Checking Standby Battery for Charge Rates

Hello, & good evening

I'm just curious about how a standby battery in a control panel is checked for its charge rate. Do you need a special tester to do this?
How can you tell that a battery is still in good condition, after say 3 years and minimal mains power disruption. The DVM can only give you a voltage reading of 13.8v, that really doesn't tell you about the charge rate or condition of the battery cells.
I only a few days ago replaced a battery in a 9800+panel which was going strong since 1999 ( changed it as a precaution), I measured the voltage, showed 13.8v.
How could I have in this instance checked the battery's charge rate?
Any reply appreciated.
Thank you

Hi, by charge rate i assume you mean the ability of the battery to accept a charge from the panel.

To check the battery you need to do a load test, to make sure the battery can perform under the total load of the system if the mains fails, that includes activations which will of course draw the most current and put the battery under the most pressure.

Just because the panel is kicking out volts, and the voltage reading across the battery terminals is OK it does not mean the battery will be able to support the system for the required standby time.

Most modern panels do this automatically and will warn if the battery cannot support the system.

If it was me i would change the battery on maintenance every two years, and charge for it they ain't that expensive.

Yes, as above, we do whats called a "load test" or "drop test" i.e we use an "intelligent battery tester", which simulates a full discharge of the battery to give an indication of the Ah capacity.

just because you can smell petrol in your cars tank, doesn't mean there's petrol in the tank, well in sorts, the same can be said for an sla battery, so reading a voltage simply wont do, as it wont give an indication of the capacity

In optimum conditions, an sla battery should last 4-5 years but must be changed at least every 5 years.

Drop test, hate that. Broke my toe last time.

Thank you guys for your valued inputs, much appreciated. Mr Alarm, I like the way you bring humour to this site
Adrian, yes I mean't battery able to accept charge & hold it for backup incase of mains failure. You're right, its wise to replace them after a few years, but i just wanted to understand how the load test is performed.
Mr young, yes know what you mean, 12v across terminals is not indicative of capacity.
Ok I'm gonna give it a try on my system to see how it works. Is this how the Load test is done?

1- Set DVM on mA, connect to battery terminals.
2- Pull the mains fuse, and activate necessary power hungry devives such as external sounders to see current draw from battery
3- Perform test for 10 sec or so 7 note down current draw.
4- reapply mains power, & then disconnect DVM from battery terminals

ok, so if I test a fully charged 7Ah 12V battery, which gives an output of 580mA, & the total load of the devices is say 500mA, I should be getting 500mA at the meter correct? if anything lower, battery is on its way out?
Sorry if I'm asking the obvious, Im just trying to get to grips with understanding load testing.
regards


A 7Ah 12V Battery will provide approx 580mA

Only sort of.
However:
When checking current, make sure you're meter is in circuit with the load, NOT across it.

alumni said:

Only sort of.
However:
When checking current, make sure you're meter is in circuit with the load, NOT across it.

Click to expand...

thanks Alumni, can you please explain that to me?
cheers