# How to charge SLA battery?

I bought an ExpertPower EXP-1270 12v 7Ah battery, and I want to know how to charge it. I don't have a battery charger, but I want to do it with my variable power supply. I had already set it to 13.8v, but after charging for an hour or two the battery had only reached 13.2v. Am I doing something wrong?

I want to use the battery for general purpose where I can charge it, disconnect, and then use it for whatever I need to. When I'm done using it, I will recharge it again.

The battery has several specifications, including two voltages:

• Standby voltage 13.7-13.9v

• Cycle voltage 14.6-14.8v

• Current limit 2.1A

• Constant Voltage Charge

• 12v 7Ah

• 20HR

How should I charge it? I'm used to charging lithium batteries that don't take long to charge.

I'm just looking for what voltage and current I should use, and how long to charge for.

• You need to tap into each cell voltage to find out if it damaged by unequal cell voltage. Commented May 21, 2021 at 12:47
• These are brand new batteries so I don't think that would be the problem. This is a sealed AGM battery so I can't easily access the individual cells anyway Commented May 21, 2021 at 12:47
• Then use CC 2.1A and compute dV/dt when <14.6 which must be a temperature compensated voltage C=IcdV/dt what is C? A needle probe would have to be used carefully. If you can’t do it right , don’t Commented May 21, 2021 at 12:49
• I'm still relatively new to electronics so I don't know all of this math stuff. Could you please explain? Commented May 21, 2021 at 12:51
• Just charge the battery with 13.8V with a 2.1A current limit at room temperature. It will be fine unless it's already damaged. In the future, invest in a good 3- or more stage battery charger. Commented May 21, 2021 at 14:57