A measure of charging rate is C, which is the rate divided by battery size. Not sure of your battery size, but let’s assume it is 65 kWh. Charging at 17a is 17/65 = .26 while 32/65 =.49
Generally speaking, anything below C=1 has zero impact on the battery. Note that charging at 48a is just .74
Also, the higher the charge rate the more efficient, so slower is also a bit more expensive.
This calculation is very wrong.
Old post but wrong and I did’nt find any correction.
Amps divided by kWh is not correct.
1C will make a charging session from 0 to 100% take one hour. The Model 3 LFP batteries is 55 or 60 kWh.
Per definition 1C is the same
current as the
capacity.
1 Amphere on a 1 Amphere hour battery is 1C.
I dont know the exact spec on the batteries, but a 55/60kWh Model 3 LFP has 106 cells in series. Each ”cell” of these 106 in series is actually several cells in parallel. The nominal Voltage is 3.2V so of 60kWh we get
60.000/(106x3.2) = about 177 Ampere hours.
If we would like to use Amps like in the post I answer to, we need to relate it to the Amphere hour from the calculation above.
As the Wall charger sends one Voltage but this is converted in the on board charger we can not use the “17 Amps” to direct calculate the C-rate.
If it is single phase 110V it is 17x 110 = 1.9kW. That is about 0.03C.
Whe need to know the Voltage and the number of phases to use the Amps for this.
The car reports the charging power in kW so it is easier to calculate via charging power / capacity.
Also,
1C is not the limit for ”safe” charging that do not cause increased degradation.
Most lithium batteries have a standard charge of 0.2 to 0.5C. Without have checked the specification on a battery we can be sure that 0.25C is a slow charging where a further reduction of the charging lower do not reduce the wear.
0.25C —> 0.25 x 55 to 60 kWh is 13.75 to 15kW charging power.
Maximum AC charge for a model 3 (at least non LFPs) is 11 kW.
This means any AC charging is “safe” for degradation from the charging power.
No need to reduce the Amps for that reason.