"Larry" wrote in message
...

Any charging system must have a series resistance to limit charging
current on initial charge. This resistance drops the excess voltage
between the battery's voltage at whatever state of charge it's in, what
the voltmeter in the dash reads, and the charger's natural design
voltage, which is around 18 volts for 12V alternators to make the
charging stable up to 15VDC, giving the regulator something to control.
(Your solar panel chargers run 18V loaded to spec and up to 28V sitting
in the sun totally unloaded. Their internal resistor is the silicon...
(major snippage)

Wow! That was a great post, Larry. Thanks!

Ummm..."MTBF"? Something do do with planned failure from context, but could
you elucidate?