Re: Single Engine OMC V8 Three Batteries and Isolator
This is a rather old thread, and Marc has posted only one time. But for the sake of on-lookers, here's my two cents.
The MBSS (main battery selector switch..... aka 1/ALL/2/OFF) poses no issues when selecting between battery banks while the engine is running.
Passing through the "OFF" position is what may damage an alternator, if the MBSS does not provide "alternator field protection".
Many today do not offer this!
So yes..... whether we have an MBSS or a BS, we should not be passing through OFF during engine operation!
Switching banks ONLY is a non-issue, as most of these MBSS's are "Make-before-Break" type contacts!
Isolators are old school technology by today's standards!
There will be an inherant .7 +/- voltage drop throuh an isolator.
Instead, we should be using ACR's or VSR's in their place.
Whe/if we use a multi-bank O/B Charger, the two bank charing (while on S/P or Generator) becomes a non-issue.
ACR's or VSR's also help in this area.
Ditto Bill re; two banks, rather than three, and in particular if an Inverter is to be used.
Inverters are power hungry, and are not very efficient at what they do.
No need for three banks, IMO.
Keep your #2 HLBB as large as possible.
This ensures that the % of discharge is less than that of a smaller bank would be, given the same load/duration.
It will be the % of discharge, the duration left in this SOD, and how soon the bank is re-charged............, that makes or breaks battery longevity!
Better yet, make the #2 HLBB (house load batt bank) 6 volt deep cycle batteries (in series/groups of two) and increase the Amp Hour capacity.
Rick ... aka Ricardo
28' SDN F/B w/ twin Volvo Penta 5.7L DP's