Battery Maintenance whilst on shore power.

Nostrodamus

Nostrodamus

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We have just increased our battery bank and had six new trojan deep cycle batteries added.
Obviously these batteries are made for cycling but what about when you are in a marina and hooked up to power for any length of time.
Should they be disconnected from shore power every so often to let them cycle as the shore power seems to keep them topped up all the time?
 
It will be interesting to see how the battery experts reply but my understanding is that it is largely cycling that kills batteries, so keeping them topped up to the maximum is a 'good thing'. In my case my solar panels keep mine at 12.6 volts minimum all day and night and they seem to last very well.
 
My understanding is that lead acid batteries like to be kept topped up. For instance - most motorcyclists will have a battery maintainer plugged into their bikes over the winter to stop the battery committing suicide. A modern charger with an "intelligent" charging profile should keep the batteries charged without over charging them. When I am plugged in, my Sterling charger (OK product, rubbish after sales support) charges up to 14.4v and then drops to a maintenance charge of around 13.3v IIRC. When on my mooring, a couple of solar panels keep them at around 12.8v and they seem to have lasted so far...
 
Nostrodamus said:
We have just increased our battery bank and had six new trojan deep cycle batteries added.
Obviously these batteries are made for cycling but what about when you are in a marina and hooked up to power for any length of time.
Should they be disconnected from shore power every so often to let them cycle as the shore power seems to keep them topped up all the time?
Click to expand...
There's evidence that brand new ones like a bit of work to get them up to full capacity.
Plus lots of info on the trojan site.
 
Except when we are away from our berth (annual fortnight away and probably thirty-five weekends) our Lifeline batteries are constantly on charge. (Victron 70A 4 stage charger which floats at 13.3v). After eight years of this regime I have no encountered no problems as yet (touch wood and fingers crossed).
 
Lead acids love to be fully charged. Providing your charger settles down to maintaining them after reaching full charge at around 13.5V (perhaps a little less if the ambient temp is very high), they'll be happy chaps. I'd suggest you download the User Guide from Trojan's website.
 
GHA said:
There's evidence that brand new ones like a bit of work to get them up to full capacity.
Plus lots of info on the trojan site.
Click to expand...

The evidence you mention relates to the fact that full capacity isn't reached when new, it takes quite a few cycles to get to the quoted capacity. It might be as many as 50 cycles but I can't remember. Once they reach full capacity then they start to slowly lose capacity again over subsequent cycles.

However, each cycle is still using up the expected battery life wrt cycles. So I can't see any reason to discharge them needlessly just to get greater capacity when on shore power at present anyway.

Just set your system up to float them at 13.2V and try to set it for 14.8V (or 2x these values for 24V system) on a normal daily recharge when you are away from shore power.
 
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Someone needs to pickle my brain when I die as it is full of totally useless information no one apart from a pub quiz team will ever need. Unfortunately it is sadly lacking the information I really need and it has got a whole huge confused section in there.
When you are on shore power I am presuming items that run on 12v such as the fridge work off your batteries but those same batteries are being constantly charged so no real charge goes out of them, they are just topping up as it were. Is this correct as does this constant charging at almost full capacity hurt them or not.
Confused of Scunthorpe.
 
Nostrodamus said:
..... does this constant charging at almost full capacity hurt them or not....
Click to expand...
No, because the battery decides how much current it will accept, not the charger. The charger just supplies a high -Bulk voltage - to do the main part of the charging, and then switches to a lower Float voltage when the batteries are 90 - 95% full. If you look at your Battery Monitor you should see 0 amps charging most of the time on shore power. As you turn on loads the charger supplies the amps directly to the loads.
 
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