Have the stock battery and the connections are tight, i read that shorai can kill the regulator...
I ordered a Oxford Oximiser 900, let's see if it fix it
Getting a battery charger will do you no good at all. I tried several, all very high quality. The issue is the lead/acid battery having a lower fully-charged voltage than the Shorai.
The Shorai or any lithium-iron battery can be hard on the regulator because those batteries want to be at a higher voltage (~14 volts) when fully charged.
If you let the Shorai run down between rides, you will be overworking your regulator. The Gen 4 eats battery power even with the ignition off and it runs down pretty fast.
If you get any kind of lithium-iron battery, get the correct charger for it and use it every day. That way when you first start the bike, the regulator won't overwork and overheat and it'll last as it should.
The point of the Li-Fe battery is its higher voltage which helps the ECU work better. If you don't keep it at full charge using a Shorai charger you will reduce the life of the voltage regulator, and maybe have a weird idle problem because the bike is fast-idling to charge the battery.
When starting a vehicle with a low battery, it will cause the voltage regulator to push high currents for a longer period of time. This duty cycle will cause the voltage regulator to run hotter. Maintaining the Shorai LFX battery above 13.3V will help to reduce stress on the voltage regulator because the charged time to reach 14.4V will be relatively short. If the battery is at 13.1V ~50% SOC or 12.86V~20% SOC this will result in higher voltage regulator temperatures.
-from the Shorai website