Monday, October 29, 2012

LiFePO4 Battery Charging Method - Don't Ruin your Expensive Cells !

and don't Burn your house !!

I learned this saturday that the new Vectrix Li and Vectrix Li+ have battery problems: These Electric Scooters here cost 11,000 and 12,500 EUR, which is a lot of money; If at this price you have problems, it is not possible ! As a result the dealer I met told me he was going to stop selling them and close his Electric Scooter business... He also told me that Vectrix may not be imported in France anymore because it is not selling ! I am very disappointed to hear that this great scooter might not be available anymore and even more knowing that it is only a Battery Management Problem Again !!

The same day I decided to write this post to try spread the word among the EV community and maybe Vectrix USA will read this too, along with other EV makers

The Method to Charge and Discharge a LiFePO4 battery pack is Very Simple :

A lot of people think they need a BMS along with a LiFePO4 battery pack, but the only thing it is doing is damage the cells !
This is not me saying this, but Jack Rickard from EVTV : he has been converting cars to Electric Drive for 4 years now and shown by practice (real world charging & driving) that this is the best way to protect these expensive cells

It seems so simple and inexpensive that after reading this some people will still not believe it, but this is the simple reality

My EV experience (since november 2009) has proven the same thing to myself too

Typical LiFePO4 Cell Discharge Curve


- Bottom Balance each cell to 2.75V (Drain them with a resistor until they reach this voltage = empty)

- Connect them in series to form a string of the desired voltage

- Under Charge the string to 3.50V * number of cells with a LiFePO4 Charger
NB: A LiFePO4 Charger charges at Constant Current, then close to the pack voltage, switches to Constant Voltage and reduces Current slowly until it reaches the set pack voltage, and eventually Shuts Down Completely)

- When discharging the battery pack, set a lower limit to 3.1V * number of cells, start alerting that you are reaching the end of the pack and reduce maximum current drawn on the controller; When the pack voltage reaches 3V * number of cells, do not go below, stop the discharge at this point by disabling the controller

That's It !!

- Bottom balancing each individual cell has to be done only once
- If you have to add some cells to the pack (to get more pack voltage), you will have to "marry in" these new cells by bottom balancing ALL the cells again (old and new ones).

This Method is based on facts: Real World EV Charging & Driving, detailed below:

-Back in 2008, Jack Rickard distroyed many cells trying to Top Balance them to perfection (keeping them at a very equal voltage); When he drove his GEM EV, as he was going towards the second half of his pack capacity, he suddenly lost several cells, because they had reached a low voltage limit of 2V, and even below, going into reversal, the stronger cells driving current through the weaker cells that had past 0V

- He explained in details, with wood sticks, how each cell has its very own capacity, and if you try to top balance each cell, you will in fact reduce even more the smaller capacity cell's capacity, and as you discharge you pack, they will be the first ones to hit a lower voltage and if you continues will be damaged or destroyed
=> His Blog post: November 13th, 2009:  "GET RID OF THOSE SHUNT BALANCING CIRCUITS !"
=> His explanation Video: EVTV News Friday Show November 13, 2009. Part 1 of 6. LiFePo4 Cell Battery Management. The truth about current shunt regulator battery management systems. Latest data indicates they do not protect cells, and can actually kill them:

Full length Video can be found at EVTV Video Archives by searching for " November 13, 2009 "

- Watch Jack Rickard explain the process has been using for years on half a dozen of converted cars, using the same tehcnic again here with the new build of Speedster Nippon (starts at 54:34)

- In early 2010, after 4 months of driving my Engineer 4kWh Prius PHEV Kit, I experienced several cells loss because of Cells Balancers, that were 24/7 drawing little current from the cells trying to have them all at he same exact voltage (it is also Top Balancing); Same as Jack Rickard, I lost one cell, then another, and did not understand why at this point... Replacing the damaged ones by brand new, I ended up drestroying some more and eventually almost burned my office underground parking while charging ! At this point I stopped everything, scared of the potential consequences of this unexplained problem ... and disconnected everything from my Prius for several months
I understood later, watching Jack's EVTV Show why this had happened and what caused it

- After that I started working on LiFePO4 Battery based  Energy Storage for Solar at home, and have been experiencing only good things, using the cells (the remaining good ones) of my Prius PHEV Kit, for a year and a half now; So there was no weak cell, but only BMS (8S Cell Balancer) causing some cells to become weak !
Jack 's Method works !

