Advantages: Unless you can get car batteries for free, no advantage.
Disadvantages:
- Less run time
- They will not tolerate discharging abuse as well as deep cycle
- Therefore you have to monitor their voltage at all times
- Charger designed to charge ~220 A/h batteries so it will cook the 50-60 A/h car batteries unless charging is monitored and shut down when charge is complete for these small batteries!
Having said all that, I AM running car batteries in my cart but I doubled up their capacity by parallel pairing up 2 and I also run twice the voltage ( 72 V)by having 6 of these pairs in series with the appropriate controller which further cuts the amperage abuse in half.
I also run voltage monitors and I do not charge them unattended!!!
It's not for everybody.
I recommend the correct golf cart batteries when it's time for a new set!