I’ve been hinting at this for a while now: TW560 is getting a major battery upgrade. Today, I’m very happy to report that the first phase of this upgrade has been completed. My TWIKE is definitely ready for our upcoming 11-day, 2500km yearly trip, TDAF2016.

This upgrade has been in the making for a very long time – more than 18 (!) months, to be precise. Yet again, since this is a major investment in a 15-year old vehicle, I definitely wanted to invest all the time necessary to thoroughly evaluate and compare all options: Buy original packs from Fine Mobile, the current TWIKE manufacturer, buy from dreifels, the TWIKE inventors or build my own pack from cells imported from china.

When buying new batteries, there are quite a few factors to take into consideration: pack size, weight, price per Ah, support by TWIKE service centers, amount of changes required to accommodate new pack, access to single cells within a pack in case of cell failure, communication quality with vendor, trust in solution, durability, cell type, long-term plan for capacity decrease, total price, financing models, second life options for current pack and much more.

To cut a very, very long story short:
After ruling out Fine Mobile’s offer mainly on price per Ah, communication quality with vendor, cell access, innovative financing models, changes required to accommodate new pack, building a new pack was also ruled out because I didn’t want to embark on yet another personal project I don’t have the time for and wouldn’t be supported by anyone.

Dreifels, on the other hand, was *very* accommodating towards my various requests for information and was very happy to provide me with ample – and sometimes proprietary – information on their solution.

One example of this open information policy is what happened when I asked about the cell generation currently being used in the 45Ah blocks currently being sold and if I might be able to have a newer generation in my block: Ralph sent me a very detailed technical spec-sheet for the cell in question and asked me to comment on it!


After much deliberation about pros and cons (higher cost per cell / lower cost per Ah was one of them) I decided that TW560 would get this cell type. See the comparison between Dreifels’ current cell, a reference cell and the newer one! YUM.


Panasonic NCR18650BD SDI INR18650-35E SDI INR18650-29E
3.0 V
2861mAh 10.088Wh
3171mAh 11.168Wh
2652mAh 9.430Wh
3.1 V
2782mAh 9.848Wh
3040mAh 10.772Wh
2617mAh 9.325Wh
3.2 V
2674mAh 9.514Wh
2852mAh 10.182Wh
2542mAh 9.091Wh
3.3 V
2409mAh 8.657Wh
2496mAh 9.031Wh
2323mAh 8.383Wh
3.4 V
2029mAh 7.395Wh
2112mAh 7.758Wh
1949mAh 7.138Wh
3.5 V
1615mAh 5.980Wh
1742mAh 6.495Wh
1536mAh 5.729Wh
3.6 V
1211mAh 4.557Wh
1384mAh 5.232Wh
1194mAh 4.526Wh
3.7 V
877mAh 3.346Wh
1033mAh 3.960Wh
912mAh 3.502Wh
3.8 V
563mAh 2.178Wh
752mAh 2.918Wh
618mAh 2.410Wh
3.9 V
282mAh 1.107Wh
398mAh 1.563Wh
367mAh 1.454Wh
4.0 V
16mAh 0.068Wh
38mAh 0.159Wh
98mAh 0.399Wh


And what a good-looking cell this is! πŸ™‚

Pink is en vogue!
Pink is en vogue!

Just to give you an idea how different the sizes of my previous and new cells are, I took this picture:

Old cell format vs. new cell format
Old cell format vs. new cell format


Furthermore, if you see how Dreifels builds their packs, you can see that access to a single cell is very easy, unlike other packs from other vendors…

Extruded plastic looks good, but there are issues...
Extruded plastic looks good, but there are issues…

Since I wanted to be able to go on TDAF2016 with a large battery, hearing that the 35E cells wouldn’t be available until *after* June was a big disappointment. Again, Ralph jumped in with an offer: You may use my personal 45Ah 29E pack until your pack is ready at zero cost. Now that is what I call customer service!

Another aspect that was very important to me was what would happen to my “old” cells which still are at 75% of their original capacity after they finished their service as traction batteries for TW560. This is also known in the industry-jargon as ‘second life’ applications.

