Pacemaker Boats

[merwin10]

I am writing this because there has been some that have asked about house batteries and starting batteries! Also there have been other that complained about spiking there electronics when starting the engine. This dual battery setup addresses both of these issues. To be sure low voltage spiking will effect the expected life of your electronics and can cause harm -

There is a separate staring battery with a disconnect switch and there is a separate house battery with a disconnect switch, both of these switches are normally close during operation. Only reason to turn them off is to disconnect the power to either the engine or the house. The third switch is a parallel switch used to connect both batteries together for emergency start, so this switch is normally open.

The trick to the isolation of the batteries is the voltage sense switch. How this works is that it senses the voltage of the batteries when the engine battery is charging the switch closes and charges the house battery also. Once the house battery is fully charge or the engine battery is no longer being charged the switch opens. There is also a diode (one way electric valve, in this case engine to house battery not the other way around) that prevents the house battery from feeding the engine battery. The switch is programmable to cut in and out at specific voltages. The switch won’t close till it sees 13.7 volts (alternator charge voltage) or more on the engine battery and opens when it sees 12.5 volts or less. So what this means is that all the electronics are on the house battery are totally isolated and won’t see the spike when the engine starts.

The one other part of this design is that there is a separate source off of the house battery for the bilge pump and any electronics that require memory voltage (GPS, Radios, CO, smoke detectors). These items are isolated from ever being shut off by one of the main switches. The only way to turn them off is to flip the individual circuit breakers for the units. Why this is done is for safety!

The house battery is the source for the panel and the panel is the source for all the electronics. I that way you have isolation and a steady (non – spiking source) 12 volt source.

Here is the schematic of the circuit and a picture of the switches and voltage sense switch:






If you have any questions please post them!

Mike - Thinking
_________________
"Best part of Boating -- is the people you meet"

[rebait]

Mike,

Thanks for the info. This is definitely the way we should all be wired. Next season the Wahoo's wiring is being upgraded, ( Engine this year ). I may go with 2 starting batteries along with a deep cycle house battery. Presently it has 2 batteries that are wired as starting and accy. batteries.


John