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thing wrote:
> I have old one one of these but its dead....I tried to charge the sealed
> 12v batteries overnight but I am getting nothing so....I am reluctant to
> buy two new batteries in case the unit itself is dead....does it need
> power in the batteries in order to come to life? I think some of the old
> ones did....ie can I connect up a couple of car batteries to give 24v
> long enough to see if it switches on?
>
> Best place to buy two batteries if this works? Jaycar?

Assuming they are 12V 7Ah your cheapest option is your local burglar
alarm suppplies place. I paid about $18 each for the ones I bought last
week.

thing wrote:
>
> Are these deep discharge though? but I may not care....

Informal testing by one of my colleagues (who uses SLA batteries for
underwater video lighting) showed that unless you spend *heaps* on
premium SLA batteries like Sonnenschein (who IIRC invented the
technology) there's little difference in performance.
>
> ie my understanding is these need to be capable of delivering a lot of
> amps....mind you the occasional blip is so rare that $18 sounds more
> than enough...

The $18 ones work ok in my UPS.

>
> My first task though is to try and get life out of the electronics....if
> that proves Ok I will phone around.

If you were in Auckland I'd lend you a couple of batteries to test it with.