This entry has been one i’ve been wanting to write for a very, very long time:
Some components in a TWIKE get replaced because they wear out.
And then there are those components that simply become part of the vehicle.
The Dreifels Controller is absolutely such an item.
In this – rather long – entry, I’m going to tell the story how I decided to purchase one and why every TWIKE pilot should get one fitted to their vehicle.
TW560 has been running with a Dreifels Controller (DFC) since October 2010. That’s a rather long time for a piece of electronics in a vehicle that has spent a substantial part of its life travelling across Europe, climbing mountains, charging creatively at some rather questionable electrical installations and generally being subjected to the sort of (ab)use that its designers probably didn’t have in mind when they first drew up the specifications.
Yet here we are, more than fifteen years later, and the controller is still doing its job flawlessly.
I thought it was about time to give this rather unassuming piece of technology its own blog entry. After all, I’ve written extensively about batteries, chargers, motors, inverter overhauls and all the other bits and pieces that make TW560 what it is. The controller has featured in quite a few of those entries, too, but mostly as a supporting character.
To understand why I ended up with a Dreifels Controller, we need to go back to 2010.
At the time, TW560 was still running on its original NiCd battery configuration. The batteries had served me well and had accumulated almost 18,000 Ah of discharged energy. Not bad at all.
But by the middle of 2010, things started going rather spectacularly downhill. Within a couple of months, the usable capacity deteriorated from the already rather modest 5.1 Ah to something that made longer journeys increasingly frustrating. Battery temperatures were becoming a problem, charging was becoming unpredictable and the range was shrinking towards 20 km.
The 2010 TDI2010 trip to Italy with Jean-Claude and his TW231 gives a rather good impression of the situation. Both vehicles were still running NiCd batteries, and the trip turned into an exercise in managing limited battery capacity, excessive temperatures and the occasional technical mishap. TW231 eventually had to be transported home, while TW560 continued with its increasingly exhausted batteries.
The full German-language travel report is available here: TWIKE Tour de Suisse 2010 (PDF).
I had, fortunately, been putting money aside for a battery replacement for more than two years. So, whilst the prospect of spending a substantial amount of money on batteries wasn’t particularly exciting, at least it wasn’t entirely unexpected.
As usual, I started researching.
There were various options available, but I was particularly interested in the LiFePO4 batteries offered by Dreifels. I had already spoken to Ralph Schnyder in early 2010 about the requirements of somebody who regularly undertakes longer journeys with a TWIKE. This was important. I wasn’t looking for a battery that would get me to work and back. I wanted a system that would allow me to travel across Europe. And since substantially larger battery capacities also mean longer charging, I was keen to finding a solution to keep charging times similar as previously, which meant some kind of fast charging solution was required.
Also, I wanted to finally have more granular and reliable information on my screen when driving and the old inverter software just didn’t cut it any longer. …And this is where the DFC30 controller entered the picture.
The decision wasn’t simply about replacing one battery chemistry with another. The battery management, charging behaviour, available information and ability to accommodate additional charging equipment were equally important.
So, what exactly is a Dreifels Controller?
In simple terms, the DFC is the battery and vehicle management system that sits between the TWIKE pilot, the battery, the charger and the TWIKE’s existing power electronics.
It is not merely a display showing how much battery capacity remains. It measures and monitors a considerable number of parameters, communicates with the drive inverter and charging electronics, takes care of the vehicle’s shutdown behaviour and offers additional functionality such as vehicle telemetry.
In other words, it is the component that makes the various electrical systems behave like one coherent vehicle… with minimal invasive changes to the TWIKE required.
Dreifels themselves describe the controller as a completely redesigned battery and vehicle controller, developed using experience gained from almost 1,000 TWIKE vehicles. An important design objective was compatibility with all previously produced TWIKEs, requiring only minimal modifications.
That last point is worth remembering: The DFC was intended as an upgrade for vehicles that were already on the road, with all the variations in their electronics and battery configurations… and I can confirm: every TWIKE is different!
The original hardware is based on an ARM7 processor and includes:
- Eight temperature measurement inputs.
- Two voltage measurement inputs.
- Two current measurement inputs.
- An integrated data logger.
- An interface for the existing two-line LCD display.
- RS485 and RS232 interfaces.
The controller also provides configurable parameters for the battery capacity, charging behaviour, energy consumption, speedometer calibration and range calculation – which nicely feed into my love for (exact) data.
For the technically inclined, Dreifels published a product sheet for the dfc 30. It is an interesting document to look at, not least because it shows how much functionality it provides..
Dreifels Controller dfc 30 – original product documentation (PDF)
And for those who want to get even deeper into the details, the complete operating manual is available directly from Dreifels:
Dreifels Controller operating manual (12 pages, PDF)
When the DFC is installed, one of the most visible changes is on and in the display.
The original TWIKE display provides the usual driving information, but the Dreifels version turns it into a comprehensive information centre.
The standard display shows speed, time, battery capacity and remaining range. A few button presses reveal additional information, including voltage, current, consumption, temperatures, power, torque and various trip counters.
For somebody who likes understanding what is happening inside a vehicle, this is rather satisfying. And, as i have already described previously, I contributed two of the main display screens myself.
But there is an important distinction between having lots of information and having useful information!
A battery gauge that simply displays voltage is of limited value, particularly when dealing with lithium batteries. Voltage alone doesn’t tell you how much usable energy is left, and its relationship with state of charge varies considerably depending on the chemistry and operating conditions.
The DFC therefore maintains an energy balance. It measures the energy going into and coming out of the battery and uses configured parameters to estimate the remaining usable capacity, besides counting the single teeth on the gears in the drive train to establish a centimetre-exact distance total for extra-exact range calculations!
The range prediction is then calculated using the configured usable battery capacity and a reference consumption figure, which is freely configurable.
This is a sensible approach. It also explains why the range estimate doesn’t necessarily increase dramatically after a long downhill section with substantial regenerative braking. The controller uses the remaining capacity and a fixed reference consumption rather than assuming that the rest of the journey will consist of an equally generous descent.
Dreifels actually explains this behaviour in its operating manual, using the Grimsel Pass as an example. When descending, consumption can reach zero or even become negative, but that doesn’t mean the TWIKE will continue downhill forever!
There is, of course, some configuration involved. The usable capacity and reference consumption need to be set appropriately, and the energy measurements need to be calibrated. The controller provides the necessary parameters to do this.
In the early versions, Dreifels even documented some of the known shortcomings and corrections rather openly. Version TW2.05 had, for example, issues with energy counters resetting after 100 kWh and with range estimates following intermediate charging sessions. These were addressed in subsequent software releases. I’ve updated TW560’s and other people’s controllers multiple times in the meanwhile – it is a fairly easy process.
I quite like this aspect of the Dreifels documentation. Rather than pretending that everything was perfect from day one, they documented what was known, what had changed and what users could expect from later versions.
Also, since I know the people behind Dreifels well, it’s fairly easy for me to get more information when something or a detail doesn’t make sense.
On to one of my favourite features: switching the TWIKE off properly
There is one feature of the DFC that I consider particularly important, even though it isn’t particularly glamorous.
The controller completely disconnects the vehicle’s consumers from the battery when the TWIKE is switched off.
This means there is no continuous standby consumption from the main battery.
Why does that matter?
Well, lithium batteries generally don’t appreciate being deeply discharged. And a vehicle that spends several weeks or months parked somewhere can be surprisingly good at consuming energy without actually going anywhere.
Various electronic components, monitoring circuits and other consumers can continue drawing current even when the vehicle appears to be switched off.
With the DFC, the shutdown process disconnects these consumers. Dreifels explicitly designed the circuit so that neither the controller itself or any other part of the TWIKE does not draw standby current from the battery in the fully switched-off state.
This is something I appreciated particularly when leaving TW560 parked for extended periods.
I actually wrote about this in September 2014, when a rather unusual problem developed with the controller’s main switch.
Repairs: when a TWIKE wants to go on and on
The switch had developed a hairline crack in the PCB connection. It meant that TW560 sometimes refused to switch off properly. After some probing, the culprit was found and I repaired it by soldering a flexible cable across the damaged connection.
That entry also shows the modifications required to implement the complete shutdown functionality.
It is a good example of the difference between simply having an electronic controller and having one that has been thought through as an integrated vehicle system.
Of course, completely switching off the 12V system also means that accessories requiring a permanent supply need their own solution.
What else? Charging deluxe.
Now, this is where the DFC starts to make a substantial difference to somebody who actually travels with a TWIKE.
In the early days of electric mobility, range was everything. Battery capacities were small, charging was slow and finding a suitable charging point could easily determine the route of the day.
But once you have a battery that can take you more than 100 km, charging speed becomes increasingly important.
After all, sitting around for four or five hours to replenish a battery is not particularly attractive when you’re trying to cover 300 km in a day.
The Dreifels system was designed with additional charging equipment in mind. The controller can manage the charging process, monitor the battery and accommodate external chargers.
