Third battery-gctid398168

[mrbigsea]

I am wanting to add a third battery. It will be the house battery ( deep cycle) so I need to figure out where the leads are for the frig and lights, so I can disconnect them from the two starting batteries.

I know the 305 are similar to the maxum 3000......

Any ideas where to start looking?

Thanks for all suggestions...

Roger:arr

[2850Bounty]

Roger.... Food for Thought:

When we increase our HLBB capacity (rather than add another separate battery bank), we gain the advantage of the now larger HLBB that offers a less likelihood of being drawing down below the 50% SOD range.

Whereas if we make two HLBBs, each bank has a greater potential of being drawn down well below the 50% SOD range.

This is what either extends or shortens battery longevity.

I'd increase the capacity of your existing HLBB, rather than add another one.

Do this, and you won't need to alter your charge system, nor alter any power to the house load side of your system.

.

[Guest]

I kind of agree with Rick that adding a third battery is more likely to cause problems than help.

What I would suggest is to completely isolate your starting battery with a Master switch. Just make sure you have charging wired properly and maybe add an ACR (blueseas) or combiner (Yandina), they are both the same device just different names.

One size 29 or 31 will easily start both engines and for a house bank I would suggest a set of true high capacity 6 volt deep cycle batteries in series.

I have one size 31 to start both engines and 4 - 250 ah golf carts. If I conserve (which I don't) I could last days but as it is my at anchor house draw with computers, frig, lights, etc. is around 10 AH. I drop this to less than 3 ah at night.

By redoing your battery setup you don't get into trying to track wiring in very difficult places.

Just a suggestion!

[mrbigsea]

I couldn't agreed more! But I have two starting batteries that are that are wired to each engine seperately. All I want to do is to get the main 12 volt lead for the frig and lights that is somewhere attached to one of the starting batteries or isolater and attach them to a deep cycle battery that is seperate of the starting battery.

Yes it is sounding like that will be the hard way so instead follow your advise and just buy two bigger batteries.Would you get two deep cycles or stay with starting batteries if I'm to leave well enough alone and go the easy route?

Thanks

Roger

[JimMc]

Roger

As my 305 was originally wired and the switches marked I had one start battery for each engine. In fact one of these was also the house battery.

So it might be worth a bit of investigation to determine how it is really setup. Do you have a wiring diagram?

[2850Bounty]

Roger, both Doug Mcburney and myself (and perhaps several more) crank our Stbd engines from our large HLBB of 6 volt deep cycles.

No issues what-so-ever.

If you were to install an ACR or VSR, you can accommodate your engine alternator charging....

Or..... add the heavy amperage version, and have auto-combining during engine cranking (taking the load from the HLBB).

You can do this arrangement, and not have to separate out house loads from engine harness loads, making this much more simple.

"Simple" does not necessarily mean a "compromise!"

IMO, to do as you propose, does pose some compromise and potential complex issues.

KIS.... Keep It Simple!

1 cranking bank per engine......... and 1 HLBB on #2 of the Stbd side MBSS.

Or.....

1 cranking bank per both engines..... and 1 HLBB on Stbd side MBSS.

.

[mrbigsea]

Jim.... I think you have made the best point and that is for me to figure out the wiring from batteries to isolaters and so forth and go from there. Both isolaters are on both ( or 2) all the time , which I never thought that was right.

A days work in which I have put off since I bought the boat 5 years ago.

K.I.S.S. is something I like to keep in my life at all times.

Thanks for all the responses!

Roger