Originally Posted by sea_hunter
It's always best to match batteries to the same amphr rating. IE a 240 amphr Trojan 6V golf cart battery circuit should have a similar +/- 20 amphr start battery. I prefer to also keep all the batteries the same brand or at least have the same factory settings for charge/float etc. We just changed out our Trojans for 251 amphr 6V Interstate and a 12V Interstate marine start/house battery. This allows the batteries to absorb equally putting less strain on the charging system.
If you are charging with an Echo Charge, Duocharge or similar it makes no difference. Commonly many have a house bank of 400AH or larger and a group 24 start. The battery is the determining factor - it accepts what it needs.