Like me, you may have a Lead-acid battery that’s lost its charge. You don’t have to throw it away, there is still hope!
In my case the battery was left in storage, without charge for some periods of time. My assumption was that it had also lost some of its water. In some cases you can revive it by charging it up at a slightly higher voltage, but if it is lacking sulfuric acid or water (De-ionised), charging it dry may just do further damage.
Buy some De-ionised water at your local tescos or such, buying online sometimes prices are inflated but they’re usally £2 for 2.5L (don’t pay more), then buy a decent charger (SKYRC iMAX B6 V2 60W 6A DC 2.5mm/XT60 Dual Input Battery Balance Charger Discharger – best price I could find, while confirming being genuine).
I recommend the charger above, because it’s going to be the same price as a decent car battery charger, but that can do a lot more. You’ll need to arrange a 14v 3-5a power supply.
Watch some of the videos below which begin by opening the battery ports, reloading the water and then using an advanced charger, charging it up.
revive lead acid battery – YouTube
How to Revive a dead 12V Sealed Lead Acid Battery – YouTube
how to check amp on car battery – YouTube
How to Use a Multimeter for Beginners – How to Measure Voltage, Resistance, Continuity and Amps – YouTube
How to Test a Car Battery With a Multimeter ( Voltage + Cold Cranking Amps) – YouTube
Basic to Advanced Battery Information from Battery University
Sulphuric Acid 1N From APC Pure | Volumetric Solutions | APC Pure
12V 15 Amp Lead Acid LED Digital Battery and Alternator Tester | eBay
Battery Hydrometer Car Motorbike Van Tester Lead Acid Electrolyte Level Density 5055058174895 | eBay
1x Laser Tools Battery Tester Work Mechanic | eBay