Why do I have 3 charging relays?

[alexkom]

Hello, I am a bit puzzled with how my Cutwater 30cb 2019 is wired.

I have 3 charging relays, but cannot understand why 3? 2 would make sense (also manual has 2 in the diagram). 1 to bridge between starter and thruster battery and 1 to bridge between starter and house. But what another one is for?

It is NW edition with AGM package (4 house batteries).

Would appreciate if anyone knows or any guesses?

 

[Jesperjo]

Just a guess, because that is weird, but is it one each between the engine, bow thruster, stern thruster, bridging to the house?

 

[alexkom]

Yeah, that is a thought I had for a moment as well, since it is like 3 charging relays and 3 switches, right?

But my boat (and probably all cutwaters and ranger tugs as well) has only 1 thruster battery. And afaik those switches are not switching charger, only to connect thrusters.

So that guess setup would bridge thruster battery with with starter by two relays at the same time, which does sound strange...

 

[QueenBeeII]

Odd to have 3, unless 1 is dedicated to solar only. I just upgraded my batteries and solar through a reputable marine electrician (2016 R29 w/Volvo 260 D4).and my layout is: engine alternator charge to dedicated engine battery, wired through an ACR to feed the house batteries (4), along with the solar, once proper charge level is met it opens through a second ACR coming off the house and going to a dedicated thruster battery again once charge threshold is reached. Total 1 eng battery, 4 house, 1 thruster all fed by 2 ACR’s originated from the engine battery/alternator providing charge from engine, through house supported by solar and eventually to the thrusters. Note, the House has the added benefit of the solar when off shore power.

 

[fishheadbarandgrill]

Unless FM has changed something , you should have 2 charge relays. One between the house and starter battery and one between the starter and thruster battery.

 

[alexkom]

I should, but I have 3...

Oh well, maybe I will get it disassembled at some point to understand the wiring.

 

[Red Raven]

I should, but I have 3...

Oh well, maybe I will get it disassembled at some point to understand the wiring.

The fact that you have separate thruster battery switches implies to me that you have two thruster batteries, one for each thruster. I would do further checking for a thruster battery up near the bow thruster. I recall some owners discussing adding one there in the past. If so, the additional ACR would make sense to support charging of that battery.

Curt