Blog: remi

Disassembly of a Renault Traction Battery (Master, Kangoo, Zoe)

This will be an article on the complete disassembly of a Renault/LG Chem Traction Battery which will be used to power the Renault Twingo. Although this type of battery has been around since about 2013, there is not much information around on these units, although they are very well designed in my eyes.

This particular battery is from a 2020 Renault Master, the very same battery can also be found on the second series Renault Kangoo. It has a capacity of 36kWh, 33kWh usable. The battery is very similar to the one used in the widely popular first series Renault Zoe, just a few minor differences to be noted.

For all that follows now: Electricity kills! Please be sure to wear full PPE if you are doing similar things in your garage. I am wearing cotton long sleeve clothes, safety/ESD shoes, 1000V electrical safety gloves, helmet and visor in case of electric arc. Here, I am measuring the total voltage of the battery pack.

After removing the main cover of the battery, we first see the high voltage connections. The main connection to the car on the right side, the service disconnect on the left side.

These here (the two black lines with a connector in the middle of the picture) are the pilot lines, one for the service disconnect and one for the main connector. The pilot lines are monitoring if the connectors are closed and disarm the connectors (by opening the main contactor) in case the connectors are getting opened on a live battery.

Within the battery box, sitting right on top of the battery modules, we find a module with the precharge circuit:

Let's have a look inside this component!

If we open the protection, it gets more visible: The main 275A fuse on the battery side on top, the main contactor (grey) just below, the black precharge relay further down and the precharge resistor (marked with a number 9) and the current sensor below the orange cable connection on the bottom left side.

Here we can see the BMS computer, which includes the voltage sensing boards and the BMS system in one enclosure, similar to e.g. the Orion BMS. The battery itself consists of 12 modules with 8 cells (technically 16 cells but in a 2p8s configuration), so we have 96 wires only for the voltage sensing cables, plus additional temperature sensors and other signalling cables.

The wiring loom leads from the battery modules to the BMS computer.

The individual modules are connected in series by busbars, which are enclosed in an orange plastic cover.

Next, we are going to work on the live battery in order to disconnect the modules. Please be aware that this is 400V DC, so we need to make sure that we use insulated tools in addition to the PPE.

By removing the busbars (second picture) we are breaking the pack and therefore reducing the voltage to a safe(r) level.

Here we can see the disconnected modules in the pack. The metal surfaces are the minus and plus connections of the modules, further right the white connector holds two thermistors for temperature control and the 8 voltage sensing connections for the individual cells to the BMS computer.

Here's another view of the liberated and disconnected modules, still within the battery case:

And here we have the first modules removed from the battery box:

If we now go down to the single module, we can see the 8 individual cells, stacked on top of each other like chocolate bars (yes, I am Swiss ;-) !)

Each of these cells is made of 2 LG Chem (what I believe to be NCM 712) pouch cells, connected in parallel within the cell module. So in practice we have 16 pouch cells per module, the BMS of course only sees 8 cells.

So that's the disassembly basically. I will now continue with some voltage measurements and the connectors pin arrangements in order to document these things here.

This battery will be going into the Renault Twingo, so stay tuned how this will work out!

Electric Drive to Business Meeting in Sardinia

A few days ago, I got a relatively short-notice invite to a business meeting in Cagliari on the beautiful Italian island of Sardinia in the Mediterranean Sea. I had to be there on a Thursday at 9 AM. The normal routine in my old days would have been to look for a flight, connections to/from the airport and probably also a hotel at the airport (depending on the time of the flight). A quick glance at the available options showed that there was only one single flight available that would serve Sardinia that day, an evening flight out of Milan. That would mean that I'd need to either drive down to Milan, park my car at some expensive parking at the airport or take the Bus over the San Bernardino Pass to Bellinzona, then take another Bus or Train to Milan Malpensa, then take the plane to Cagliari, arrive late at night, arrange a transfer to a Hotel in Cagliari for a short night. I would need to leave home at about midday the day before in order to get to the Airport in time. As I try to avoid flying as much as I can for environmental reasons, this option didn't sound very intriguing at all.

