Good point, Floyd, hadn’t thought about that. -D
> On Jan 8, 2024, at 5:57 PM, Floyd Thursby via Mercedes > <mercedes@okiebenz.com> wrote: > > And in northern cold climates the batteries will degrade capacity and output > considerably, and will require self-heating to make them work. All that will > degrade range considerably, I don't know how much a battery is affected in > that regard. > > --FT > > On 1/8/24 5:38 PM, Craig via Mercedes wrote: >> On Mon, 8 Jan 2024 20:46:12 +0000 (UTC) Curt Raymond via Mercedes >> <mercedes@okiebenz.com> wrote: >> >>> And they all need to be recharged by the time they're put into use >>> again. >>> >>> This is a case where failure is not acceptable, they MUST be recharged >>> in the time allowed so the electricity for them to be recharged MUST be >>> available. We're talking batteries in the 250kwh range, if you're >>> discharging them, say, 50% daily and there are 10 busses you're talking >>> 1250kwh. Figure 14 hours max that you can charge in, you'll need 89,000 >>> watts per hour or 202a at 440v. >>> >>> Unless my math is bad, which has been known to happen... >> Well, you math is not bad (the actual number is 89286 watts), but the >> phrase "watts per hour" is nonsense. >> >> 89.286 kilowatts for 14 hours = 1250.004 kWh >> >> However, you also need to account for inefficiencies in generating the >> charging current (say 95%) and then the overcharging the batteries need. >> For nicads in the 1980s, they needed to be charged for 14 to 16 hours at >> their C/10 rate, so 40 - 60%. Say the current batteries need 40% >> overcharge, that implies 71.4% efficiencey ( 1 / 1.4 ). >> >> So the overall efficiency from utility AC to battery is going to be >> >> 0.95 x 0.714 = 0.6783 >> >> So _IF_ the fleet needs 1250 kWh (taking your numbers for it), the utility >> will have to supply >> >> 1250 >> -------- = 1842.8 kWh >> 0.6783 >> >>> OTOH my math suggests charging that fleet isn't going to cost all that >>> much... >> 1842.8 kWh x $0.20/kWh = $368.57 >> >> With diesel about $3.75/ gallons, this will buy 98.28 gallons. >> >> Now how much all this relates to the real world remains to be seen, since >> we don't have good information on >> - How much energy electric buses consume >> - The actual cost of the electricity >> - How much energy (fuel) the diesel buses consume >> - The efficiency of charging and using the batteries >> - The propensity of both types of vehicles to break >> and the cost to repair them >> - Probably something I have forgotten >> >> >> Craig >> >> _______________________________________ >> http://www.okiebenz.com >> >> To search list archiveshttp://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> > -- > --FT > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
