I have and use two C40 voltage controllers, one of which is from 2014. All are still working. However, this C40 failed two months after it was installed in September of that year. I used to be able to call and get tech support with the C40, now I can't even use email. What's even trickier is that there is no way to return this or contact anyone as the return window and support window have expired per the fulfillment center policy: 1. This device could mean life or death for someone offline in the middle of nowhere. When a device fails, you don't know until you realize your inverter is beeping to indicate it's out of battery2. If you're still planning on buying them, make sure you get a few. and understand that if one fails, you will not get your money back.3. The best approach is not to order from the Revain Fulfillment Center but from other suppliers who risk losing their business by acting as Revain Fulfillment. :-(
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