Currently, the market for used traction batteries is very good – Germany is struggling to stabilize their grid which is receiving large amounts of high-fluctuation renewable energy (May 16, 2016 almost 100% of Germany’s energy consumption was covered by renewable energy) and a crazy market of negative energy costs which sees owners of battery-powered power-plants earning money twice: quickly taking in energy when there is too much renewable energy on the market and selling it at a premium later, when renewables contribute less to the overall mix.

Dreifels is currently investing heavily into second life applications of their technology and install base of LiFe batteries and as a result had a very compelling offer for me and my current pack – take back the pack at a premium (in comparison to the Germans) and install them in Switzerland – supporting a household to gain full independence from the grid. Yes, please!

To summarize:

tick pack size: 3.67x more energy @ 85% volume
tick weight: 25kg lighter than today
tick price per Ah: lower than all available options – full pack costs considered
tick support by TWIKE service centers: 100%
tick changes required to accommodate new pack: very low
tick access to single cells within a pack: yes, without destroying pack enclosure and little work/risk
tick communication quality with vendor: see above!
tick trust in solution: yes – was part of process myself πŸ™‚
tick durability, cell type: trusted type, major vendor
tick long term plan for capacity decrease: Dreifels controller gives me full control
tick total price / financing models: CHF ~18k – acceptable due to Dreifels financing offer
tick second life options for current pack: YES & part of pack vendor offering! (i.e. discount on new pack)


As you can imagine, I counted the days until I was able to go and get the loaner-pack installed, ready for my trip.

Monday May 23, was the date. That rainy morning I drove to Sissach, the last trip with my trusted 20Ah pack that was my travel companion for ~110,000 km.

The Dreifels crew welcome me and assign me their meeting room as my temporary office – outside, work on TW560 commences immediately.

TW560 waiting for new batteries
TW560 waiting for new batteries

I reflect on the situation happening outside… the battery pack that has been with me on so many adventures all over the world is being extracted from TW560 and will be replaced with a new pack. It’s like parting with a good old friend. I’m happy knowing that they will have a very meaningful purpose for the next 5-10 years, serving a Swiss family as their means to live off-grid. More on this in my next entry!

Ralph’s loaner-pack is extracted from TWIKE 001 (yes, the very first one – and still in active service!).

Loaner Dreifels batteries "only" 14Ah instead of 17.5Ah
Loaner Dreifels batteries “only” 14Ah instead of 17.5Ah


With all the packs extracted and ready to be transferred to TW560, a very familiar feeling comes rushing back: It was like last time when I first saw the 20Ah pack – I was very underwhelmed by the volume and appearance! See for yourself πŸ™‚

Not much to see for 17,000 CHF
Not much to see for 17,000 CHF

With just two new brackets the new pack finds it’s place in TW560’s battery bay.

New packs mounted
New packs mounted


Nearly done: Some re-cabling and new AK-print brackets
Nearly done: Some re-cabling and new AK-print brackets


AK print and DCDC converter
AK print and DCDC converter


All done. So much space left over!
All done. So much space left over!


With my requirement to be able to access as many cells as possible directly, dreifels offers me, yet again, all the access I might require:

Sooo many balancing ports!
Sooo many balancing ports!

Opening the TWIKE’s battery bay and retrieving the controller had some other advantages, too: discovering some connectors in imminent need of replacement πŸ™‚

Definitely time for a refresh
Definitely time for a refresh

After a short morning working from my off-site office, I was able to drive off with a completely transformed vehicle which will take some time to get used to. A new discharge profile means me getting used to how the battery reacts to low SOC’s, temperatures, load profiles etc. I feel like a neo-driver again πŸ™‚

But what gets me is the range prediction I get when i power-up my TWIKE:

With 35E's TW560's range will be around 420km
With 35E’s TW560’s range will be around 420km

This is going to be fun! (And I’m looking forward to a) TDAF2016 and b) my 35E pack in July!)

PREVIEW of the up-coming 2nd-life entry

TW560's old blocks, ready to be re-conditioned for a 2nd life application
TW560’s old blocks, ready to be re-conditioned for a 2nd life application

Ralph and Jane about to open TW560's first block
Ralph and Jane about to open TW560’s first block

Salt & electrolyte: Don't go well together!
Salt & electrolyte: They don’t go well together!

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