-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Charging the Roadster
- Thread starter malcolm
- Start date
Heating of wires goes by the square of the current, so lowering the current can save a lot in wasted heat. Half the current generates a quarter of the heat. But it also takes longer to charge, so you're wasting energy through the fixed "overhead" of the charging circuitry. The sweet spot is reported to be somewhere in the 24 to 32 amps range. I charge at 24, "dialed down" at the VDS in the car; it's enough for a full overnight charge, and nicer to all components involved. I can go to 40 amps if needed, but I seldom do.
In the Summer and in the Winter, is it best to keep my Roadster 2011 2.5 Base connected to a 220 Volt charger OR the 110 Volt charger?
I think in general, the recommendation was for 208/220/240v, and the 110/120V was only meant as a last resort if you were stuck somewhere with no other choice.
Perhaps set for a low battery friendly current like 12A.
tomsax
Member
When charging at 120V, the coolant pump runs for a longer period of time. Some believe this leads to the coolant pump failing sooner or more often. It's probably not an issue if you're leaving the car parked for the winter, but I believe there's a small increased maintenance cost for replacing that pump if you charge from 120V for your normal daily charging.
Even charging at 240V/32A is pretty kind to a 53 kWh battery pack.
At least for the v1.5 Roadsters, the pump is cheap and not difficult to replace if you're into doing that sort of thing yourself to save a few bucks. Tesla Roadster Coolant Pump Failure
Even charging at 240V/32A is pretty kind to a 53 kWh battery pack.
At least for the v1.5 Roadsters, the pump is cheap and not difficult to replace if you're into doing that sort of thing yourself to save a few bucks. Tesla Roadster Coolant Pump Failure
There may also be some efficiency of charging to consider. I think perhaps when doing 120V you are saddled with the basic overhead of pumps, fans, and stuff and less of the wall current gets stored in the battery.
I don't don't know the exact "wall to battery" of the various charging rates, but I thought some 208-240V charging was better that way than 120v. If you crank up the current too high, then I think some active cooling kicks in an starts to make it worse for efficient charging.
I don't don't know the exact "wall to battery" of the various charging rates, but I thought some 208-240V charging was better that way than 120v. If you crank up the current too high, then I think some active cooling kicks in an starts to make it worse for efficient charging.
tomsax
Member
Good point! Charging at 120V takes about 50% more energy than 240V/32A.
Tesla Roadster Charging Rates and Efficiency - Tom Saxton's Blog
I placed the car at 22 amps on 220 Volts.
Will the sheets stay balanced this way?
I always used the 110 V to keep sheets balanced, or was I mistaken?
Thanks,
T
Will the sheets stay balanced this way?
I always used the 110 V to keep sheets balanced, or was I mistaken?
Thanks,
T
Yes to both. As Tom says, just leave it plugged in, and in Standard charge mode. The voltage / current doesn't matter as far as balance is concerned. I believe it's triggered by being above about 80% charge, with Standard charge completing with the battery at about 82%.
The importance of being on a 240v charger is that it's more efficient, and more importantly, if the pack is warm, the higher voltage can run the car's A/C from shore power to pull the temps down. The sweet spot in terms of efficiency is somewhere in the 24 to 32 amp range. I run mine at 24 amps; thermal losses in the wiring also go as the square of the current, so lower current is a lot less heat, and less potential for issues with any mechanical joints (e.g. the 14-50 wall plug and the charger's contactor). If it's really hot, I might drop the current down to 16 amps, but I don't know how much that really helps. The car seems to focus on battery temps over battery charging.
The only advantage of the 120v charging is that the car "sneaks up" on being full, so you get a few more indicated miles of Ideal range. But the difference is minor, and around here where summers can top 110 degrees F, having the ability to actively cool the battery is critical for keeping the pack happy.
I recall there was a study where they found that charging at a higher current (supercharging levels) resulted in much shorter charging sessions, and that the shorter time at elevated temperature was beneficial to battery longevity. So I've been more focused on battery temps than charging current. Given how many battery cells are running in parallel, even at a max 70 amp / 240 volts, the charge current in terms of "C" rates is still fairly low.
All that said, I'm down to a CAC of 136.85Ah on the original 2010 pack, which is towards the lower side of average according to the battery survey. So, who knows what is actually best...
my CAC is 3 pts higher @ 139.8 and i get 166 ideal on my regular 240V/32A charge and 169 on 120V/15A
dhrivnak
Active Member
I would do 240v as there is not enough power to cool the battery in the summer and charge on 120v.
In theory, yes. Similar was done to modify other brands of 120v EVSE to work on 240V. But I think you would be better off just getting a proper 240V EVSE so it has all the correct safety features. You may also want something that can signal higher ampacity so you could charge above like 12A.
(3.0)CONVERTING a LEAF LEVEL 1 (12AMP) CHARGER TO a LEVEL 2 (12AMP) CHARGER
EVSEupgrade.com used to convert a lot of (non-Tesla) 120V EVSE, but it appears that they shut down now.
Archived page:
EVSE Upgrade - Low-Cost EV Charging Solutions
(3.0)CONVERTING a LEAF LEVEL 1 (12AMP) CHARGER TO a LEVEL 2 (12AMP) CHARGER
EVSEupgrade.com used to convert a lot of (non-Tesla) 120V EVSE, but it appears that they shut down now.
Archived page:
EVSE Upgrade - Low-Cost EV Charging Solutions
Similar threads
