Thunder Sky Batteries; Dark Cloud or Silver Lining?

I’ve received quite a few email over the last few months asking about one Chinese battery manufacturer who appears to be offering the backyard EVer the ultimate battery solution; Lithium on a budget. Thunder Sky have been making Lithium batteries for years but unfortunately it is a name that sends shivers down many an EVer’s spine. Basically this web site explains why.

A few years ago Thunder Sky (TS) were offering large format Li-Ion cells which they promoted as being suitable for electric vehicles. As far as I know – several individuals, at least one university (QUT) and a couple of groups (UK and USA) bought batches of various sizes and quantities of these cells. I also was very tempted to part with many thousands of dollars to be part of the action. Fortunately for me, I only went as far as requesting a price list from them and that was enough to encourage me to try something less expensive first.

Victor Tikhonov from Metric Mind Engineering organised the USA group buy of TS batteries. Victor is no dunce, he is an electrical engineer and sells advanced AC EV motors and controllers that are to drool over, he sources other EV components from Europe which just ooze quality (read $$$!) and he recently designed the ultimate in EV instrumentation – EVision. (As a matter of fact Victor’s conversion web site was the inspiration for me to do my own conversion and to document the process on the web.) Anyhow, if you were to ask Victor what he thinks of TS now he wouldn’t be inspiring. TS simply ripped him and many others off with poor quality, grossly under performing cells.

OK so now TS are making large format LiFePO4 cells and initial independent testing shows that these cells are performing as specified but the BIG question is how long for??

I notice that for their 160Ah cells they specify a maximum constant discharge current of 480A (3C) yet a “standard” discharge current of 48A (0.3C), presumably to get >2000 cycles (80% DOD). 48A is barely enough to maintain my EV at 40km/h on the flat. So how many cycles do you get when you need much more than 48A for normal driving? I don’t know and as far as I know neither does anybody else.

Be warned; if you purchase TS LiFePO4 batteries you are participating in an expensive experiment, a one year warranty is no protection for poor cycle life.

23 Responses to “Thunder Sky Batteries; Dark Cloud or Silver Lining?”

  1. Alex Says:


    Wots the unit price difference between the A123 Developer Kits and these new TS’s?

    Is it worth it?

    As Victor from MME likes to say on his site – upfront savings often end up costing more later.

    Interesting that he’s used supercaps to mitigate the performance issues of the TS’s in his Civic EV.


  2. shaun Says:


    As I see it, you can’t calculate whether or not it’s “worth it” until you know how many cycles you are going to get from the TS batteries.

    The best independent testing I’ve seen so far is a few thousand kilometres over a year or so, i.e. nothing better than much cheaper lead batteries.

    Given TS’s past record, IMHO, anybody purchasing their products now are taking a huge risk but unfortunately some EV suppliers are promoting TS batteries as the converter’s holy grail without actually having any proof of the claimed cycle life.

    I have to say, it was no fun writing this post, I mean talk about a rock and a hard place! Nobody wants to promote EV’s more than I do and ultimately that is my motivation, it would have been irresponsible of me to say nothing.

    BTW, Victor doesn’t use TS, his conversion info is way out of date.

  3. matt Says:

    i wonder which series of cells the linked web page described, the lcp series or the lfp. based upon the old part number i think it might be the equivalent to the lcp90aha. In the earlier batches QA was non-existent, with battery life varying wildly. I know the west australian distributor is having much more success with his lfp90aha batteries. He converted a suzuki mightyboy and is in the process of converting a holden rodeo. Im shortly going to buy 15 lfp40aha cells from him, hopefully these will meet product specifications, though at least these for me will have a warrantly, albeit a short one, backed by an Australian distributor.

  4. shaun Says:

    Hi Matt,

    They’re the LFP, same as on Rod Dilkes website here;

    I know Rod is pushing these batteries very heavily but he has no evidence, that I’m aware, of their claimed cycle life.

    How much are you paying?

