Testing deep cycle batts

Thread Starter

Poor old sod

Joined Jul 25, 2017
193
Have 2x 65ah deep cycle batteries abt 2yrs old from emergency standby ups. Have digital battery tester v, ah. Cca
At full charge what readings can I expect and what would be minimum for mobility scooter use. Avg 10A for 2.5-3hrs discharge is required. Is there a chart of degradation v life remaining?
 

MrChips

Joined Oct 2, 2009
30,714
I use an automotive headlight bulb with two filaments, normal and high beam, for testing 12V SLAB (sealed lead acid battery).

I mount the bulb in the proper automotive socket on a hobby metal box with two toggle switches. One switch selects the normal filament. The second switch connects the high beam filament in parallel with the first.

I place a metal shield over the lamp because the light output is intense.

A freshly charged 12V SLAB reads between 12.8V and 13.6V. You should not run the battery at lower than 10.5V.

Besides falling battery voltage the other important parameter is the battery internal resistance.
I measure the voltage and current delivered to the lamp over time. This gives me a measure of the internal resistance of the battery.

For more information on how to charge batteries Battery University.
 

Ian0

Joined Aug 7, 2020
9,675
Are you sure that they are deep cycle? UPS batteries tend to be designed for long life on float, but only a small number of charge-discharge cycles.
 

Thread Starter

Poor old sod

Joined Jul 25, 2017
193
Are you sure that they are deep cycle? UPS batteries tend to be designed for long life on float, but only a small number of charge-discharge cycles.
Yes ups or stdby but Def deep cycle
Will read ah with auto batt tester for 100ah batts. check capacity as a reference. Hope more than 60.
 
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