You can parallel these batteries but there will be some mismatch and they wont share the load equally. Negative to negative and positive to positive.
Energizer Rechargeable 9v Battery 9 Volt Battery 1 Pack
9v battery in parallel. Paralleling is a way to get more currentby paralleling them you are making. Paralleling batteries can be done if they are both new and equal type. For example if a 3v and a 9v battery were wired in parallel the output voltage would be 6v 93 divided by 2 however the current will be total amperage of all batteries in the circuit minus any losses. If you have one that is partly drained connected to a new one then the new one will drain trying to charge the old one. So if my calcs are right the resistor for each of the il604s parallel with each other should be 50. Two 6 volt 45 ah batteries wired in parallel are capable of providing 6 volt 9 amp hours 45 ah 45 ah.
With a good switching voltage converter circuit you should be able to get more than 600 hours. To join batteries in parallel use a jumper wire to connect both the positive terminals and another jumper wire to connect both the negative terminals of both batteries to each other. You should be able to get that to about 90. Connecting multiple 9v batteries in parallel is fine for the most part but you would need to replace them all at the same time. One 9v battery will give you somewhere between 120 and 200 hours of illumination with the simplest circuit a series resistor. You can connect your load to one of the batteries and it will drain both equally.
The basic concept is that when connecting in parallel you add the amp hour ratings of the batteries together but the voltage remains the same. Forward voltage is 30 36 volts to be wired in parallel the third will be a blue led 34 38v 20ma in series with the parallel circuit of the il604s. As it is now your power supply is only 56 efficient. But these arent rechargables so it would partly work but mostly be a waste. Unlike wiring batteries in series when batteries are wired in parallel the voltage does not increase the output voltage is the average voltage of all batteries in the circuit. But as a rule paralleling batteries is not good because you cannot control the above requirement.
The 2nd config is 4 parallel connections at each battery end also 2 rows of 4 batteries each row connected in series and of course the 3rd image is 3 parallel connections with 3 batteries connected across their and terminals and a single row of serial connected batteries to make 48v. Begingroup btw my ultimate goal is to have the 9v battery power three leds. Two are microtivity il604 5mm rgb slow rotating led. A much better solution is to use a buck switcher instead of the 7805.