- A lot of EV converters applied his Method, and do not have any Battery problem ever since; Many of them were at EVCCON last september

- CALB has released a new serie of great LiFePO4 cells, the CA serie, replacing (?) the SE serie
If you get these amazing cells (Jack Rickard's words after Charging them at 3C and dischanging at 12C !),
and damage or destroy them because of a bad method or BMS / shunt balancers, you will be very sad ...


CALB CA Serie (New & Very good)

* I will had more details to this post on this subject (To Be Continued) *

August 29th, 2013


To prove you that this Method works, here are videos of regular voltage checks performed on my DIY ESS Battery Pack, Bottom Balanced and installed in January 2013:

March 2013

May 2013

July 2013

October 2013
=> Conclusion: It works: All the cells are still perfectly in balance after 6 months ...

Vectrix tires changed :-) Bad Vectrix News :-(

My rear tire has been flat for two days with a nice hole in it; I pumped a lot of air in it (4 Bars), using the LEAF 12V electric pump, to hold until I get to the Elecity garage in the East of Paris (zip code 75013), 13 km away from Boulogne

Arrived at Elecity and Motos 13 Repair Shop

I left it there at 11am and had to pick it up around 5pm

That is the boss's Vectrix in red (I like this color)

Mine, still with the old tires

As I asked my wife to follow me in case I had to refill air halfway, I called and she had not left home yet; I said the journey to the shop had been fine and pretty fast, I that I will meet them for lunch later... I then took some time to go visit the Elecity store acrros the street 

They are selling the Vectrix Li and Li+ and I had a little chat with the dealer 

Looks nice in black

Vectrix Li+

Behind the scene, in the back of the store: a Vectrix with a battery problem, waiting to be repaired, if they can identify the problem he told me; He also said it took 4 months to get a charger from the US last time he ordered one !

He showed me some replacement cells, told me they changed LiFePO4 cells on new generation Vectrix with Li packs, but that the problems still remain...

After a lazy afternoon in Bon Marché (well heated BTW in this cold & wet weather), back to Elecity and I could pick up my Vectrix with its brand new tires: Michelin City Grip ! They told me these were way better than the original ones... I talked to the shop owner who actually did the tire change and he said he inflated them at much more than required, and that it is always better for Electric Scooters, reducing the drag (he is right)

He also told me that the new company importing Vectrix in France will probably quit because they are not selling any or very little, and that maintenance was catastrophic because of the delay to get spare parts from the US :-( I was really sad to hear this
He also confirmed that the Vectrix Store (the first dealer in Paris and in France for years) had closed and showed me the scooter shop lift he bouhgt from him as a proof

and back home in the parking

Back in the cage

Friday, October 26, 2012

Renault Twizy EV goes firefighting

When Renault showed the two-seat Twizy electric city car at the 2009 Frankfurt Motor Show, we never expected to see it haul firefighters – meter maids, maybe, but not firefighters. The vehicle is about as far from a fire truck as you can get while still discussing motorized vehicles. That hasn't stopped the French company from outfitting its diminutive electric car for the purpose of firefighting.

Renault and its vehicle conversion subsidiary Renault Tech worked closely with the Paris firefighter brigade to create this response-ready prototype. Envisioned as a complement to, not a replacement for, more traditional fire trucks, the prototype is designed as an early response vehicle, with the anticipation that actual fire trucks with water, hoses and gear will be close behind. For that purpose, Renault ripped out the rear seat and replaced it with a storage trunk to house emergency response equipment including two fire extinguishers, two oxygen tanks, a fire suit and helmet, and a first aid kit.

From next month, Paris firefighters will begin an eight-month test of the Twizy prototype before a decision is made about a more permanent fleet of light electric vehicles.

Source: Gizmag & Renault

Renault Press Release:

The Twizy prototype was co-developed by Renault, Renault Tech, the company’s vehicle conversion subsidiary, and the Paris firefighter brigade. The special model was designed for early interventions ahead of the arrival of more consequential lifesaving equipment.

The rear seat has been replaced by a trunk used to store emergency response equipment, i.e. two fire extinguishers, two oxygen tanks, a fire suit, a helmet and a first-aid kit.

Tests of the prototype will begin in November for an eight-month period, the aim being to use Twizy as a support vehicle in Paris and its immediate suburbs and when setting up temporary safety installations (for major public events, July 14, New Year’s Eve, etc.). The Paris firefighter brigade is reviewing the long-term possibility of setting up a fleet of light electric vehicles, for more efficiency and environmental respect.

For Claire Petit Boulanger, tertiary safety officer at Renault, “This initial prototype is real-life proof of the research and development work carried out together with the emergency services, demonstrating Renault’s ability and determination to innovate to meet the needs of firefighters.”

