New battery advice, please...

Tranona said:
You can achieve exactly the same thing with a paralleling switch as suggested earlier. There is no benefit of a 1,2 both if you have two clearly separate banks and split charge.
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If you have a completely dud battery, a 12B allows you to isolate it completely and to run everything from the good one. You can't do that with the dual-circuit + parallel switch I use, which is one reason why I have breakers for each bank as well. Not an issue with the cluster mentioned, but it's easier to mismanage, having three switches instead of one.

Ultimately, though, none of this matters in the least.
 
We used to have two 110ah batteries, one for starting and one for domestic. Then I fitted a fridge and it was a struggle. So I made the two into one big domestic and bought a small 78ah big kicker for a starter. I can now run the fridge for more than two days without being plugged in. I never put the battery switch on Both. I hard wired the Cetrek type charger into the back of the 12b switch and can charge either by pointing the switch at it. No issues for several years.
 
Thanks to everyone ... plenty to ponder there.

At the moment, we're ashore, incurring higher fees than on our summer mooring, and I'm keen to get afloat again.

So, for now, I've ordered a couple of cheapish Numax 105 AH replacements.

Fancier upgrades can wait a few weeks (till I've read more by that geezer Voltaire, who I assume, invented volts ........ yes, yes, that's a (weak) joke, honest).
 
I have just replaced my 2 no Numax 110 a/h batteries after 9 years service and they were still holding 12.7 volts over the winter although I do charge them once a month or so. I have replaced them with the same Numax batteries which are shown as 105 a/h now. I have a 1/2/3 switch which has served me well, and I have had them on my boats for the last 20 years . I tried a VSR but it kept “hunting” as evidently there was a problem with my low a/h Red Flash starter battery compared with my 220 a/h domestic bank. I always start my engine on the Red Flash AGM and after about 15 or 20 minutes switch over to my domestic bank . I find that I leave my batteries on the domestic bank as they start the engine well when it is warm so I don’t have to go down below to switch over again. I hope these Numaxs last as long as the previous ones
 
Just yesterday, a yacht from the marina here was stuck in an anchorage, unable to start his engine because he'd left the 1-2-B switch on "Both".

To the OP....

If you fitted a small engine battery and connected the two leisure batteries in parallel, you double your domestic capacity for little cost. A split charge system (even with the 1-2-B switch) means you don't ever get tempted to switch to "Both" when charging or have to faff around changing back and forth between batteries. Vics diode suggestion would work, or a VSR. I do often suggest a VSR because they are inexpensive and they work. They are ideal for many of the boats we discuss on here, but it's not the only thing i use, i also like the Victron FET based devices.

Solar is a very cost effective power solution these days. It doesn't take a massive amount of money or panels to become self sufficient. Good quality panels and controllers make sense to me. They are a long term investment (i still have a pair of 30w panels that were fitted in 1988), so cheap and nasty don't really work out good value if they don't last a long time.
 
Thanks Paul.

I think more sophistication will soon be on the agenda, though I've never had any problems, or noticeable faffing, with 1,2, B switches (indeed, changing the system seems far more like faffing to me).
 
JumbleDuck said:
Just as bad as if he'd left his bridging switch closed, then.
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With a proper design he'd need to leave both his engine battery switch and 'bridging' switch closed. I hide the third key necessary to do that so it would be a very deliberate act to link all the batteries together. Would be a bit desperate if a 360Ah domestic bank failed to start the engine after I'd given up on the starter battery.
 
JumbleDuck said:
Just as bad as if he'd left his bridging switch closed, then.
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Exactly the same. Same as you leaving the BlueSea switch set to combine.

Differences are, you never leave the switch on combine and bridging switches don't get left on, because there is no need to switch them to those positions, except in case of emergency. A lot of people leave 1-2-B switches on "Both", because that's how they charge both batteries at once.
 
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