I recommend these chargers -
https://www.maypoleltd.com/product/mp7423-4a-6-12v-electronic-smart-charger/Used Optimate and Accumate before hand and found the Maypole more reliable. Sold my collection of Optimates (9 of them) and replaced with the Maypole.
Fraction of the price of the CTEKs and work with Lead and AGM.
No idea how old my MGB Battery is - was in the car when I bought it so over 3 years. SInce then I've completely drained it on numerous occasions (at least 6 times, and so flat that it wouldn't even light the LED interior bulb). Jump start to get to work and back, and then overnight on the Maypole and it's still going strong. I have also fixed the wiring so it doesn't drain any more
