-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
EVNow
Well-Known Member
The reason for my question is the question I got from Daniel on PriusChat about my EV comparison chart.
All EVs, PHEVs specs/dimensions compared - Page 3 - PriusChat Forums
All EVs, PHEVs specs/dimensions compared - Page 3 - PriusChat Forums
Maybe the 2.5 cars use the 2.4mah cells, but the early cars sure didn't. Either way, Tesla is very secretive now about what cells they use/test, so unless you personally know some top of the food chain insiders, it's all a guess.
Martin explicitly said on his blog when this topic came up (sadly now gone) that his car had 2400 mAh cells. You can't get much earlier than that.
His car, or all of the cars? There are various tales of founders cars having different cells in them including the Musk cars. I have confirmation from a very valid source, that the early cars had 2.2mah cells because they were the cheapest at the time. That source no longer works at Tesla, so whatever cells they use now are pure speculation unless someone can confirm otherwise.
Since the early cars had the 2.2 cells in them, what does tesla do in a case of a brick going bad? They have been replacing entire packs in some 1.5 cars with no question, while other cars just get a single brick replaced. I would venture as far as to say that since the cells cannot be mixed, that is the reason for the difference in pack warranty work.
JRP3
Hyperactive Member
I always thought that they may de-rate them. Say for instance they used 2400mah cells, but programmed the firmware to charge / discharge them as if they were only 2200mah. Then they might get much higher cycle life out of them by avoiding the extremes where the most battery aging / damage happens. (In particular, charging the max full level the battery allows is not very nice to it.)
Last edited:
JRP3
Hyperactive Member
Without a doubt they under charge the cells, it's the best way to prolong their life. Limiting the finishing voltage keeps them under charged and keeps the electrolyte away from the breakdown voltage, and of course limiting the discharge cutoff voltage as well on the other end. A123 cells have tested out to 100,000 cycles by shallow cycling only between 40-50% SOC. Page 14
stopcrazypp
Well-Known Member
That doesn't really prove the point. 100k 40-50%SOC cycles is equivalent in utility to 10k 0-100%SOC cycles. To really see if there is any gain in life from shallow cycling, A123 has to overlap that graph with battery tests for 0-100%SOC cycles with the cycles for scaled for the difference in utility.
JRP3
Hyperactive Member
I believe A123 is under 2000 cycles at 100% DOD cycles. As with most cell specs I've seen shallow cycling increases cycle life in a non linear fashion.
JRP3
Hyperactive Member
Just a tad. For reference here is a data sheet from Sinopoly, (Thundersky), showing 2000 cycles at 80% DOD and 3000 cycles at 70% DOD, 10% shallower discharge leading to 50% more cycles: http://sinopoly.todayir.com/attachment/201110101251233_en.pdf
In THIS document, dated August, 2006, in the last paragraph of page 1, they say the pack operates at 375 volts and holds 53 kWh. But in an undated article on THIS page in the second paragraph, they say 56 kWh. That page includes a link to another article dated January, 2011, so I take it as being more recent.
EVNow asked the question because on a different board I had asked him about a chart he had posted, because people ask me the specs of my 2.5 non-Sport Roadster. Acceleration, torque, HP, and battery size. I wanted to be able to give an accurate response. Charts of range:speed and wH/mile:speed look to me like indicating a total battery capacity closer to 56 than 53.
The question of Who cares? comes down to, people who ask about my car would like to know. I like to give the most accurate answers I can. So it's not Earth shaking or life-and-death. Just a matter of curiosity.
Hello everybody,
Does anybody has experience in bringing a roadster battery back to life? It undercharged due of the parasitic current while standing still. We are experienced in EV's but havent worked on Tesla's so far. I remember seeing a forum where a (i think) company in the US brought these dead batteries back to life by taking the battery apart and charging cells individually. But i can't find the website/forum anymore. Any help of advice would be very appreciated!
Thanks in advance,
Niels
Does anybody has experience in bringing a roadster battery back to life? It undercharged due of the parasitic current while standing still. We are experienced in EV's but havent worked on Tesla's so far. I remember seeing a forum where a (i think) company in the US brought these dead batteries back to life by taking the battery apart and charging cells individually. But i can't find the website/forum anymore. Any help of advice would be very appreciated!
Thanks in advance,
Niels
JRP3
Hyperactive Member
It doesn't seem likely to give a good result, but it also seems to the the only chance there is.
JRP3
Hyperactive Member
All the cells connected in parallel are effectively one single cell at the same voltage, separating them to charge individually would provide no benefit. If some of those cells are completely dead and can't be charged then physically removing them from the pack and replacing them would, but that's a different issue.
Similar threads
