Battery Bank Configuration.

[SiteSurfer]

I'm at the point where I need to replace the battery bank on the n2me boat and having seen this thread http://www.ybw.com/forums/showthread.php?509374-Hot-Batteries which is in fact exactly why I need to do this - of the 2 140 aH batteries, one of them is getting very warm when charging using the CTEK 200 charger. It's also clearly dragging the other down as each time I have been (with 7 days in between) with no usage, the bank has slipped in its capacity.

Preamble over:

Currently the bank comprises of 2 of these:


The perceived wisdom is that AGM is 'better' but given our expected usage (usually 3 or 4 days between marinas on a max 3 week holiday, normally less) - I see no particular reason why this deal isn't worth pursuing:

Normal Wet Leisure : £280 https://advancedbatterysupplies.co.uk/product/pair-abs-l140-140ah-leisure-battery-copy/

AGM version: £445 https://advancedbatterysupplies.co.uk/product/pair-of-agm-140-leisure-batteries-140ah/

I presume that I am far better off replacing both rather than one at a time?

My other consideration, having perused the thread above is whether its is a better idea when cabling the batteries to have the positive and negative take off for the house power from opposite ends of the banks, at the moment the leads come off one battery and simply spur to the other. My plan would be to have the neg at one end and the positive at the other - sensible or a waste of time?

 

[pvb]

My other consideration, having perused the thread above is whether its is a better idea when cabling the batteries to have the positive and negative take off for the house power from opposite ends of the banks, at the moment the leads come off one battery and simply spur to the other. My plan would be to have the neg at one end and the positive at the other - sensible or a waste of time?


View attachment 73792

Yes, marginally better to take the cables from opposite ends of the bank.

 

[lw395]

Yes, marginally better to take the cables from opposite ends of the bank.

Indeed, it makes a marginal difference.
Unless the wiring is very thin, it's hard to see it as an explanation for one battery to die young.
Do charge and load connections go via the same wires?
I have seen boats with the batteries banked as in the upper picture, with load on one end and charging on the other. Which I could well understand causing issues. But it didn't really, apparently the batteries lasted many seasons.

 

[SiteSurfer]

Yes, its a standard Bavaria wiring set up I think.

I appreciate that it's got to be marginal at best, but every little helps.
I suspect that the major cause of complaint was the Halfords 24V battery charger which was being used...

 

[matthewriches]

Actually quite important to to a tap off each "end" of the batteries when looking at high current draw applications (e.g. electric stabilisers, bow thruster or fishing winches). It is standard practise on all new boats, especially with most high spec boats coming out with AGMs and now lithium ion.

 

[SiteSurfer]

Interestingly, having now had the CTek 200 going at the battery bank for 2 weeks, it seems to have a very positive effect on the bank to the point where both batteries are now stone cold during charging. Looks like their suggestion that the charger can help towards rejuvenating a tired (previously poorly charged) battery holds water.

The voltages are holding much better and whilst I know I'm going to have to replace them at some stage - at least I can get a stay of execution until next year.

 

[Momac]

Looks like their suggestion that the charger can help towards rejuvenating a tired (previously poorly charged) battery holds water.

The voltages are holding much better and whilst I know I'm going to have to replace them at some stage - at least I can get a stay of execution until next year.

I found similar using a similar charger rather than the fixed charger on the boat - no particular explanation. I thing perhaps one poor battery connection can make difference leading to one battery being under charged .