Renault and the French national firefighter association, FNSPF, signed a partnership agreement on June 21, 2012 to step up their collaborative efforts in fields including technical cooperation and donating vehicles to firefighters for vehicle-extrication training.

Masdar: The City of the Future | Fully Charged

Masdar City is a project in Abu Dhabi, in the United Arab Emirates. Its core is a planned city, which is being built by the Abu Dhabi Future Energy Company, a subsidiary of Mubadala Development Company, with the majority of seed capital provided by the government of Abu Dhabi. Designed by the British architectural firm Foster and Partners, the city will rely entirely on solar energy and other renewable energy sources, with a sustainable, zero-carbon, zero-waste ecology.

Robert Llewellyn wanders in the desert heat ...

Masdar, The Mirage City

Huge solar plant

Solar water heaters

Narrow streets to keep the shade and cooler air in

Robert Llewellyn talks to Youssef Baselaib, Director of Operations of the Masdar Projet

Source: Fully Charged

e-Solex is back in service after more than a year of sleep

Bad News: my Vectrix has a flat rear tire :-( I will have to go change both tires tomorrow because they were getting too old and used up anyways

Good News: my e-Solex is back in service :-) after charging up its LiPo battery last night as I kept it half charged in storage (that is recommended), and I used it on my way to work this morning after more than a year of sleeping in the parking; Everything was fine, and it is sometimes nice to go slow (max speed of 30 km/h), enjoying the woods and beautifull cities I go accross: Bois de Boulogne, Neuilly, Levallois, Clichy

LiFePO4 ESS - Auto Adjusting Power Supply Up & Down

Shot last night while my LiFePO4 ESS was auto adjusting its Power Supply Up & Down
Take a look ...

It is keeping Wattson colors Greeen (but not too much) and Blue ... the ideal spot close to 0W

And here is a graph of the evening power (red is the usage (peak at 2500W), blue the generated power (1250W max for now), and green the power imported from the grid)

along with the day Energy Breakdown

The Numbers Behind Tesla and SolarCity’s Home Energy Storage Play

IDC Energy Insights breaks out how Tesla and SolarCity’s play for residential solar battery backup systems may play out in California and other states.

Have electric carmaker Tesla and solar power installer and financier SolarCity cracked the financial code for backing up residential rooftop solar panels with household batteries?

Over the past year or so, the two companies have been quietly installing Tesla’s lithium-ion batteries to back up SolarCity’s solar panels. That’s no secret -- SolarCity advertises its home energy storage system on its company website.

But battery backup for solar panels has been too expensive to justify for all but the wealthiest of homeowners. Simply put, batteries are too expensive, and the price of power too cheap, to justify the expense.

That’s too bad, because battery backup could really help solve some of the larger-scale problems associated with connecting lots of intermittent, on-again, off-again solar power to the grid. Energy storage could help mitigate the distribution grid voltage sags and surgesthat can occur when clouds pass over neighborhoods with lots of rooftop solar, for example. It could also help shift stored solar power to cover peak loads that may occur slightly later in the afternoon than solar’s peak production times.

Enter the Tesla-SolarCity technology combo. So far, the two companies have submitted about 70 applications to Pacific Gas & Electric under California’s Self-Generation Incentive Program (SGIP). That program offers credits for on-site generation sources like solar power, biogas digesters and fuel cells. Starting in 2009, SGIP started offering credits of $2 per watt for energy storage systems that can store power from an eligible on-site generation system and discharge it at rated capacity for a four-hour period.

IDC Energy Insights analyst Sam Jaffe has reviewed Tesla and SolarCity’s SGIP applications with PG&E, most of which fall in the 5-kilowatt size range, and estimates that the two companies have applied for a combined 500 kilowatts of storage systems. In a Friday blog post, he extrapolates from the SGIP rule requiring four hours of discharge at rated capacity, and projects that the two companies’ applications add up to about 2 megawatt-hours of storage capacity.

That’s a lot of storage, and Jaffe predicts it’s just the beginning of Tesla and SolarCity’s plans. California’s other two big utilities, Southern California Edison and San Diego Gas & Electric, haven’t published their lists of SGIP applicants yet, and even PG&E has yet to announce the next wave to come later this year, he noted in his blog post. Given those variables, he estimates that the two may be eyeing as much as 10 megawatt-hours of home battery-solar backup systems in California in 2012.

Jaffe also states that SolarCity is offering the systems at a cost of $2,000 per kilowatt-hour, which would add up to $40,000 for a 5-kilowatt system. SolarCity bills the system as a way for homeowners to back up their homes in case of power outage, but it’s likely the bigger financial benefit would be to put power back on the grid to manage peak grid power, which could get the utility involved in further subsidies.

