Deep-cycle lead batteries can give years of trouble-free service, provided we care for them. The less expensive ones need topping up from time too, through caps in their upper casings. In this way, they are quite different from gel / agm auto-starter, ups, and boat batteries, although they do appear externally similar otherwise. Deep cycle storage can give years of trouble-free service. However, we do need to test a deep cycle golf cart or scissor lift battery from time to time, to make sure it is still in good shape.
How to Test a Deep Golf Cart or Scissor Lift Battery
Here are the basic steps to test a golf cart or scissor lift battery. This high-level summary is for information only. Battery testing in more complex, and requires specialist experience and knowledge. Please note this does not apply to sealed lead batteries (readily distinguishable because they have no filler caps in their upper case).

# Visually inspect the battery, and the connections at the terminals. Top up the electrolyte with distilled water, unless the battery is a low maintenance gel / agm sealed one.
# Recharge the battery to 100% power, making sure to do so with any filler caps removed, and in a well-ventilated space away from children, pets, and open flames.
# Allow the battery to rest for between 4 to 12 hours. Apply a 33% load for five minutes. After 10 minutes apply a 50% load for fifteen minutes. Rest the battery for 10 minutes.

# Allow more time to cool if the electrolyte is above 43.3º C. Compare cell hydrometer readings against the specification. A 0.05 difference between cells indicates one or more dead ones.
# If satisfactory, apply a known load and measure how long the battery takes to discharge down to 20%. Compare this with the battery specification to confirm good health, and have confidence to continue using it.
Fully recharge to full power as soon as possible afterwards, assuming a satisfactory test completed.
Use a Specialist to Test a Deep Cycle Battery
We strongly advise consumers do not try this procedure themselves. Accurate test equipment is expensive, and electricity needs respect. However, now you know how to test a golf cart or scissor lift battery in principle, you know the right questions to ask when you take it for testing.
Related
Deep Cycle versus Starting Batteries
Making Deep Cycle Lead-Acid Batteries Last
Preview Image: Lead Battery Showing Top Up Points