In article .com,
wrote:
On 16 Jun, 22:40, "Dave Plowman (News)" wrote:
In article .com,
wrote:

SLAs have different charging requirement to non-gel cells. They
should not be charged with a car or bike charger. Charging v should
be significantly lower.

Assuming a reasonably large battery and a normal sort of domestic
charger,

from the pic it looks like a typical small SLA. A standard car battery
charger will charge it, but far too fast, so it wont last well. If youre
thinking more of a NiCd charger, that would be ok, if extremely slow.

Ah - didn't look at the picture. I just assumed an emergency power source
meant a hefty battery.

the internal impedance of the battery will prevent the voltage rising
too high to damage an SLA until it is near fully charged.

Are you sure thats what you meant? Internal R is typically a fraction of
an ohm, which will have more or less no effect on charging, and
especially so when full and charge i is at a minimum.

It limits the current a charger can supply - you'd need a mighty meaty
unregulated type which could supply enough voltage and drive a battery
without using a series resistor.


Of course the correct charger should be used, but other methods can be
devised for a cheap and cheerful solution as it would appear is needed.

sure. the simplest of which is a wallwart.

Or how bout what they recommended in one of my old books, putting the
battery across the mains light switch contacts, so its in series with
the bulb. Would work on dc mains, until you operate the switch... Would
desulphate it too. Good idea?

;-) Any port in a storm.

--
*When cheese gets its picture taken, what does it say? *

Dave Plowman London SW
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