calculating leisure battery capacity ? Am I on right lines?

[Sailingsaves]

I would consider them totally inappropriate for solar use, or cycling. Sounds a dishonest sale. Can you return them?
What was claimed to be the history?

No, can't be returned.
No worries, I can use them as a sort of buffer perhaps, i.e. if I have 3 turbines in the garden and 40 W of solar panels, then if I can keep the battery near its float charge of 13.68V, I can draw off 12.7 volts or whatever I need for the odd small bit of equipment free of charge (thank you sun and wind). Stick in some protection to stop the voltage dropping below 12.6 ish?

Out of interest, what are these batteries designed for? To back up what? How are they supposed to work? Do they back up a system and after a few discharges get thrown away as they are not designed to be cycled as leisure batteries?
cheers.

 

[Plevier]

Out of interest, what are these batteries designed for? To back up what? How are they supposed to work? Do they back up a system and after a few discharges get thrown away as they are not designed to be cycled as leisure batteries?
cheers.

They are intended for back up of critical equipment, typically telecoms and data handling, where outage is absolutely unacceptable. e.g. all the mobile phone masts you see around, hospitals, bank data centres, military comms etc. Often there will be standby generators too and the batteries will just bridge the gap if the generator starts, but they are of a capacity to work for some time if the generator doesn't start, while other action is taken. They are very unlikely to undergo enough discharges during the 10 year service life to shorten the service life. Generally the toughest thing they ever have to do is the initial commissioning test which usually is to the client's maximum specified duty. Subsequent annual tests are usually for a shorter discharge but with the voltage monitored and full capacity calculated from that. If calculation suggests they won't achieve 80% of duty then a full test will be done and if they again fail to achieve 80% of specified duty the whole battery - that may be several hundred units - will be scrapped. Sometimes a dealer will get hold of them and resell them for less critical duty. In such a case manufacturers would like to see them marked as rejects to protect reputation but you can't enforce it.
The battery will usually be specified around 125% of the required duty when new, to allow for the decline to 80% of nominal capacity. i.e. if the duty needs 1000Ah you'll buy 1250Ah.
If regular discharging is anticipated you would use a different type of battery which in general would take up more space, have a shorter life and probably cost even more!

 

[Sailingsaves]

They are intended for back up of critical equipment, typically telecoms and data handling, where outage is absolutely unacceptable. e.g. all the mobile phone masts you see around, hospitals, bank data centres, military comms etc. Often there will be standby generators too and the batteries will just bridge the gap if the generator starts, but they are of a capacity to work for some time if the generator doesn't start, while other action is taken. They are very unlikely to undergo enough discharges during the 10 year service life to shorten the service life. Generally the toughest thing they ever have to do is the initial commissioning test which usually is to the client's maximum specified duty. Subsequent annual tests are usually for a shorter discharge but with the voltage monitored and full capacity calculated from that. If calculation suggests they won't achieve 80% of duty then a full test will be done and if they again fail to achieve 80% of specified duty the whole battery - that may be several hundred units - will be scrapped. Sometimes a dealer will get hold of them and resell them for less critical duty. In such a case manufacturers would like to see them marked as rejects to protect reputation but you can't enforce it.
The battery will usually be specified around 125% of the required duty when new, to allow for the decline to 80% of nominal capacity. i.e. if the duty needs 1000Ah you'll buy 1250Ah.
If regular discharging is anticipated you would use a different type of battery which in general would take up more space, have a shorter life and probably cost even more!

Many thanks.