How come my conversion (Porsche) can only go 21 miles? 14 golf cart batteries with 192AH and 84V is over 15KWH. I have an WH meter with the charger and I am using abt 300WH per mile. If I have done my sums right I should be getting 50 miles.

From my understanding with SLA you should really only drain to 70%, plus you have to account for the fact that most batteries actually perform at ~80-90% of rated capacity…
Generously we’ll say: .9*.75=.675 = 68% max… [(19284)/300] = 36 Miles… So Maybe you are seeing voltage drop that is leading you to stopping short but I would only anticipate 36 Miles Tops with those batts…

And the opposite end of the spectrum = .8*.7=.56 * [(192*84)/300] = 30 miles

What is making you stop at 21 miles? Is the drop in performance that significant? Or is it a low voltage cutoff? Maybe you have a bad battery that drops faster and drags it down? What are your symptoms?

My controller (altrax) apparently has no low voltage cutoff as it will still function down to 20V (in a previous car). The reason it stopped (it didn’t actually come to a stop; a neighbors house was downhill 200 yards away and I quit there) at 21 miles was that it simply ran out of juice and was down to walking speed and less than 50 volts. This happened gradually as you would expect if the batteries were being depleted. In my car the battery voltage will decline slowly from the full charge level to about 70 V then at an ever increasing rate.

You have probably caused damage to your battery capacity by draining them down so low. You would normally want to stop draining them ~70 volts and re-charge. Remember Lead Acid Batteries are not conducive to full draining of the batteries, they work better and last longer with 1/2 draining.

Are the batteries new to this car? Have there been any electrical problems that could have contributed to this damage?

Good Luck, sounds like you need more batteries or different batteries…