I made a fairlylarge error that was very misleading to you and I do apologize.The 600 AMPS was not part of my calculation, I did say it was.I have consistently saidthat current was a major problem with 48 volt design. I original showed it for battery and motor.A few weeks ago AUS published an article where in a lab they managed to control 500 AMPS by mounted SS devices on a liquid cooled ceramic substrate. He said problem solved. I said even at 600 AMPS that would not do it. So in this post I associated the 600 amps with the 90%.I am sorry this was misleading, my bad.The 10% is based on motor and battery capacity.I have not seen a belt driven motor greater than 25KW .This is for only a second or two. Steady state is usually half but let’s say 15KW which is what the new transmission motor AUS has been pushing to use is, 30KW for 1.5 seconds as well.So 15 KW at 48 volts about 31 amps.Brings your number down to 10% Next is battery pack, now originally it was at 0.5 KW but AUS has said small battery size is not part of MH the only thing he includes now is 48 volts.He has consistently made fun of the half ton of batteries that Toyota andHonda use so let’s increase batteries 4X from original to 2 KWH. (their packs are nowhere near a 1/4 ton for record) I will use the following battery for an example.There are now larger batteries but the ratio of charge and discharge current to WH stored remain the same.
https://www.batteryspace.com/lithium-21700-rechargeable-cell-3-65v-4000mah-14-6wh---un38-3-passed.aspx?gclid=Cj0KCQjwqs3rBRCdARIsADe1pfR2dPp9w1nQNpOwhgE88JBY-vZL-E6RhEhrvdL7OfYMxbaTKZwz72caAlnTEALw_wcB
So this batterystores 4 WH of power Has an absolute max charge current of 1 AMP and even at this rate close to 25% of energy put into battery is loss to heat.Also note that max discharge current is 4 to 12X Max charging current depending on Temp.
Some 48 voltbattery pack manufactures use 13 cells.Most use 14.14 greatly extends the life since the batteries can be run at less than full charge and not depleted as far.Of courseit adds cost weight and size.Lets not worry about life and use 13 cells in a string.The string would support 52 WH of storage and have an absolute max charging current of 1 amp if the batteries were cooled. Now in the original example I used 10 strings for 0.5 KW so absolute max current of 10 AMPS not 600 again I apologize for this mental lapse.Now let’s saywe let battery pack increase 4 X to 2KWH still only40 amps.Still less than 10% energy stored.I know charge rates are proportional to battery storage and mathematically it makes no difference how they are arrayed.However high voltage fewer strings requires less monitoring.SS devices switch voltage much more efficiently than current for same amount of power being switched.This lets high voltage systems do much more complex charging when the string count is lower and voltage higher for the same power level increasing both battery life and charge efficiency.
A couple ofgood articles on charging.
https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
https://www.microchip.com/stellent/groups/designcenter_sg/documents/market_communication/en028061.pdf
Again sorryfor combining subjects and being sloppy in what I said I know it cost you time.
Highervoltage is just easier to work with.It is why solar Cells are going to more cells.Why hand tools that started at 3.6 volts are now at 20 volts with some newer tools at 56, 60 and now 120 volts DC.It is why industrial motors stop using 120 volts AC at 2 HP, 240 AC at 5 HP and 3 phase 480 over that.Could 48 be made to work? yes it could.Everything is concentrating on higher voltage lower currents.You are fighting the tide going with high current low voltage.When the whole world is asking for SS devices that control high voltageat low currentit is hard to convince manufactures to do allot of work on a low voltage high current device.I find it interesting that AUS and others on this board totally get what changing the primary voltage in a car from 12 to 48 volts will enable. Active suspension, intake air compressor, electric AC, power steering, water circulation and many more, were enabled by a 4x increase in voltage and cutting current by 4x.This applies equally to traction motor systems.It is why Toyota, Honda, GM, Ford, Nisan,Hyundai go up in voltage with every new generation.Only Ram introduced a product with 48 MH. EPA showed zero improvement in fuel economy and RAM withdrew it after a year.
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