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Be sure to watch today's IEVs podcast. He showed the fast charge curve. He had all kinds of problems that EA's engineers told him were vehicle-related, not charger related. The Hummer appears to have some significant charging issues. Tom is researching with GM to get the straight scoop.
I am willing to bet EA has charger issues, I have experienced all kinds of them and I predicted there would be issues when they do the fast charging test on the Hummer. Since EA deleted the display of what the vehicle is requesting, how can they prove the issues are on the vehicle side? There are apps that can be connected to the OBD ports in the vehicle to get the real data.

The older ABB units that EA built claimed 350kw, but they had a 450A limit, thus would only get that level with 780V, which is at a very high SoC for an 800V system. Many of their chargers have been current limited to 350A recently, due to over heating issues. Kyle Conner saw this when he charged a Hummer in Phoenix and has also seen it with his Rivian.
 

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The Hummer charging does have some quirks, I have seen too, on EV-Go, our other EV's start at a hight rate then taper, but the Hummer starts at its high rate, and will have dramatic drops, then go back up, then drop again, sometimes dropping to as low as 20kW, then back to 150 kW within a minute. GM definitely still has work to do on the battery management.
I think they have some software bugs/issues. Those steep drops are an indication charging is stopping or pausing for some reason. The TFL guys saw it drop to 12kw, before climbing back up. Tom M saw it completely shut off a couple of times and he had to unplug and restart.

When the Rivian was first released, it had thermal limits causing power drops, but those were not as steep or as far down as these cliffs the Hummer is seeing. Rivian later did software updates to fix the issues and increase the current up to 500A. But at least one of the tests on the EV6 showed something very similar to what the Hummer is doing.

All of the EA chargers have had their communications off for the last few weeks and EA has been upgrading them to 5G, everyone has been getting free charging during this time. Yesterday things came back online and real time charging status is up again. I was surprised when Tom M indicated that EA was able to monitor the charging station in real time when he had the issues. A tech told me they are also replacing circuit boards in all the chargers, but that is going slow to due supply chain issues.
 
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