If SolarCity sets up the batteries to go beyond backing up solar power -- say, by charging with cheap nighttime grid power and combining it with rooftop solar power in the afternoon to make the home energy-neutral or even a net producer of energy -- that could yield additional payoffs under PG&E’s residential time-of-use tariff, Jaffe noted. That could shave about $500 more off the price of the system, he estimated.

But the big question for Tesla and SolarCity is whether or not they’ll be able to bundle the battery costs into the overall solar system costs that are eligible for the federal government’s 30-percent investment tax credits. Jaffe predicts that the two may be the first to try to do so, which would instantly pay for one-third of the price of the system.

Adding the ITC benefits to the SGIP incentives cuts the cost of the system to a mere $800 per kilowatt-hour, Jaffe estimates. With time-of-use benefits added to that, “the homeowner is paying about $6,000 for the benefit of having reserve power during short-term blackouts, which is roughly equivalent to what an advanced hard-wired generator would cost,” he said.

All in all, it’s still an expensive proposition for most homeowners. Jaffe notes that the two will have to figure out how to cut the price further to create a truly disruptive play in the home energy storage space. Still, if battery prices continue to fall as IDC predicts (down to $600 per kilowatt-hour in 2012), that could cut the overall system cost further.

Tesla and SolarCity aren’t the first to try out batteries to back solar power. Japan’sPanasonic and Hitachi are installing home-based, solar-backed energy storage in pilot projects. In the United States, battery startup Xtreme Power is eyeing smaller-scale solar-backed applications to match their big, substation-sized grid batteries, and utility AEP is working with S&C Electric Co. on “community energy storage” systems that back up grids at the neighborhood level. General Electric just inked a partnership to integrate its nickel-saltDurathon batteries with Arista Power’s power balancing system to back up solar and wind power.

One interesting note on the Tesla-SolarCity effort is that the two are offering the systems for lease in California, according to SolarCity’s website. That could open the door to SolarCity managing the batteries en masse, to maximize the value of the energy they’re storing. That sounds a bit like the plan from Stem, the startup formerly known as Powergetics, which has shifted from a straightforward home energy storage play to a cloud-managed, energy optimization technology play that manages home batteries without the customer getting involved. Of course, SolarCity and Tesla haven’t publicly disclosed any such plans. But it may be one way to squeeze more value out of what could end up being a common good.

Source: GreenTechMedia

Thursday, October 25, 2012

Tesla Free Supercharger Network Now Officially Open, Ready To Use

Just under a month ago, Tesla Motors held a gala event at its Hawthorne, California design studio to mark the switching on of its proprietary Supercharger rapid charging network. 

On Friday, Tesla held official ribbon cutting ceremonies at four of its six initial Supercharger locations, making them officially open for public use.

Opting to ignore both the J1772, level 2 charging standard found on every other production electric car today--not to mention both Chademo andrecently-announced J1772 “combo connector” rapid charging standards--Tesla Motors [NASDAQ:TSLA] has designed the proprietary Supercharger system specifically for its range of current and future electric cars.

At the moment, that means only 2012 Tesla Model S luxury sedans, with the exception of base-level 40-kilowatt-hour models, can use the Supercharger network.

Over time, however, Tesla says the range of Supercharger-compatible cars will rise as it builds the technology into all of its future cars.

That includes the highly-anticipated Model X Crossover SUV, which Tesla unveiled earlier this year.

Unlike other types of rapid charging stations, Tesla’s Supercharger is built from multiple, smaller charging units.

Initial locations for Tesla Supercharger fast-charging system

In fact, each Supercharger is built from 12 chargers identical to the 10-kilowatt charger included as standard onboard every 2012 Model S Sedan.

Rated at a maximum power of 90-kilowatts, with a future capability of going as high as 120-kilowatts, the charging stations can add as much as 150 miles of range to a Tesla Model S in half an hour.

Eventually, Tesla aims to cover major road routes throughout the U.S. with its Supercharger technology, allowing its customers to drive from coast-to-coast, or the length of either coastline, with ease.

For the moment, however, the first six Supercharger locations are located in California, connecting Lake Tahoe to San Francisco, San Francisco to Los Angeles, and Los Angeles to Las Vegas.

Tesla won’t be charging customers for recharging, although if we’d paid upwards of $90,000 for the car--and $600 a year for servicing--we’d expect a bit of free electricity too.

Source: GreenCarReports

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