z32

Was told if you fast charge everytime, it'll prematurly degrade the battery fast.. hence the slower you charge the longer the battery lasts. Do you guys alternate charging speed? Or 70% fast 30% slow?

bytemaster0

Charge whatever makes the most sense for you. Proper cooling on the MB cars significantly reduces some of the damage typically caused by DC fast charging. That being said, some degradation will still occur - just not as much as people may have feared, and it may be statistically insignificant. My rule is, if I'm road tripping, or if I did a bunch of driving and need to quickly turn around and drive a bunch more, I'll DCFC. Otherwise, always AC charge. If you've got the time and the charger, just use it. Honestly, the few seconds it takes to plug in a car before going to bed or after coming home is far more convenient than hunting down a DCFC, even though we have one 3 minutes away from our house. Better for the car, better for you.

bytemaster0

I'll add on to this. NCM batteries, like the ones in MB EQ cars to date, prefer lower states of charge and smaller charge cycles. In the summer, when we have higher heat, I'll set charge limit to 70%, and then charge every time I get home. That might mean charging back 3% or 30%, depending on how much I used that day. I've never run anywhere close to low with a 70% charge limit even commuting back and forth several times and adding errands. Road trips are of course, a different story, and I'll bring it up to 90% or even 100% right before we start the first leg.

In the winter, where efficiency is lower, I'll set charge limits to 80%. Again, charge every time you get home, or at least every night. Range anxiety magically disappears completely.

ehildum

I set my DCFC per the Mercedes recommendations in the manual which are 80% charge limit and Eco mode. Eco mode limits the fast charging to ~100 kW, about ⅔ the maximum DCFC the car is capable of, which significantly limits the strain on the battery during fast charging. The 80% limit helps in two ways, the first being reduced strain on the battery and second improving charging time as charging up to 80% can be done at 100kW, while charging above that occurs at a rapidly decreasing rate so that final 20% takes as much time as charging to 80%.

AC charging, which for Mercedes occurs at up to 9.6 kW, puts less charging strain on the battery due to the lower power. In my case, I have found that I don't need to install a 240V circuit, as for my driving even the 120V 15A circuit supplies enough power to charge the car over my average daily use of about 30 miles a day.

By the way, the 9.6 kW limit of the built in inverter means there is no point going above 50A if you are going to install a 240V socket. (Tesla home chargers use a 60A circuit as the built in Tesla inverters are 11 kW.) Since Mercedes are 9.6 kW, the max current will be 40A. US electrical code allows a continuous load of 80% the rated current for a circuit, hence the use of 50A circuits to support the 40A continuous load. This will save some money as the cabling and components for a 60A circuit are more expensive than a 50A circuit.

Phatfill

Goid to hear, have had a 350+suv for a month and have been using slow charging w a wall outlet. Works fine for UA as car maybe gets 20-30 miles a day. Have been recharging primarily on weekends back to 80% and am thinking I really have no need to stall a mid level plug for charger.