Thudersky Real World Experience

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retepsnikrep
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Thudersky Real World Experience

Postby retepsnikrep » Fri Jun 08, 2007 4:28 am

It's been a while since I posted an update on the older TS 200ah cells, but with the recent discussion on the list, here is what my real world EV experience over 20,000 miles tells me.

1) I bought 30x200ah TS cells in August 2003 (Nearly four years ago)

2) I use them in my pure EV van at www.solarvan.co.uk

3) Initially I used all 30 cells in a 108v DC drive setup.

4) 2 years ago I changed to a 28 cell 96v AC regen drive. (I have two spare cells now)

5) The cells have worked absolutely fine over this time.

6) They are rugged and easy to link together (unlike Kokam), and do not require a complicated BMS. I use Cedric Lynch's simple cell protectors, and a Zivan NG3 IUa charger.

http://agnimotors.com/home/index.php?op ... &Itemid=39

7) They do not burst into flame or explode at the drop of a hat, a switch fault a while ago meant my cell protectors became disconnected during a charge cycle, the zivan charger just completed it's normal cycle and switched itself off with no harm done. (It was adjusted initially to provide about the right pack end voltage though)

8) They are ageing of course, and this manifests itself as higher internal resistance rather than reduced capacity. This means it is more difficult to charge or discharge them quickly, as the voltage rises too high or drops too low at high currents, and they heat up more quickly.

9) They do not like cold weather, and need to be at a minimum 20C+ to work effectively now. 25C-35C is better. (I keep them in a heated insulated box)

10) The voltage sag under load is increasing as they age, especially at low temp. A fully charged cell at 20C will still supply 300A+ but the voltage will drop from 4.2v to <2.5v under load. I try to keep to <200A max discharge current. When warm at 30C+ voltage sag is much less.

11) When regen is operating, partly charged cells will still accept charge currents of upto 100A, so long as the cell temp is at least 25C.

12) The limiting factor in their life in my vehicle will be the internal resistance build up to the point they cannot deliver the currents required without damage/overheating. I estimate at the current resistance increase rate they may last another 3 years in my EV application. This gives me a useful life of 7 years. Range is not my limiting factor as my work commute is 26 miles a day total.

13) They may well still be ok as a standby power pack, or ev charge dump pack when EV life is over. I certainly won't be skiping them anytime soon.

14) Would I buy them again? Yes, and I would never go back to lead again. Once you have been spoilt by Li-Ion range/capacity you just can't put up with anything less.

In conclusion I would buy TS cells again tommorrow, I recommend 200ah cells as the mimimum size for most systems, the newer TS 200ah cells are 1.5x heavier than the ones I bought, and I understand have lower internal resistance, and can deliver higher currents. Technology marches on, and I expect their performance will continue to improve. You could wait forever for the EV battery holy grail, and be dead before it arrives, I and the other early adopters of these TS cells took a big gamble. For me it paid off and I have been very happy with them. Good luck.

Peter :D

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ChrisB
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Postby ChrisB » Fri Jun 08, 2007 1:10 pm

Great write up there Peter, thanks for sharing it with us.

Its interesting that you havent needed any flashy BMS on them as this was the one thing that really put me off them 3 yrs ago, I could see the money drain on my walet just on going with BMS, special chargers etc etc and with the cells at the price they where and the gamble that they "might" not be suitable I walked away from it :cry:

I'm now more than ever keen to fit a set into the berlingo when my current Ni-Cads give up the ghost

ChrisB
I reject reality and substitute my own !!!!!!

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aminorjourney
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Postby aminorjourney » Mon Jun 11, 2007 7:18 pm

Interesting Peter,

Do you think you'll be exchanging your batteries in the future for more of the same technology or would you be tempted to try other compositions?

I'm just about to put some high-internal resistance Lithium Ion cells in my City El so I'm interested to read about the current drain limitations.

Nikki.
Nikki Gordon-Bloomfield

EVangelist and Media Relations Coordinator, www.ZeroCarbonWorld.org
Host, www.transportevolved.com

http://about.me/aminorjourney/bio

MalcolmB
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Postby MalcolmB » Fri Jul 06, 2007 7:34 pm

I've just joined the Thunder Sky discussion group at http://tech.groups.yahoo.com/group/ThunderSky/ and will be scouring the archives to learn as much as I can, but in the meantime I wonder if anyone has any first-hand experience with the new generation of lithium iron cells shown on the Thunder Sky site http://www.thunder-sky.com/products_en.asp

If so:
Where did you buy them from?
Do they require:
a. a BMS
b. special temperature control measures, such as heaters, insulation, etc.
c. any form of restraint to prevent electrolyte separation

Malcolm

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timpootle
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Postby timpootle » Mon Jul 09, 2007 9:40 am

Did you mean iron? or ion? The only batteries I saw on that page seemed to be lithium-ion batteries.

The only thing I could find on the wider internet about lithium-iron (LiFe) batteries said that they were primary cells, i.e. use once, do not recharge.

I'm quite happy to be proved wrong- we're all waiting for a fantastic new chemistry to power our cars. Just not sure that ThunderSky are selling them yet.
Tim Crumpton

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aminorjourney
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Postby aminorjourney » Mon Jul 09, 2007 9:44 am

Hi Tim,

I think it was probably a typo, and, let's be fair, we all make them from time to time! :)

Nikki.
:lol:
Nikki Gordon-Bloomfield

EVangelist and Media Relations Coordinator, www.ZeroCarbonWorld.org
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MalcolmB
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Postby MalcolmB » Mon Jul 09, 2007 10:01 am

Nope, not a typo, not this time anyway :D
Lithium iron phosphate (LFP), as sold by Electric Motorsports (see about halfway down the page). They are also lithium ion.
http://www.electricmotorsport.com/PARTS/parts.htm

zhaozilong
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Postby zhaozilong » Tue Oct 23, 2007 8:12 am

I think the Thundersky battery are absolutely junk.

I have used the battery they supplied, simply the devil and all.

they-thundersky- :evil: killed my car.I wil bring an accusation against them!!!
:evil:

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qdos
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Postby qdos » Tue Oct 23, 2007 9:03 am

zhaozilong wrote:I think the Thundersky battery are absolutely junk.

I have used the battery they supplied, simply the devil and all.

they-thundersky- :evil: killed my car.I wil bring an accusation against them!!!
:evil:


This is a serious allegation and one that you should be backing up with some facts rather than simply flaming on this forum.

In view of you having posted what is basically an advertisement elsewhere on tthis forum I suspect that you are actually just trying to throw mud at your competition.

If however your comments are valid then I'd be interested to hear what you have to say but please do not spam our discussion forum. You'll actually only serve to turn people against you.

If you've got something valid to say then by all means say it but if you are simply trying to promote your own business and knock your competition then thank you but please go away it's not acceptable. :!:


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