Thread: Advice re Capacity Checking Lead Acid Batteries

I have a digital capacity checker for lead acid batteries which is rated for 6 to 18v, is it possible to cap check a 24v battery by the inclusion of a resistor in the circuit ? I can set minimum cell voltages etc !
Any advice appreciated.

Does it test the capacity or only the state of charge. If it is the state of charge, it is probably just measuring the open circuit voltage. A resistor would not help. If it's somehow measuring the capacity, you would need to know the principle of operation. What is the brand and model of your tester?

It is this one thanks for your interest.

KILTER ELECTRONIC INSTITUTE CO.,LTD MULTIMETER AIR ION DECTOR AIR PURIFIER CLAMP METER BATTERY TESTER OSC CABLE TESTER

Originally Posted by lupomen

is it possible to cap check a 24v battery by the inclusion of a resistor in the circuit ?

The resistor load must be major compared to the amp hour capacity of that battery. A good and fully charged 24 volt battery under heavy load will maintain at least 24 volts. A defective battery will output maybe 23.4 volts during the same load. How degraded is that battery? Better specifications for that particular family of lead acid battery must be obtained from datasheets. Above is a ballpark battery checker.

Originally Posted by lupomen

I have a digital capacity checker for lead acid batteries which is rated for 6 to 18v, is it possible to cap check a 24v battery by the inclusion of a resistor in the circuit ? I can set minimum cell voltages etc !
Any advice appreciated.

One good way to check a battery is measuring the short-circuit current. This determines the internal resistance of the battery. However, for a large battery such as a car battery, the short circuit current could be as high as 1000 Amperes. This is difficult to measure unless you have a battery tester designed for this purpose.

Checking the open circuit voltage is less reliable.