Battery Bank wiring

[Javelin]

Having read a few previous threads on battery wiring it's made me double think about my own set up.

I have 2 banks of 2 110ah batteries with a 12v output plus a smaller high crank battery for the engine.
I've tried and failed to get my head around how they are wired as there are two isolating key switches plus a 1-2-both-off switch.
There's a Sterling split charger that seems to suggest that it charges the engine battery first and then the house batteries, though I'm not at all sure whether I need to have the multi switch on Both for this to happen.

Turning the multi position switch off does shut everything down.
The key type switches are more of an enigma, as they didn't seem to do anything so they might have been bypassed by a previous owner although they appear to be wired up,
As usual the wires all disappear into the nether regions and will be hard to trace without dismantling half the boat.

I thought that maybe I should check here to see what the general advice is on a recommended layout for 2 banks +1 so I can spot the difference before deconstruction.

 

[William_H]

I would imagine the 2 big banks are wired to one position of the "1,2,both/off" switch. They would be wired as is advisable via a separate isolation switch. These isolation switches would not normally be opened but would be useful if you have any doubts about the performance of the big batteries. ie You charge them both with isolation switches closed then isolate one bank. Note how much you can discharge that while monitoring voltage. The isolate that bank and do the same with the other bank. Compare performance. As batteries often fail with just one cell sick you may find you can get better performance using just a good bank. Likewise any doubts about charging ie high charge rate then you can isolate the 2 banks and compare.
Normal charging will be both at once as this will get the max total charge current proably not taxing the alterrnator (or if it does just for a short time).

Regarding charging a clamp type amp meter
Heres one that looks OK and cheap. http://www.banggood.com/UNI-T-UT203...m_content=vera&emst=EzQIH4eJFS_9889_991497_34
or installed amp meters might show how the charger is working ie to which battery. I would imagine that id the charger connects to both engine battery and combined banks with separate leads then it will charge each individually as needed. ie "1,2,both/off " left in the off position.

Lastly of course you will need to put 1,2,both switch to engine battery for start then to both for charging of big bank, then back to house bank for camping overnight etc when batteries will be discharged. A far better arrangement is a VSR between the engine and house batteries so that charging is automatic and so is isolation after charge.
I would move all the doemstic loads (switchboard) to permanent connection to the large battery bank via another isolation switch. So 1,2,both switch only switches engine starting and guages and charge.
good luck olewill

 

[Javelin]

Thanks for that.
If you see a drawing or Diagram of a similar system anywhere I'd love to see it.

Currently I don't have any voltage display other than the one that comes on with the echo sounder and B&G Hornet system but these rarely agree anyway.
I am considering getting a dedicated Voltage meter like a BM1 to keep a better track of the banks condition.

 

[jac]

Not sure if you mean that you have a dedicated engine start plus 4 batteries, split into 2 equal banks that are both used as domestic or some other arrangement.

Nigel Calder goes into some length re this and his advice was that it is better to wire the 2 domestic banks into one big one as it is kinder to the batteries. Discharge to 60% -70% being kinder than discharge to 50% - 60%. If that is the plan then suggest wiring together.

I suspect that the boat originally had 2 separate but equal banks with everything wired via the 1/2/both/off switch. As best practise has moved on, it sounds as if the split charger (basically just a VSR ) and dedicated engine start have been installed.

I know it's a pain but I would suggest removing the 1/2/both/off, wiring the 2 domestic banks into 1 then use one isolator for the engine start and another for the domestic. Make sure that only the engine starter (plus anything purely engine related etc) is on engine start and domestic for anything else. Add in a separate isolator to allow the domestic to be used to start the engine when required when all else fails.

Took me weeks to work out how mine was wired and rewire but worth doing in the end.