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

On Sun, 26 Sep 2010 11:02:00 +0930, "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
:

Do some reading...

Here is a typical info sheet
http://www.jaycar.com.au/images_uploaded/slabatts.pdf

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


Continuous (trickle)charging is bad for all lead based
batteries.
Best treatment is to get a computer based charger, which
can adapt itself to the battery type and capacity.
There are two much used ways to kill batteries: total
discharge and excessive overcharging.

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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I won't see Google Groups replies because I must filter them as spam

"mark krawczuk" wrote in message
...
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


As part of the procedure for desulphating SLAs, Yuasa suggest current
limiting to 1/3 the Ah rating, but this would be too high for long term
float charging.

Microcontroller based maintenance chargers like the Optimate 4 do a
controlled normal charge then back off to voltage controlled float charging
at about 13.6V - apparently this is the optimum level to avoid electrolyte
loss from gassing.

Apparently some Honda motorcycle spares stockists sell Honda branded 6-12V
switcheable microcontroller based chargers.

Some of the budget goods stores (like Lidl in the UK) do cheaper less
sophisticated microcontrolled chargers - you can leave them soak charging,
but if there's a power outage you have to reset them.

Lidl have the chargers in every few months - there's also Aldi and Netto
stores probably do something similar.