VSR vs diodes vs 3-way (1-2-both-off) switch.
All do basicly the same thing, allow the isolation of a start battery from the house battery. The 3-way also allows you to start from the house if need be. The VSR and diode method do not without additional switches/cables.
VSR and diodes do not requrie human intervention, 3-way do
VSRs cost you a small amount of current to operatie them
Diodes cost yo a small amount of voltage to operate them
VSR and diodes can leave you high and dry with out warning
I do not know of a 3-way that has ever failed
the current needed by the VSR is ignorable as you will have to have a charging source turned on to even get them to work
The voltage needed by diodes is important (1ish volts) so it pays to understand how your regulator is getting its voltage info, before or after the diode (after is recomended)
combining batteries or getting the house bank to start the engines is more complicated with VSR and diodes, with a 3-way it is brainless and easy
The cost is about the same for all these systems.
Bill,
Unless I read it wrong it appears the OP already has a 1/2/BOTH/OFF switch and intends on adding an ACR or voltage sensitive relay to it? I install VSR's with 1/2/BOTH/OFF switches quite often and it is a great option. They are not exclusive of a 1/2/BOTH/OFF and make a great addition to one.. I am actually installing an ACR tomorrow on an older Ericson along with a new charger, dedicated reserve battery and re-wiring the alternator and battery system...
I don't know any marine electricians that currently install diode isolators due to the numerous obstacles associated with installing them. Many chargers and solar regulators these days need to see a voltage to even turn on. Most diode isolators have no voltage at the "input" lug when not actively charging making turning on of the charger or controller a difficult feat. Some chargers do have a sense wire but I have yet to find a decent solar controller that does and here in Maine we have LOTS of moorings and lots of supplementary solar.
I was at Hamilton this morning and asked the electrical aisle guy to search the system for the last time they even sold a diode isolator...2007! They still have two very, very dusty ones on the shelf that look to be about 6+ years old. ACR's on the other hand fly off the shelves. I have also yet to see a failure of an ACR except for one or two Pathmakers which were discontinued. They are very reliable and if installed with a 1/2/BOTH/OFF switch you can always still use the switch in the event of a failure. There are many boats out there with diode isolators and many of them are installed incorrectly and the batteries suffer a voltage drop and under charge as a result. An ACR or an Echo Charger can easily be installed with solar or an alternator or charger without a sense wire, a diode isolator should not be installed without sensing the battery.
For charging of a start bank these days the Echo Charger or an ACR are the two most popular choices. It's seems nearly everyone is now in the VSR game including Blue Seas, Victron, Sterling, BEP, Yandina and more. I tend to install the Yandina's or the Blue Sea's units but do more Blue Sea than anything else as Hamilton stocks them and they are less money than the Yandina nad have heavier lugs and a very robust case.. The Victron is inexpensive, under $50.00, but I am not crazy about the way it wires up so usually spend the extra $20.00 on the Blue Sea ACR..
