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Forum » Three Weehler EVs » TWIKE / TW4XP

Zebra TWIKE

Author	Message
Written on: 25 December 2007 [14:30]
ecoadmin Administrator Topic creator registered since: 20.07.2007 Posts: 517	Hello, On a meeting of the Twike Club in Germany in April 2007, the feasibility of using a ZEBRA battery for the Twike has been discussed. A detailed document showing the pros and cos of the Zebra battery in the TWIKE has been released. The document (in german) can be found here. The study concluded that the introduction of the Zebra battery is generally possible if the Twike is used often enough (>8000km/5000ml/year). The manufacturer has recently launched the Li-Ion Twike which gives the vehicle a range of up to 200km(125miles). Does this mean the end for the ZEBRA battery project for the Twike? Or is the TWIKE maybe available in two versions in the future? Lion / Zebra? ecocarforum.com - Green Car Network
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Written on: 11 February 2008 [18:36]
childress Administrator registered since: 14.08.2007 Posts: 136	Every battery chemistry has a different positive and negative attributes... From reading on Wikipedia (english link): http://en.wikipedia.org/wiki/Molten_salt_battery And the recent work I've done inside Twike 433, the 250degC operating temperature seems a little extreme for the amount of ABS and Luran S plastic in the Twike... "When not in use, zebra batteries typically require being left under charge, in order to be ready for use when needed. If shut down, a reheating process must be initiated that may require up to two days to restore the battery pack to the desired temperature, and full charge. This reheating time will however vary depending on the state-of-charge of the batteries at the time of their shut down, battery-pack temperature, and power available for reheating. After a full shut down of the battery pack, three to four days usually elapse before a fully-charged battery pack loses all of its significant heat." While the extra heat would be welcome in the wintertime (today I Twiked 10 miles to the babysitter's, my daughter's school and then work at 7degF -- 16km at neg14C), I can't imagine Twiking in the summertime with an extra 250degC in the trunk! Any chance of getting a pro/con list in English, please The fact that currently-on-the-road Twikes can take the Lion battery upgrade is most exhilerating, and speaks well of the initial design. M@ Commute suck? Twike it; You'll like it! http://www.uiuc.edu/goto/twike
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Written on: 24 February 2008 [21:28]
ecoadmin Administrator Topic creator registered since: 20.07.2007 Posts: 517	Hi M@, If I remember correctly from technical reports I read earlier on, the Zebra battery does not get very warm on the outside due to excellent isolation. I haven't seen it myself yet though. I personally give the Lion-Twike better chances than the Zebra-Version. Lion batteries can be recharged relatively quickly and you do not need to have your Twike under charge all the time. Here a summary of the report translated into english: .The introduction of the Zebra Battery is generally possible. By adding the Zebra battery to the range of possible battery types, it is possible to attract a new range of potential Twike buyers. Twike owners driving more than 50km a day or more than 8000km/5000miles a year would have a battery offering more reserves compared to batteries currently in use. However, the following issues mus be addressed: -Battery and operating costs will not be lower than at current levels (CHF 2000-3000/year) -The lifespan of the battery probably exceeds the span of electrical components of the battery system, connectors and of the Twike. -If used less than 5000km per year, the Zebra battery consumes more electrical power than other battery types because of its standby-power consumption of about 50 Watts. In contrast to the NiCd battery, the Zebra battery should always be recharged after each use of the Twike and is therefore usually always on charge over night. That requires a parking space with a power socket. -If the Twike uses a Grell/Rüetschi electric motor, the available range will be reduced to about 50% of the normal range. Reason is the high inner resistance of the battery and the associated voltage drop when the Twike is driven at high speeds. This would affect about 100-200 Twikes Translation to be continued...(running out of time...!) ecocarforum.com - Green Car Network
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Written on: 25 February 2008 [16:20]
childress Administrator registered since: 14.08.2007 Posts: 136	I'm betting on the Lion Twike as well -- it has such a sweet logo/name, and most folks are comfortable with Li-ion technology, even with the exploding laptops Li-ion technology did not become like Hydrogen/Hindenburg in the US psyche... which is the first thing someone from the US asks when you mention Hydrogen Fuel Cells... The long lifespan seems interesting, though disappointing that the operating costs would not be reduced. The reduced range for some Twikes (is there an easy way to tell which Powerplants have which motors?) is a serious hit though -- I drove all around town on Saturday with a 3-pack NiCad and still had juice to spare... I've also figured out that I can get back and forth to work 8-10 miles (13-16km) with just a quick charge (at 16amps). It by no means fills it up completely, but given the self-discharge of the NiCads, makes me feel a lot better to be able to alternate a full charge with partial charges... not to mention not having to worry about remembering to plug it in at night -- just the first thing when I get up in the morning... One possibility is that with such an extended lifespan, power leveling could occur... that's when your electric vehicle's stored electricity is used to level out brief power drops from the power company -- your car essentially becomes a UPS (uninterruptable power supply). Of course that's a lot of cars/Twikes Thanks so much for the translating work! I really, really appreciate it (not to mention my brain.... Google's translation services are amazing, but you still have to alter your brain quite a bit, where Google translates the German word for electrical current into the english word 'river') M@ Commute suck? Twike it; You'll like it! http://www.uiuc.edu/goto/twike
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Written on: 29 February 2008 [12:43]
ecoadmin Administrator Topic creator registered since: 20.07.2007 Posts: 517	I have the feeling that the Zebra Twike will remain what it is: a study. The Lion batteries are on the rise and as you say, people know better what a Lion battery is compared to a Zebra battery. I think that is a very important factor. Even though we hear that occasionally batteries catch fire etc, there are the billions of batteries that work fine. And thats I think why people trust the Li-Ion technology. A Zebra Twike might become reality one day when they are used on large scale by for instance taxi or delivery companies using their vehicles round the clock. Then the energy used because they are continuously on charge (to keep the battery at its operating temperature) would be used. ecocarforum.com - Green Car Network
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