Recently had a battery not holding a charge. Replaced it and now a bit paranoid. Got a new products ad from Revzilla. Which showed a TecMate State of Charge Monitor from Optimate. It replaces the tender pigtail on the battery. Has a LED monitor for battery charge and when the bike is running indicates charging system status. So far seems to work as advertised. Was about $30 after shipping. Just my two cents.

 

Been running with one from Kuryakyn for about 12 years now good to see the volts but I thinks amps would more important. I got mine wired into my tail light running circuit.