dgadee
Well-Known Member
Having to buy two new house batteries, I fear. A friend says he never connects his together as when one starts to go it destroys the other and you need to buy two rather than one.
Is he correct?
Is he correct?
Parallel or divide house battery bank
- Thread starter dgadee
- Start date
lpdsn
Well-Known Member
How does he use them then?
If they're the same age and type one shouldn't go significantly earlier. My two 2 X 180Ah are still getting by reasonably well at 9 years old. Bit unreasonable of me to expect many more years yet, but so far so good. A cell went in one of the batteries of the previous set which dragged the other down but they were either 11 or 16 years old and I suspect they'd been badly abused by a PO or two.
If they're the same age and type one shouldn't go significantly earlier. My two 2 X 180Ah are still getting by reasonably well at 9 years old. Bit unreasonable of me to expect many more years yet, but so far so good. A cell went in one of the batteries of the previous set which dragged the other down but they were either 11 or 16 years old and I suspect they'd been badly abused by a PO or two.
RichardS
N/A
Indeed. If one wants a battery capacity which is greater than one battery, and the maximum one could have with lead/acid without involving batteries which are too heavy to install without mechanical assistance is around 200Ah, then one has no choice but to connect batteries in parallel.
However, it's an interesting point which has been debated on here before, because I was taught 50 years ago never to connect lead/acid batteries in parallel because of charge/discharge oscillation leading to both batteries being quickly depleted. However, it practice, it is not an issue.
Richard
dgadee
Well-Known Member
Not sure - he is old school and believes in hardship - but maybe one for the cool box and one for everything else. Will ask.
Mine are just 4 years. I have been aboard 4 or 5 months each year, so maybe that's why their life is shorter than the Scot in me would wish.
dgadee
Well-Known Member
He says: "I use them individually, occasionally connect all when solar is producing excess."
PaulRainbow
Well-Known Member
If the two batteries are correctly connected in parallel they will be subjected to the exact same charge/discharge cycles, so there is no technical reason why one would last longer than the other, so of course they will both fail at about the same time. That's due to sharing the same pattern of use, not because one has killed the other. There are certain failure conditions, where a battery that has prematurely failed, where that battery will drain the other battery, but not necessarily leading to it's failure, just a flat battery.
Millions of boats have batteries in parallel, as do millions of road vehicles. No reason not to. But it is important to wire them correctly.
<152587>
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When doing harbour movements on cathedral engines with air start the air receivers are always divided for the reason of having a full capacity in reserve. I always treat batts with the same procedeure.
PaulRainbow
Well-Known Member
As we are not using our house batteries to start our engines, it's perfectly normal to run the batteries as a single bank, in parallel.
lpdsn
Well-Known Member
Indeed, they are the full capacity in reserve. Mine are >6 X the starter battery capacity.
PaulRainbow
Well-Known Member
I recently rewired a 60ft classic "gentlemans motor yacht", she had 8 batteries (excluding the genny battery). Wonder what the switching arrangement for that would have looked like with all the batteries separate. Be interesting getting them all charged up too. Maybe i could invent a 1-2-3-4-5-6-7-8-All switch
lpdsn
Well-Known Member
Maybe i could invent a 1-2-3-4-5-6-7-8-All switch
Or a 1-2-3-4-5-6-7-8-Few-Some-Lots-All-MaybeMost switch.
