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Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Tue, 07 Jan 2020, 01:04
by gyrovague
Thanks @weber. The evidence you and others submitted in this thread is very compelling indeed. The supercapacitors are currently being actively marketed and promoted in South Africa unfortunately, wonder how many people have fallen for it already.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Wed, 08 Jan 2020, 09:00
by antiscab
Even with LTO cells, it will be a long time before any capacity loss is noticed.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Thu, 09 Jan 2020, 17:06
by gyrovague
Yup, but at least if they market it as LTO instead, you know what you're getting. The only reason I was even considering the supercap (at 50% more cost per kWh) was because of the (claimed) essentially infinite lifetime without degradation, irrespective of DoD etc. etc., but if all those claims are false, I'd rather just get some Li-ion solution at less upfront cost and know I'd need to replace in probably 10-15yrs.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Thu, 09 Jan 2020, 17:23
by antiscab
Even real caps dry out after 10 - 15 years. Ceramics might get to 40 years, but they're far from energy dense

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Sun, 16 Feb 2020, 15:53
by gyrovague
Thoughts on these?
https://zoxcell.com/supercapacitors/
https://zoxcell.com/supernova/

Claims look almost identical to the Sirius module.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Mon, 17 Feb 2020, 08:04
by Adverse Effects
there just relabelled Arvio units by the look of it

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Tue, 18 Feb 2020, 11:06
by weber
Yup. Zoxcell is the same old scam with a new face. Thanks for letting us know, @gyrovague.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Wed, 19 Feb 2020, 03:46
by gyrovague
Attached is a quote they (Zoxcell) sent me for individual supercapacitors. They also have a new flat pouch unit available (as opposed to the cylindrical ones), 21000F 4.2V 75Wh. (According to me that should be more like 51Wh, shrug...). Makes me wonder whether "Fared"[sic] is really a new unit they invented :P

I wouldn't mind getting my hands on some of these to test, but a bit pricey and shipping from UAE will no doubt not be cheap -- assuming I even eventually receive something at all.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Wed, 19 Feb 2020, 09:13
by weber
Ah yes, the fared [sic] the unit of capecitance [sic], named after Fareed al Shadi the Ig Nobel prize winning scam artist. ;) Its symbol is F, the same as the farad. Couldn't this cause confusion? Of course not. Move along. Nothing to see here.

For a battery of capacity Q in amp hours, maximum voltage Vₘₐₓ and nominal voltage Vₙₒₘ, its capecitance in fareds is calculated as
C = (3600×Q×Vₙₒₘ)/(0.5×Vₘₐₓ²) and its maximum working voltage is given as Vₘₐₓ. 3600 is the number of seconds in an hour, and is required to convert amp-hours to coulombs, or watt-hours to joules. All this assumes the "capecitor" is discharged to zero volts. But never mind that.

So for example, a 1.3 Ah lithium titanate (LTO) cell (2.4 V nominal, 2.7 V max) becomes a 3600×1.3×2.4/(0.5×2.7²) ≈ 3000 F 2.7 V capecitor.

To reverse the process we have:
Q = (0.5×Vₘₐₓ²)/(3600×Vₙₒₘ)
To determine Vₙₒₘ, find the high-discharge-rate lithium ion chemistry that has the same maximum voltage as the capecitor and use its nominal voltage.

So max 2.7 V means LTO with nominal 2.4 V, and max 4.2 V means LCO with nominal 3.6 V or NMC with nominal 3.7 V.

So the 100 000 F 2.7 V capecitor is a 42 Ah LTO, and the 21 000 F 4.2 V capecitor is a 14 Ah LCO or NMC. But not an ordinary LCO or NMC. Probably one with "graphene balls" added to greatly improve the conductivity and hence the maximum discharge rate.

It's interesting that they are now using high rate 4.2 V cells. I hope they didn't get the idea from me. :o Because that's what I predicted they were using, starting here, before we knew anything about the internals of the module.

Re: Arvio 3.5kWh drop-in-battery-replacement supercapacitor on sale

Posted: Wed, 19 Feb 2020, 09:24
by weber
gyrovague wrote: Wed, 19 Feb 2020, 03:46 I wouldn't mind getting my hands on some of these to test, but a bit pricey and shipping from UAE will no doubt not be cheap -- assuming I even eventually receive something at all.
You would be doing the world a service. But make sure that when you test them you do the same test to some "controls", which would be known hi-rate lithium ion cells (clearly labelled as such) and real supercapacitors, both in the same package with the same dimensions as the Zoxcell device.