Blink / Rav4 Blows Out a Contactor Pin (with gory pics)

[TonyWilliams]

Unfortunately, I don't think there would be an easy way to do this as an add-on since it is the pilot signal duty cycle that controls the maximum allowed charging rate.

Also, prior to a complete shut down at 70C, perhaps a 55C threshold that reduces current (by changing the ohm value to the pilot pin) from say whatever it is to 30% less.

With OpenEVSE, we can control the amps, so it seems that this feature could be integrated.

 

[Ingineer]

This is relatively easy to do on the OpenEVSE, and I'm going to work with Chris to make it happen. The best thing to do is simply reduce charging to a very low amount until the connector is cool, then the EVSE's LED indicator can begin flashing to indicate a stored thermal fault. Once the connection is cool again, full power charging (or maybe some %) can resume, but the fault indication can remain latched until acknowledged by the owner by the button. (Maybe a press while powering up)

I've come up with a simple way to let the microcontroller "know" the temperature has exceeded a certain threshold without needing any more conductors in the cabling.

For people without OpenEVSE's and EV's capable of pulling over 20A, I recommend the installation of the thermostat as I showed earlier in this thread. In fact, it's probably a good idea anyway.

-Phil

 

[TEG]

...Here's my two cents on thermal monitoring; I would absolutely want a fault light that left no doubt that there had been a thermal issue. Also, prior to a complete shut down at 70C, perhaps a 55C threshold that reduces current (by changing the ohm value to the pilot pin) from say whatever it is to 30% less...

Anyone (Phil?) know if all EVs will dynamically change charge rate if you change the pilot signal during an active charging "session"? I think some EVs could be designed to just check the rate when they start charging and assume it would stay the same, as I am not aware of any current model EVSEs that change the pilot signal in the middle of a charging session.

 

[bowthom]

Hello,
I tested the leaf with several evse's and if you dynamically change the pilot signal the onboard charger responds appropriately. Somewhere on this BB it is posted.

Found it
Column A is EVSE commanded amps - Column B is Leaf actual amps.

 

[waidy]

Anyone (Phil?) know if all EVs will dynamically change charge rate if you change the pilot signal during an active charging "session"? I think some EVs could be designed to just check the rate when they start charging and assume it would stay the same, as I am not aware of any current model EVSEs that change the pilot signal in the middle of a charging session.

In the case of Tesla's Model S, I saw the voltage and amperage changes during charging (Model S displays it, really cool). Changes are +/- 1-3V and/or +/- 1-3 Amps.

 

[TonyWilliams]

The Rav4 does ramp down the amps near the end of the charge. The last time I was watching, it was only pulling 20 amps near the top, instead of 40 amps for most of the charge. I suspect most cars can change amps during a charge, but obviously the Tesla chargers can (Rav4 uses a 10kW Tesla charger).

 

[TomT]

I believe he is asking the opposite: Can the EVSE change the charge rate of the car via a change of the pilot signal duty cycle during a charge session... My gut feeling is that answer to that question is yes. We already know that a car's charger can and does vary the charge rate internally under some circumstances...

Anyone (Phil?) know if all EVs will dynamically change charge rate if you change the pilot signal during an active charging "session"? I think some EVs could be designed to just check the rate when they start charging and assume it would stay the same, as I am not aware of any current model EVSEs that change the pilot signal in the middle of a charging session.

In the case of Tesla's Model S, I saw the voltage and amperage changes during charging (Model S displays it, really cool). Changes are +/- 1-3V and/or +/- 1-3 Amps.

 

[Deleted member 3147]

I actually asked that one on MNL a while back in the context of a multi-head EVSE which could reduce the charging rate of the first car when a second car plugs in. The answer I got back then was that part of the J1772 spec is that the car must respond to pilot signal changes within a certain period of time (a few seconds?).

I believe he is asking the opposite: Can the EVSE change the charge rate of the car via a change of the pilot signal duty cycle during a charge session... My gut feeling is that answer to that question is yes. We already know that a car's charger can and does vary the charge rate internally under some circumstances...

Anyone (Phil?) know if all EVs will dynamically change charge rate if you change the pilot signal during an active charging "session"? I think some EVs could be designed to just check the rate when they start charging and assume it would stay the same, as I am not aware of any current model EVSEs that change the pilot signal in the middle of a charging session.

In the case of Tesla's Model S, I saw the voltage and amperage changes during charging (Model S displays it, really cool). Changes are +/- 1-3V and/or +/- 1-3 Amps.

 

[TEG]

I believe he is asking the opposite: Can the EVSE change the charge rate of the car via a change of the pilot signal duty cycle during a charge session... My gut feeling is that answer to that question is yes. We already know that a car's charger can and does vary the charge rate internally under some circumstances...

Yeah, that was my question.

 

[TEG]

I actually asked that one on MNL a while back in the context of a multi-head EVSE which could reduce the charging rate of the first car when a second car plugs in. The answer I got back then was that part of the J1772 spec is that the car must respond to pilot signal changes within a certain period of time (a few seconds?).

