learn this my friend, the battery (no matter what battery) is only for start up the engine, once the engine is on the battery is useless, engine will run on alternator
so your dear battery is useless, but the good thing about that is you can discharge your battery and it can recover energy without damage, that make the gel battery better than the regular acid battery
ok, how to solve the problem... bad news about that, you have to mood your alternator. take out your alternator and go to a good alternator and starter store and compare yours to another alternator who has more amps than yours
your alt has 80amp and after a search i found the alternator of ranger 2002 4cyls has a 105 amps, but the problem is the housing of the alternator dont match 100% with yours so you have to ask a alternator tech if is possible to swap your housing into the ranger alternator
if so... you are save but also you have to know you will need to trick the plugs and cables to make it work
