Domestic Battery replacement

[risingsun]

I have a 2015 Jeanneau 50DS which has 4 dealer installed Exide ER550 Deep Cycle (115Ah), 12v, Wet batteries, Wh550, Capacity (C20) 115Ah, CCA (EN) 76A.  3 of the batteries test as good, 1 as weak.  Can I replace just the one weak battery and if so, can it be a different brand as long as it is of the same type, dimensions, etc. ?   

[Don Reaves]

You could, but you probably shouldn't. If you have a 5-year old battery that's gone bad, the rest will probably follow shortly. It would be false economy to avoid replacing them all.

When you have batteries in a parallel (or series-parallel) combination, it's important that the batteries match. The best way to do that is to buy them all at the same time (check the manufacturing dates).

[risingsun]

Thanks again Don.  That's the same advice I received from the dealer.  Looks like it's all or nothing. 

[fakinx]

There is also an option to just disconnect bad battery and go with the rest. There is always better to have 3 good batteries than 4 with one bad. The bad one will ruin rest of the system much faster.
Perhaps there is enough juice in good ones to last for a seasson or two. If not you can always exchange for new.
I would seriously consider LiFePO4 for replacement (if in your shoes).

[risingsun]

Thanks.  Will check those out.

[Maravilla]

Also consider FireFly batteries.  They are more of a drop in replacement with significantly better performance than flooded lead acid.  They don’t require so much of a system-level upgrade like going to lithium does.

[zaphod]

Jun 28, 2020 19:58:01 GMT Maravilla said:

Also consider FireFly batteries.  They are more of a drop in replacement with significantly better performance than flooded lead acid.  They don’t require so much of a system-level upgrade like going to lithium does.

I just ordered 4 Fireflys for my 39i. Moving from flooded cells to AGM would be a good upgrade, and going from AGM to Carbon Foam AGMs is an even better upgrade.

Fireflys can be discharged well beyond 50% without damaging them, they will tolerate being partially charged for long periods without sulphation, and they accept a charge much faster than regular AGM.

They are expensive, but not as expensive as lithium, and they don't require a complete system upgrade like lithium does.

[Bora]

Looking forward to mine arriving, won't be here till mid august though so not sure how much time i'll actually get this season to try them out :-(