  5. matt Says:

    at the moment im using it to convert a emax to lithium, the 48v 40AH pack with bms will cost me approx 2500. some time next year ill need a much larger pack for a car conversion, however i prefered to have some track record before spending some very large amounts of money for a pack. unfortunately the only way to substantiate cycle life is by, well, long term use:p

  6. shaun Says:

    Good plan Matt, feel free to let us know how they go, good or bad.

  7. Carl Sparre Says:

    Hi Shaun,

    I’m off topic as usual. A couple of news bits.

    First, I saw something about plug standards being defined by the US Auto Industry and fired off an email to Willet Kempton (the professor working with Google on V2G) to ask if they had the standard right.

    The answer was depressing, he felt that had it completely wrong. The auto industry, surprise surprise, was pushing for a low voltage plug – totally unsuitable.

    The good news, I bought a Prius. Love it to bits.


    (I’ll find that email from Kempton and a link to the news item and post it. It’s at work.)

  8. shaun Says:

    Hi Carl,

    Sorry about the slow response again but you were buried in the middle of the spam pit again.

    Great news about the Prius, thinking of getting a plug-in kit if they become available?

  9. Alex Says:

    Hey Shaun

    How’s the cycle testing of the A123′s going?

    Things have gone quiet – are you about to spring a surprise announcement upon us?

    “A123 Echo” :)

    Or are you just busy like the rest of us, with the end of year madness?

  10. Matt Says:

    Hi again,

    I just stumbled across this so i thought i might give a bit of an update.
    Ive had the thunderskys in since Jan 2008.
    in that time ive clocked up 6500km
    ive killed one cell by over discharge (pulled 37AH out of it when the 1C rating is 36AH, interestingly the rest of the pack survived…..stick to 80-90%dod max).
    The rest of the cells are still going strong, and the scooter is still my daily, i know only buy petrol for the car once every 3 months.
    My experience with the thundersky batteries has been good enough that ive gone on to order a 288v 90AH pack for my mr2.

    The cells sag 0.2v per C of discharge. so at 1C (40A for my scooter pack) expect more like 3v instead of 3.2v.
    come on over to the AEVA forums for more regular updates:)


  11. shaun Says:

    That’s interesting Matt but I’ll keep my money for a surer bet.

  12. Clint Says:

    Pulling 480amps out of the cell intermittantly does not automatically mean you have used your 80%DOD. Yeah you will get to it faster of course but the batteries will give you plenty of oomph when you need it.
    As long as you dont push past your 80% then why should there be a problem?
    The question should be, as long as you maintain the companies 80%DOD will the batteries make their stated 2000cycles?

    I looked into a set of 90Ah LiFePo4 cells for 86V pack. $5500 including the Battery monitors and charger to run the 27Hp sepex motor. They would weighed around 80oddKg.
    Lead acids would weigh in over 3times that much easily and only have a life cycle at best of 400max.
    So look at it this way. You have just shead 200odd kg of your vehicle if not more depending on what volts your running.
    Your 48amps might actually see 50 or 60km/hr now..
    Cost wise I can see how the LiFePo4 cells look better on paper.
    Im not trying to put you down either. $5500 for just the batteries is steep but I think its worth it if they perform as expected…

  13. shaun Says:

    Clint wrote “but I think its worth it if they perform as expected…”

    Precisely Clint, given TS past history I wouldn’t put my money on their LiFePO4, I’ll be buying someone elses.

    BTW it’s well known that that higher discharge currents reduce battery life, the question is how much is too much fo TS? LiFePO4 does not suffer so much from how much you discharge (as long as you don’t go below the min voltage!) just how quickly you discharge.

  14. Bryan Miller Says:

    Durability does seem to be the major unknown with the new battery types.

    I wonder how easy it would be to design a test rig that could simulate an EV scenario, with say a 6 volt source and a proportional resistance load. Could you scale it down to test with a single battery or small battery pack (to keep test cost reasonable), and get realistic scalable results? Run it with a computer to control charge and discharge loads, with results gathered by a data logger?

