Smart Charger - Battery / Inverter Connections

[Ammonite]

I currently have 2 x 12v 110 ah batteries in parallel in the domestic bank and 1 x 12v 55 ah as a starter battery. I also have a Waeco iu252a 25 amp charger with 3 outlets (one for the starter battery and two higher rated ones). At the moment each domestic battery has it's own supply from the charger.

Is this pointless given the domestic batteries are wired in parallel or is there any reason for keeping it this way? The batteries are roughly 2 metres away from the charger and each one is connected with 16mm2 cable.

I only realised this when looking to wire in a 300w (max 600w) pure sine wave inverter. I was planning to tap into the positive and negative charger cables feeding the domestic bank (along with a suitably rated fuse and isolator) as VicS had suggested earlier - at which point I discovered there are two 16mm2 positive cables to choose from! The inverter will not be connected to the existing shore power circuits.

Just pondering the best way of tidying this up? I already have the inverter, 12v isolator and midi fuse.

 

[nigelmercier]

Leave it as it is.

 

[William_H]

So you have 2 outlets from a charger connected to 2 batteries which are paralleled at the batteries. If you take the +ve for the inverter from one of the charger wires you will get the volt drop of that one wire. If however you also parallel the charger wires at the charger you will be using 2 wires in parallel hence less volt drop.

Having a 3 outlet charger with 2 for 2 batteries I would suggest a better option might be to fit a 1,2,both switch for the domestic batteries. This would allow that the 2 domestic batteries are charged individually with switch off. It also means you can discharge them in parallel anormal arrangement but also that you can discharge each individually so comparing performance when and if they start to get old. Good batteries are fine in parallel but if and when one or both get old they tend to drag one another down both on charge and discharge. You will probably end up really exercising these batteries when driving an inverter. If you fit a off,1,2,both switch then feed the inverter via a fuse from the centre contact witha heavy wire. (not the charger wire) good luck olewill