angrypengu

This is concerning. If you folks want to do more research on NMC/graphite battery longevity, there are a LOT of papers out there. This article states about 2000 charging cycles, which is in line with what I have read elsewhere. So key takeaway for me? Disable auto start stop for every drive. Less wear/tear on the battery.

https://www.designnews.com/materials...18340601859495

angrypengu

Found the battery.

If you look at page 19 of the self study program (SSP), you'll see a closeup of the 48V battery.

It says:

VW AG
Made in Korea
LGC

So LG Chem makes the battery. Further research to follow.

Edit, also confirmed here: http://www.rnd.lgchem.com/global/lgc...ut/History2010 Under 2014: 08.Selected as a supplier of Li-ion battery for Audi’s(Volkswagen Group) next-generation plug-in hybrid vehicle (PHEV)
and micro hybrid vehicle (mHEV) model

So if you want to learn more, (I'll stop posting), google "LG Chem NMC battery" and there's a bunch of technical papers on their implementation, namely different battery chemistries. Looking at the SSP, it appears the 48V D5 battery utilizes 13 "pouch" cells, which, based on my perusal is of the "622 chemistry" design. Whatever that means.

Edit 2:

Here's everything you ever wanted to learn about LION batteries. https://batteryuniversity.com/learn/...of_lithium_ion

Edit 3:

Mercedes is using NMC batteries as well.

https://insideevs.com/mercedes-benz-...lug-in-hybrid/
https://insideevs.com/mercedes-benz-...e-diesel-phev/

angrypengu

To answer your thermal runaway issue, it shouldn't be an issue. https://batteryuniversity.com/learn/...of_lithium_ion

That said temperature and depth of discharge are variables that impact cycle longevity, as per the above. So we need to keep the car as cool as possible, and disabling auto start stop may help.

I'd like to see if we enthusiasts can figure out a way to completely get rid of that crap (the 48V battery), like in the SQ7 (IIRC) application.

derfA8L

angrypengu

Absolutely.

The other piece that I need to figure out is if we can turn off the boost feature which is part of the BAS. I think it remains on even after disabling auto start stop, sadly and this would drain the 48v batt

angrypengu

@derfA8L did you hear back yet by any chance?

derfA8L

angrypengu

So this topic has continued to be one that I've been working through. Initial thoughts to help with the longevity of the MHEV battery involve adding insulation to my garage doors and adding air conditioning, but that does appear to be a rather large initiative, mainly because I have to punch a hole in the exterior wall in order to vent the hot air.<br /><br />Don't laugh too hard at this idea, but bear with me here. The main concern I have is the temp in the garage on a really hot summer day, and as I mentioned upthread, it can hit close to 40-50'C which is really hot. As we know, heat kills batteries, so instead of going overboard with ideas such as the one above, why not buy/use a massive freezer ice pack? E.g. keep said ice pack in a top loading freezer, and after parking said car, put in the ice pack in the trunk, have a towel around it to deal with the condensation, and call it done?<br /><br />I'll full well admit this sounds like an incredibly stupid idea, but I figure that I can control the condensation using said towel, and a really large ice pack = should be able to help with temperatures for hours, at least in a sufficient enough manner to get from the max heat of noon time to sunset.

Thoughts and/or immediate concerns with my idea?

dwboston

You're way overthinking this. You don't think Audi tested this for "car in garage" conditions?

angrypengu

I don't really trust Audi with anything novel as Audi's track record with anything 'new' has been incredibly poor. I've had this discussion with a few other Audi members already.

Perhaps they have, or they have not, the fact remains that the thermal management systems stop running once the car is off, and that like every other automaker who should be using liquid cooling for the battery cells - don't, because of cost reasons. The other fact remains that temperature is what kills batteries and while I don't have any concerns of the battery performance in the cold as it has an internal combustion engine (vs say Teslas), the heat does concern me.

I mean, it's only $3800CAD a piece, and is not covered by warranty.....

But yes, you're probably right. I've just been burned by Audi's too many times, and yet, bought an A8 anyways. I'm clearly an idiot!