Maybe they confused "balanced" and "stiffened"? I don't know as I did
not read the Tesla driver's experience as there was no link provided.
As far as I know, the Tesla has ~24V modules (blades) with 6 series
connected herds of round cells (approx 6-7 dozen in parallel) and the
BMS only has access to each interconnect point between the cells, so 7
points in each module.
I do not know when the BMS is balancing, so if this only happens during
charging then I can see that a continuous cycle of 1/2 hour fast charges
may not provide enough balancing time to keep all cells properly
balanced, while a slow overnight charge may provide ample time and thus
make all cells behave more in line so there are fewer outliers, which
might resemble a stiffer pack (but it not actually stiffer as the
operation of the  cells is not affected, so they sag exactly as much as
before the balancing - only with less variation between cells!

The Leaf's BMS is powered 24/7 so it balances at all times, which is
also needed since the balancing current is extremely low (10mA)
So for the Leaf it makes no difference if you do a fast or slow charge,
the BMS has exactly as much time to balance (24 hours each day).

Hope this clarifies,

-----Original Message-----
From: EV [] On Behalf Of paul dove via
Sent: Sunday, May 21, 2017 4:14 AM
To: brucedp5; Electric Vehicle Discussion List
Subject: Re: [EVDL] @50kW: Chevy Bolt charge times with a level 3

I don't know what stiffen the pack means. Sounds made up.

I did watch my car charge on a chademo charger though. I had 15 miles
range showing when it started. It said 27 minutes to charge. It started
at 100 amps. After about 8 minutes I was up to a 60% charge and it was
charging at 48 amps. It had steadily dropped as it charger. Not sure why
they do this but I suppose they don't want to overheat the cells. 

I don't believe it's necessary based on my testing of LiFePO4 but maybe
these other chemistries heat more rapidly. At any rate chademo doesn't
use consistent power to charge if they did it would be much faster. I
don't know if ccs does the same thing.

Sent from my iPhone

> On May 21, 2017, at 4:49 AM, brucedp5 via EV <>
> When people talk of performance EVs, they usually forget about 
> performance charging.
> I have always had a keen interest in quick charging even in the old 
> (90's) days of PbSO4. I had 6 chargers on-board with their output tied
in parallel.
> With all of them on I could push 22+kW into my pack (I had the fore 
> runner of a l3 charging ability).
> GM bullied Euro automakers into going their way away from using 
> CHAdeMO to using ccs combo l3 DC.
> GM's Bolt as a maximum l3 charging ability of 80kW. Where most public 
> l2 EVSE only offer 50kW.
> When you read GM's pages, they spec a 80kW time.
> I suggest you read
> ing-rate-in-2017-chevy-bolt-ev-electric-car
> and it's source
> html
> The charging rates are broken down to what a Bolt driver can expect 
> from a public 50kW l3 ccs EVSE.
> If the ambient temps are optimal, the 0 to 50% SOC will be the highest

> charging rate.
> The 50% to 80%SOC will progressively taper slower, until at the 80% 
> most eVgo L3 EVSE will shut off.
> Other ccs combo EVSE will allow you to charge at a slow rate to 100%, 
> but really at 80%SOC you really ought to move out of the l3 EVSE spot 
> and to a
> l2 EVSE spot if you feel you really need to charge to 100%SOC.
> With today's larger amount of public L3 EVSE available, the fastest 
> method is to only charge to 80%, unplug and hit the highway to the 
> next L3, charge to 80% and repeat (never charging to 100% unless you 
> had to because of the large EVSE gap). After being on the road with 
> multiple l3 charges, a slower overnight charge while you sleep will
help balance/stiffen your pack.
> Tesla drivers have shown, the best method of re-conditioning your pack

> after multiple l3 charging sessions (in their case using 
> superchargers), was to come home near 10%SOC and l2 charge overnight. 
> They reported it took a long time, but it made the pack stiffer, and
helped reset the guessometer.
> For EVLN EV-newswire posts use: 
> {}
> --
> View this message in context: 
> t-charge-times-with-a-level-3-charger-tp4686787p4686793.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
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