E Bike Light Problem

[Bongopete495]

I recently purchased a Recon E HL 1000 light for my ebike which has a Shimano E6001 drive unit. I connected the new light unit using the connections for the B & M installed front light. The E HL 1000 switchs on ok but after a short period of time about 20-30 seconds it swithces off. I've tested the light with a DC supply indoors and it works ok. The E HL 1000 according to the manufacturers is compatible with all of the Shimano drive units.
I was wondering if anyone can suggest what the cause of the the problem is and a possilbe solution. Many Thanks