Quote:
Originally Posted by goboatingnow
if your starter and house are similar batteries, then a really is fine , otherwise a diode splitter is better. |
Split Diodes were the first automatic solution but they have a voltage drop of 0.7 volts across each diode, maybe double this at high charge currents. This causes a huge power loss, but this loss can be compensated for by having regulators that sense the
service battery voltage and boost the
charger output. This can produce the right voltage at the
service battery but can produce too high a voltage on the starter battery. Consider a heavily depleted large service bank - and an almost full smaller starter battery. The voltage drop across the diode feeding the service bank increases with the
current so may well reach 1.4 volts or more. The
alternator senses the voltage at the bank and ups the output by 1.4 volts to say 15.8 volts. The voltage drop across the diode feeding the starter bank is only 0.7 volts because the smaller service bank is taking a much smaller
current. So the starter bank is sitting at 15.1 volts for maybe several hours! This is almost an equalizing charge - so not very good for any sealed, Gel, and
AGM batteries.
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