So I started investigating the option of an electric drive to Sardinia with my Renault Zoe. Unfortunately, all ferry connections from the north (Livorno, Genoa and Savona) would lead to Porto Torres in the very north of the Island, whereas Cagliari is on the southern tip of the Island. Of course, this is not ideal, but the island itself isn't too large: The whole distance between the very north and the south is less than 300 kilometers. And the ferry times are ideal: Departure in the evening at 8.30 PM, arrival the next morning at 6:00 AM. The driving distances seem ideal on the map:

The distances from my home in Thusis to Genoa and then from Porto Torres to Cagliari on the Island are both around the same distance (300 kilometers), so just within the range of my all-electric Renault Zoe. So the decision was made to turn this meeting into a little adventure and take the Renault Zoe to an unexpected drive to Sardinia!

And what a good idea it was: The original plan worked out perfectly, so that I left in the afternoon in Thusis, drove all the way down to Genoa, charged the car before reaching the port (in Serravalle to be precise - went to the hairdresser just in front of the charging station during the charge!), and then boarded the Tirrenia "Superman"-themed Ferry named "Athara" in the evening, had a meal and a beer in the onboard Restaurant, watched the busy port of Genoa on the upper deck while the ferry was leaving, before going to sleep in my comfy cabin.

The next morning I got up early, had a Brioche and an excellent Italian coffee on board, and then watched the landing manoeuvres in the port of Porto Torres, where actually a small pilot ship had to push our ferry with its big nose in order to turn the back side of the ship to the dock.

The rest then was just plain sailing in a fully charged electric car towards a beautiful sunrise, I was greeted by palm trees and wonderful nature. There is a dual carriageway all the way from Porto Torres down to Cagliari, but I had to stop a few times to admire the beautiful nature on this island.

The charge lasted all the way down to Cagliari, where I arrived just a few minutes late (due to a slight delay of the ferry and my photo stops), but of course I wasn't the last participant to arrive , those who know the Italian punctuality know what I am talking about ;-) !

So in the end the trip really turned into a relaxing holiday instead of a bleak business trip. I lost less time, spent more quality time, saw more of the country and used less energy. And you know what's best: I decided to take my son with me, too (you might have spotted him at the charging station), so he could enjoy a free adventure without any more energy consumption. What a cool adventure we had!

Renault Zoe R240: Range test and Battery health

Today the Renault Zoe R240 went out to the Swiss consumer magazine Ktipp for an external range and battery health test and it will stay with them for the next couple of days.

Purpose of the test is an article in the magazine on what to expect when buying an used electric car, and the different possibilities to test the battery beforehand, also outside of the official Renault network.

The Renault R240 has been chosen as it has quite a substantial mileage of about 150'000 kilometers on the clock, all cars in the test will have similar mileage to compare the results.

I can already tell with some confidence that the results will be surprisingly positive: My own diagnostics on this 2015 Renault Zoe R240 suggest a State of Health of about 90% and no noticeable drop in range since new.

The car will be back for the weekend, and I will of course let you know when the article will be published. Maybe I'll even be allowed to share the findings here with you!

Choosing the Motor for the Renault 4CV ¦ Electric Conversion

Let's talk about the motor options for the Renault 4CV.

I had four (and a half) parameters to consider:

1) power around 15 HP (+/- 10%, although there is some play with peak power and nominal power)
2) Voltage of 96V
3) CE conformity mark and documentation
4) air cooling
...and suitable dimensions to use the existing motor mounts (these were not super strict as I could have fabricated necessary mountings if needed)

The first idea was to use a LETRIKA/ISKRA motor of the type AMV7118, which can be found in the Renault Twizy. This motor however uses a different system voltage than I was planning.

I then got to know Erich from bdrive.ch who successfully converted a classic Mini into full electric drive and passed the homologations in Switzerland. He used a motor of the Italian manufacturer Fimea Engineering which comes with a full CE documentation and passed the Swiss testing procedures. The dimensions were super ideal, too, and it is an aircooled unit. And as I am living close to the Italian border anyway, that decided it for me!

