Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Battery Drain Lead Acid

Status
Not open for further replies.

Cicero

Active Member
Hi,

Just want to check something with you guys.

I need to work out battery requirements to backup a piece of equipment for 5hrs which draws 12W normally, 12V @ 1A. The battery would be float charged to 13.8V before it needs to kick in for the 5hrs.

Would a 5Ah 12V battery work fine, or is there more to it than that?
 
How frequently are you going to discharge the battery? One that is repeatedly discharged to 100% of its capacity might make 200 cycles, while one discharged to 50% of its capacity should make thousands of cycles.
 
A 5Ah lead acid battery has a capacity of 250mA for 20 hours, or 1A for maybe 4.5 hours, or 5A for maybe 4 hours when it is new and less as it ages.
 
Like AG said, the capacity in AmpHours is rated at a 20 hour discharge rate. You will have less capacity if you're discharging it faster than 20 hours.

Look at the chart on the second page of this datasheet. https://www.powerstream.com/bb/bp5-12.pdf

If you need 5 hours at 1 amp, you will need a larger battery.
 
As everyone mentioned I would consider a larger AH capacity battery. A 12 Volt SLA 8 AH battery is a pretty common off he shelf battery from any battery supplier. For example a Werker WKA12-8F2 SLA Battery - 12 volt 8ah (amp hour) only cost about $23 give or take from a large variety of distributors including Amazon and Granger, locally even Batteries Plus sells them.

Several years ago we had a company come in to replace our emergency cypher lock system (battery backup) and they gutted several of these little boards. I made sure they were removed from the old panels before they went to the dumpster, not that dumpster diving is below my dignity. Ended up with a few variations including the one I linked to. All that is required is an external AC transformer commonly available. Here is the data sheet for the linked unit. If you do not want your load to miss a beat during a power failure these things are great! They maintain a charged battery ready to automatic transfer.

Ron
 
Cool, thanks everyone, appreciate the input.

Good thing I asked, never as simple as it may seem in this industry.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top