I'm planning to buy chargers for two types of sealed lead acid batteries: one for a 12V, 4Ah battery, another one for a 12V, 1.5Ah battery. I'm planning to buy from Mouser Electronics. From their catalog shown in
Dead link.
One SLAC charger should be able to charge either type. Lead Acid batteries should be charged with a temperature compensated constant voltage source. It should sense the terminal voltage and switch to a float charge at something like 95% charge. SLACs should last ten years if treated properly. Don't skimp on the charger.
-- Keith
Manufacturers of small SLA's recommend limiting the charging current to 30% of the battery's capacity. So for the 1.5 Ah battery, a .5 amp charger would do. For the 4 Ah battery, get a 1 or 1.5 amp charger. You don't have to adhere to that 30% figure rigidly; it won't kill the battery to go a little over, and going under just means it will take a little longer to charge.
Thanks for the tips. According to the catelogue choices, I personally think there's no point of me of buying a 0.5 A and 0.8 A charger separately. I'm planning to use a .5 A charger for both, although it will take the 4Ah battery about 8 hours to charge.
No, lead acid battery charging is about 66% efficient, it will take about 12 hours.
The charger range you gave a link to is a boost+float type acording to the brief description so it should get the battery up to close to a full charge fairly quickly. On float charge the current does not stay at the maximum capacity of the charger then suddenly drop to zero when the battery is full, the current drops slowly over a few hours.
I had one of those huge torches ("flashlight" to merkins) that have a 100watt bulb and a small lead acid battery inside. The unregulated wall wart charger produces a rarther high voltage with little load. The torch was left on charge for weeks. No wonder the battery failed after a few months.
Bob
Just got the battery charger. I've managed to charge my 12V 4Ah battery in half an hour with the 500 mA charger, which I expected to take longer. I got a suggestion that it may be charged beforehand and to get the runtime, I would have to put a load on it. I removed this battery from an alarm system that is saying I have low battery. Does it mean the battery would have to be replaced as well?
Your gel cell was either almost fully charged, or it is sulfated and needs to be replaced, assuming your new charger is working properly. If you are interested in digging in to learn a little more about your battery read on. If not, the most likely problem is the gel cell - just replace it.
Here's a circuit you can use to discharge a lead acid battery to a specific voltage with a known load, to get a good runtime test.
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