Voltage Transients in a Marine Battery System

In this video I'm walking through the very typical, though not necessarily ideal, marine battery system which utilizes the 1, BOTH, 2, OFF battery switch for bank charge selection and bank use selection. With this switch configuration the battery bank selected via the switch serves as both house and starting bank and the bank which gets charged.
Starter motors are just one example of devices that can create a voltage transient so where you connect your DC panel loads, to the bank, matters and can greatly minimize the potential for transients.
By connecting the loads or equipment closer to the engine or tapping into a negative near the engine or positive lead near the engine you increase the potential for equipment seeing a transient.
In well wired boats I rarely measure transients above 14V - 15V but when boats have been wired haphazardly I can measure spikes upwards of 25V+. Just because you find a live 12V feeder near the engine does not mean you should simply tap into it to power that new depth sounder..
It is important to recognize that the act of using a dedicated starting battery does not absolve your house bank of the risk of voltage transients because starter motors are not the only potential source of transients.

[@cordelmar]

Good video showing that you know electrical systems on boats, so i wanted to ask you can you recommend a switch that can connect two engine battery's on one setting and can connect a Blue Sea Battery Link Automatic Charging Relay for four 6volt House batterys.

[@Ian-ke6wx]

Good video. How come the 300amp fuse doesn't blow on the starter battery when you pull 360+ amps through it?

[@MarineHowTo]

TripDelay curves answer this. They are on the BlueSea Systems we site..

[@Ender_Wiggin]

Man i want that fluke