What is a battery isolator?
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What is a battery isolator?
I've used them on commercial vessels we built for the oil patch. It's a selecter switch you use to change from one battery to another, or to change from 12v to 24v. I never installed them on small fishing boats, but that doesn't mean they won't work on a fishing boat.
I use one on my boat to isolate my starting battery from the one I use for accessories. When the motor is charging it allows the accessory battery to charge, but when your not running, it isolates the starting battery to keep the accessories from draining the starting battery.
A battery isolator is an electrical device that divides direct current (DC) into multiple branches and only allows current in one direction in each branch. The primary benefit of such an arrangement is the ability to simultaneously charge more than one battery from a single power source (e.g., an alternator) without connecting the battery terminals together in parallel. This is beneficial because a weak or dead battery will drain the charge from a strong battery if both are connected directly together. The disadvantage to an isolator is added cost and complexity, and if a diode-type isolator is used (which is very common) there is additional voltage drop in the circuit between the charging source and the batteries.
Battery isolators are commonly used on recreational vehicles, boats, utility vehicles, airplanes, and large trucks where one battery is dedicated to starting and running the engine and another battery or batteries run accessory loads (e.g., winches, radar, instruments, etc.). A battery isolator helps to ensure that the starting battery has sufficient power to start the engine and recharge the batteries if, for example, loads on the auxiliary battery (e.g., refrigerator or navigation lights) cause it to be drained, or if an auxiliary battery fails. Isolators are also used in vehicles with large, high-power car stereos requiring multiple batteries.
Several technologies have been used to achieve control of DC in this manner: silicon rectifier[1] packages, Schottky rectifier packages, MOSFET rectifier packages, and conventional mechanical relays
I'm not an electrical engineer... But looks like you found your answer..
Man, I'm highly impressed FWB. I saw one for sale on Craig's list and was wondering what it was and how it works. Thanks for your help.