General recommendations for system design
All battery installations should be complete to meet any local or national
standards or building codes. If none are locally available, international
standards can be considered, such as EN 50272-2:2001 or IEC 62257 for off grid
power systems.
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Always install a battery in a well-ventilated container or room. There must be
sufficient airflow, which is top-vented to the outdoors to allow the gas to
escape. Never install any battery inside a completely sealed container since
all batteries will produce hydrogen and oxygen and may cause a risk of
explosion. Industrial standards allow for VRLA batteries to be installed in
areas with a reduction of the air exchange rate by a factor of four in
comparison with flooded batteries.
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Never mix different types and sizes of batteries in the same battery bank.
Putting a new battery in an old battery bank should be avoided.
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It is not recommended to buy a flooded battery when it is more than 3 months
old unless it has been recharged periodically or it has been stored
dry-charged, without electrolyte. Depending on the storage temperature AGM and
gel batteries can be stored up to 6-18 months before internal damage has
occurred. Always commission a battery properly by giving it a full charge
(according to DIN EN or battery manufacturer recommendations).
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In a renewable energy system without a backup generator the battery capacity
and size of the photovoltaic (PV) array and/or the wind generator must be
matched to make it possible for the generators to fully charge the battery
regularly (at least monthly).