Battery questions

New to forum and I had a 2000 Bombadier that I was having too many problems with so decided to sell. Now have a 2000 GEM. I have a question about the batteries in this. My Bomb. had 12v Trojans that I purchased when I first bought the car (the person b4 used marine batteries so I had no range) This GEM has Econo Power? korean batteries AGM (6x12v) and again I run into range problems. I should be getting 20-25 range at full speed but need to reduce to turf mode after about 4-6 miles. Full range with having to limp it home is somewhere about 10 miles. The Bomb (with the batteries noted above) I would easily get 10-15 miles at full power. My question…does anyone know what the batteries are (there are not marking except a dayglo green Econo Power logo on battery) Any idea of amp hours? The guy I bought it from indicated that they were Interstate and checking online they might be re-furbished interstates!? I live in Phoenix, AZ so cold isn’t a problem (it would be heat here!). I checked one of the batts after a full charge and it measured 13.15v. The charger is a Zivan (this was an after market upgrade and I assume it’s set up right…does voltage of battery indicate?) Ideas about why range is short (perhaps amp hours low??..how to tell)
Thanks

1 For max range Trojan T1275s flooded are the best. They are a 150 hour battery and weigh 80 pounds.

2 Next is T1260 flooded.They are 140 hour and weigh about 78 pounds

3 Next is 30XHS flooded They are 130 hour and weigh 70 pounds

  1. Next are Size 31 Deep Cycle/Marine from almost anybody. They are typically 105 hour batteries and weigh 60 pounds. East Penn manufactured are my choice.

The GELL batteries from all major manufactures are 102 hour and weigh 70 pounds.

Trojan 1275’s will give the most range HOWEVER: Expecting 20+ miles at full speed without a break is a reach. Typically they MIGHT get 25 miles in average driving without taking them below 50% charge

GELL’s have only 2/3’s the capacity so don’t get the range.

Size 31 flooded deep cycles will give 18 to 20 miles at 50% I have East Penn MDC31’s in my 99 E825 4 seater, If I don’t put my foot in it I get up to 20+ but this is hard on the batteries and I plug in after every use. Roughly the same range as GELL’s and AGM’s

My cart pushes with minimum effort with the brake off NO DRAG, I have stock tires and keep them at 30+ PSI. My front end is lined up with 1/16 inch of toe in for minimum drag.