I have a MY LR took delivery in June. Only about 5500 miles. My range has lagged the Teslafi fleet since almost the beginning and was recently reported as dead last out of 207 vehicles. See image showing down to 285 range (rated is 326). I know, congratulations, I am the Biggest Loser, LOL. I asked my SC to run a check and they told me that my CAC was 208 and average for fleet (my model/age) is 210. Told I am within 1% and that means my battery is fine. I live in Coastal So Cal, moderate climate for charging and driving, but I think my issue is I have been doing short cycles and commonly charge to 60-70% SOC. I've read dozens of posts including the famous one about how "I recaptured half my lost capacity" (or whatever that huge thread is called). So I know what I need to do if if want to rebalance to increase my range. I have been doing that without much change so far...but understand change could take many deep cycles and months. Not sure I want to do that but also don't want to have my car report low range especially when I want to sell someday. So need to think about that. My questions: Anyone else have CAC measurements to confirm battery is okay and is 208 a good number? Secondly, can I use this 208 as a benchmark to measure in the future...and is there a way to get the CAC without having Tesla run the test? Thank you.
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CAC Measurement/Range Loss
- Thread starter jmichaels
- Start date
Considering that the Calculated Amp-hour Capacity (Ah) multiplied by the nominal pack voltage (V) equals battery capacity (Wh), then battery capacity divided by the nominal voltage equals the CAC.
If the MY's total pack capacity is about 75,000 Wh, and the nominal voltage of the 96s pack is 350 volts, then that equates to a CAC of about 214 Ah when new.
The part I'm unsure about is whether this value is calculated including the top/bottom buffers, or is it useable capacity only. If we calculate this value based on useable capacity instead, 72,500 Wh, that equates to a CAC of 207 when new.
If the MY's total pack capacity is about 75,000 Wh, and the nominal voltage of the 96s pack is 350 volts, then that equates to a CAC of about 214 Ah when new.
The part I'm unsure about is whether this value is calculated including the top/bottom buffers, or is it useable capacity only. If we calculate this value based on useable capacity instead, 72,500 Wh, that equates to a CAC of 207 when new.
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Thanks for the info...trying to figure out your math...can you help with that? Also several other posts have said the actual pack with reserve is 78 kWh. So if its 78 kWh, what's the calculated CAC when new?
Anyone else heard of what the CAC is when new? I have searched the web...can't find anything. Thank you.
I have a MY LR took delivery in June. Only about 5500 miles. My range has lagged the Teslafi fleet since almost the beginning and was recently reported as dead last out of 207 vehicles...
I think we sometimes trade placed for being last. I've tried all of the tricks in the various threads, but my total range keeps dropping pretty fast like yours. Not sure if this is real degradation or BMS error. It is a little disheartening though.
The equation is: capacity in Wh / nominal pack voltage = CAC
1 kWh = 1000 Wh
If it is 78,000 Wh, then that would equate to about 223 Ah.
Since it’s a calculated number, that would suggest to me that it can go up just as it can go down.
I’m very familiar with that thread already. I’m curious to know the specifics about how you went about following the process. SoC, sleep time, frequency, charge set points, etc..?
Ah, thank you. I've always thought that amp hours was a dumb measurement of supposed "energy", because it's incomplete. Asking what the energy of a battery is and getting amp hours does not answer the question, because you need to know the voltage too. Is it a 1.5V battery? 5V? 12V? 350V? That number of amp hours can mean anything in different batteries with different voltage levels, so it's only useful if you're comparing batteries that you know are always of the same voltage level. And since Tesla cars have some with 350V batteries and some with 400V batteries, that's not a useful measurement between different car versions.
The reasoning behind this basically boils down to the difference between current vs power.
Current is the flow of electrons, measured in amps. Something I didn’t know until reading into this just now is that one amp is equal to one coulomb per second. Apparently, one coulomb is equal to so many electrons, which happens to be 6.2 x 10^18, a huge number. Current can be compared to water flowing through a pipe, while voltage is the pressure of the water in the pipe.
Power, on the other hand, is the amount of energy transferred or converted per unit of time. Electrical power is the rate at which electrical energy is converted to another form such as motion, heat, etc. Electrical Power is calculated by voltage times current and is usually used to describe a circuits ability to do work. Power is measured in watts and, for example, is lost most often in the form of heat.
Having said all that, I think of Amp Hours as the measurement of the stored electrical energy before it enters the circuit, compared to Watt Hours being the energy consumed after entering the circuit to do the work inherent in the circuit.
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