John Lussmyer wrote: > Since my Sparrow looks like it's killing the YT's I have, I'm > looking into > possible alternate batteries. Preferably ones with more range! I > currently suck about 5KW out of my pack for my average > commute. (This is > really hard on 13 YT's.) > Saft NiCd: > The problem I see here is their physical size. The > extra 2.5" height of > the STM 5-100 over YT's is a real killer, as well as not > being able to > stuff 156V worth of them into a Sparrow (even ignoring the height > problem.) I dug around on their web page, and found some > info on other > sizes of NiCd, but the only one physically short enough is > only 15AH (the > SBM 15). By the time you bundle 10 cells of those together > to get 12V, > they are larger than an Optima YT - yet have 1/3 (or less) of the > capacity. This seems weird.... > > Evercell NiZi: > The new Evercell MB80-12-8 looks promising - but their > availability is > very questionable. > > Li-Ion: > Are any of these kinds of cells available to the > hobbyist in the sizes > needed? I know they would be $$$, but I am looking at > $/mile, not at up > front costs currently. > > If my YT's only work for me for 2000 miles, that is 80c/Mile!
Hi John, I know we discussed this over a year ago, so I assume you've chosen not to take my advice. That's your right, but I'll restate my objection here for the benefit of those who didn't catch it first time around. In a Sparrow, the weight of the batteries is an advantage (I would argue a requirement) in terms of stability. The degree to which you lighten your pack is the degree to which you increase the likelihood of a rollover. I think the weight difference when changing to an Evercel pack was around 150 lbs. I know that doesn't seem like a big deal. But the Sparrow is so tiny that it doesn't take much in terms of weight reduction or movement of your cg location to make big differences in handling. In a normal car, you can make big changes in weight distribution just by moving a few batteries around. You're suggesting you pull the equivalent of three batteries from where you need the weight most. If you don't believe me, ask Corbin. I'll bet they tell you not to do it. I can understand the temptation. I'd sure like to see what difference in range you'd get, and what's involved in making the swap. But I'm fairly sure you will at least have a white-knuckle moment sometime as a wheel comes up unexpectedly. Or worse. If it was any other vehicle, I'd say make the swap. I believe that's not a viable option on a Sparrow. If it was me, I'd be looking for another EV. Chris
