You should flush it but dont worry about it to much. People would be amazed at what will run in vehicles. One of the advantages of growing up where everyone drove a claped out cobbled together piece of crap was that you could try all kinds of stuff you wouldn't dare do to a 30k plus "nice" car...
Not a good idea to run it below its nominal voltage. A 48V should be run from around 52v "full" down to about 48.5-49v "dead". Going to low can burn up the motor controller, SCR's arnt to fragile but MOSFETS will burn up pretty easy.Will damage batterys too. Putting in 12v's will save a lot of...
I inherited my grandfathers 92 Chevy 3500 with the 6.5 turbo diesel. It had sat with 3/4 of a tank for 6+ years. Poured a full bottle of treatment (treats 300gal) and changed the filter but that fuel burned pretty good.
Yep, an on board charger for scissor lifts, golf carts that kinda thing. You wire it up and leave the charger on the piece or equipment then just plug it into your 110v AC when you want to charge. Ive used that brand in 24v DC. Good chargers for the money, $300 ish new.