 25-30Lakhs.

3. If Mahindra wants a mass market, it should look at a EV-Petrol hybrid (like GM-Volt). A range of about 30km on battery, and then on petrol works for most folks, and avoids the need for a second car.

4. EV is a long term play. It is a bet of minimum 10 years. I hope Mahindra doesn't get tired of a few experimentations and failures on the way.

If feel it'd be good for Mahindra to try out a plush narrow track city vehicle, targetting the self-driving rich class. i.e. folks who won't mind paying 8-10lakhs for a Reva++ (which has only two seats back-front bike like format), but has all pleasures of a good car, and has same range as E2O. Something that can park even in Bike parking lot, like reva used to.


E2O is too big for that purpose!! :)

For the past one week I had a weird problem with my car. When the car is stopped in an incline and when brakes are released the car tend to jump forward (like sudden release of clutch in ice cars). It was very occasional. Opened an sr with customer service and they send an engineer to upgrade the software. Post upgrade the vehicle is very smooth and the brakes has become better. No sudden bite which was there earlier. Will have to see if the jumping issue has gone.

I have been facing the same issue. But I have faced it only a couple of times, if there is a software update, then let me get that myself.
Thanks for sharing.

Even I faced this couple of times on inclines. It jumps forward when the brakes are released.

Do you know the software version that is installed on your car? Would be good to check if its indeed an software upgrade or just a reload of the software. IMHO, Mahindra Reva should provide the software upgrade to all the cars directly without any request and I thought they have that provision, since all the cars are connected to their centralised server.