On 28 Oct 2014 at 7:34, paul dove via EV wrote: > He says right up front in the article, > > "On the first part of the steep downhill run, we could recover about > 5% of the total capacity through recuperation."
In the paragraph before, Axel has been talking about battery capacity. He means that he was able to recover 5% of the total battery capacity, not 5% of the energy used in climbing the hill. The recovery was 6.7% of the energy used - almost 7% if you discount the energy used for the headlights. Also keep in mind that after climbing for 125km, he actually used regen for only 15km in recovering that 6.7%. That's pretty good regen! After that, there was still more distance to travel, but it was a less steep descent. Thus he found it more advantageous to coast rather than using regen. (It's always more efficient to coast than to regen.) To look at it another way (I hope this table works) Location dist elev DOD Gams 0km 490m 0% begin steep ascent San Bernardino 125km 2066m 74% begin steep descent Not stated 140km ? 69% begin shallower descent Bellinzona 165km 238m 69% begin ascent Stabio 215km 352m 100%?* end of trip *Final DOD not stated. However, the battery required 23.5kWh from the mains to charge. Typical efficiency of the Brusa NLG4 chargers was around 92%. Thus he probably put about 21.6kWh into the battery. (Pretty good for a battery with a nominal rated capacity of 18kWh, but Saft STM5 NiCd modules often ran 15-20% over rated capacity when new.) The big takeaway here is that Axel went OVER THE ALPS, valley to valley, covering a total distance of 215km (133mi) on one charge. He used only 10.7 kWh / 100 km (162 Wh/mi). That's energy input at the mains, not at the battery. Some of that is no doubt down to a fairly light and efficient vehicle (900kg all up). He probably could have coasted just as well in a car without regen, though I personally wouldn't want to try that in the mountains with a series- motor conversion EV unless I'd really beefed up the brakes. Based on the somewhat sketchy information provided, I don't think he would have been able to finish the trip on one charge without the regen. The decision of whether or not to have regen in your own EV will usually be based on the terrain where you live and whether you have a lot of stops on your daily use profile. The more hilly the area, the more you'll get back out of regen. Same with more stops. You basically get regen "sort-of free" with AC induction motor controllers and with some sepex controllers. However, with a series motor, regen is almost never included in the controller by default. In fact it's usually difficult and expensive to implement for series motors. So this may be a factor in your motor choice when converting. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
