3 ms·

AFAIK it currently takes ~20 minutes to half-charge a Tesla. 20x would mean charging fully in ~2 minutes - nearly as fast as the automatic option for replacing

by loceng 12y ago

AFAIK it currently takes ~20 minutes to half-charge a Tesla. 20x would mean charging fully in ~2 minutes - nearly as fast as the automatic option for replacing depleted batteries with fully charged ones.

masklinn 12y ago
> 20x would mean charging fully in ~2 minutes Charge profile is not linear in existing batteries. A supercharger is 40mn to 80% and 75mn to 100%.
- loceng 12y ago
  Ah, good to know - thank you.
- danielweber 12y ago
  How does a quick-charge affect the longevity of the batteries?
  - mikeash 12y ago
    I don't believe it's known yet. Battery longevity seems to involve a lot of trial and error, and there isn't much data. As far as I've been able to gather (and I have no real special knowledge here and could be way off), the main problem with quick charging is that it heats the batteries a lot, since charging is not a 100% efficient process and any waste energy turns into heat. Heat is bad for batteries, so it could affect their life. However, Teslas have active temperature management for their batteries (both heating and cooling, as required) which should mitigate that.
  - mnw21cam 12y ago
    Not sure for LiIon batteries. However, back in the days of NiCad batteries, some formulations could cope with really fast charges - and in fact would behave better and last longer after a very fast charge than they would after a slow charge. We're talking about shoving 20 amps into a C cell for five minutes here. You needed to carefully monitor the cell temperature - the charging process wouldn't generate much heat until the cell was nearly full, at which point nearly all the energy going in would convert to heat. 20 amps would heat a full C cell up very quickly indeed.
- JoshTriplett 12y ago
  > Charge profile is not linear in existing batteries. A supercharger is 40mn to 80% and 75mn to 100%. Many people have a mental model of battery charging like a tank of gas or another fluid, in which the first 10% and the last 10% take the same amount of time and effort. It seems like a better mental model of battery charging would be a pressurized container of a compressible gas: the more you put in, the more it takes to put the next bit in.

by loceng 12y ago

masklinn 12y ago

> 20x would mean charging fully in ~2 minutes Charge profile is not linear in existing batteries. A supercharger is 40mn to 80% and 75mn to 100%.

loceng 12y ago
Ah, good to know - thank you.
danielweber 12y ago
How does a quick-charge affect the longevity of the batteries?
- mikeash 12y ago
  I don't believe it's known yet. Battery longevity seems to involve a lot of trial and error, and there isn't much data. As far as I've been able to gather (and I have no real special knowledge here and could be way off), the main problem with quick charging is that it heats the batteries a lot, since charging is not a 100% efficient process and any waste energy turns into heat. Heat is bad for batteries, so it could affect their life. However, Teslas have active temperature management for their batteries (both heating and cooling, as required) which should mitigate that.
- mnw21cam 12y ago
  Not sure for LiIon batteries. However, back in the days of NiCad batteries, some formulations could cope with really fast charges - and in fact would behave better and last longer after a very fast charge than they would after a slow charge. We're talking about shoving 20 amps into a C cell for five minutes here. You needed to carefully monitor the cell temperature - the charging process wouldn't generate much heat until the cell was nearly full, at which point nearly all the energy going in would convert to heat. 20 amps would heat a full C cell up very quickly indeed.
JoshTriplett 12y ago
> Charge profile is not linear in existing batteries. A supercharger is 40mn to 80% and 75mn to 100%. Many people have a mental model of battery charging like a tank of gas or another fluid, in which the first 10% and the last 10% take the same amount of time and effort. It seems like a better mental model of battery charging would be a pressurized container of a compressible gas: the more you put in, the more it takes to put the next bit in.