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> Date: Sat, 7 Jan 2017 21:32:51 -0800
> To: [email protected]
> Subject: Re: [EVDL] TESLA - Patent Issued for Transient Detection of an
> Exceptional Charge Event in a Series Connected Battery Element
> From: [email protected]
>
> I read the claims of the Patent (which is the meat of the invention)
> and while I understand that you can establish parameters for a pack and
> determine for example loss of a single cell in a parallel configuration
> in a number of ways, for example because that set of parallel cells will
> have lower capacity than the other (series connected) sets, so the
> voltage of the set with one less (functioning) cell will rise and fall
> faster with SoC;
> it is also possible to determine (increase of) impedance of a set of
> parallel cells by monitoring the short-term voltage variation correlated
> with changes ("transient" in terms of the patent) in the current flowing
> through the cells (from acceleration and regen or charging start/stop),
> but I do not understand their claim that they determine an overcharge
> event by finding a *lower* impedance of the cell than normal ????
> All data that I have seen show that pack impedance goes *up* at the low
> and the high end of SoC, so how can they determine overcharging from
> lowered impedance???
> Unless the Panasonic/Tesla cells react differently to overcharge than
> other chemistries.
> For over*dis*charge they do expect and detect a rise in cell impedance.
>
> After Claim 9 we find the usual stuff for a Lithium-ion battery with BMS
> that balances cells, the only really new thing that this patent seems to
> claim is the *de*crease of impedance during overcharge and the fact that
> it uses an independent system for the over- and under-charge threshold
> detection so that if the main BMS fails and balancing is unavailable, at
> least this backup system prevents the battery from over- and
> under-charge so the car can continue to be used (and driven to the
> service appointment) with the main BMS out.
> This fact of a backup BMS as well as the *lowered* impedance measured to
> represent overcharging was probably never claimed before and thus it is
> possible to get a patent on this, but I find this a very flimsy basis
> for a patent.
> It is always possible that I misunderstood the patent - reading and
> interpreting claims is never easy stuff but I have a bit of experience
> ;-)
>
> Cor van de Water
Hmm,
all decent bms do allt/most of this already today, right?
At least the one we build at the hobby-level, hehe
Statistics used on all individual cells/modules and using the peak load/regen
and the charger, no load voltage drop after charge andso on, statistics on
temperature dependancy at high currents,
Dont we all use the car as the ultimate "heavy duty battery tester"?
Also the "oooh-shit"-redundant solution from Linear about 7-10 years ago, had
a fallback, at least monitoring the min max voltage -levels(?)
This was Done at a different chip,
..if the main ltc680x chip or computer / signal lines
fails for any reason, right?
if I remember their solution right it was just pulses out, as long "all ok",
it could be daisy-chained on all pack cells groups,
just monitoring a single output "allgood"-pulse,
or monitor individual banks pulse-chanels in paralell,
one pulse channel for each bank of 12 cell-levels, if you did like that.
At least I think I have this redundant circuits on my now very old 48chanel
dev-boards from Linear.. :-)
/ John
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