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Forum » Three Weehler EVs » TWIKE

New USA Twike owner (TW 434)

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Author	Message
Written on: 22 July 2008 [06:42]
webfootguy Topic creator registered since: 22.07.2008 Posts: 9	I've just purchased a 10 year TWIKE and I'm in the process of getting it back in running order. My blog is at http://twikepdx.blogspot.com/. Should be fun. I hope to get it to 100% operational by the end of the summer. I'm planning on investigating doing my own Li-Ion pack with A123 cells and custom BMS. --phil [This article was edited 1 times, at last 22.07.2008 at 06:58.]
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Written on: 24 July 2008 [09:44]
Yardonn registered since: 22.08.2007 Posts: 156	I wish you good fortune with your project! I dropped the Idea off doing something special with Twike Batteries because of the complicatied electronic involved (And my first Job was hardware related programming!). And because of this decision i droppe the Idea of buying a twike, because in the middle last year Li-Ion was no option availible at Fine Mobile. The chance to blow something (expensive...) is a little to high in my opinion, so i would take the fine mobile solution even if it is expensive. I haven't yet seen a sucessful Li-Ion conversion for a twike! And the A123 Batteries aren't cheap eather. But i would be glad to hear that I am wrong. I would have it a little bit easyer to get A123 Batteries working in my Alleweder, because i only need a voltage (not to mucht) above 24 V (proboably 8 cells) and beetwen 20 and 40 Ah. I now using the same NiCd Cell's (5 Ah) as the latest NiCd-Twike-Generation, and ofcourse i would love to replace my 32 kg Batteries (2 * 20 Ah for app. 100 km range) by extimated 10 kg of Li-Ion, but i fear the answer when i try to by 160 A123 Cells (modell 26650...) Alleweder 4 http://www.akkurad.com allmost full weather protection for one person at 0 - 1.5 kWh / 100 km CityEl as secondary E-Car
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Written on: 25 July 2008 [13:57]
ecoadmin Administrator registered since: 20.07.2007 Posts: 504	Hello Phil, welcome to the Green Car Network! I wish you all the luck for your project and hope that you get your TWIKE soon onto the road. Please let us all know how you're getting on. It would be one of first homemade Li-Ion conversions! and who knows, maybe other North American TWIKE pilots are also interested in your solution. Please do not hesitate to use the forum if you need any help. Many TWIKErs are regularly browsing this forum and you might get useful advice. Cheers, Stephen ecocarforum.com - Green Car Network
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Written on: 27 July 2008 [14:17]
Franko30 Moderator registered since: 08.09.2007 Posts: 79	Hi, I welcome you to this forum, too. But I guess I have to disappoint you right away. I don't think you're going to be able to use your own LiIon-batteries as replacement for the NiCd ones, let me explain: Yardonn wrote: I wish you good fortune with your project! I dropped the Idea off doing something special with Twike Batteries because of the complicatied electronic involved (And my first Job was hardware related programming!). The main problem is that LiIon batteries have to be charged and decharged differently than NiCd batteries. And the charging specifications are hardcoded in the EPROM of the Woods-Etrac. So, you can replace the NiCd batteries with LIon ones without changing the EPROM - but you might destroy them while charging (they are not supposed to be charged over their maximum voltage, but the NiCd programming doesn't have any restrictions here) or destroy them while driving (NiCd batteries can be decharged till the voltage "collapses" - LiIon are not to be emptied that much. Again: The NiCd programming doesn't limit decharging to a certain voltage value). And another problem: The EPROM program is locked to the Twike it runs in. Even if you get hold of a LiIon EPROM, its use needs a (changing) password from Fine Mobile to unlock it on the Twike it is supposed to work in. So, you have to get an "OK" Fine Mobile, no matter what. Your only possibility without the "OK" from Fine Mobile is to use LiIon in addition to the existing NiCd batteries. This means, the only connection of the LiIon batteries to the Twike is via the existing NiCd batteries (kind of a support to them). The problem here is weight (NiCd + LiIon = too heavy). My suggsestion is to order LiIon-batteries from Fine Mobile. They installed this scheme to keep people from fiddling with the batteries etc. Why? Because tehy don't want bad news about the Twike batteries or electronics - nobody distinguishes between batteries that don't work because somebody tampered with them or batteries from Fine Mobile that might not work... Therefore they sell the batteries with a very low margin, so that the most crucial parts always come from them. I hope everything made sense, as I'm not a native speaker. Cheers Franko30 Twike 891 easy: 24 Ah Li-Ion-Mn batteries, 360 V, about 7 kWh/100 km (336 US-miles per Gallon) | Citysax 002: 160 Ah Li-iron phosphate batteries, 83 V, about 13 kWh/100 km (180.93 US-Miles per Gallon)
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Written on: 29 July 2008 [08:37]
webfootguy Topic creator registered since: 22.07.2008 Posts: 9	Franko30 wrote: Hi, I welcome you to this forum, too. But I guess I have to disappoint you right away. I don't think you're going to be able to use your own LiIon-batteries as replacement for the NiCd ones, let me explain: ... rest of message removed ... see above Hi Franko30, your English is far better than my German! I understand your points about a do-it-your-self solution being difficult, but I argue not impossible. I have not yet committed to building my own Lithium pack, it is just a potential goal. Nothing says you have allow the firmware to treat your pack as NiCd. I know the BMS communications has been reverse engineered as I have found some details of it online. One real possibility is to "spoof" the charging logic into doing what you want it to do based on the NiCd charge profile (i.e. a 7 degree rise in temp ends one phase of the charging is easy if you spoof the temp reported by the BMS). This would mean understanding the charging profile very well but the available documentation is very complete in this area. Another way to avoid this is to use an external charger and not charge via the on board system at all. I'm not sure which is "better" at this stage. I have the means to completely record the RS485 BMS protocol and will be doing so shortly. I do think a US available LiFePO4 solution that is safe, not too expensive, and has a good lifetime would do all US TWIKE owners a service (as well as myself). That is my goal (to make the info available on how to do this yourself). Of course, I could just spend the $20,000 USD to purchase a new Li-Ion pack from Fine Mobile but that is many time what I paid for my used TWIKE. Not my cup of tea I'm afraid. I'm in the process of setting up a TWIKE Technical Wiki to share my findings so stay tuned. If this works out well, anyone could build their LiFePO4 packs for a TWIKE.
