Why isn’t my MME getting 150kw at EA chargers?

[billy_at]

I’m sure this question has been asked before but I haven’t been able to find it. The MME has a max charge rate of 150KW. I went to an EA charger today that had a big sticker that says “CCS up to 150KW.”

However, the EA console mostly shows around 90KW during the charge session. Occasionally, it would hit 120 for a short while, but then drop back.

I’m not complaining - the overall charge time is fine - but I am curious to know why it isn’t getting closer to the 150KW rate.

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[mamejunkie]

key word is 'up to'. A lot also has to do with the charge curve. The condition of the battery will determine how fast it is able to be charged at without damaging it.

 

[Petey]

this is one of the more controversial parts of the MME - they really kind of hold back on the rate of charge, from what you'd think they are capable of. Search for charging curves and you will find the MME quickly spikes up to higher rates of charge (like your 120) for a very very short time, but most of the charging is closer to 100k. It's too bad, I think there are many who speculate Ford is being too conservative and could stick in the 125-150 range for longer periods of time during the charging curve.

 

[Cm12]

The highest charge rate can only be achieved when the battery is already at the ideal temperature AND nearly fully discharged. Also, the charger may not actually be able to put out that much even if it says it can. I’ve been at EA chargers that only put out 35kw of the 150 or 350 rated so I switched it to another empty charger and got 3 times as much. Lots of variables.

 

[ZoNiE]

The highest charge rate can only be achieved when the battery is already at the ideal temperature AND nearly fully discharged. Also, the charger may not actually be able to put out that much even if it says it can. I’ve been at EA chargers that only put out 35kw of the 150 or 350 rated so I switched it to another empty charger and got 3 times as much. Lots of variables.

Same goes for normal Level II chargers, (not high speed) and especially those dual cable chargepoint peds. If you are connected alone, you get all the juice, if another driver connects, they get half, and you only get half... I dealt with this at my workplace.

 

[RedStallion]

That's how the advertisement works, if you can hit 150kW occasionally in some conditions then it's advertised 150kW, and a small print saying it will practically never happen. Just like my AT&T internet advertising 1GBs, while it's half of that most of the time.

 

[DevSecOps]

I’m sure this question has been asked before but I haven’t been able to find it. The MME has a max charge rate of 150KW. I went to an EA charger today that had a big sticker that says “CCS up to 150KW.”

However, the EA console mostly shows around 90KW during the charge session. Occasionally, it would hit 120 for a short while, but then drop back.

I’m not complaining - the overall charge time is fine - but I am curious to know why it isn’t getting closer to the 150KW rate.

Check out this post, around page 6-8 we get into technical limitations, charge curves etc. It's a lot to read, but there's some interesting stuff in there if you have time.

https://www.macheforum.com/site/thr...-charge-curve-and-maybe-power-delivery.13747/

There's s lot of really good threads on this topic beyond what I linked.

 

[TheVirtualTim]

I have a Job 1 (1st Edition) car. The actual rate that it *can* hit ... is nearer to 170kW -- but only briefly. Extended range battery pack cars can charge faster -- because they have more cells across which to distribute the incoming power.

Prior to my car being updated to the new charging curve software, the rate averaged slower. It is noticeably faster now BUT ... there are MANY nuances that impact charging rate.

The DC Fast Chargers need active cooling if the charger is too hot (never mind the car) then it will throttle back -- regardless of what car you are charging. If an Electrify America station is having a problem it goes into a reduced-rate speed ... about 38kW (I think it's typically in the 35-40kW range). If you never see an EA stall get above that speed then the problem is likely the charging stall and not your car.

The Mach-E's battery temperature also matters... either being too hot OR too cold will result in slowing down. Again, this is normal for ANY electric car. It isn't specific to the Mach-E. When too cold (winter charging) you'll notice the DC Fast Charger putting out a lot of power ... but the car wont seem to be charging. This is because it's actually using that power to drive the battery heaters ... and wont start charging until the batteries are up to a reasonable safe-charging temperature.

The car's current state of charge also matters. You'll get the fastest charge rates when the battery is mostly (but not completely) drained. e.g. 15% (and it's not a good idea to push it below 10% before making it to the charger as this is stressful to the battery and reduces overall life).

When I plug in, it will normally start out at a slow-ish charge rate but within a minute it will REALLY start to speed up ... and keep speeding well into the upper 160's. But it will stay there only briefly (perhaps a minute ... two tops) and then start to back off. But this a gradual process ... so it'll be charging at above 140kW for a while, then 130's, and so on. The car will continue to charge at speeds faster than 100kW up until around 70-75% "ish" when it will dip into the 90's.

The moment it hits 80% you'll see a cut back to about 45kW (almost instantly) and then it will very gradually continue to slow down from there all the way until you hit 95%. At 95% you are charging no faster than a level 2 home charger.

 

[noway]

This is actually very common all over and a generally big issue. In the area around here a whole lot of 180kW are just able to peak at 140kW because of the cable having current limit of 400A, which is a huge issue for us with 350V batteries. I even drove in sweden where they had put 200A cables on a 180kW charger, so it could just do 90kW peak on the mach e on 350V. its just so much cheaper cables than 500A cables required for 150kW on 400V.

Just look forward to Tesla V3. Super thin cable and 250kW for 400V batteries. We have a few of them around here, and the mach e will peak at 160kW on those with no problem. If they could just place the chargers so the cables did not have to be 10 meter long (like tesla does, just a little bit too short), those issues would almost not exists.

 

[newmme]

Just look forward to Tesla V3. Super thin cable and 250kW for 400V batteries. We have a few of them around here, and the mach e will peak at 160kW on those with no problem.

Maybe a dumb question, but if the Tesla supercharger is 250Kw, why is the MME peaking so low? Is it the connector not compatible maybe?

 

[noway]

Maybe a dumb question, but if the Tesla supercharger is 250Kw, why is the MME peaking so low? Is it the connector not compatible maybe?

Because the car cannot by design charge at more than 160kW, so getting the 160kW peak means the charger is able to max the capabilities of the car, most high power chargers will never reach the peak

 

[generaltso]

Maybe a dumb question, but if the Tesla supercharger is 250Kw, why is the MME peaking so low? Is it the connector not compatible maybe?

The CCS standard is limited to 500A. Teslas are not bound by this limit. But even in Europe where they use CCS, they can bend the limit because they control the charger and the car.

 

[RickMachE]

I’m sure this question has been asked before but I haven’t been able to find it. The MME has a max charge rate of 150KW. I went to an EA charger today that had a big sticker that says “CCS up to 150KW.”

However, the EA console mostly shows around 90KW during the charge session. Occasionally, it would hit 120 for a short while, but then drop back.

I’m not complaining - the overall charge time is fine - but I am curious to know why it isn’t getting closer to the 150KW rate.

Next time try a 350kW EA charger. It will peak higher in my experience.

 

[AZBill]

Not all chargers are created equal. The new Signet chargers used by EA can provide 500A, whether they are rated to 150kw or 350kw. On those I have seen my MME pull 150kw on a 150kw charger. The older ABB units have a 350A limit for the 150kw chargers, so those only pull about 125kw. The ABB 350kw chargers are rated to 400A and the MME can pull close to 450A, so you will also see lower kw.

There is even a rumor that EA has limited all of the ABB chargers, including 350kw ones, to 350A, and I saw one in Tucson only give me 123kw. I have seen a peak of 160kw on a 350kw Signet charger.

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