It took a little longer to get back than expected, with an update, but it’s good news.
I’ve now completed the tests I wanted to run and I’m pleased to say the replacement battery performed well and, in my opinion, is a very good replacement for the original LCD5802D battery.
You can find the battery available here https://www.goav8.uk/product-page/lcd5802d-monitor-battery-replacement
For anyone interested in learning how I ran the tests, please see below.
Using two separate monitors, one with the original LCD5802D battery in place and another with a new battery, I fully charged them, until the monitor’s battery LED turned green. I then disconnected the charger, turned each monitor on and let them run until each turned off.
They both lasted just short of 3 hours; 2 hours and 47 minutes. The on-screen bars, for the new battery, dropped faster than the bars for the original; the new battery dropped to zero bars at 44 minutes, whereas, the original dropped to one bar at 44 minutes.
Re-running the test, I found that turning the monitors off, once zero bars where shown, I was unable to turn the monitors back on. The monitor presumably recognising the battery level being below the minimum allowed.
The new battery, placed outside the case, did not run hot, being ambient temperature to touch.
I’m really pleased with the result, and more so to have finally found a replacement battery.