Approx. 60w .50amps

Unregulated voltage from lesser made genset units will cause unit to heat too rapidly so pay attention to that , honda , yamaha and other quality brands are regulated so no issues

Thanks

How much mah I need to heat the engine. Our ambient temps are always above 86F. Trying to get the required lipo. Also will low discharge be sufficient (20C)?

a 5000mA battery will give you approx. 1 hour of heating. Higher ambient temps don't need as much preheating time.
It's wise to use a voltage alarm or voltage cut-off for Lipo batteries.

Yes, 20c is more than enough. The unit only draws 5 amps. On a 5000mA battery this is only 1c.