OK, that basically answers it then.
I will conclude that:
A> A well designed EV should be able to change charge rate on the fly if the pilot signal changes during charging.
B> Most EVs probably do this. (I leave room for there to be possible exceptions due to bad implementation. For instance, I found out the hard way that the old RangerEV charger was designed to only work properly from 208/240V even though the spec allows 120V input.)

We have heard stories about failure to charge due to J1772 handshake issues, pilot signal issues, etc.
So, assuming that something on paper works in all cases could be risky.

 

[colby]

The Fit EV doesn't currently do this, but I understand Honda is playing with reducing the charge rate as the temperature rises to let the connector cool off. I think this is okay IFF it is clearly communicated to the user when this occurs.

 

[jkirkebo]

CHAdeMO/SAE Combo will easily take the >10kW stuff, so why bother with 70A AC?

-Phil

Except the cat is already out of the bag with Tesla Roadster and Model S with "twin chargers" using the 70 - 80 amps.

Yep. Hopefully they will mostly use the HPWC for >40A charging. The Tesla inlet should have no problems at all with 80A charging as it can take 250A(!) DC when SuperCharging.

 

[waidy]

CHAdeMO/SAE Combo will easily take the >10kW stuff, so why bother with 70A AC?

-Phil

Except the cat is already out of the bag with Tesla Roadster and Model S with "twin chargers" using the 70 - 80 amps.

Are the charging behavior the same using 80Amp AC and CHAdeMo/SAE Combo (DC charging) (i.e. charge rate dropped after 80% SOC) ?

 

[LEAFfan]

With Blink QC, the Amps begin to decrease just after it starts, and really slows well before 80%.

 

[TonyWilliams]

Except the cat is already out of the bag with Tesla Roadster and Model S with "twin chargers" using the 70 - 80 amps.

Are the charging behavior the same using 80Amp AC and CHAdeMo/SAE Combo (DC charging) (i.e. charge rate dropped after 80% SOC) ?

With Blink QC, the Amps begin to decrease just after it starts, and really slows well before 80%.

The LEAF is charging at 2C rate (48kW on 24kWh battery) using CHAdeMO, and begins the ramp down at about 50% SOC, from 120 amps. The Blink charger only takes commands from the LEAF... not the other way around.

The Rav4/Tesla 50kWh battery is charging at 1/5C rate (one tenth of LEAF) and only begins a ramp down well above 90%. I wasn't trying to document it, but only noticed pulling 20 amps instead of 40 amps because I was expecting the charge to end soon, and because I had an ammeter on it.

The Tesla 85kWh at 80 amps (20kW) is still only a bit less than 1/4C rate, so I don't imagine it will slow down much until the very end (like Rav4 does).

The Tesla on the 90kW - 120kW Supercharger is still only slightly over 1C rate, so yes it will no doubt start slowing from over 200 amps somewhere past 50%, but I don't have any first hand experience here.

The real point is that the non-temperature controlled LEAF is pushing the charging envelope much more aggressively with nothing but crossed fingers to hope it doesn't overheat.

 

[surfingslovak]

Interesting discussion. Here is another datapoint: this past weekend I managed to record an entire charging session from turtle to full on the ActiveE. The vehicle has an active temperature management system, and it charged at 5.54 kW initially, which is about 1/5 or 1/6 C rate. Although this has been often debated and second-guessed in our owner community online, the chart shows clearly that the ActiveE charged at maximum power available from the EVSE until it reached approx. 25% SOC, when the power level fell from 5.54 to 5.39 kW, which was maintained until 90% SOC was reached. Power then started to ramp down, and it took almost exactly an hour for the remaining 10%.

 

[Ingineer]

All J1772 EV's MUST respond to pilot signal changes. This means if you drop the pilot specified amperage, the EV must drop it's amperage to at or below the pilot limit within 10 seconds.

-Phil

 

[GRA]

From plugincars.com, referencing both Tony and Phil:

http://www.plugincars.com/honda-fit-ev-overheats-blink-charger-126246.html" onclick="window.open(this.href);return false;

 

[colby]

From plugincars.com, referencing both Tony and Phil:

http://www.plugincars.com/honda-fit-ev-overheats-blink-charger-126246.html" onclick="window.open(this.href);return false;

Plug In Cars wanted me to condense my earlier blogpost and provide an update from Honda and Ecotality, so I did.

Ecotality is claiming a communication issue between the Fit EV and the Blink, which directly contradicts (1) What Honda Engineers have told me (2) The high temperatures I have observed and of course (3) the melted charge port and poor crimp that started this thread.

Honda has since released a software update that throttles back the current as temps increase, so the connector never hits the threshold temperature and charging doesn't stop. So far I've tried it with one known bad Blink station and I was able to charge without any issues.

I'm pleased that Honda was able to find a workaround for REMA's inadequate connector.

 

[MikeD]

Colby: Do you have any specifics about the actual threshold temperature values detected by the Fit EV's inlet temperature sensor that you mention in your last post?

Did the Ecotality spokesperson deny that any of their plug connectors of any of their installed EVSE's have been replaced due to a defect that was causing excessive temperatures during charging?