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.