As long as you work out the wiring and get the voltage and connections correct you can check the unit by using car or even flashlight batteries.
You don't need capacity to do that, just the proper voltage present.
- With the correct voltage present and AC applied it won't be trying to charge those batteries and your status lights should come on. If they don't the unit is bad and needs repaired.
DO NOT try to use it to power anything with that battery set-up.
It's only for a quick circuit check.
