On 11/07/2019 10:09, Daniel60 wrote:
Xeno wrote on 22/06/2019 9:03 PM:
On 22/6/19 8:00 pm, Brian Gaff wrote:
Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know and

A 12 Volt lead acid battery will show 13.2 volts straight off the
charger, about 2.2 volts per cell. That will drop to about 12.7 volts
after a day or so, a tad over 2.1 volts per cell.

On the other hand, a vehicle's nominal *system voltage* is 14 Volts.
That's because the *alternator typically operates in the 13.8-14.2 range.

Due to increasing loads on vehicle electrical equipment, manufacturers
were pushing to a nominal 42 Volt electrical system on cars. They were
to be equipped with a 36 Volt battery. It may not happen now.
https://en.wikipedia.org/wiki/42-volt_electrical_system

Do Electric Cars have a 'standard' operating voltage?? Or does it vary
from one manufacturer to another??


There would be no reason to have a standard voltage - standard charge
voltage, yes. 230 single phase or 400 three phase (same thing)

A far as battery voltages go - looking at say 200bhp (around 260Kw) is
around 660A at 400V.

which is still a lot of amps. I'd say the ideal is probably near the
limit of *cheap* semiconductor power FETS probably around 1kv or so.

I am a long time out of that field though, so it may be higher.

What I am fairly sure of however is that battery voltage will be decided
by cost of using that particular voltage and that will be down to what
semiconductors are available.

Should the market develop towards standardised batteries that could be
replaced by a local kwikfit etc, then I am sure manufacturers would
develop a common standard.


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