Slow Ford Mobile EVSE: it cannot sustain the rated 32 Amps

[RobbertPatrison]

I notice that my Ford mobile EVSE charging cable cannot sustain the rated 32A (7.6kW) for long. After about 15 minutes the yellow light comes on periodically and it throttles back to 20A. And then it starts oscillating with a period that changes over time. Here is a plot of the power usage when charging over a 45-minute period. You can see it flip between 32A and 20A constanty:

In some cases, it switches down from 32A briefly to 20A and then to 12A, and then back again. All in less than a minute:

The result is that the effective charging speed is significantly lower. Here is what I suspect is happening:

1. The EVSE heats up internally at 32A
2. The EVSE tells the charger in the MME to throttle down
3. The EVSE cools down a little
4. THE EVSE tells the charger in the MME to throttle up again
5. goto step 1

This is nuts, especially becasue it happens every minute. The EVSE is just a glorified cable that does almost nothing except talk to the car about its limitations. If it heats up internally it is only because of improperly dimensioned conductors inside of the EVSE. With proper 10AWG gauge wires, there should be so significant heat. It is supposed to add safety, but it can only measure the temperature inside of the module. So it is basically reacting to a problem of its own making, rather than a real issue with the wiring.

The problem seems worse when it is warner, which is consistent with the temperature sensor triggering the events. In a 60 degrees garage at night, I got about 16 minutes of 32A before it started oscillating. When the garage is warmer the problem begins earlier.

The EVSE itself does not seem very hot. I took this picture with an infrared camera. You can see that the hottest part of the EVSE is 28C, and that the bottom cable is warmer than the top endthat connects to the wall plug. That is likely because the longer cable is 12AWG and the short end 10AWG.

There are some possibilities:

1. Throttling back is a 'feature', meaning the EVSE is not really designed to sustain 32A charging. But in that case, it would have been better and safer to always cap the charging speed at a lower rate, rather than this silly oscillation. The cable appears to be 12AWG, which is thin for 32A.
2. Many others reported slow charging or the yellow light coming on. So it could be a design flaw causing overheating.
3. This could be my EVSE with a defective temperature sensor, or a bad contact. I might have to claim this under warranty. In my 10 years of driving electric, I have never been back to the dealer for a service issue. So that would be a first...

I don't see this issue when charing using my 10-year-old EVSE, but that one is capped at 20A.

 

[bshaw]

What's the ambient temperature in the garage / outdoors where the EVSE is located when its being used? If outdoors, then are the cable or EVSE sitting in direct sunlight?

What happens if you add an external cooling source (i.e. point a fan at the EVSE/cable)?

 

[MONDO]

How did you determine these wire sizes?

 

[COACH CHRIS]

This is a known issue, assuming you've been using the EVSE for a few months.

 

[Maquis]

My 2 cents worth:
1) A surface temp of 28C is not excessively hot for an electric power device. Without knowing the design criteria, we can’t say if that’s a problem or not. My guess is that it’s not.
2) The fact than many of these problems are being reported after the FMC has operated successfully for several months (even during hot summer months) suggests that something in the device is deteriorating over time.
3) It’s still unclear whether these problems are caused by marginal design or some component defect.
4) Ford needs to step up, get to the root of the problem and, if necessary, issue a recall.

 

[ripperAZ]

I’m not an electrical engineer but my brother is and he says it is simply cheesy cheep components That are overheating and causing the unit to fail by software safety measures. Bad solder chintzy resistors. Just truly cheap electronics that eventually degraded further as the heat gets To more components

There are about six or seven other better choices just don’t buy this and if you have a bad one return it if possible and get something else

Jes sayin

 

[Awmustang]

I’m not an electrical engineer but my brother is and he says it is simply cheesy cheep components That are overheating and causing the unit to fail by software safety measures. Bad solder chintzy resistors. Just truly cheap electronics that eventually degraded further as the heat gets To more components

There are about six or seven other better choices just don’t buy this and if you have a bad one return it if possible and get something else

Jes sayin

He's talking about the EVSE that came with the car, so didn't "buy" it and can't return it.

 

[Tampamike]

Ok, so this problem has been going on for a while as evidenced by multiple threads on it and dozens of responses from multiple owners - me included.

Has anyone actually gotten their mobile charger replaced and, if so, how did you make it happen?

 

[RobbertPatrison]

How did you determine these wire sizes?

This is an educated guess as it is not printed on the cable. But the wire looks the same size as my old EVSE that is marked 12AWG x 3.

 

[DR.J56]

Are we sure this is not a supply side issue?

 

[RobbertPatrison]

I’m not an electrical engineer but my brother is and he says it is simply cheesy cheep components That are overheating and causing the unit to fail by software safety measures. Bad solder chintzy resistors. Just truly cheap electronics that eventually degraded further as the heat gets To more components

There are about six or seven other better choices just don’t buy this and if you have a bad one return it if possible and get something else

Jes sayin

I am an electrical engineer and concur with your brother. The principle is simple: using thin components increases resistance. And with higher currents that resistance causes heat. That heat is detected by a sensor.

The measurements show that the sensor triggers the EVSE to throttle down to a lower current. Since the issue is widespread, this looks like a design flaw rather than an individual manufacturing defect.

Ford will likely claim that they err on the safe side: rather reducing current too early than too late. So no reason for a recall. It is true that lower currents are always safer, just like driving slower is always safer. But in this case, it is more likely that the issue is due to cheap components and/or poor design. No matter what: the result is that this EVSE charges much slower than the 32A/240V setting. It is also likely that the constant switching between different current modes increases the charge losses. We pay more per mile.

 

[mkhuffman]

I know this is unlikely your issue, but did you double check the pigtail adapter is fully seated into the EVSE body? It has been known to become slightly unseated causing intermittent connection. It's a long shot...

 

[ripperAZ]

He's talking about the EVSE that came with the car, so didn't "buy" it and can't return it.

Indeed I see that now….. Unfortunately the same crappy components were used in Fords level two device that almost everyone buys and is disappointed in. In fact it even flows over to the ridiculous tiny 12 VOLT battery that they slapped in that causes so many issues…My Jet Ski has a bigger battery

disappointing to see basic crap electronics used as the basis of an electric car. All through the system. FMC Needs to do better
Jes sayin

Jes sayin

 

[vortix]

Does this type of issue also exist when charging via regular 120V outlet? Wondering if this EVSE serves a purpose at the slower L1 charging rate...and if a more reliable L2 EVSE should be considered for regular 240V use. Though Ford really should offer a solution for everyone experiencing 240V charging issues with their EVSE.

 

[JohnnyForensic]

I know it’s an unpopular opinion, but I really recommend just throwing that Ford EVSE into the trunk for out-and-about emergencies and purchasing a better brand of EVSE for full-time home use. I’ve been spectacularly happy with my ChargePoint Flex, and I know there are other solid brands out there too. That Ford-included one is enough to get you started and to take on trips, but it’s just not up to the task of routine day-to-day charging.

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