Charge while driving

[NicksCarHistory]

Alright I'm ready to be burned at the stake for this perhaps ignorant question:
Can you completely circumvent the OBC on a first gen Model S?
If you could, this would open the door to charge the battery pack directly with solar or extend range with an extra battery pack in the trunk with higher efficiency (no DC/AC/DC conversion). I think this would be a pretty big game changer if it could be done without triggering any software faults. Bonus points if you could charge the car with solar while driving (yes, it would be small range boost, but plenty of people don't drive 10,000 miles+ per year!).
Can you feed 400V DC straight to the rapid splitter? What's the voltage and current range you can get away with there?
I currently have a 2014 MS with a salvage title so I can't DC fast charge anyway.

[tom91]

You can put DC power back into the pack while driving yes.

How you do it without upsetting the car is the question. No idea is the Tesla Model S has monitoring of where all the current flows out of the pack is going.

By offsetting it by pushing solar power on to the HV bus should be possible with an appropriately rated solar inverter. It will be very little power on average you would be able to harvest.

[NicksCarHistory]

You can put DC power back into the pack while driving yes.

This makes sense right? Because the splitter goes straight into the battery pack and is connected to the rear drive unit inverter (which provides regen braking current).
My concern is that if you try to send external power to the splitter, there is some logic that will trigger a fault in the software. Does anyone know if that is the case?
And what is the voltage/current range of DC power you can put straight into the rapid splitter?
There are some 400V MPPTs out there, but if I could use a bit higher or lower voltage that might expand the options a bit.

[Zieg]

The good news is that if it's from solar, the current is going to be pretty low so less likely the car will notice or get pissed off.

I've thought about getting a smallish (probably BMW 9kwh) 'range booster' pack that I can parallel with my main battery and remove while racing. The main hurdles to that are how to independently charge it and match the voltage when connecting it, and how to manage the BMS of both batteries so they don't end up fighting each other or something. You'll have to figure that out too if you go down that route.

[Aragorn]

There was a company that sold a rapid charge kit for the RAV4 and B250e models, which were using Tesla Model S drivelines.

It basically worked somewhat as you describe, it "started" the car so it was in drive mode, and then fed the charge current into the DC bus. Seemingly the car didnt care that power was going in. I guess the BMS just sees it as "regen". The inverter doesnt see any current flow so doesnt know anything untoward is happening. I dont know how much integration was required though beyond tapping into the HV bus.

I suspect trying to charge from a "range extender" style pack you'd want a DC-DC converter sitting between the car and extra battery. Otherwise your going to have to be very careful about matching voltages etc etc. Might actually be that the simplest thing to use is an actual EV charger, assuming you can find one that will accept DC on the input. Many switch mode PSU's will.

Solar is mostly limited by practicalities over surface area. A modern 400w solar panel measures around 1m x 2m. Something akin to plonking a full sheet of plywood on your roof... I think folks see those panels up on the rooftops and dont quite realise how big they actually are... And 400w is not a lot, when a car is using 15-25kw just cruising on the highway. Its simply not worth the effort and you probably add more in aero drag than the panel can ever give back.

[Aragorn]

currently have a 2014 MS with a salvage title so I can't DC fast charge anyway

Cant DC fast charge, or cant supercharge?

My understanding was salvage Teslas were blocked from the supercharger network, but could still fast charge elsewhere. Maybe i've missunderstood or it varies between cars.

[P.S.Mangelsdorf]

Cant DC fast charge, or cant supercharge?

My understanding was salvage Teslas were blocked from the supercharger network, but could still fast charge elsewhere. Maybe i've missunderstood or it varies between cars.

The last I saw from Jason Hughes, he found that Tesla was disabling all DC charging, not just supercharging. Even when he went in and re-enabled it, the moment Tesla had a connection to the car, they re-disabled it.

In my opinion, disabling use of their own network is aggressive but reasonable; disabling the use of any DC fast charging is ridiculous overreach. I get that there's a safety argument, but it's not their car anymore. They shouldn't be able to disable features without the owner's consent. Limiting access to their own equipment is a different question, but remotely preventing an owner from using a third party's services is just wrong.

Apologies for the rant, but it's a pet peeve.

[P.S.Mangelsdorf]

I suspect trying to charge from a "range extender" style pack you'd want a DC-DC converter sitting between the car and extra battery. Otherwise your going to have to be very careful about matching voltages etc etc. Might actually be that the simplest thing to use is an actual EV charger, assuming you can find one that will accept DC on the input. Many switch mode PSU's will.

There is a thread about this here: viewtopic.php?t=4920

Solar is mostly limited by practicalities over surface area. A modern 400w solar panel measures around 1m x 2m. Something akin to plonking a full sheet of plywood on your roof... I think folks see those panels up on the rooftops and dont quite realise how big they actually are... And 400w is not a lot, when a car is using 15-25kw just cruising on the highway. Its simply not worth the effort and you probably add more in aero drag than the panel can ever give back.

Agreed. A family friend has/had? an early Fisker Karma, and the integrated rooftop solar was just enough to keep the interior fans running on a hot day to keep air circulating.

[NicksCarHistory]

Cant DC fast charge, or cant supercharge?

My understanding was salvage Teslas were blocked from the supercharger network, but could still fast charge elsewhere. Maybe i've missunderstood or it varies between cars.

I can't DC fast charge at all