Annabel,Annabel wrote: <snip>
So if I understand this correctly. I want to power a maglock that uses Voltage 12/24v DC 360/180 Current mA
The battery I'm looking at is http://www.vapextech.co.uk/acatalog/info_26.html
3300mAh / 360ma would give just over 9 hours of battery time in an ideal world but after taking away factors such as temperature etc it could decrease by as much as 30% give just over 6 hours battery time.
Now this battery is Measured at 660mA discharge which is well above the 360mA requirements so the battery rated discharge rate should not be exceeded.
Am I understanding this correctly?
You're getting closer, and that battery should work. However, I'd like you to understand *why* it's suitable so you'll be safe. So here are a couple clarifications:
If your maglock will nominally take 12 volts, from which it will draw 360 mA, then do NOT try to operate it from 24 volts! If you connected it directly to 24 volts, it would draw 720 mA, NOT 180. More to the point, if connected to 24 volts, it would have FOUR times more power dissipated in it, and that would probably burn it out.
> Max Discharge Current : 30,000mA (30 Amps)
This battery is rated at 30 Amps max discharge, way way more than the 360 mA you need. Having lots of margin is safer and is in general a good idea,
The "Measured at 660mA (0.2C) discharge" means that something (probably the 3300 mAH capacity) was MEASURED with a load (resistance) that drew 660 mA from the battery. 660 mA is not the maximum rated discharge current; they've told us that the battery's max. rated discharge is 30 Amps, or 30,000 mA -- which is a LOT of current!
(0.2 C, if I recall correctly stands for, in this case, "whatever current will discharge this battery from full to empty in 5 (= 1/0.2) hours." Since the 360 mA you need is less than the current draw under which they measured (something, probably nominal capacity), that's another indication that this battery can safely operate your maglock, and do so for several hours.
I strongly suggest that you buy the charger for this battery from the same folks who sell the battery -- a charger the vendor says is suitable for that particular battery. Charging a battery SAFELY involves considerably more than hooking it up to the right voltage (DON'T do that!) IMHO, recharging circuits should be designed by somebody who understands that battery very, very well.
Hope this helps.