The diagrams here show typical 12 VDC, 24 VDC and 48 VDC battery wiring configurations. Batteries can deliver extremely high current. Always install overcurrent protection on any positive wiring connected to batteries.
With lead-acid batteries it’s best to use one series string of batteries to get the desired voltage and capacity. If that is not possible, using up to three strings in parallel is acceptable. Note in the diagrams below, that when using parallel battery strings it’s essential that the bank’s output cables be connected to opposite corners of the battery bank. For instance, if using two parallel strings, connect the positive bank output to the positive output terminal of the first string, and the negative bank output to the negative output terminal of the second string (or vice-versa on the polarity). If using three strings, one output cable would attach to the first string, and the second output cable would attach to the third string. This helps insure equal current flow through all strings of the battery bank.
Using four or more parallel strings is not recommended without taking extensive care that all the strings receive the same amount of charging current and load. Large central buses should be used, with equal-length cables (hence equal resistance) between the buses and each parallel battery string. This also is a good method to use with two or three parallel strings.