Charging a 12V Lead-Acid Battery with a CSI12003B

Recently, my parent’s 12V lead-acid Battery for their LiftMaster garage stopped working. Although the garage door opener is hardwired to a 120VAC electrical outlet, it contains a backup lead-acid battery in case of a power outage. If the backup battery goes bad, however, the garage will continuously beep which can be quite annoying. On top of that it wouldn’t serve its intended purpose of being a backup during a power outage. I initially replaced their battery with an equivalent model found online. But I sometimes need a 12V battery to power other electronics. And they may need to replace another one of their batteries eventually. So I decided to try to revive it by charging the 12V lead-acid battery using our new CSI12003B 0-120V, 0-3A power supply.

The initial voltage of the 12V battery was 4.947V as measured by my OWON B35. It is the latest version of these Bluetooth multimeters available. Which includes Bluetooth connectivity for displaying and recording data on your smartphone. The LiftMaster battery contained charging instructions at ambient temperatures. Therefore, I followed the cycle use instructions of charging between 14.40-15.00V (set the CSI12003B voltage to 14.7V) and at a max current of 0.300A. A good resource is here for charging lead-acid batteries and what type of CV / CC ramps and patterns to expect, below is a figure from their site.

charge curve for lead-acid battery cells from battery university

The battery initially charged at constant voltage, only accepting a few thousandths of an amp. Before slowly ramping up to 0.5W, then 1W, then 2W.

Eventually, the current exceeded 0.300A as I couldn’t set the current limit until the battery would actually accept enough current in order to limit it to 0.300A. At this point, after noticing a current above 400mA I reduced the current down to the sticker recommendation of 300mA max for constant-current charging.

Using the coarse and fine adjustment knobs on the CSI12003B 0-120V, 0-3A made it a breeze to dial in precision. On both the voltage and current limits to the thousandth of a volt and amp respectively. Although this high-voltage power supply was more than I needed for this job. By having the flexibility to charge other higher-voltage devices with it makes it a good deal for the price.

Thanks for reading! We hope this blog post helps you if you ever need a guide for charging a 12v lead-acid battery! Furthermore, on your next Circuit-ing journey.

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