I encountered the following issue: the lead-acid batteries (2 * 12V 7Ah) that power up the stair lift motor (24V, 0.3 kW) died (the motor wouldn't start anymore, with a nominal voltage at no load of about 12.0V or less for each battery; didn't check them at load) after just 1 month of usage. The lift was lightly used, at most 6 times a day, with a ride of only 6 steps.
The previous batteries lasted for one entire year.
I checked the charger (24V, 300mA switched mode power supply) and is suplying succesfully 24.6V when the lift is at the end of the rail. The new batteries are charged full time with 24.6V and 0.04A (which means that the batteries are full from what I can remember.. 3% of 7Ah is 0.21 Ah).
- should I change the power supply with a less nominal current given the fact that the batteries are full time on-charge?
- should I disconnect the power supply from time to time so that the batteries won't charge continously?
Best Answer
The long term "float voltage" is 27.1V for a flooded lead acid battery (at room temperature).
When recharging, it is common to pull them up to above 28V until the current drops below some threshold and then go down to 27.1.
Not an ad for them but this can help:
https://www.power-sonic.com/blog/how-to-charge-a-lead-acid-battery/