Already in November 2010, TW560 was equipped with two additional chargers and extended controller software. I took the vehicle to Vienna and Graz to test the arrangement and get a feel for how it would work in practice.
The two additional chargers were installed in the space previously occupied by the third NiCd battery, behind the driver’s seat.
This arrangement provided some interesting possibilities.
For example, I could use the additional chargers independently when I wanted to give the motor and inverter a break during charging. And because the charging arrangement allowed me to use three separate phases, I could also obtain power from three different single-phase connections.
That last bit was particularly useful when travelling. Finding one suitable three-phase socket wasn’t always straightforward. Finding three individual single-phase sockets was sometimes considerably easier.
In the original 2010 configuration, TW560 could achieve charging rates that were rather remarkable for the time.
The November 2011 Dreifels product sheet describes the optional fast-charging arrangement as providing up to 6 kW, corresponding to a theoretical charging speed of 120 km/h at the stated consumption figure.
In the 2011 Tour de Danmark report, I described TW560 as having the unique feature of charging faster than it could drive: approximately 144 km/h charging speed!
Later configs took this number all the way up to 158km/h!
That was based on the actual configuration and the assumptions used at the time. It made for a nice headline on my blog, even if the more conservative 120 km/h figure in the Dreifels product documentation is the more useful published specification.
For the original trip report, have a look here:
TWIKE Tour de Danmark 2011 – The Land of The Naturally Blond (PDF)
And if you want to see how the charging arrangements evolved further, my Type 2 charging upgrade for TW560 is another interesting chapter.
The controller’s ability to integrate additional charging equipment made this kind of development possible without having to reinvent the entire vehicle’s electrical architecture.
The DFC does quite a bit more than simply switch a charger on and off.
For starters, it monitors the charging process and displays the current charging speed in km/h.
I find this a particularly nice way of presenting the information. Most people understand km/h. Fewer people immediately understand what 5 A at a particular voltage means in terms of how quickly their vehicle is being replenished.
The controller also allows the charging current to be adjusted. The original software offered several charging-current settings, with the lowest setting intended to work safely with ordinary sockets and the higher settings available when the electrical installation could support them.
There is also a charging timer, allowing the start of charging to be delayed. This is useful when taking advantage of lower electricity tariffs or when charging needs to be coordinated with other consumers.
And then there is the automatic shutdown after charging.
In the early software versions, Dreifels even implemented a holiday mode. When the vehicle remains connected to the mains for several days, the controller periodically checks the battery.
These are small details, but they make a considerable difference to the everyday usability of an electric vehicle.
As mentioned before: the ability to update the software of the controller is key – I’m one of the few TWIKE pilots with the required cables doing it myself – normally one would go to one of the TWIKE service points to have the update done.
The first documented software versions date back to June and December 2010.
TW2.05 and TW2.07 were initially designed for the Dreifels LiFePO4 batteries. In June 2011, TW2.10 added support for FINE batteries.
Then came TW3.03 in January 2012, which introduced support for older NiCd two-block systems.
This was an important moment: The controller was no longer restricted to one particular battery technology.
Some of the subsequent improvements included:
- More sophisticated range calculation, with several different calculation models.
- Temperature-controlled NiCd charging, including balancing and cooling phases.
- Improved battery self-discharge calculations.
- Additional temperature monitoring.
- Improved calibration of energy counters.
- Support for external charging equipment.
- Additional interfaces for external devices, including the Dreifels LED matrix display.
- Improved motor temperature monitoring and warnings.
- Additional battery identification and capacity parameters.
In 2011 – after my input – Dreifels was also working on an SMS module.
The idea was simple: the TWIKE would send an SMS when the battery was fully charged or if charging had been interrupted.
For somebody travelling with the TWIKE, this would be extremely useful. Imagine leaving your vehicle charging somewhere, going for dinner and receiving a message when it is ready. Or, perhaps even more importantly, being informed that somebody has disconnected your charging cable prematurely.
The feature wasn’t ready in time for the 2011 trip, as documented in the Tour de Danmark report.
The controller’s software development continued for years. Dreifels’ online documentation now includes revisions up to TW3.19, with further functions and adjustments described in the manual.
For anybody interested in the details, the online Dreifels controller manual is probably the single most useful resource available.
Another thing I love about the DFC is the data logger: because knowing is better than guessing, right?
The controller records relevant operating data onto an SD card, allowing the battery’s behaviour and the vehicle’s operating profile to be analysed afterwards.
This is useful for several reasons.