This thing is perfect, and I am still convinced that it was the best choice for the Renault 4CV. The only little downside is its weight, which is over 60 Kg, but that's the price of air-cooling I suppose.

If you have a quick glance at the technical specs, you will see that this motor fits perfectly to the original power output of the Renault 4CV engine. A bit more torque, which could also be limited through the controller settings. The problem with too much torque is that the original gearbox could be damaged, and the driveshafts could snap. This is a common problem with the Renault 4CV, the tuned or Gordini-prepared versions of the car were changing the driveshsafts for those of the Renault Dauphine, as these were more stable. And we're still talking sluggish petrol engines here, not electric torque from 0 rpm!

The guys at Fimea were super supportive when placing the order which gave me further confidence. About a month later I went down to Milan to pick up my new motor!

Here's the motor in my workshop, ready to be installed into the car:

As the motor is pretty heavy (about 66 kg), I used a forklift to lift the motor into the vehicle. On the far side you can see the adapter plate towards the gearbox.

And here you can see the whole drivetrain installed for the first time in the car. Note how perfectly the motor sits on the original motor mounts (the crossmember below the motor is actually the original part that used to support the petrol engine!)

Still super happy with my choice, I can recommend Fimea Engineering to anyone!

The ZEBRA Ni-NaCl Battery

Now that we have removed all the covers of the battery box, let's have a look at the molten-salt (Ni-NaCl) battery that was used on this Renault Twingo. It is a pity really that I have to remove it: These batteries would be very environmental friendly, as the components of the battery are widely available without major impacts on the eco-system such as extensive mining etc.

If you want to read more about these batteries, check this Wikipedia article.

Here you can see the main battery with the HV and communication connections on the right side.

There were a few tests for the use of these batteries in the automotive industry. The first series of the Ford/Pivco Think were also powered by these batteries. In order to work, these batteries need to be kept at an operating temperatures of about 300 degrees Celsius / 570 degrees Fahrenheit, in order to keep the salt crystals in a liquid form. The heat is generated primarily by the chemical reaction within the battery while charging/discharging. If the battery is left idle, an external power source needs to be applied in order to keep the chemical reaction alive.

In a car, this means that the car must be plugged in when leaving it idle for more than 24 hours, otherwise the salt would crystallise and become solid, which would mean that the car needs to be heated up with an external power source for about 30 hours in order to liquidify the salt before the battery is ready to operate again, and the car wouldn't be usable during that time.

Plugging in the car at home wouldn't generally be a huge problem, as it can be plugged into a normal household socket and it draws only a very small amount of energy, just to keep the chemical reaction alive. But of course the handling is a bit less carefree than with a traditional car, so that's maybe one reason why the Ni-NaCl battery never got a more widespread use in the automotive industry, which is a pity really. The second reason might have been that there are only two serious larger-scale manufacturers of these units globally, which resulted in a very limited support network for these batteries. Ask some early users of the Think vehicles for their experience, and they will all tell you the same: The battery was absolutely great as long as there were no problems. The smallest problem however more often than not meant the end of life of the battery (in the better case) or (in most cases) even the whole car, as nobody was able to actually diagnose or even fix these batteries. That's probably also the reason why most of the Think vehicles were gone pretty quickly, even in Norway where they had quite some success in the very beginning. The ones still on the road underwent a similar surgery as I am planning on my Renault Twingo actually.

And here's a better look at the connections:

And this is very interesting now: The technical specs of this battery block. As you can see, the capacity is approx. 20 kWh, which considering the battery dimensions is a surprisingly good density. And another thing is quite surprising: This block has been built quite recently if you look at the sticker, the manufacture date reads March 2016!

The problem with the battery is that there are plenty of errors on the system, indicating either a isolation problem or indeed a faulty cell. It is quite hard to get these things diagnosed as there is little knowledge around on these special batteries. The main use of this kind of batteries nowadays is grid storage, which makes a lot of sense especially also as a network buffer for renewables (e.g. solar), where you could collect and store energy from the sun during the day and then power your appliances at your house in the evening or at night.

The plan now is to see if Fiamm/Sonick are willing to diagnose the battery, and if there's a chance to bring it back to life I might indeed be using it in a future solar application!