LOVE, LOVE, LOVE my new blue seas add-a-battery combo

[StephenD]

It's a blue seas item, maybe $135-150: essentially a battery switch completely segregating the start and house side plus a combiner relay to charge both sides when the alternator is spinning (or solar/wind generator is charging) . All good, but why so damn happy about it? Well, first I'll never accidentally run my start battery down and be stranded, but truly the best part is when I'm ready to fire up I just switch the main battery switch ON, and when I'm done I just turn it OFF. That's it-nothing else to do! I leave the individual electronics and items I usually use switched on on the main DC panel, and never have to think about any of it, nor remember to switch to both/2/1 when motoring, etc. It has simplified things to the degree that I can even ask guests to switch the battery main switch for me if I'm busy (mixing daiquiris or whatever). There is virtually nothing to think about or remember-It's as if they had me in mind when they designed it!
(there's a small issue if one is using a multi-bank smart charger in port- but easily remedied for about $10)

 

[jssailem]

Good for you. It is wonderful to hear a happy boat owner.

 

[Don S/V ILLusion]

It's a blue seas item, maybe $135-150: essentially a battery switch completely segregating the start and house side plus a combiner relay to charge both sides when the alternator is spinning (or solar/wind generator is charging) .

Would you or anyone else elaborate- specifically what does this do different from a one-both ACR switch?

 

[StephenD]

I think the difference is besides the acr the possibility of running both batteries down concurrently in both mode is nil. Conceptually its easier for me to understand, and when I switch it back to off it let's the smarts in my charger do their thing.
Ideally Don Casey described the best configuration, which is discrete switches for each battery bank, plus a bridging switch for 3 total.
Then you can power either side with either bank, while excluding the dead one. But I digress....

 

[jdrutten]

Would you or anyone else elaborate- specifically what does this do different from a one-both ACR switch?

From the Blue Sea webpage, it looks like the switch is essentially a house bank on/off switch with the option of combining with a starting bank in an emergency. Similar to a 1-2-both switch, but you can't use the starting battery for house loads without combining with the house battery. So you might be able to call it a 1-both switch. The two banks are otherwise isolated except for the ACR which of course allows both banks to be simultaneously charged.
Edit: Sorry Don, as I re-read your question I'm not sure I actually answered anything that wasn't already implied in your question.

 

[Don S/V ILLusion]

From the Blue Sea webpage, it looks like the switch is essentially a house bank on/off switch with the option of combining with a starting bank in an emergency. Similar to a 1-2-both switch, but you can't use the starting battery for house loads without combining with the house battery. So you might be able to call it a 1-both switch. The two banks are otherwise isolated except for the ACR which of course allows both banks to be simultaneously charged.
Edit: Sorry Don, as I re-read your question I'm not sure I actually answered anything that wasn't already implied in your question.

No problem. You actually confirmed what I thought.

 

[Stu Jackson]

The very LAST thing you want to do is to combine a bad bank with a good one. That is ALL this switch can do.

To remedy its limited abilities compared to a 1-2-B switch, here's how to do it and why:

How to properly wire & switch a DCP switch - Maine Sail's "workaround" explained Replies #28 & 29
What size fuse for automatic charging relay?

Maine Sail's DCP Wiring Diagram
Operating the House/Start battery selector

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries