Battery confusion

[Gregorys6601]

I have a couple of questions regarding batteries - hope to get some help.
I have three battery banks - see included photo.
The Port engine and Generator Batteries has a starting battery and a deep cycle battery.
The forward battery bank (one center right) has a starting battery and a deep cycle battery.
The center left has two deep cycle batteries.
I do not have the Inverter battery option.

It doesn't make sense to me to have a deep cycle and starter battery connected together. That battery should simply be the starter battery for teh starboard engine and the other set the starter for port engine and generator.

The third set of batteries would be the house batteries (should be all deep cycle). Did whoever I bought this boat from not know what the heck they were doing or am I off base here?

This is on a 1999 Maxum 4100 SCA with twin 330 Cummins and a Westerbeke generator.

Thanks in advance!
Scott

[smac999]

no pictures posted

if batteries are connected together they should be indenticle. in brand / type / date.

yes you should have starting batteries for the engines and gen. and deep cycle for the house.

unusual to have more then one battery for the engines. unless they are really big.

normally you'd have one battery for port, one for stb. not banks of them. and a bank for house

[ranger58sb]

Yep, sounds like worth a second look... or three.

First probably useful to pin down which bank really does what. It's not uncommon in that style of boat to have dual-purpose banks which start one engine and run approx. half the house. IOW, you may or may not really have a dedicated "house" bank. And then sometimes a genset has it's own starter, or is serviced by another bank. Once you can say for sure what's what it'll be easier to help you get to where you want to be.

Doesn't take all that much to start your diesels; maybe a good Group 31 apiece with serious cranking amps. Or two G31s each, if necessary; that wouldn't be unusual. You can look up minimum required cranking amps in your Cummins documentation. And then also look to see if you have a paralleling switch at the helm; that'd be useful to know, also.

Genset starter can be a whole separate one-battery bank (G34 is usually large enough) or maybe it can piggy-back on on one of the engine banks. And maybe that's what your port engine/genset bank is about. And then your "forward/center bank is for the starboard engine?

Then if you do have a dedicated house bank -- your "center/left" bank? -- that'd be where deep cycle batteries are better.

Anyway, just some initial comments. It'll take knowing more about your system to home in a bit closer... Might just be you need decent start batteries for your "port/generator" and "forward/right" banks. IOW, could be it's close, just needs a bit of tweaking.

-Chris

[Gregorys6601]

Here is the photo I think....

[ranger58sb]

Pic seems a bit weird. Port engine battery and optional gen battery located on the starboard side of the boat? Where is the generator physically located? Where would the optional invert have been located?

I'd start tracing wiring, were it me, maybe do some disconnecting if necessary to see what stops working when.

-Chris

[Gregorys6601]

Here is what my owners manual says.
Scott

[Gregorys6601]

Here is what my owners manual says

[Gregorys6601]

The generator is center aft of the two engines. It didn't make a lot of sense to me to have the port starting engine on the starboard side either. I will do my best to trace the wires. You know they give a guy so much room to work on this stuff (said sarcastically!)
Thanks again!
Scott

[smac999]

so from the factory, all the house loads came off the stb engine battery. and you would have only had 2 banks.

you're going to have to trace it all out. who knows what's been done.

[Colin A]

Looks like one engine and Gen are tied to one battery. The other engine and house are tied together ( looks like with 2 batteries in parallel) . So only the STBD batt charges the house and only the port starts the Gen. (unless paralleled which based on the description is likely via a solenoid or contactor controlled at the helm).
Pretty simple system but not the most ideal.
I can see the appeal to this system it's simple to setup uses simple on-off switches and should work fine in many use cases. If you kill the STBD bank running house loads you can still crank the Gen or Port Eng and parallel to start the STBD.
I would prefer a separate house bank with automatic charge combiners myself.

[smac999]

from the factory yes. he now claims he has 3 banks. so the manual can be thrown in the garbage. and all the wires need to be traced. sounds like people have changed things and added a house.

Originally Posted by Colin A

Looks like one engine and Gen are tied to one battery. The other engine and house are tied together ( looks like with 2 batteries in parallel) . So only the STBD batt charges the house and only the port starts the Gen. (unless paralleled which based on the description is likely via a solenoid or contactor controlled at the helm).

[Colin A]

Originally Posted by smac999

from the factory yes. he now claims he has 3 banks. so the manual can be thrown in the garbage. and all the wires need to be traced. sounds like people have changed things and added a house.

Yeah just reread the first entry. Yep wire chasing time.

[boatpoker]

No one can help you from that those photos. The chances that the boat is still wired as from the factory are slim anyway. You need to create a new schematic.