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Old 25-09-2013, 03:43   #436
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Re: Lithium Batteries (for the rest of us)

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Terry-
Does the NASA guy mention that most of their projects are probably designed to run at -270C with a battery pack heater to bring them back UP to an optimized temperature?
He did mention testing the cells for thermal effect, over night in liquid nitrogen and the defrosted, they still performed as designed.
I'm guessing they fully understand the issues with low temps and the effects that has on the cells, but I doubt there is the luxury of heater packs for the cells. The cells will create their own internal heating if the current draw is controlled to stay under the damage threshold until the cells are up to temp. The cell heat would swing both ways, during the periods in the Martian sun the whole unit would heat up considerably as well.
There is no doubt in the world these cells were tested and picked to be the best available, but you need the people who understand the batteries the best to be doing the testing, NASA picked this guy.

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Old 25-09-2013, 04:45   #437
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EV guys are down around 40Ah so there are very high demands on the cells. T1 Terry
Terry, 40Ah might power a scooter or motorcycle, or maybe a dragster. But it would have no range in a 4 wheeled car. Tesla has banks that last for around 300 miles, which would be 5-8 hours of operation. I've heard of no DIY cars with that kind of range, but some are using 180Ah cells.
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Old 25-09-2013, 18:34   #438
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Re: Lithium Batteries (for the rest of us)

A wander off topic, but in propulsion it's all about Kwh storage, 40Ah x 400v is the same as 160Ah @ 100v, but the motor windings are far smaller and the cable size no longer becomes the bottle neck at the higher voltage. When the 1000v controllers hit the market the whole scene will change, high speed motors driving constant variable transmissions.

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Old 25-09-2013, 18:37   #439
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Re: Lithium Batteries (for the rest of us)

A series string of over 100 of those 40 Ah cells.
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Old 25-09-2013, 18:41   #440
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Re: Lithium Batteries (for the rest of us)

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Terry, 40Ah might power a scooter or motorcycle, or maybe a dragster. But it would have no range in a 4 wheeled car. Tesla has banks that last for around 300 miles, which would be 5-8 hours of operation. I've heard of no DIY cars with that kind of range, but some are using 180Ah cells.
Those banks are about 6,800 of the little 18650 cylinder cells. That's a lot of series/parallel.
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Old 27-09-2013, 19:11   #441
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Re: Lithium Batteries (for the rest of us)

So i have two extra 3V cells as spares, can I hook them up on the existing bank to keep them charged and healthy? That would be 5 cells in two 3V banks and 6 cells in two 3V banks for a total of 12V in series?
If not how do I keep the 2 spare cells healthy should one of the other cells go bad in the next year or so?
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Old 27-09-2013, 19:47   #442
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Re: Lithium Batteries (for the rest of us)

"Tesla has banks that last for around 300 miles, which would be 5-8 hours of operation."
According to Tesla. But there was a major dispute last year where a NYTimes reporter claimed he drove one and had a much reduced range, and Tesla accused him of outright lying. I never heard the outcome to that, has anyone here?

No doubt they build an interesting car, but a reliable range (using the heater or AC) of only 200 miles followed by an overnight recharge just still doesn't compete.
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Old 27-09-2013, 20:45   #443
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Re: Lithium Batteries (for the rest of us)

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So i have two extra 3V cells as spares, can I hook them up on the existing bank to keep them charged and healthy? That would be 5 cells in two 3V banks and 6 cells in two 3V banks for a total of 12V in series?
If not how do I keep the 2 spare cells healthy should one of the other cells go bad in the next year or so?
Keep the 2 spares as they were delivered, if between 3.2v and 3.3v, in a cool place, 25 degC is good. They will last an estimaed 10 yrs like this and still be ready to perform duties. there is some question as to whether capacity decreases during storage time, a test on A123 cyclindrical cell said yes, but my Thundersky LFP cells were 3 yr old in the packing case and delivered more than the advertised capacity after the initial condition charging, so there is some debate as to whether fidings on cylindrical cells crosses over for prismatic cells (the battery box shaped ones)

T1 Terry
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Old 27-09-2013, 20:57   #444
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Re: Lithium Batteries (for the rest of us)

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Originally Posted by hellosailor View Post
"Tesla has banks that last for around 300 miles, which would be 5-8 hours of operation."
Quote:
Originally Posted by hellosailor View Post
According to Tesla. But there was a major dispute last year where a NYTimes reporter claimed he drove one and had a much reduced range, and Tesla accused him of outright lying. I never heard the outcome to that, has anyone here?

