[mattW]

I was a little worried about the current rating Of the thundersky cells I was planning to get, I have heard they over play their specs, but here are some encouraging real world numbers from our Aussie EV forums, I asked about pulling 5C:

as far as doing it healthy, i would say so, rod dilkes pulls 450A out of his 90AH (also 5C) pretty regularly in his conversion. his pack is now a year old and going strong.

Most i have pulled out of my pack is 250A (just over 6C) and it sagged to 2vpc.
The thundersky batteries seem to be pretty consistent as far as volage sag goes, 0.2v per 1C of current.
so at 250A my pack sagged from 3.2v to 2v, at 70A it sags to 2.7v.
rob masons old 200AH packs in his mustang fall to 2.6vpc at 600A (3C).
the new 200AH pack in his triton ute fall to 1.7vpc at 1600A (8C)

Those are the packs i have seen in person.

Id doubt your bike would pull 300A continuous, at 60kmh, mine pulls 40-50A@58v (i also have a yesa booster pack in series with the thunderskys in case you were wondering).

[Manntis]

Originally Posted by mattW

I was a little worried about the current rating Of the thundersky cells I was planning to get, I have heard they over play their specs, but here are some encouraging real world numbers from our Aussie EV forums, I asked about pulling 5C:

Rod is the TS guru. I know he sells TS cells, but he's one of those mates who sells them because he knows they're good - not pushing crap on people for a quick buck. I've had the pleasure of talking with him at length on the phone (haven't been fortunate enough to visit Australia in person yet) and he comes across as a real stand-up bloke.

[mattW]

So that means that the current levels are confirmed, the quality control is confirmed and all that is left to see if the cycle/shelf life lives up to the various 1000, 1500 and 2000 cycle claims I have seen.

By the way I just got a quote for my 72V 60Ah pack delivered for $1.80 per Ah or AU$2484 for the whole pack. The supplier just waits for a big enough group buy and then buys them in bulk, seems like every 3 months or so.

[david85]

This sounds promising.......

[DVR]

Originally Posted by mattW

By the way I just got a quote for my 72V 60Ah pack delivered for $1.80 per Ah or AU$2484 for the whole pack. The supplier just waits for a big enough group buy and then buys them in bulk, seems like every 3 months or so.

Matt who quoted you that? Was it Trev at F&F?
Have you had any discussion about BMS?

[mattW]

Yeah it was trev, he said he has an electrical engineer working on a prototype and wondered whether EV power would sell me a BMS without buying the batteries from them. I am hoping I could just get the components from EV power and solder up the 24 units myself to save the labour time/cost but I haven't followed that up yet.
The batteries will still cost close to 5 grand once the BMS and charger are paid for, but I think it will be worth it. Performance estimates look good too.

[JeffPritchard]

Is a BMS for lithium battery charging only critical when charging the cells in series?

If one were to come up with a clever switching "mechanism" to charge the cells in parallel, and use them in series, would that negate the need for a multi-segment BMS?

thanks,
jp

[david85]

I sent an Email to this guy a little while ago: http://www.evalbum.com/1497

He had nothing bad to say about the TS batteries, but he also mentioned that he only had about 50 cycles on the pack at the time.

[alex]

Originally Posted by JeffPritchard

Is a BMS for lithium battery charging only critical when charging the cells in series?

If one were to come up with a clever switching "mechanism" to charge the cells in parallel, and use them in series, would that negate the need for a multi-segment BMS?

thanks,
jp

So what? a 3.2v charger system?

Don't you get the battery balancing problems whether you do it in series or parallel?

[Manntis]

parallel is, in theory, self-balancing but adding all those switchers would be complex.