Re: Electrofuel: it would appear that the batteries are hand-made, and you order direct from the manufacturer. No price or availability is given. From the specs they would appear to be using lithium-cobalt (see calcs below), esp. considering that the darn thing is packaged in a TITANIUM case (concerned about overpressure situations from overheating, perhaps?).
The chart they show comparing their 'super battery' to other li-ion and li-poly cells is somewhat misleading (probably for some 'future' battery system). When you go to the specs for the 'extended life battery' you can reverse-engineer that it provides only an 11.7% improvement over the published specs for Valence's MnO2 cells (which are likely being underreported). Valence could show similar charts using various 'next generation' specs which would show the Valence cells superior to anything else in the lithium arena.
The specs Electrofuel gives for their 'powerpad 150' model are 14v,11.5Ah,160w(s.b. 161 'watt-hours', not watts), 980 g (yielding 164 w-h/kg), in a package .37"x8.75"x11.75" (=9.5mmx220mmx295mm).
This would appear to be 4 cells in series, which in theory would provide 4x3.8v=15.2v using Valence's MnO2 cells, but in application these would be voltage-limited to the circuit needs, so let's assume a comparable Valence construction would only be used to provide 14 v as well. (Note: voltage limiting 'loses' the excess power that would be 'available' if the circuit was designed for 15.2v, as it's dissipated as heat, usually using passive resistor networks.)
So if you take the 4 electrofuel 'cells' as each being 9.5mm x 4.375" x 5.875", and scale up the old Valence specs for their 4.45mm x 4" x 4" cell, the scaling factor is 3.429. Multiply by 3 A-h for the old Valence 4" x 4" spec, and you get 10.29 A-h for each of the 4 Valence-equivalent 'cells', versus the 11.5 A-h Electrofuel quotes. This is an 11.7% difference.
This exercise is just to show that this product is competitive with Valence's OLD specs. But we don't know what Valence is really selling right now. There's a justifiable argument that what Valence published is purposefully below what they actually sample to customers, so that the competition doesn't really know what Valence has. Since Valence only wants to sell to these OEMs, and isn't interested in direct-market applications, they have no motivation to 'inform' the outside world via their website as to what they actually have in hand.
Another aspect of this Electrofuel cell is that the data on the number of recharge cycles is conspicuously absent. Maybe the battery conks out after 100 cycles. (Valence's MnO2 exceeds 1000 cycles, at room temp, and exceeds 500 cycles at elevated temp of 45 degC, according to comments to shareholders at the SM in Feb.) It is somewhat telling that no OEM is going after the Electrofuel product and they are forced to go directly to the aftermarket.
The titanium case implies that Lev (Valence CEO) was right in telling us that it would be very difficult to make a 'large safe battery using any technology other than MnO2 (or some formulation thereof, such as the 'doping' methods Valence has developed).'
The most important point would be the need for mass production in volume , with consistent quality, with high yields and profit margins. Whoever comes to market with THIS is the 'winner.'
BTW this set of observations resulted from various conversations over this weekend with other individuals, I'm just reporting them.
Rich |
