[rpmerf]

I've used the harbor freight one for years. I've read some bad reviews on them, so seems they might be hit or miss. I keep them on old batteries that I wouldn't trust in my car, but still hold a charge, so not a huge deal if they don't get charged. Overcharging is a different issue, so I have it on a lamp timer I run for about an hour a day. I check the voltage on and off every once in a while.