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Maximum regen amps

asgard

Member
Aug 17, 2013
310
9
CA
Hi folks,
The maximum regen amps I am seeing on my Roadster is 83 amps when driving at 60-70mph on a level road and letting go of the accelerator pedal.
Is that in the normal range. I recall seeing over 100 amps at one point but maybe I am not remembering correctly?
 

Mark77a

Member
Jul 7, 2012
457
179
Poole, Dorset, UK
If that c 84 amps is at c 400v its over 33.6 Kw ! ... which is in 3-phase, rapid charging territory !

iirc the Roadster charging/regen system uses the motor windings in a clever way.
 

dpeilow

Moderator
May 23, 2008
9,152
892
Winchester, UK
If that c 84 amps is at c 400v its over 33.6 Kw ! ... which is in 3-phase, rapid charging territory !

iirc the Roadster charging/regen system uses the motor windings in a clever way.

Peak power for a few seconds though - a different beast to sustained power over an hour.
 

gregd

Active Member
Dec 31, 2014
2,555
1,777
CM98
Peak power for a few seconds though - a different beast to sustained power over an hour.

A different vehicle, but I read somewhere about a guy who recharged his Leaf by towing it behind a pickup truck... Probably not a good idea.

A question, though: Where are the measurements taken? Is the LCD display measuring the net going into/out of the battery itself, or is it measuring where else? Same question for the analog meter on the 2.0/2.5 models? I.e. if you are regenning, say, 5kw on the analog display, but have the heat + AC on max, would the digital display net out to about zero?
 

asgard

Member
Aug 17, 2013
310
9
CA
I am not sure the LCD displays net current. When I have the headlights on and heater or AC on, it barely registers 2A.
 

hcsharp

Active Member
Jun 7, 2011
3,400
1,411
Vermont
The LCD displays the current going in our going out the batterie.
Full regen is indeed 33 kW, with 400V counts for 82A.

Then why do I often see the kW meter go to -40 on my 2.5? Are you saying that the motor might be generating 40kW but what's going into the battery is only 34kW? Perhaps the overhead of the electronics are only 85% efficient?
 

gregd

Active Member
Dec 31, 2014
2,555
1,777
CM98
I believe Tesla stated 80% (IIRC).
I also see around 34kW on my 2.5

I thought that 80% included the battery itself and heat losses therein, i.e. net effect on range due to regen. The meter is in front of the battery, so you're measuring what goes in, not what gets stored. The electronics themselves should be much better than 80%, no?
 

BartJ

early member
Dec 13, 2014
542
303
Belgium
today the SC installed new brake discs and pads and now regen goes up to 98a.
versus 84a max last week with the old brakes...
new brakes = less friction = more regen ?
 

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