The message 20051117150105.GA21211@areti.co.uk from Chris Green chris@areti.co.uk contains these words:
On Thu, Nov 17, 2005 at 12:25:56PM +0000, Anthony Anson wrote:
The message 20051117090122.GA18892@areti.co.uk from Chris Green chris@areti.co.uk contains these words:
A bigger battery won't take more charging current, it'll just take longer to charge. The internal resistance of just about *any* lead acid battery will be negligable compared with that of the charging circuitry, the charging circuitry will set the current at any given voltage and will not be affected by the (negligable) internal resistance of the battery.
That's what *I* thought, but I used a plug-in lead-acid charger block meant for a burglar-alarm-sized battery to charge a small motorcycle battery - and the charger burnt out.
In that case I'd guess that there was some circuitry in/close to the burglar-alarm-sized battery.
Just an ordinary lead/acid 12v sealed unit with two tongue connectors, intended in fact, for a burglar alarm. It charged that without demur, but putting it on to a similar type, but larger accumulator borked it.
It's also *possible* but rather unlikely that the batteries actually had slightly different chemistry. Apparently some of the latest 'Calcium' car batteries (which are still basically lead-acid) need a slightly different charging voltage.
This was about six or seven years ago, and both batteries were standard sort of things, one off the shelf from a security firm and the other ditto from a small motorcycle shop.
... or it may just be that the charger was crap and would have burnt out whattever battery you connected it to. I assume by the way that the burglar alarm battery was a 12 volt one, and so was the bike battery.
This is possible, and yes, they were both 12v accumulators.
The delivered voltage of the block was, IIRC, 13ยท8v