Apparently knowing how many hours of use is necessary to keep your portable generator working properly is the way to maintain it. I have several coiled cord cig lighter adaptors for old cell phones I no longer use- they provide 6vdc,when plugged to a 12V auto outlet. I found an hour meter on E bay that has a minimum 6v input so for $8 it works perfectly, you do need to have a cig adaptor outlet to use it......I cut the end off the adaptor and used generic spade connectors from a kit I bought at a hardware store years ago.