Separating House and Start/Windlass cicuits

[phill_nz]

i was going to work out something like this

but by the time i had worked out the price and assembly of all the balance chargers and components required along with some redundancy safeties

i figured it was easier to just put in an adjustable voltage cut off .. voltage adjustable from 10.5 - 12 v settable voltage ( i have mine set to just over 11 )

when it hits 11.2 volts everything cuts off  i can reset it and have enough left to restart the engine even when its being a bitch .. i also have a pull cord for those it just wants to fuk with me days

 

[Mark Morwood]

I personally think you should aim to simplify your whole setup. Your's is already sufficiently complicated by the separate windlass battery that it requires more electrical knowledge than you (or most boat owners) have to understand in detail what is happening. As has been pointed out above, if your boat is actually wired as you drew there would have been some big sparks when you connected the battery.

As boats get more than one charging source and multiple loads, it can really help to think separately about the charging side and the load side. One approach that is quite popular with cruising boats with a large house bank is as follows (modified to include your windlass battery):

Charging:

 - all charging sources are connected to the house bank. For best results if you are changing to LiFePo4 you will need to check and adjust all your charging sources regulation

 - start battery is connected to a DC to DC regulator/charger from the house battery - it gets charged whenever the house battery is being charged

- windlass battery is setup the same as the start battery with its own DC to DC regulator/charger. This assumes your windlass battery can run the windlass without the alternator also providing current

Loads:

 - house loads are connected to house battery with an on/off switch

 - starter is connected to starter battery with an on/off switch

 - windlass is connected to windlass battery with an on/off switch

 - for emergencies where you have somehow managed to discharge the engine battery or the windlass battery, add a bridging on/off switch that allows you to parallel the start and windlass batteries

 - I'm not certain if you can also safely add an on/off paralleling switch between the house LiFePO4 bank and your starter battery as an additional backup or if you would be better just using a A/B battery switch to connect the starter either to the starter battery or to the house bank for emergencies. The issue is the different chemistries - I believe it is fine to parallel them in these circumstances - but check.

To get the details right, you will need someone to help you design and layout the whole system, but the above is one strategy you could take.