[drgrieve]

94 * (3.35V - 2000A * 8 mohm / 8) * 2000A = 254 kW
94 * (3.35V - 2000A * 4 mohm / 16) * 2000A = 534 kW

I haven't seen this calculation before (the dividing by parallel part). Do you know of a video which shows this during battery testing? I find that easier to digest.

Interesting when you plug in 1000A

94 * (3.35V - 1000A * 8 mohm / 8) * 1000A = 221 kW
94 * (3.35V - 1000A * 4 mohm / 16) * 1000A = 291 kW

Doubling the amps for the 16ah only gains you ~15% more power ....

This gives me much food for thought.

[DavidDymaxion]

I don't know of a video, but it is basic electronics. Resistive loads in parallel lead to less overall resistance. Because the resistances are presumably the same between the batteries, you can just divide the resistance of one battery by the number of batteries in parallel.

Testing batteries is not rocket science. Buy a Harbor Freight adjustable battery tester (about $50), buy a few 16 Ahr and 8 Ahr P Headway cells, and see for yourself how the power differs. I wear safety glasses, put in ear plugs, and throw a mat over the batteries when I test.

Originally Posted by drgrieve

I haven't seen this calculation before (the dividing by parallel part). Do you know of a video which shows this during battery testing? I find that easier to digest.

Interesting when you plug in 1000A

94 * (3.35V - 1000A * 8 mohm / 8) * 1000A = 221 kW
94 * (3.35V - 1000A * 4 mohm / 16) * 1000A = 291 kW

Doubling the amps for the 16ah only gains you ~15% more power ....

This gives me much food for thought.

[rwaudio]

Originally Posted by steven4601

That is a pretty good car as an EV. Also your plans sounds like it will be a rocket.

Robin, that looks like some battery origami for the next few weeks What config 100S2P ? How much did that set you back? $65,- the piece?

Yes, lots of work with the batteries, and with my current schedule, more than a couple weeks. 96S2P as a minimum but ideally 96S3P... less than $65/pc

I will admit the headways were a lot easier to work with. It's too bad these A123's aren't more "available" it would probably spawn 5 companies to build DIY assembly systems for the cells so that just about anyone could use them...

[powerhouse]

OK im back, ive been busy doing nothing

good news, ZILLA 2000 is on its way!

I am going to have Dennis Berube build my motor
A couple of things have been decided with his advice
The car will be running @ 350ish volts, as opposed to the 280ish I was planning before
Also, the car will contain 2 Traction packs, 1 consisting of 10 AH Headway cells, in parallel, enough to get 2000 Amps out of it. And another traction pack made up of GBS batteries, which are practically thunderskys, but better.. This pack is going to be in series, and will be a high voltage low current pack.

[albano]

Originally Posted by powerhouse

OK im back, ive been busy doing nothing

good news, ZILLA 2000 is on its way!

I am going to have Dennis Berube build my motor

Good choice you got here,

[Bowser330]

Originally Posted by powerhouse

OK im back, ive been busy doing nothing

good news, ZILLA 2000 is on its way!

I am going to have Dennis Berube build my motor
A couple of things have been decided with his advice
The car will be running @ 350ish volts, as opposed to the 280ish I was planning before
Also, the car will contain 2 Traction packs, 1 consisting of 10 AH Headway cells, in parallel, enough to get 2000 Amps out of it. And another traction pack made up of GBS batteries, which are practically thunderskys, but better.. This pack is going to be in series, and will be a high voltage low current pack.

^^^ This!
(1) Great Donor
(2) High Voltage Built Motor
(3) Interesting hybrid battery pack

So when the controller demands the amperage from the battery pack, the Headway's will provide the amps and the GBS's will not be damaged?

[x88x]

Originally Posted by powerhouse

Also, the car will contain 2 Traction packs, 1 consisting of 10 AH Headway cells, in parallel, enough to get 2000 Amps out of it. And another traction pack made up of GBS batteries, which are practically thunderskys, but better.. This pack is going to be in series, and will be a high voltage low current pack.

Interesting hybrid pack choice. There may be a problem with that though. What it sounds like you're proposing in your description (please correct me if I'm wrong) is a low voltage pack of headways several wide, stuck in series with a high voltage pack of GBS. That won't achieve the results you're looking for. The headway pack would be boosting the voltage, yes, but the pack would not benefit from the additional current-draw ability of the headways. What would achieve the intended results would be to turn that on its head. Have two packs the same voltage, one GBS, one headway. Wire these packs in parallel, and the headways should serve to boost the current draw capability of the pack. I have seen this done with success before using Turnigy Nano-tech LiPo packs in parallel with SLA. That required a bit of protection circuitry because the packs were different chemistries and thus slightly different voltages, but the end result worked quite well. Here's the guy that did it:
http://endless-sphere.com/forums/vie...p?f=14&t=26797

EDIT:
That being said, assuming you can pull ~1,000A out of the GBS (assuming 100Ah cells; btw, you might want to take a look at the CALB cells; at least on paper they look a little better), you would need a 7P pack of 10Ah headways pushing at 15C (1,050A) to make up the difference. That would be almost $12,000 for the headway booster pack (at CurrentEVTech's prices) for a 94S pack...that's almost what the GBS pack would cost. Personally, I would look at just building a wider GBS/whatever pack; say, a 200Ah. That would still be able to hit 2,000A (according to the specs), but would give you twice the range when you're not pushing massive power draw. If you can fit it in the car, imo that would be a better choice.

[x88x]

Originally Posted by powerhouse

BUT some news! I'm currently planning on purchasing about 20kwh worth of A123 Batteries, the same type CroDriver is using, except more consistent and reliable. .

Nice. From which vendor? What sort of price were they? They're really nice cells, I just tend to ignore them since there's no non-grey-market way to buy them and even grey-market sources tend to be at least twice the cost per Wh compared to, say, TS, CALB, or TS.

[powerhouse]

Better news!


Battery order is going in this week!


Decided im going to go with 1018 8ah Headway cells, 112s/9p
Should have a peak power of 551kw, according to the formula supplied above. The batteries are rated at 25c continuous, so I figured that they should be able to handle 28c for 3 seconds!


The completed pack should get me about 100 miles of range, assuming 250whm^-1 , and a pack energy of about 26kw's


WOO!! Im excited!
Batteries should take 3 weeks to arrive after I order them. For those wondering, the unit price will be about $12.50, and the customs/shipping cost will come up to $700


The Zilla should get here in the next two weeks I hope, however it is the first Zilla 2k EHV coming from Manzanita Micro (BTW they have great service, very helpful!).


I *need* to get this car done by Dec. 31st 2011, in order to get a tax credit on the conversion.


therefore, the Motor order is also going in this week!


One question for everyone, what BMS should I use on this thing??? I really like Crodrivers, however I dont think he will disclose any info on it. A visual display would be really nice on the car.

Thanks for the help everyone!!

[Bowser330]

Super excited to hear more about your build.

Has the S2000 been replaced by the Exige?