    Run the same test cycle for lead acid batteries (wet/gel/AGM), then LiPo and A123. Could you get comparable results, that wouldn’t be skewed by BMS or charger design?

  15. Matt Lacey Says:

    ive found the most effective way to simulate an EV scenario is to actually put it in one:p

    another update, just past 8500km (400 or so cycles to 60%dod, plus a couple of 100%dod), today still going strong.
    turns out the cell i thought id killed had survived.
    turns out i have a corrosion issue at the terminals, causing significant voltage drop.
    scary what a little water can do.
    tip for young players: tin your copper interconnects with solder to prevent oxidation of the copper.
    also make sure no water gets in :)

    also turns out that the cells are more tolerant of overdischarge than i first thought. last week i ran the scooter until every cell in the pack was below 2.5v (not completely intentionally of course, home was only 2-3km away when the volt gauge started heading further south than id ever seen).
    charged up fine, i havent seen any immediate effect, though this pack is certain for an early death.
    definately wont be doing that for my car pack.

    for those who have a dislike for TS, there have been rumours of another cheap large format manufacturer called sieden. similar construction by the looks of it.
    K2 cells also look interesting. I might build myself a pack out of those project after next.

    shaun – out of curiosity, what batteries are you using now?


  16. shaun Says:

    Hi Bryan,

    I actually went a long way towards building a test rig for 12 x A123 cells in series but got a bit frustrated by the complexity required to monitor / log each cell voltage + total current in both directions, have a realistic charge / discharge profile and keep all the cells balanced. Believe me it takes a lot of work to build something like that with proper fail-safes etc for stand-alone cycling. By the time I’d done all that I might as well have built a whole battery pack!

    Hi Matt,

    I’m just in the throws of testing a BMI 144V 10A LiFePO4 battery pack (14410-HPS). Will be doing a detailed blog of the results but see to get a taste of what I’m playing with.

    I put one (that’s ONE) of these 24kg batteries by itself in my car on the weekend and drove up our very steep street trying not to go over max constant current of 120A (that’s 12C). It continuously pumped out about 15kW (that’s 20HP) no problems up all of the 200 metre climb. Imagine 8 of these in parallel!



  17. Laith Says:

    Hay hay…

    You haven’t updated in sooo long… …Hope everything is still going well with the E-E and yourself…

    I’ve been thinking of converting my Nissan Skyline over… …Or getting another one that’s had the motor thrashed and doing it…

    Are there any books you’d recommend or “Go To” web sites to get info???…

    There were three books I was looking at on Amazon… …”Build Your Own Electric Vehicle” by Seth Leitman and Bob Brant… …”Convert It!” by Michael Brown… …and “Electric Motors and Control Techniques” by Irving M. Gottlieb…

    Amazon seem to sell all three in a package and I was wondering if you’ve read them or at least had a look at them…

    Again… …Hope all is well and I look forward to your next post…

  18. shaun Says:

    Hi Laith,

    I bought the first book but it was a bit disappointing, lot’s written but not much said that actually helped with my conversion. Wouldn’t hurt to get them all though if the price is right.

    As for websites, there are many and I haven’t checked them for a while but my favourite has always been Jerry Halstead’s;

  19. Ghita Says:

    Nice work! I’ll have to do a cross post on this one ;)

  20. John Hardy Says:

    Re Laith’s question about books…

    My EV/Hybrid reading list is on LibraryThing at

    If you drill into the books, you will see some reviews including mine. Leitman and Brand is so-so. “Electric Motors and Drives” by Hughes is brilliant although it does demand some basic physics

    If you know of a good book on batteries, I would be very glad to hear of it.

    Warning – at the moment I’m an EV Newbie. The last car I built has a small block Ford V8!

  21. Tom Says:

    Any updates on ThunderSky batteries as 2 years has gone by since the experiment began? How is the life cycle?

  22. Vladimir Says:

    Это должно быть в цитатнике

  23. Davis Says:

    i have nissan 300Z can this car be converted to Electric Car? And if so how can i get kit for it