Testing Lead Acid’s
I have four old lead acid batteries stored in the garage.
All of these batteries have been retired for some time but I keep them in the garage and charge them up every 3-6 months.
This is the technique I used to measure the capacity of these batteries:-
Charge the battery fully on my Ctek charger
Connect a load across the battery designed to take around 25% of the battery over 4-5 hours (based on the C20 capacity of the battery)
Disconnect the load and leave the battery overnight.
Measure the open circuit voltage and use this to deduce the state of charge.
From the state of charge and the known drain, calculate the capacity of the battery.
To be honest, I don’t know if this is a sound method, but it seems logical to me. Read more