Super-capacitor Batteries

[Coulomb]

20 hours ago, Martinv said:

2. These may not be actual capacitors as we know them, perhaps more related to Solid State Batteries?;

Solid state batteries are still in the development stage, with several serious problems to overcome.

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3. The safe charge and discharge currents exceed the capability of lithiums;

LTOs are extraordinary lithium cells, with typically very high C rates compared to other lithium chemistries.

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4. The charging current follows that of a capacitor when 'empty" and near full charge;

It's hard to tell from the outside, with the supposed DC-DC in there to give you a relatively constant terminal voltage. But the current curves for batteries look much like capacitors, except for the voltage.

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5. The safe operating temperature is up to 85 degrees Celcius, normal lithiums cannot work above 35;

You only have the word of the manufacturer that it will operate successfully and with long life at 85°C. Lithium cells will work hotter than 35°C, just that their life is curtailed.

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  6. The warranty is 10 years irrespective of charge and discharge cycles, no lithium is warranteed like this;

With all the odd claims from this manufacturer, I wonder how well the 10 year warranty will work. But LTO cells are known to have long life, and ten years warranty is not unreasonable for those. Some Mitsubishi iMiEVs were built in Japan with LTO cells. They would be highly sought after now, as only a relative few were made. They are great cells, just very expensive (roughly 2x for the same energy capacity) compared to other chemistries. Some high end solar batteries use them.

[Speedster]

On 2020/09/01 at 5:10 AM, Coulomb said:

The Sirius product is NOT a capacitor. It seems to be an LTO battery, but why don't they tell us what it actually is?

It's so fishy I would not touch it. I'm sure this is discussed on this thread, but not in the first page.

Beware!

How are you so sure of this? Why would a US company risk running foul of their authorities by deliberately misrepresenting a product?

[Coulomb]

11 hours ago, Speedster said:

How are you so sure of this? 

Basically, there isn't enough room in the box for current technology capacitors to add up to 3.5 kWh.

Others, especially my colleague Weber, have looked into this far more than I have, and frankly I'm not that interested except to warn others not to be scammed. Though they might actually be a reasonable value for money battery, depending on the quality of the cells in there. But they won't last millions of cycles; we don't have the technology to do that at present.

This long thread on AEVA discusses the topic in excruciating detail. I couldn't quickly find the post (amongst the nearly 400 posts) where Weber concedes that they are probably LTO cells (initially he thought that any LTO cells would be way too expensive, but it seems that inexpensive Chinese LTO cells of unknown quality are now available).

[weber]

Anyone thinking they might take a risk on these so-called "super-capacitors" on the basis that LTO is a long-lived battery chemistry, should forget it. That's only the case if the LTOs are properly manufactured and are protected and balanced by a proper BMS. The BMS in this device is rubbish. The photos of the fire should have been enough to convince us of that. But some more information has recently come to light, thanks to a brave volunteer guinea-pig.

I received the following email 6 weeks ago. I asked the author to please post the information himself directly, but because he hasn't yet done so, and I'm concerned that people might still be thinking it's worth the risk, I post the email below, unedited. "Arvio" is the Australian agent for these devices.

The executive summary: It lasted about 2 years. The warranty was not honoured. Disassembly found bulging cells and leaking electrolyte.

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Hello Dave,

I hope to find you well.

I have a little story and an offer that may be of interest

I have been taking a look at the forum relating to the Arvio "supercap"
A few years ago, I had some spare cash that I could afford to throw away and purchased one for my off grid system at home.
It turned out that charging these to the correct specifications was a bit of a challenge at first as my SMA inverters would not accept a profile that could charge the supercap correctly.
The option was either over or under...
Time went by and my lead gel batteries started to fail after 4 years and only taking less than 15% off the top and well looked after. The house was running on them (1000AH * 48 batteries) with a Selectronic inverter.

