Ever built a battery? Or a charger?

Seven cell battery, you're not talking about an 8 volt battery are you? Those were fairly popular with farmers who had old Allis Chalmers B, C, WC and WD tractors with the OEM 6V system. Even with a good battery they'd hardly turn over, so people would replace the 6V battery with the 8V and turn the voltage regulator up to keep it charged fully. At least they'd turn over in winter that way.

Do you remember a "hoop" (long pipe over the end of a wrench for more leverage), gin pole (for lifting objects), panther pi$$ (penetrating oil), tiger crap (tough, yellow clay soil) or sideboards on a truck or wagon?

6V batteries have 3 cells, often seen in older things

12V has 6 cells as seen in all modern bikes.

Would it be safe to assume a 7 cell battery would output a 14volt capacity?

Maybe used as a backup battery for emergency lights or possibly radio communication equipment in the event of a blackout. The internals of many 110V/220V appliances feed on under 10V after a step down transformer.

Crowbar? No idea aside from the obvious, which i'm positive you don't mean....

I remember making basic batteries in high school out of salt water, copper and silver i believe....

Never built a charger, just took them apart and soldered this or that on a monthly basis in the shop. They tend to get jostled around in a shop enviroment.

I wish i knew why you were looking for the information.. the best answer i can give is "why not just buy one" like everyone else.

I've never heard of anyone building a battery. as for 7 cells, that's basically the amount of reservoirs a battery has.. each res. is a cell... each of them are independently filled with acid.

as for where it may be used... i dunno........... a tractor??????