How to top up a Century Maintenance Free Battery

[campbeam]

With a maintenance type battery, you can easily check the fluid level in each battery cell and top up as required.

It is a different matter with a maintenance free battery but the fluid level in each battery cell will eventually go down. When this happens, the state of charge indicator will go from green to red.

The attached document shows how to restore the fluid level in the battery and potentially restore the state of charge indicator back to the green.

This has worked for me in restoring 2 Century Maintenance Free Batteries, one back in 2018 and one in July 2020.

How to easily Fill a Century Maintenance Free Battery.docx

[Tony Prodigy]

That's really interesting Ashley. Thanks for posting. 

[campbeam]

It has taken about 4 weeks for the state of charge indicator to be consistently back in the green. Certainly took longer because of my driving short distances and with the headlights on all the time. Eventually I went back to just having the parking lights on during daytime and this has helped with maintaining a full battery charge. 

Next target will eventually be the battery in the girlfriend's Yaris. A few months ago that battery was complimentary tested at 89% by a local tyre workshop and they recommended that she buy a new battery. I was not happy and that battery is still going strong. 

[campbeam]

As a follow up, I am now rejuvenating a different brand maintenance free battery. It is marked 03/2016 so more than 5 years old. Unfortunately the battery case is black i.e. non-transparent so unable to see the fluid level in each cell. 

Using a syringe and plastic tubing I was able to pump in about a cupful of distilled water via those side vents to refill the battery cells. This proved to be a bit too much as there was some overflow water discharge from the side vents during battery charging last weekend.

Battery is now back on the charger and charging. Initial reading last weekend was 10.5 volts. Today's initial reading was 12.5 volts.  

[campbeam]

As a follow up to the previous posts, both Century batteries NS70L purchase dates May 2017 and June 2019 are still working fine with a green charge indicator. I swap them between my registered Aurion and the backup unregistered one. They do not have a hard working life so hopefully will last quite a few more years.

Century battery fitted in the Yaris is also working fine and has yet been refilled.

I was not successful in my attempt to rejuvenate that other brand maintenance free battery.