I am the guy the ask and found a great guy who has one I am buying. Those onboard chargers do not give equivalent charge to the Lester. Running the ultrex you need all batteries 100% powered the spotlock will drain batteries charged with an onboard charger much quicker than those charged with the Lester. From a sale standpoint it should be offered on rigs who have the 36 v ulterra they demand a lot of power while using the spot lock. Just my two cents