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Written on: 29 July 2008 [13:26]
Franko30 Moderator registered since: 08.09.2007 Posts: 79	webfootguy wrote: I know the BMS communications has been reverse engineered as I have found some details of it online. I didn't know that. The problem is: You might get a problem with copyright/intellectual property on that one if you use it. I know, it's lame citing IP rights, but as much as I hate these, we still live in a world where they exist. Therefore you might want to actually talk to somebody at Fine Mobile about this problem. They're nice people and might be able to give you some legal security in that. webfootguy wrote: I have the means to completely record the RS485 BMS protocol and will be doing so shortly. This sounds like fun! webfootguy wrote: I'm in the process of setting up a TWIKE Technical Wiki to share my findings so stay tuned. If this works out well, anyone could build their LiFePO4 packs for a TWIKE. That's really going to be interesting. There's already a German language wiki on stuff like that. Let me know if you need help with translations - i.e.: where online translation services are not good enough. Twike information: http://elweb.info/dokuwiki/doku.php?id=twike Twike technical stuff: http://elweb.info/dokuwiki/doku.php?id=twike_technik_und_artikel Twike modifications: http://elweb.info/dokuwiki/doku.php?id=umbauten Cheers Franko30 Twike 891 easy: 24 Ah Li-Ion-Mn batteries, 360 V, about 7 kWh/100 km (336 US-miles per Gallon) | Citysax 002: 160 Ah Li-iron phosphate batteries, 83 V, about 13 kWh/100 km (180.93 US-Miles per Gallon)
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Written on: 19 November 2008 [07:07]
webfootguy Topic creator registered since: 22.07.2008 Posts: 9	Just an update. I've got enough lithium (A123 cells) for 10 mile range. I'm in the process of designing the battery pack / BMS. I've written a C# app that emulates the entire BMS logic well enough to completely satisfy the Twike Battery Service App (v3.6). Tomorrow, I'll try it against the car itself. If it works, I should be on the road shortly.
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Written on: 19 November 2008 [11:12]
ecoadmin Administrator registered since: 20.07.2007 Posts: 504	Great news! Please let us know how the road tests go...Best of luck and keep those cells cool! ecocarforum.com - Green Car Network
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Written on: 07 December 2008 [16:00]
Franko30 Moderator registered since: 08.09.2007 Posts: 79	Hi Phil, found your November entry after some weeks of forum-diet. webfootguy wrote: Just an update. I've got enough lithium (A123 cells) for 10 mile range. (...) Tomorrow, I'll try it against the car itself. If it works, I should be on the road shortly. How was it - I hope the lack of a "results" article doesn't mean anything severe happened! Cheers Franko30 Twike 891 easy: 24 Ah Li-Ion-Mn batteries, 360 V, about 7 kWh/100 km (336 US-miles per Gallon) | Citysax 002: 160 Ah Li-iron phosphate batteries, 83 V, about 13 kWh/100 km (180.93 US-Miles per Gallon)
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Written on: 27 January 2009 [17:35]
webfootguy Topic creator registered since: 22.07.2008 Posts: 9	Just an update for those interested. My progress was slowed by the Holidays and by the severe weather we had here. I have BMS code that will bring the car up to the message "Everything OK". I have purchased more lithium and have enough cells to build a 3.4KW pack. I'm working on a hardware design for the BMS that will do low voltage cutoff and high voltage shunt bypass to protect the lithium cells. This BMS will interface via RS485 to the existing controller to manipulate the charge cycles (I won't need firmware upgrades in the controller). Designing the BMS is taking longer that I was hoping for but trading off cost of the BMS vs the safety/features is a struggle. In the end, I should have 40 miles of range with LiFePO4 cells that just plug into an existing vehicle for a reasonable cost. I have been stuck with the car in "Precharge" state with my fake software BMS but I think I have that problem solved with some help from Peter Zeller. Once I have fully proofed my BMS code and finished the hardware design for the BMS, I will move the BMS code to the new hardware, build the lithium packs, and go for a spin. I have learned a tremendous amount of technical information about the vehicle (including disassembly of the 68HC11 based BMS code, fully decoding the BMS protocol itself, battery service program 3.6 patched for English, etc). What Fun!
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