Home Charging Best Practices

[Canuck]

Wait, @Rocky_H was talking about the UMC which is correct but you added in the "car electronics" which is incorrect. The OP can charge at any amperage he wants without damaging his car.

That's probably true for time under warranty at least (and perhaps beyond for most cars) but I've read posts here about charger failures. They are high wear items, that require liquid cooling. I wonder if this one was charged at 21 amps daily (being 42 over dual chargers) it would have failed:

Tesla Model S Charger - NEEDS REPAIR

Perhaps not? Or maybe it still would have? Regardless, I'd rather spread the amps over two chargers, then pile them all into one. For only $500 for a HPWC I also get to keep the UMC in my car in case needed.

 

[scottm]

..it would have been cool... and maybe Tesla can do this with firmware change OTA... but why not have have dual chargers share the load before one is maxed out. Say, anything above 20A is split so 10 + 10 on the on-board chargers. That way people with NEMA in the garage and 2 chargers will get 20 + 20 split, which is not achievable with the current (ha!) scheme which dumps all 40 on a single charger.

Yes, you'd lose some efficiency for sparking up (ha!) the second charger and incurring the losses there.. but we're thinking longevity of parts here now. And a little extra electricity is cheap insurance.

Maybe this is so far down on the list it's not funny because new cars only come with single charger.

 

[Vic4Model3]

Charging at 120 VAC at 12 amps was putting excessive wear on one of the coolant circulation pumps, as the pump runs for the entire duration of charging. So now charge at 240 @ 24 anps, which reduces circulation pump run time to 25 percent of the former, a big difference.

 

[cvrcv]

What do you mean by auxiliary losses are too high. Source?

Power draw that is not going into the battery, not including charger efficiency. Somewhere around 300-400W, significantly more if the cooling pumps need to go to max and the AC needs to come on to cool the battery, which happens sometimes.

 

[flipb]

New question, and figured I'd revive my old thread rather than starting anew.

Scheduled Charging
After all the discussion above, I've been charging to 70% at 32amps, using Scheduled Charging to start at 2:00am. I don't have discounted rates at night; just doing this to feel like a good citizen by using some of the extra generated capacity at off-peak hours.

A couple of times, I've left my S plugged in for ~24+ hours. It seems to charge to 70% as scheduled at 2am, but then never charge anymore as long as it remains plugged in. My rated range at 70% is 138 or 139 miles (60kwh, apparently some degradation before I owned it). After sitting for another day or so, I'm typically down to ~135mi range. That seems like fairly high vampire loss to me, and it doesn't seem to "top off" the second night it's plugged in. It's also unclear to me whether the car is using tethered power if I get in to play around, demonstrate the touchscreen to neighbors, etc -- once the scheduled charging time is over.

Can anyone verify whether a plugged-in Model S, where scheduled charging has occurred/concluded, still uses tethered power for aux stuff? Also, Am I correct in observing that leaving it plugged in for 24+ hours, the scheduled charging doesn't "top off" the second night? In my situation, am I better off to disable scheduled charging and just let it charge when I'm home & plugged in?

 

[DarkMatter]

It won't top off until it loses a fair bit from the battery. Anything you do runs off the main pack until it uses enough to engage charging again, which it also won't do until the scheduled time.

 

[Rocky_H]

From what I've seen reported on both forums, 3% below your target level before it will do another recharging cycle.

 

[AEdennis]

New question, and figured I'd revive my old thread rather than starting anew.

Scheduled Charging
After all the discussion above, I've been charging to 70% at 32amps, using Scheduled Charging to start at 2:00am. I don't have discounted rates at night; just doing this to feel like a good citizen by using some of the extra generated capacity at off-peak hours.

A couple of times, I've left my S plugged in for ~24+ hours. It seems to charge to 70% as scheduled at 2am, but then never charge anymore as long as it remains plugged in. My rated range at 70% is 138 or 139 miles (60kwh, apparently some degradation before I owned it). After sitting for another day or so, I'm typically down to ~135mi range. That seems like fairly high vampire loss to me, and it doesn't seem to "top off" the second night it's plugged in. It's also unclear to me whether the car is using tethered power if I get in to play around, demonstrate the touchscreen to neighbors, etc -- once the scheduled charging time is over.

Can anyone verify whether a plugged-in Model S, where scheduled charging has occurred/concluded, still uses tethered power for aux stuff? Also, Am I correct in observing that leaving it plugged in for 24+ hours, the scheduled charging doesn't "top off" the second night? In my situation, am I better off to disable scheduled charging and just let it charge when I'm home & plugged in?

I don't charge to 70%, I charge to 90%... vampire at 3-4 Miles's day seems low to me... mine is closer to 6-8 miles... and it starts to recharge every other day after it has lost closer to 9 or 10 miles.

 

[hingisfan]

I have a 60 with a Nema 14-50. I charge at 32 amps every night and charge to 90%, works great for me, and never have to think about if it's time to plug in.