mixed frequencies

I was on my bike last night as it was starting to get dark so I flipped on the lights. A few minutes later I noticed that my odometer/speedometer had stopped counting – it was displaying 0mph. Then I noticed that one of my lights was low on power. (I have two headlights. One of my friends asked me once why I have two headlights on my bike as if it was extravagant or something. There are stupid questions.) I flipped the headlight to a different setting and the speedo started working again. Then stopped again. Then I turned the light off completely and the speedo started again. So apparently my light was interfering with the wireless signal for the speedo. But there hasn’t been a problem between these two before so I’m wondering if maybe at lower battery charge levels the headlight gives off a slightly different frequency/radiation that interrupts the speedo. Will the problem correct itself when I recharge the batteries? We’ll see…