First, it allows you to understand what actually happened during a charging cycle. How much energy went into the battery? How did the temperatures develop? Was there an interruption? How did the system behave towards the end of charging?
Second, it makes troubleshooting considerably easier.
Third, it gives you the opportunity to evaluate changes to the battery configuration or charging parameters based on actual measurements rather than assumptions.
And fourth, it’s the basis for Dreifels’ external, newer, cloud-based vehicle telemetry solutions… which I have not opted for.
For somebody who likes measuring things, this is a rather dangerous feature. You can spend an entire evening looking at data that most people would never even know existed.
But it is also one of the reasons why I have been able to understand TW560’s battery behaviour in such detail over the years.
When I installed the new battery pack in 2016, for example, the controller remained an important part of the overall system. The new battery configuration required me to become familiar with a different discharge profile, different capacity characteristics and different behaviour at low states of charge.
My original entry about the replacement is here:
TW560’s New Battery Pack Installed
It is also a nice illustration of how the controller has outlived several generations of battery technology in the same vehicle.
In 2016 I purchased a new battery – the controller stayed the same:
When the original Dreifels LiFePO4 battery pack had accumulated around 110,000 km, it was time for another major upgrade.
After considering various options, I once again chose Dreifels. The new battery was based on LiNiCoAlO2 cells, rather than the original LiFePO4 chemistry.
This was a substantial change in battery technology, and naturally required a different set of parameters and a fresh understanding of the battery’s behaviour.
What didn’t change was the fundamental role of the controller.
It continued to manage the battery, monitor charging, provide the range calculation and give me the information needed to understand what was happening.
It also demonstrates the value of having a controller designed with some degree of flexibility rather than being permanently tied to one particular battery configuration.
So… is the DFC perfect?
This isn’t the right question. It takes a TWIKE to a next level with regards to usability and dependability.
One of the most important changes is the user interface. It is functional, information-rich and gives a pilot all the information necessary whilst allowing for super-granular configuration of the vehicle.
I want a system that starts when I press the button, tells me what I need to know, makes long-distance travel hassle-free, charges my batteries correctly and switches everything off when I leave the vehicle parked for a few weeks.
And that is precisely what the DFC has been doing for me.
Looking back at the original conversion in 2010, it is quite remarkable how much of the electrical architecture has remained relevant.
TW560 has gone through several battery configurations since then. The vehicle itself has been extensively rebuilt following its 2018 accident. I’ve changed charging arrangements, added charging hardware, modified cabling and spent countless hours looking at battery measurements.
I’ve driven it across borders, through mountain passes, along some rather questionable roads and to places where finding a suitable electrical socket was sometimes a bigger challenge than finding somewhere to sleep.
And throughout all of this, the Dreifels Controller has remained an integral and dependable part of the vehicle.
There is a lesson here that goes beyond TWIKE technology.
When upgrading an older electric vehicle, it is tempting to focus entirely on the battery. After all, the battery determines the range, the weight, the cost and a substantial part of the driving experience.
But the system managing the vehicle and the battery is equally important. It needs to understand the battery, communicate with the charging equipment, provide reliable information to the driver and protect the vehicle when it is not being used.
A good controller also needs to be adaptable. Battery technology changes, charging equipment changes and the expectations of the owner change. Being able to accommodate these developments without having to replace the entire electrical architecture is a considerable advantage.
It makes or breaks the overall experience of a vehicle!
And this is where I think Dreifels got a lot of things right back in 2010.
They didn’t simply build a replacement battery monitor. They developed a battery and vehicle management system that could grow with the vehicle.
Of course, I have no idea how many more years the original controller will continue to operate. Electronics age, components become unavailable and eventually something will fail.
But having a component survive more than fifteen years of fairly intensive use, multiple battery generations and hundreds of thousands of kilometres is a pretty good result in my book.
Not bad for something that most people never even notice when they climb into TW560.
And perhaps that’s the best compliment I can give it.
It just works.
Most of the time, anyway. 🙂
…
For those interested, as mentioned before, there is extensive Dreifels documentation available on the controller.
- Dreifels Controller – online operating manual and software revision history
- Dreifels Controller – operating manual (PDF)
- Dreifels Controller dfc 30 – original product sheet (2011)
- Dreifels – electronics and controller overview
- Dreifels – additional fast chargers for TWIKE
- Dreifels Lithium Power battery – technical documentation (PDF)
And, naturally, a big thank you to Ralph and the Dreifels team for developing and supporting a system that has accompanied TW560 through so many adventures.