Buzz on Tesla's Published US Patent Application 2017/0093156
Electrek reported on a patent application of Tesla on 31 March 2017:
In a new and updated patent application, Tesla explains how these grid-tied projects are using its Powerpacks and inverters for what the company describes as a scalable “turnkey” solution.
Tesla first applied for this patent back in September 2015, a few months after it launched ‘Tesla Energy’, and it updated it and applied again a year later when it was working on the second generation of its Powerpack.
It was released publicly yesterday.
As to subject matter, the "background" states
 Various approaches for energy storage have been tried. Some batteries that are designed for large scale energy storage have smaller cells arranged in series and parallel. For example, some cells are arranged in parallel, and then that unit is arranged in parallel with another similar unit, and so on. This can require the system to have a disconnect and fuse, and to apply some management strategy that occurs at the high level. These systems can be configured so that they are paralleled at an electrical interface, which can make them complicated to parallel.
 One problem with such approaches can be that when batteries are paralleled, one must match their voltage characteristics precisely because they in parallel electrically. This can significantly limit scalability of the system. For example, one may need to use very similar chemistry, or similar cells, or come up with particularized balancing strategies, to manage the different cells within their ranges of operating characteristics. Also, with regard to the individual cells, the system is in a sense limited by its weakest link. That is, if one cell malfunctions this typically renders the whole array of batteries out of service.
The first published claim states
An energy storage system comprising: a grid tie unit comprising at least one DC/AC converter, the grid tie unit coupling the energy storage system to an external AC system; a DC bus coupled to the grid tie unit; a plurality of pods connected to the DC bus, each pod including: plurality of battery cells; a power electronics unit configured to galvanically isolate the plurality of battery cells from a plurality of battery cells of at least one other pod of the plurality of pods and to allow the plurality of battery cells to float relative to the grid tie unit.
The priority is to a PROVISIONAL patent application:
The present U.S. Utility Patent Application claims priority pursuant to 35 U.S.C. section 119(e) to U.S. Provisional Application No. 62/235,509, entitled "SCALABLE AND FLEXIBLE CELL-BASED ENERGY STORAGE SYSTEM", filed Sep. 30, 2015, which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility Patent Application for all purposes.
Some of the COMMENTS to the Electrek post may be of interest to patent attorneys:
*VERY* poorly written and poorly described patent. They refer to 'power electronics' in the pod that isolate the pod, but this crucial claimed element is not explicitly shown in the figures and is not described further except for 310. This aspect risks taking the whole patent down for lack of enablement, and it appears this might be where the secret sauce has been improperly hidden. The key description in para 36 appears entirely nonsensical or lacking coherent description at a minimum, while the patent drafter uses pronouns in a very unclear and unprofessional manner. Aside from writing non-sentences, it gives the impression that the patent drafter does not really understand the electrical meaning of the words 'isolation', 'floating', and 'leakage or short'.
"The cells of the pod are isolated, if there is any leakage or short from any battery point to ground, this may not pose an immediate hazard. Rather, the battery can be floating, so that is any point is grounded the battery loses isolation. The power electronics, in turn can detect that and report it (e.g. to a DC bus controller)."
It's known that the Patent Office typically only searches older patents, even though they are SUPPOSED TO search the published literature.
This is bad behavior on the part of the patent office, but it's what they do habitually.
Therefore it is wise to put in a patent, even a badly written one, so that it will come to the notice of the patent examiners BEFORE they issue a patent to someone else, rather than after.
Don't get me started on this problem. The patent office is simply not managed properly, and it isn't really their fault; it's the fault of two entities: Congress which doesn't give them proper funding, and the specialized patent courts which keep ordering them to issue garbage patents which are not legal.... OK, I really don't want to go into more detail now.
"Prior art" is useful for establishing who came up with the idea first, in court after someone else patents your idea. The patent office does not do Google searches for similar ideas posted on webpages, it searches prior art in the form of previous patents issued. If it does not find conflicting claims, and deems your claims to be novel, it issues you a patent.
So it is better to have a patent in hand, because that means the patent office will not issue a conflicting patent to someone else (usually) in the first place and rights are clear. Posting on a webpage just gives you the right to sue after the fact, after someone else has a patent in hand for ideas you had first, and judges are far less willing to toss out an issued patent than they are to protect an existing patent from infringement.
I am not a lawyer, but I do have a patent and so I know a little bit about it...
***[IPBiz comment: Under AIA, we live in a first inventor to FILE world. Disclosing on a webpage without filing establishes NO patent rights.]
Paragraph 36 of the Tesla application states:
 The following is an example relating to the DC/DC converter 310A. The battery inside the pod can be on the order of about 30-50V. The power electronics can take that volt power, isolate it, and bring it up to a higher level, such as on the order of about 350-450V. The cells of the pod are isolated, so if there is any leakage or short from any battery point to ground, this may not pose an immediate hazard. Rather, the battery can be floating, so that is any point is grounded the battery loses isolation. The power electronics, in turn can detect that and report it (e.g., to a DC bus controller). That is, because the battery in each pod is floating--it is isolated from the high-voltage system, and to ground--it may take two separate faults to occur before a significant electrical hazard is present.