High Voltage Battery Data

[FordAnglia]

Greetings,

I'm bored during my daily commute. I use the time behind the wheel, while traveling in heavy traffic on both side streets and in the HOV lane, to explore the B250e. Recently I discovered the "Hidden Menu" thanks to Cardonman and my follow up post.

Yesterday I was able to see the charging voltage and current while on an L2 charger.

The L2 EVSE at work (ClipperCreek) doesn't connect to my iPhone (the public ChargePoint equipment does) so I don't know the charger power level.
From the vehicle display we have 318V and +15A, or 4.77kW - this is DC at the vehicle's high-voltage battery. The (+) means current flowing into the battery.
The numbers are lower than I was expecting. Shouldn't the L2 charger be 6.6kW? AC input of 32A at 208V. When I returned to the vehicle it was fully charged, and current fell to 0A. I'll repeat this experiment next time I'm on the "high power" L2 charger at work.


The vehicle also displays the 12V battery data. A lead-acid (ordinary "car battery") requires 14V to charge.

Oops - Can't post more than two PIX here, need to make a reply post to upload the next PIX.

 

[FordAnglia]

Now we drive the vehicle on the road.

We have a full charge, 334V and no current (vehicle not moving)

Accelerating to highway speed draws high current from the high-voltage battery. The (-) indicates discharge.

Wow, nearly one hundred amps, and I'm being gentle!


I don't have much runway in heavy traffic, and I'm in "E" Mode, even more current. Now 230A!

I'll have to find a longer runway and select "S" Mode, wondering how many Amps we can get.

To Be Continued...

 

[FordAnglia]

Now we do some Regen braking. Energy from the motor is returned to the High-voltage battery.

As expected the current is (+), the high-voltage battery is charging. Notice the high-voltage battery voltage goes up slightly.
The Regen will always be less than the energy taken out. We don't have a perpetual energy machine. The principle of "Conservation of Energy" - and Mother Nature rule here.

Now we're coasting. No energy in or out of the high-voltage battery.


To Be Continued...

Peter,

 

[hallcp]

This is fascinating! Thanks for doing this experiment. And it looks like the needle on the dial to the right also matches what you're seeing, only now we have some notion of what 75A looks like.

 

[FordAnglia]

This is fascinating! Thanks for doing this experiment. And it looks like the needle on the dial to the right also matches what you're seeing, only now we have some notion of what 75A looks like.

I was quite surprised to see "hundreds of Amps" flowing! In my day job we're chasing microAmps of power...

I'm trying to wrap my head around the current flow during B250e charging. So far I've only seen 15Amps (and roughly 320V) displayed on the secret menu during charging.

That is roughly 5kW (15*320) Yet we know the B250e has a Tesla 9.6kW on-board charger. The secret menu display is most likely DC values as recorded by the BMS (Battery Management System)

To add further confusion, when I'm connected to a ChargePoint public charger is says I have 6.6kW, sometimes a bit more (7.6kW) This would be 208V * 32A, or 240V * 32A depending upon what voltage is fed to the EVSE.

Fellow Tesla Model3 owners (using the same charger at work) say their car reports 32A (roughly 6.6kW assuming the charger is fed from 208V AC)

Does this mean the B250e is not using all the available charging power? Could the 6.6kW be reduced to 5.5kW of useful charging due to less than 100% efficiency in the B250e electronics? (Where did that missing kilowatt go? Heat?)

In the B250e regular settings menu the charging current can be selected, presumably to stop nuisance tripping of the EVSE if it's on a lower Ampacity feed. This would likely be the case in a private home. While not clearly stated in the manual, I recall finding the menu item and given a choice of "8A, 13A, Maximum" (where I left it set) Makes sense to me, 8A is a popular 'phase current' for domestic three-phase AC in Europe, while 13A (single phase) is the domestic outlet rating in the UK.

Anything I've missed? Anyone seen more than 15A draw while charging?

