Hi, I currenty have an ebike with a 24V 15 amp circuit system with a 300 watt hub motor. it runs off of 2 12V 12ah sla batterys and I would like to upgrade to a lithium battery system. I'm not real sure about the switch or if I can without it costing me a ton of money. The Sla batterys have done fair but are getting worn out. Any upgrade recommendations would be greatly appreciated.