Did any of you monitor the voltage of the most negative cell and the most positive cell during the charging cycle and discharge cycle using a very high charging system?
My first EV came with a on board 50 amp charger and a off board 100 amp 3 phase charger. These were SCR chargers which you could dial from 0 to 100 amp at 90 volt to 280 volt output with a AC input of 125/250 VAC. Did not have any BMS back in the 70's at the time. During the discharging cycle which may be up to 800 motor amperes, the most positive cell would always end up less voltage than the most positive cell. This effect was also noted in a article call the Electric Vehicle News which was cause by the flow of electrons from the positive to the negative plates during discharge. During the charge cycle, the most positive cell may end up with more voltage then the most negative cell. It was noted at the time, this effect was not to get concern over. This same charging and discharging voltage difference can be seen with the Li Ion pack that's has BMS. The difference is very slight which is only 0.01 volt difference between the most negative and most positive. My battery pack consist of six strings of 54 cells in series at 33 ah for 226 volts with the six strings in parallel. Charging at 42 amperes with a 50 amp /250 vac charger, each string only receives 42/6 = 7 ampere per string taking the battery voltage only to 95% of the maximum rating of the cells. Driving only 10 miles, and charging at this rate, the voltage is reach in with 30 seconds. The voltage is then held until the ampere hour reaches 100% SOC which may take about 40 minutes. Using these superchargers, what is the recommended maximum charge current that can be use on one string of cells? Roland ----- Original Message ----- From: Ben Goren via EV<mailto:ev@lists.evdl.org> To: EVDL Administrator<mailto:evp...@drmm.net> ; Electric Vehicle Discussion List<mailto:ev@lists.evdl.org> Sent: Thursday, May 14, 2015 10:21 AM Subject: Re: [EVDL] Supercharging is not the way. On May 14, 2015, at 6:35 AM, EVDL Administrator via EV <ev@lists.evdl.org<mailto:ev@lists.evdl.org>> wrote: > On 13 May 2015 at 10:58, Ben Goren via EV wrote: > >> 15 kWh / 15 minutes is 60 kilowatts...not quite the level of >> insanity of a megawatt, but still in a range far beyond what you'd ever see >> in >> a residential setting. > > Not so far beyond at all. A typical US suburban tract home has a 200 amp, > 240 volt service. If devoted entirely to an EV such an electrical service > could charge an EV at a continuous rate of over 38kW. > > Many modern "mcmansions," which are often built by the dozens in high end > developments, now have 400 amp service. This would allow for a continous > power of almost 77kW. > > Thus I'd say that the electrical infrastructure for 60kW charging is fairly > widely available right now. Er...no. Indeed, I think you just proved my point. 60kW is over half again as much as you get at the meter in most homes, and nearly 80% of what you get at the meter in a McMansion. How many people living in McMansions are going to be happy shutting down basically everything, especially all the air conditioning and pool equipment they paid so much extra to get the 400A service for in the first place, every time they want to charge the car? Worse...I don't think I've ever seen anything bigger than a 220V / 50A breaker in a residential panel -- though, granted, I'm certainly not an electrician. That's 11 kW. You're going to need half a dozen of those, almost as many as will physically fit in a typical panel...and just the cost of the copper for the wiring is going to be insane -- especially since the meter is, as often as not, on the opposite side of the house as the garage. And the cost of retrofitting a neighborhood for 400A...it'd be cheaper to cover all the rooftops in solar panels, add a bunch of batteries, and cut the grid connection entirely. I just don't see it. What I expect to see is, especially when 200+ mile ranges become the "new normal," for most people to do almost all their charging on a 110V / 15A (or maybe 30A, since that's not uncommon in garages) circuit, the types of people who buy the top trim level packages to get L2 chargers installed, and then a footnote for some sort of on-the-road rapid charging that only gets used out on road trips or out of desperation. And I expect to see those roadside charging stations struggle for profitability at the same time they charge exorbitant fees.... b& -------------- next part -------------- A non-text attachment was scrubbed... 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