The energy harvester potentially can develop up to 40v. The problem I have is that I want to shut off input voltage from the harvester if it goes below 3.5v. I have looked at many circuit designs similar to what I need, like solar panel battery chargers etc. But I cannot find anything that goes up to 40V.
The reason for this is that we have lots of these energy harvesters and we want to later connect them in series, so at the moment I have them connected to XL6009 buck boost device and have it set to 40v. So that when connected in series all the devices are at the same voltage and we don't get a drop in voltage from a weaker energy harvester. The problem is that when the voltage from the harvester is lower than 3.5v the XL6009 doesn't function but just passes the lower voltage through.
I want to stop this happening so when they are in series all the devices either have a voltage of 40v or nothing at all.
Hope this makes sense.
Thanks for any input on this problem. John