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Is the dual charger option useful and worth getting?

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Not that it matters much, but awhile back I asked a Tesla Ranger tech (whom I know and trust) about whether the dual 40 amp chargers do any sort of load sharing or splitting, and he said no. The primary unit handles all charging up to 40 amps and the slave unit kicks in to supply more than 40 amps when required.
That's kind of a mix of yes and no. It's true that the primary charger does handle everything up to 40A and won't turn on the secondary charger, but if it's more than 40A, then it does split it evenly in half, rather than 40 + 5 or 40 + 20. Plenty of people have been able to observe this in the car, where if you have 50A, you can watch it run up to 25A and then stay there for several seconds, and then finish running the rest of the way up to 50, as it turns on the second one.
 
Plenty of people have been able to observe this in the car, where if you have 50A, you can watch it run up to 25A and then stay there for several seconds, and then finish running the rest of the way up to 50, as it turns on the second one.

Interesting comment.
I have the double charger on or S85, and at home, on the HPWC, which is 32A powered, I always see the charging climb pretty quick to 16A, the pause for a few seconds, and eventually rise to 32A.
 
Interesting comment.
I have the double charger on or S85, and at home, on the HPWC, which is 32A powered, I always see the charging climb pretty quick to 16A, the pause for a few seconds, and eventually rise to 32A.
I see you're in Belgium. Is that on a 3 phase electrical supply? If it's 3 phase at 32A, I think that would be more power than one onboard charger can handle anyway, so it would be splitting it between the two chargers.
 
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I see you're in Belgium. Is that on a 3 phase electrical supply? If it's 3 phase at 32A, I think that would be more power than one onboard charger can handle anyway, so it would be splitting it between the two chargers.

Yes, I’m in Belgium.
At our home, The power power provided to the HPWC is 240V 32A on a mono circuit.

I initially also thought of upgrading to three phases 32A but the 240v/32A mono phase is enough to recharge overnight my average daily use. (Charge speed is 20 miles/h).
 
Yes, I’m in Belgium.
At our home, The power power provided to the HPWC is 240V 32A on a mono circuit.

I initially also thought of upgrading to three phases 32A but the 240v/32A mono phase is enough to recharge overnight my average daily use. (Charge speed is 20 miles/h).

IIRC, Euro spec Teslas (pre-refresh) had chargers capable of 16 A each. Both chargers are needed to charge at above 16 A, even if only connected to a single phase supply.

Since the chargers are capable of rectifying three phases, they can charge at up to 11 kW each, for a total of 22 kW. This is roughly equivelent to the NA spec single phase 40 A, 240 V, 10 kW chargers offered at that time. Also IIRC, the 22 kW was software limited after the first cars were sold, at least in some countries.

GSP
 
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When we considered dual option the example we were given is a medical personnel on call, who may come home and want to have the vehicle rapidly charged for an overnight emergency call. They talked us out of it and I would say only one or two occasions it would have made a difference was the rare day with regular commute and home for a few hours before starting a drive out of town at night.

Agree with others, now with significant expansion of superchargers even that situation for us would be less of an issue. Only worth the expense if you have a unique work/lifestyle situation that necessitates regular readiness of full charge.
 
I’m not sure how it works, but can you plug into two SC stalls with the dual charger and charge twice as fast? Or if you went to a friends house for dinner and could only use 120v outlet, would it charge at the 120v rate twice as fast? Or if SC stations are able to put out more than 40amps in the future, would this be beneficial? Curious as to the real world examples this could be a useful function.
 
I’m not sure how it works, but can you plug into two SC stalls with the dual charger and charge twice as fast?
No. On-board chargers are bypassed during supercharging and have nothing to do with supercharging. What you are suggesting would require a second port on the car to attach the second supercharger. Even if you could, the current cars couldn't benefit. Supercharging speed is already limited by what the battery can take. Doubling the available power won't help; current batteries are limited to ~120kw peak at low state of charge (SOC), and that rate drops as the SOC increases.

There have been sightings of the Semi charging on multiple superchargers at once (4 max, I think). They use a special combiner cable/extension cord that only works with the Semi.

Or if you went to a friends house for dinner and could only use 120v outlet, would it charge at the 120v rate twice as fast?
No, the limiting factor on 120V charging is the capacity of the plug. It doesn't matter if the car can draw 40A, 48A, 80A, or whatever if the plug can only supply 12A (or 16A for less common higher capacity versions).

There are no common outlets that allow you to charge over 40A (80% limit of a 50A outlet), regardless of voltage. Charging at these rates requires a hard-wired charging station. There are specs for 60A outlets that could, in theory, allow you to charge at 48A (80% of 60A), but Tesla doesn't make an adapter for them, the UMC is not rated to run that high, and the outlets are very, very rare (so no adapter will ever be made).

Or if SC stations are able to put out more than 40amps in the future, would this be beneficial? Curious as to the real world examples this could be a useful function.
Superchargers already put out way more than 40A. Remember, on board chargers have nothing to do with supercharging. Higher capacity on-board chargers do allow faster charging at high current J1772 and Tesla HPWC installations, but these are not common (at least not outside of CA). I've used 3 in 2 years (an 80A J1772 at a public garage in VT, and 2 open-to-the-public 80A HPWC's at office parks in NH and MA).