In article ,
"mark krawczuk" wrote:

hi, is there a way to work out the charging current for small capacity sla
batteries 12 volt 1.2 ah and 6 v 4.2 ah ?

it doesnt have to charge quickly . and can accidently be left on..?

mark k

SLA makers have charge specifications online. Essentially, the battery
is brought up to a top-off voltage then dropped to a float voltage.
There's a voltage region when the charge current may be high for faster
charging.

For example, you could have two regulators. One regulator limits to
13.4V and 600mA. Another regulator limits to 80mA. The 13.4V 600mA
regulator is always on. The 80mA regulator turns on below 13V and turns
off above 14.5V. The actual numbers and conditions for ending the
top-off depend on the battery's specifications. You can also find
charge specifications for salvaging an extremely dead battery (often 16V
for a few hours and wishing for luck).

It's possible to have a manually activated top-off using a simple
mechanical timer. You can also use a simple single voltage regulator
with some reduced performance and life.
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