"Stefan" wrote in message
...
In article ,
says...
100AH is its total capacity. Normal rule of thumb is to only
discharge it down to 50%. So, you have 50AH of useful
capacity.
The advice for NiCad batteries for mobiles etc. is that it is good for
them to go through complete discharge-recharge cycles. Anyone able to
explain why lead/acid batteries are different - if indeed they are?
I think - and it is only think, that it is to do with how the plates are
constructed and move when they afre accepting or delivering high current
flows.
A lead acid battery has its plates made of a grid of lead latice upon which
lead oxide powder is compressed, a bit like plastering a wall.
When high currents are passed the plates actuall flex, the higher the
current the greater the flex. Domestic batteries tend to have thick plates
to give capacity, this means that when they flex the outer particles of the
oxide are compressed or streached so tend to fall off. When they build up in
the bottom of the cell and short a pos. & neg. plate the battery has failed.
The flatter the battery the higher the charging current it will accept for
any given charging voltage, so the more teh plates flex and the more they
shed oxide.
This explanation does for me, although there may be chemical one as well.
This also explains why tubular plates (being curved so resisting flexing)
tend to have a longer life than "normal" flat plate batteries.
Tony Brooks