No doubt they build an interesting car, but a reliable range (using the heater or AC) of only 200 miles followed by an overnight recharge just still doesn't compete.

Tesla have a fraud and defamation case in the courts against both the reporter and the NY Times. What the reporter didn't realise is the on board computer records everything in a data log and the satellite tracking follows the every move of the vehicle.
That British motoring show was caught out the same way, after they pulled the first stunt, Tesla put data recorders into all the demo vehicles. In court the motoring shows producers admitted to the fraud and said they were really an entertainment show, so they shouldn't be held to account on facts..... it cost them big $$ I believe.
the Tesla will fast charge in around 30 mins I believe and travel 300kms on that charge. The average traveller spend 30 mins min and 45 min average per fuel stop, that makes it realistic, as long as there is suitable fast charger outlet. I believe this is what Tesla are in the process of setting up now, a fast charge network.

But this way off topic.

T1 Terry
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Old 27-09-2013, 22:22   #445
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Re: Lithium Batteries (for the rest of us)

Talk about thread drift AAAAaaaagggghhhhh!!!!!!
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Old 28-09-2013, 16:10   #446
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Quote:
Originally Posted by T1 Terry View Post
According to Tesla. But there was a major dispute last year where a NYTimes reporter claimed he drove one and had a much reduced range, and Tesla accused him of outright lying. I never heard the outcome to that, has anyone here?

No doubt they build an interesting car, but a reliable range (using the heater or AC) of only 200 miles followed by an overnight recharge just still doesn't compete.
Quote:
Tesla have a fraud and defamation case in the courts against both the reporter and the NY Times. What the reporter didn't realise is the on board computer records everything in a data log and the satellite tracking follows the every move of the vehicle.
That British motoring show was caught out the same way, after they pulled the first stunt, Tesla put data recorders into all the demo vehicles. In court the motoring shows producers admitted to the fraud and said they were really an entertainment show, so they shouldn't be held to account on facts..... it cost them big $$ I believe.
the Tesla will fast charge in around 30 mins I believe and travel 300kms on that charge. The average traveller spend 30 mins min and 45 min average per fuel stop, that makes it realistic, as long as there is suitable fast charger outlet. I believe this is what Tesla are in the process of setting up now, a fast charge network.

But this way off topic.

T1 Terry
Just to correct a very erroneous comment

"The court of appeal signalled the end of the road for Tesla's legal claim on Tuesday, rejecting the company's complaint that its reputation was damaged by Clarkson's typically provocative review of the Tesla Roadster car.

The lengthy legal affair is likely to have proved expensive for Tesla, which hired London libel specialists Carter-Ruck and a top QC to fight its case from 2011. In the past year alone, Tesla has been ordered to pay £100,000 in costs on account to the BBC
......


However, Andy Wilman, the executive producer of Top Gear, said: "I am pleased that the appeal court has upheld the previous ruling and the case has been struck out. I'd also like to apologise to the judges for making them have to watch so much Top Gear."

"

Despite a three year Libel case , tesla lost on all counts against the beeb

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Old 28-09-2013, 19:11   #447
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Re: Lithium Batteries (for the rest of us)

Coming back a bit on topic, Tesla (Musk himself) claim specifically that they are using small cylindrical cells, as opposed to larger prismatic ones, because the larger cells present an inherent danger from fire. His logic is that a small cell will never make a big fire, and that it is easier to separate, control, and contain them, apparently. He was rather blunt about that when he offered Boeing help, indicating that their battery fires were predictable and avoidable if they only had the engineering knowledge that he has. (Hmmm.)

But it does make one wonder if these batteries, regardless of exact chemistry, shouldn't be housed in robust sealed caskets, not just braced and bolted down.