Peter,

 

[hallcp]

Bjorn Nyland did a brief video https://youtu.be/G1e_vJcVqLI where he got 11kw charge rate. Could it be that his charger is 3-phase? Is that the difference?

 

[FordAnglia]

Bjorn Nyland did a brief video where he got 11kw charge rate. Could it be that his charger is 3-phase? Is that the difference?

Thanks for posting the link. I'm skeptical, as we don't know the volts and amps actually flowing into the vehicle during this demo.
According to this table, Norway (also Sweden and Germany) provide a 400V 3-phase domestic supply.
Working backwards we have 11kW/400V = 27.5Amps, or 27.5/3 = 9.16A per phase. So far so good.
A three-phase supply can deliver three times the power, because each phase is carrying one third of the total current.

BTW, we see the B250e is spec'd for a 9.6kW charger, working backwards we get 9600/(400*3) = 8A per phase.
I've posted about the EU 3-phase domestic supply being "8A per phase" and in my B250e there's an 8A setting for limiting charge current. QED.

This video demo used an EU Tesla charger cable. What's not clear is the vehicle plug arrangement, I doubt it's a J1772 (as we have in the USA)
There's only two AC pins in the J1772, so it can support only one phase (120V or 240V for L1 or L2 charging)
US Teslas come with an adapter to allow vehicle charging from EVSE J1772 connectors, as the US Tesla connector is proprietary. Could there be a reversed Tesla to J1772 adapter somewhere? Or does EU Tesla vehicles use the same connector as other EVs in that market?

I can't think of a way to combine the three-phases down to one pair of AC connections, so either the video has a vehicle plug with three AC pins, or the Tesla charger has internal diodes that send DC to the vehicle over two connection pins. Six diodes would be required.



Now we have a new question to consider, will the B250e accept a DC feed for charging? We're told it's an AC-only vehicle...
Any brave soul willing to give this a go? Or, can someone crack open a EU spec Tesla charger and look for six diodes?

Peter,

 

[hallcp]

From this Wikipedia explanation https://en.wikipedia.org/wiki/SAE_J1772 it sounds like European cars have a different standard to accommodate 3-phase. Something called "IEC 62196",https://en.wikipedia.org/wiki/IEC_62196#VDE-AR-E_2623-2-2. It shares a common protocol with the J1772 standard.

So maybe UK Electric B's have that connector.

 

[FordAnglia]

So maybe UK Electric B's have that connector.

Thanks for doing the research into EU connectors for EVs. "Within the European Union, regulation requires all public AC charging stations to be equipped with a type 2 socket-outlet or a type 2 connector."


Europe/Worldwide Tesla Supercharger with dual cables: Type 2 for Model S/X and CCS Combo 2 for Model 3


Tesla Supercharger outlets in Europe/Worldwide (left) and North America only (right)

Looks like even Tesla had to adopt the seven contact charging "socket-outlet". With five AC (high current contacts) this can deliver three-phase power.
Therefore the vehicle charger combines the three phases and converts to DC. This can be done with the six diodes, or with other electronic switches (SCR - Silicon Controlled Rectifiers, or MOSFets, or IGBT) and not in the UMC (Tesla Charging cable) as I thought yesterday.

This closes the book on whether we can use three-phase charging on the US spec B250e.

Bonus content! Check out this experiment where a Tesla Model 3 is towed and the battery charged by recovered energy (Regen Braking).
https://youtu.be/RaGVoB4Zn-Y

Peter,

 

[FordAnglia]

Greetings,

Today I used the L1 EVSE charger at work (obviously the L2 chargers are faster)
I have a new data point derived from the "Secret Menu" in the B250e



High Voltage Battery Charging



12V Battery Charging (which is derived from the HV Battery charger)

Recalling the L2 charging data: 318V x 15A = 4.7KW (we assume this is the actual power flowing into the High Voltage Battery)
For the L1 data: 302V x 5A = 1.5KW

L2 is therefore at least three times faster!

Peter,