Hey everyone,
So I was wondering if the battery hack that some people do with their panels is actually safe. If you aren’t sure what that is, it’s basically when the positive of the 24V Aux power is connected to the positive of the battery terminal on the FACP, which essentially dummies out the battery trouble. Most people that do this apparently just use a straight piece of wire to go between the battery and auxiliary power connections, which I’m going to assume is not safe since power from the battery charger can flow back into the FACP. I am wondering though if it would be safe if you used a diode instead that way power would only flow in one direction (from the auxiliary 24v to the battery). I would like to do something like this so I don’t have to purchase batteries, I just need to know if it’s safe.
Most panels charge the batteries at a certain AH, so probably not a good idea. You could fry something of you did that. Some panels like the Notifier SGL series allow you to resistor off battery backup, but that violates NFPA 72.
I have used a capacitor on some panels. How well that works and the size capacitor needed depends on the panel. I have a 33uF that keeps a 4002 happy all the time. A 4002 just checks for presence of battery voltage and does not shut off the charger in alarm. Some panels load test the battery so need a larger capacitor. Some panels shut the charger off in alarm to divert that power to NAC use. On those the capacitor will discharge during alarm and a battery trouble will show. The capacitor will recharge when the panel is reset. Any capacitor should be at least a 50 volt unit. You just have to try it on your panel to find out how it will work.
Of course, I only use this method on demo/test panels.