At least there is some agreement as to how a wet lead battery can or will explode, and how that nasty situation can be avoided, even though thousands (?!) of people manage to explode wet lead batteries in the US alone every year trying to jump start or charge their cars. Safety is a relative thing.

Apparently IBM is one of the major players betting on lithium-air chemistry, predicting a real product of some kind in 2014.
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Old 29-09-2013, 06:34   #448
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Lightbulb Re: Lithium Batteries (for the rest of us)

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Coming back a bit on topic, ...are using small cylindrical cells, as opposed to larger prismatic ones, because ...
Thanks for coming back to "the cell question"...
Why are we using (few,large) prismatic LFE cells for boat energy storage?
Real/serious question - real answer appreciated: Everybody else (i.e. all those in mobility)
seemingly(?) use a large number of small cells (maybe even LiPo)(proof?).

{- compared to Pb-Acid ("better": noPeukert,price-lifetime,weight)
I do not really want to discuss the basics so just for reference}


- compared to multicell LiPo storage
(0) safety
(1) mechanical construction
...
- compared to multicell LFE storage
(0) ease of mechanical construction
(1) price (as in $/kWh)
(2) maybe cost (as in $/kWh/lifetime)
(3) thermal considerations (as in heat)?
...
...
...

... am I the only one that finds the lack of "serious" "scientific" data on prismatic LFE cells unacceptable ?
(I doubt that I'm just too dumb to find the research)(see also next post).
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Old 29-09-2013, 06:36   #449
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Lightbulb Re: Lithium Batteries (for the rest of us)

this is not so OFF-Topic ... please bear with me to the end
2.15 seconds: Students break 0-100 acceleration world record for electric cars
(2.15 seconds: Students break 0-100 acceleration world record)
The DUT Racing team from TU Delft, The Netherlands, has broken the world record for acceleration from 0 to 100 km/h for electric cars. The previous record stood at 2.68 seconds, but as of today the record is now held by the TU Delft students with 2.15 seconds. 'We thought that under these conditions we'd be happy with 2.30, but we really didn't expect 2.15,' says team manager Tim de Moree...The students used their self-built racing car from 2012, the DUT12: a compact racing car with full four-wheel drive, weighing only 145 kg. The car was built for the Formula Student competition and the students won the unofficial World Championship with it at Hockenheim.

Battery Pack (http://dutracing.tudelft.nl/explore-the-car/powertrain/)
The main parts for the battery pack are battery cells, similar to the ones found in cell phones or laptops, but then in large quantities (in the order of 300 individual cells!). This means that the battery pack is one of the heaviest components of the car. Keeping the weight low is of paramount importance for a race car, hence a lot of time is spent on selecting the best kind of cells. ‘Best’ is defined as having the highest energy density and being capable of delivering and absorbing the large power the motors demand/produce without excessive heat production and performance degradation. Lithium Polymer type cells are used, provided by Melasta and tested at KEMA in order to accurately determine how the cells perform. Furthermore, simulations are done in Matlab to determine the required energy capacity to run the Endurance, and from this the design of the battery pack follows. 288 cells, of which 2 in parallel and 144 series give the DUT13 a battery pack which can deliver well over 85 kW of power, absorb 50 kW of regenerative power and stores 6.3 kWh of energy at a peak voltage of 600V. The total weight of the pack is 43 kg, divided over two compartments on either side of the driver, close to the centre of gravity. (Melasta -- A professional portable power solutions provider)

Now if someone wants to "read up on" "real scientific electrical storage" here is an address:
Delft University of Technology: hydrogen-and-electrical-energy-storage-couse home (note: study load (hrs) 112, level Master)

...and Yeeees I know we do not want/need kV but stick to our 12V surroundings (why? :grin)
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Old 29-09-2013, 08:33   #450
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Re: Lithium Batteries (for the rest of us)

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... am I the only one that finds the lack of "serious" "scientific" data on prismatic LFE cells unacceptable ?
(I doubt that I'm just too dumb to find the research)(see also next post).
Here we go again
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