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New Pack Architecture that is Likely Used in P100D and New TE Products
- Thread starter vgrinshpun
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- Tesla Inc.
Ubbe
Member
Yes, so I'm agreeing with you then
Not sure who suggested the spot-weld as a fuse? It is more likely that the traces on the flexible circuit board are constricted at certain points thereby acting as built in fuses. Or perhaps surface mounted micro-fuses, but that would be less elegant and add two solder points.Interesting thread!
It appears that P100D pack supercharging is significantly better than supercharging of P90D pack: P100D SuperCharging Rate
It is very difficult to conclude this from a single charging session. If you look at the link I posted in reply to you, you will notice the 90D is charging faster than the 90D in the referenced thread. The 100D charges slightly faster, but not significantly.
Heat pipes will always flow energy from hotter to colder. If you introduce a bunch of warm coolant into the central channel, the pipes will distribute it out to the cells.
To add to this, the patent explicitly mentiones both cooling and heating via heat pipes.
So, as Saghost indicated, pumping heated coolant through the central channel will reverse condensing and evaporating ends of the heat pipe, and, therefore will facilitate heating of battery cells.
lolachampcar
Well-Known Member
Do heat pipes not use fluid density to transport vapor to a "higher" point in the system where it is cooled, condensed and then allowed to "fall" back down to a "lower" part in the system? It was my understanding that passive phase shift heat pipes were designed to work in one direction.
Early systems did. More recent ones have a capillary membrane sponge inside - the gaseous working fluid condenses at the coldest point, and the capillary membrane wicks it out to everywhere in the system, where the hottest point evaporates it. At least, that's what I've read.
dandurston
Member
This is true, but I think there's more to it than this.
The wall thickness in a 2170 likely constitutes a smaller proportion of the cell diameter than it does in an 18650. In other words, they're probably using a similarly thick wall in both cells, so a larger proportion of the diameter is actual energy storing substrate in a 2170. My guess is a 2-3% gain would be possible here.
This earlier Tesla patent application appears to give details of the printed-circuit used in this system, including the use of narrowed traces a fusible links:
Patent US20140212695 - Flexible printed circuit as high voltage interconnect in battery modules
I found it relevant.
If the cells are truly only cooled from one side, and this is what a P100D pack looks like, look for significant heat related degradation as one end of the battery runs much hotter than the other end. One it's just hotter but two there will be uneven thermal stresses across both the anode and cathode. Maybe we'll have to have a customer subsidized study to find that out.
Majority of competitors also have bottom cooling for the battery pack. It is more robust than cooling using ducts between the rows of the cells. Since one side of the cell needs to be used for the terminals/connections, bottom cooling is the best way to cool the packs.
What is your point?
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stopcrazypp
Well-Known Member
Would there really be that much of a difference if the thermal conductivity of the cell walls are good and they design the cell cap to reduce heating? Even in the old design, probably only 1/4 of the cell was in contact with the coolant pipe (edit: it's actually way less than 1/4, it's more like 7.6% because the cooling tube is only 30mm tall and from the curvature only 68 degrees of the cylinder is in contact).
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His point is that the original pack architecture could be better than this new as far as thermal gradients go. You seem to disagree. Why is the new architecture as good or better than the old one?