My main system at that stage consisted of 20 x 215W solar panels in one array, 12 x 175W panels in another 4 arrays with the Selectronic inverter.
My auxiliary system was a pair of SMA 6.0H inverters to charge the supercap which I used to dump excess energy into making hot water for shits and giggles.
I also have a 10KWH LG (LV) lithium battery which to date is unconfigured other than via the Selectronic.
(I have plans for it)
I also have a 13.8KWH diesel generator that on a full tank can run the house for around 200 hours as my final backup.
After the lead gel batteries started to fail, I purchased 3 x BYD 13.8KWH batteries which one hiccup aside, have worked flawlessly. These I hooked up to the two SMA Sunny island 6.0H inverters and connected the Selectronic inverter to the Supercap which again I used to heat water.
It takes about an hour to dump all it's energy into the HWS and raises the temperature a few degrees in the 315L tank.
I turn off the heater well before the supercap low voltage dropout kicks in and it waits for the next day to charge and dump again. I think the heater element is around a 4KW load but never measured it to date.

About a year ago, the supercap failed.
There was a reasonably bad smell coming from it, akin to leaking dielectric...
So I disconnected it from service and sent it to Arvio for a warranty claim.
Not happening...
Apparently, I had water damaged it somehow.
I had it returned to find that they had not taken the supercap pack packaging apart at all to investigate the fault.

I am a tech and I have a fully qualified repair center. So I found their methods of testing and investigation pretty appalling.
Bear in mind, I can fix pretty much anything, I don't need schematics to fix something. You can see what parts are used, you know how they work, there is your fault.

I have been designing and building power supplies for most of my life.
The Supercap is a very very agricultural build. I would be ashamed to release it, if I were responsible.
 
When it originally arrived, as it had come a long way, I pulled the cover off and had a look on my bench.
The unit uses 5 Arduino modules to monitor and control charging cells, the IP connectivity which was in a useless range that could not be changed and to drive the display, and some DC-DC modules for balancing.
Some of the socketed TH parts were not seated properly, and one IC had a leg bent under that would have caused failure fairly quickly on it's own. (I took some happy snaps and sent it to Arvio who were not interested at that stage)

Anyway, I figured that since I had paid to get it to Melbourne for them to look at and back after they refused to fix it, I would investigate the cause of the failure.

So I dismantled my unit to find that the bottom layer of cells in fact looked like a leakage had damaged and spread across the bottom of the pack. (it is bad...)
There was a piece of ply separating the two layers and the top layer looked reasonably OK, aside from some cells that had not seen a correct charge profile and the ends of some have expanded. The Arduino modules look like they didn't work as expected.

I removed some cells from both blocks and started testing, My engineer also did a few tests and his conclusion was, battery.
My conclusion was that the chemistry also contains Titanium.
My background in electro chemistry (39 years recently) has had a lot to do with Ti Cathode destruction over the years.
Once you see it, you can't un see it. These looked to me like the Ti part had dissolved.
When I test cathodic destruction, to accelerate destruction, you increase the voltage.
I can dissolve a 1mm piece of solid Ti metal in about an hour @ 80V
The Ti will turn into off white snowflakes in water.
Quite entertaining to do.  

Anyway, I was wondering if you wanted a few cells to play with.
I can provide a selection of dud --> partially --> mostly working cells.

Sorry for my long winded story above.

Andrew

 

Edited April 9, 2021 by weber

[Missing link]

On 2018/08/30 at 1:59 AM, Coulomb said:

Yes, here:

http://forums.aeva.asn.au/viewtopic.php?f=17&t=5486

The conclusion is that they are not supercapacitors at all, but LTO (Lithium Titanite Oxide) batteries. They're possibly OK as a battery, but why lie about what's inside them? They certainly won't have supercapacitor-like life (millions of cycles).

All high C rate units have liTiO this because of “ELECTRIC VALENCE” if you understand the concept and periodic table enable high electric transfer or C rate. Sirius in the background that is hidden from your eyes consist of normal EDLC of about 40F each. Just the control ie solid state I a proprietary thing. That is why WEST could build their units just now with MFB and Wi-Fi.

Toyota is going for the Hybrid Supercaps since with the 37.5vdc to 58.2 range is a drop in and as high as 6C rate such as E-Prix that managed to blow 5x 1MW generators.

they keep the hybrids to 2C max due to domestic use and safety. With a guaranteed 100% cycle at maximum C rate of 50000that is 100 years with 100% use every day.