Diagram for twin engine boat electrics

[Tom Webber]

Our boat is a 1980's steel Dutch motor boat, without any diagrams for electrics or engines, (they are a couple of DAF 675's).
Despite hunting on the web we have not been able to come up with any wiring diagrams other than the simple twin engine, twin battery view.
We would like to have a battery for each engine and a separate bank for domestic use, that is 3 banks in all.
How do you wire this up so that you can charge each bank or all together? We don't want to have a issue if one engine electrics fail.
Just to add to the fun we also need to be able to start the generator.

 

[jfm]

Our boat is a 1980's steel Dutch motor boat, without any diagrams for electrics or engines, (they are a couple of DAF 675's).
Despite hunting on the web we have not been able to come up with any wiring diagrams other than the simple twin engine, twin battery view.
We would like to have a battery for each engine and a separate bank for domestic use, that is 3 banks in all.
How do you wire this up so that you can charge each bank or all together? We don't want to have a issue if one engine electrics fail.
Just to add to the fun we also need to be able to start the generator.

It depends on lots of things including what battery charger you have. Mastervolt (Dutch) chargers these days have 2 slave trickle charge outputs for the 2 engine batteries, and a main output for the house batteries. You might have this if your charger is mastervolt

Failing that look in Mastervolt or Victron catalogues and they have charge splitters that do what you're asking for

With the genset starting you have to make a choice about which battery to use. One of the engine batteries is likely sensible choice. You can have crossover relays so you can make a different choice on occasions if you need to

 

[dpb]

I tried to keep mine simple.
One engine set up with one starter battery
The other engine set up the same.
Domestic bank of two batteries in parallel feeding the domestic circuits.
Two outputs from charger, one to each starter battery.
positive terminals of second starter and domestic batteries linked via voltage sensing diode.

There is also a relay that connects the positive terminals of the starter batteries at the push of a button in case one goes flat.

Doesn't cover everything you ask for I know but thats what I have.

 

[Trundlebug]

It seems to be standard thinking to have one starter battery per engine.

I don't know why. An additional battery can be allocated to the domestic bank by having one starter battery shared for both engines.
My thinking is:
After all, any starter battery can start an engine twice without difficulty, so why not share the starter battery?
If one engine doesn't start straight away, then start the other one (thus recharging all batteries but most importantly in this circumstance the starter battery) then you can persist with trying to start the awkward engine.
And if the starter battery does fail, (e.g. due to end of life or internal short) the system can be set up (as is usual) so the domestics can be bridged across to enable starting from them.
And with one extra domestic in the bank you benefit 99% of the time rather than the 1% when you have a problem.

The only thing you may be limited on is starting both engines simultaneously. But do you really need to do that? Or indeed, do you ever do it?
I always start mine one at a time, so having one starter battery doesn't rob me of anything and benefits the domestic system hugely.

Just my two penneth!

 

[macnorton]

I have two totally independent systems one for each engine, each side has two batteries (four in total) each side has an isolator switch so one battery on each side cannot be discharged when moored.(as long as you turn the isolator)
The domestics are shared between both banks, heating, lighting and Vhf from port and inverter, audio and gps from stbd.
As most of the systems are replicated on 240v (light, heat, fridge tv ect) I don't need constant charging when moored with shorepower.

Seems to work.

 

[bozlite]

Our boat is a 1980's steel Dutch motor boat, without any diagrams for electrics or engines, (they are a couple of DAF 675's).
Despite hunting on the web we have not been able to come up with any wiring diagrams other than the simple twin engine, twin battery view.
We would like to have a battery for each engine and a separate bank for domestic use, that is 3 banks in all.
How do you wire this up so that you can charge each bank or all together? We don't want to have a issue if one engine electrics fail.
Just to add to the fun we also need to be able to start the generator.

Merlin Power produce a good document (http://www.power-store.com/includes/download.asp?docid=3006) which explains - complete with diagrams - how split charging can work with a three bank system. Of course, they're trying to sell you their SmartBank/SmartGuage system, but it's an informative read nonetheless. And a lot of people think their system is a pretty good one.

 

[MYStargazer]

I'm planning just such a twin-engine system.

I recon the first step is not to include a confusing 1-2-off switch, but instead have all battery banks leading to bus bars, in a water-resistant box, with a clear cover, and labelling so you can at-a-glance what's what. Each bank (2 x 12v for my mostly 24v setup) has it's own simple on-switch. It's taken an age to figure out previous owners' spaghetti...

 

[gordmac]

I have a twin engined boat with two batteries, one starts both engines, does the lights, bilge pump etc. The only thing that seems to be attached to the other battery seems to be the port alternator! I wouldn't recommend this setup but at least I have a fully charged battery to start the engines when the starter one is flat which given it does everything does happen, no I didn't wire the boat.

 

[Robg71]

My old sunseeker has two banks. One does just the port side engine. The other does the rest, with a battery combiner solenoid.
I quite like this on a small boat. My domestic and stbd bank is 360 Ah, (2x180 @12volts.
Engine start battery is a single 180Ah.
Since swapping my batteries to these, my charger is not big enough, (wasnt big enough before i changed batteries in reality)
Im considering, when i fit invertor/new charger, to combine all three for domestics,and adding a fourth, smaller, correct type battery forthe engine starting.
On my 36footer, I like the keep it simple approach of just two banks.