Charging levels in theses Covid times

@Landshark

Sorry, getting late so will be unusually brief - yes every single one of you reading can stop laughing now... I know!

1.0C would be ~54.6A at 345VDC, correct?

1C is 54.6 amps per hour (volts is unimportant for this variable)

Cell target voltage of ~4.1VDC x 84 cells = 344.4 VDC rated at 27.3Ah wired in parallel with 84 additional cells creates a ~345VDC battery pack rated at 54.6Ah. Or ~18kWh, 345 x 54.6 ~18,800.

All correct except the "rating" of the pack. I did a breakdown of the math at some point but that was to illustrate efficiencies and pack protections. When you "rate a pack" for watt hours (think of the pack in your laptop) you use the "nominal voltage" if the rating is not given by the manufacture from their tests. This gets complicated as you really have to test a cell and determine it's discharge voltage over constant current curve and get the midpoint. It generally falls around 3.7 for Lipoly (ours) and 3.6 for Li-Ion. However the packs in our new cell phones are charged to 4.35 volts and their midpoint may be 3.8? Either way absent published data from the cell manufacturer you take the midpoint times the nominal Ah rating for the pack Watt-hour. In our case, 3.7x84x54.6 = 16,970 Wh or ~17kW. (with the usual caveats of when charged at .5C and discharged at .2C until limits at 25 degrees C (to many C's now...)

The built in charger can’t charge at a 1.0C rate, so what voltage and current is being created by the ICE generator and how is it being converted to a voltage and current that is capable of charging the batteries at a rate that exceeds the capability of the built in charger?

The ICE Generator is connected to the traction inverter system and is part of the integrated powertrain. It is not even wired to the HV Pack charger in the back of the car. It has nothing to do with it. The best way to think about the ICE generator is it is a traction wheel being spun by the ICE in FULL REGEN mode. It puts AC wave energy converted into DC current directly back into the HV pack the same way the traction motor does during regenerative braking (ok, there is a slightly different current path, but this is functionally correct as far as I know). The "charging" parameters are controlled by the vehicles EV system (inverter etc). It is also part of my earlier discussion about how the car limits overcharging by using the ICE-Gen (they are one unit for all practical purposes, inseparable).

I only have a rudimentary understanding of the subject from having a solar array with a 48V LA battery backup at the house and a motorhome with a 12V house battery bank and inverter/charger. And now, a Clarity.

I’m trying to learn and greatly appreciate your efforts.

No worries, glad to help. Your solar system is very similar except you are always dealing with DC current (the MPP charger may have a buck converter in it) and your house is powered by the AC from the inverter - but unlike the clarity where all power into the battery starts as AC, yours is DC.

I've just been in the battery world for a while but there are a lot of people WAY smarter than I am on this. I am a "pro-consumer" hobbyist level DIY guy. I did work in the UN38.3 arena for a project and have some pretty good knowledge about Lithium Iron Phosphate LiFePO4 cells (3.2 volts, way different behavior from our batteries and likely most Lithium cells you are familiar with)... However since you have a Solar System, you may actually be familiar with them. They are the most common Lithium chemistry used to replace lead acid batteries as they are similar in voltage and extremely safe. Plus you get thousands of charge cycles (full discharge, not they "20%" stuff). A company, gone now, called A123 pioneered them for the DOT and Military and wanted to put them in cars. Actually, for a PHEV or conventional hybrid I think they would be great. They don't have the energy density. Our car would likely get half the EV range. But the cells would likely NEVER fail, or catch fire, etc. You can overcharge them and cut them open with an ax (most designs) and only get smoke - no Tesla nuclear bombs. However, they would likely last longer than the physical car. However, we like range and big numbers for for now our NMC cells or Tesla's NCA are the kings. NCA is powerful, but the most volatile of the current mainstream tech. They require NASA grade management systems and design. They are safe in Tesla's but oh boy are they capable of destruction if charged/discharged recklessly.

Lithium will stay for a long time, it is the highest energy option we have industrially but the real trick will be the electrolyte and separator material. When we can go to a "dry cell" and solid plastic separator design (Mr. Goodenough) and solid state then we will achieve the next generation. We need more power density but what we really really need (as demonstrated by all the threads about it on this forum) is a cell that can handle itself like LiFePO4 but with the energy density of NCA! Get all the power, all the safety, and 10's of thousands of full cycles before losing ANY capacity. That is the next holy grail.

The link is from my distributor/vendor I use for some of my commercial applications. The packs are good examples of LiFePO4 and they have a lot of very technical information about their products. Battery University is still one of the best "non-researcher/commercial" resources for information generally, but Batteryspace is a good place to rummage around if you are curious about OEM style solutions that you don't have to be a member of the secret club (Honda-GM, etc) to see.

And finally, our level 2 charging at 6.6kW is a SLOW charge relative to what our pack "could" accept. A .5C or C/5 rate is very common and safe for end point protected batteries like ours (we don't get to "top off" at 4.2 volts per cell). That would be an 8.5 kW charger, not much more - but still a less than 2 hour charger. As such, the charger doesn't matter, heavy use of regen down a long hill (like 5-10 minutes worth) on a mostly charged battery would concern me greatly now that I have looked at its behavior. I completely get the ICE dissipation strategy now - you could really cook a battery at 2C, yes that is over 100 amps or 34 kilowatts of charge power, using full regen on a mostly full battery.

https://www.batteryspace.com/128vlifepo4batterypacks.aspx

Cheers and stay safe - my brain now hurts as I have vomited up every scrap of knowledge I possess,
(my brain is like a Li-Ion, overuse and it's capacity diminishes substantially)

Cash