[Michael Bush]

>Turns out that the one I bought has a "safety feature" that requires it to detect voltage at the other end before it turns on the juice.
>I gather this is a pretty standard feature on any basic car charger.

It is now, which is why they are worthless. They will only charge a battery that already has some juice. They will NOT charge a totally dead battery. When I pull out a charger it's usually because I have a totally dead batter and those will not work on them. Give them to someone who would otherwise spend their money on a charger, or save them for AFTER you charged the batter on a real charger to top them off and turn off before it overcharges the battery, but they don't work to charge a DEAD battery. The automatic ones are great to KEEP a battery charged without overcharging it, but they are worthless for charging a dead battery. There are some out there still that are not automatic, but they are harder and harder to find.

You want one that is described as "Manual". You do not want one that is described as "Automatic".

http://www.amazon.com/Schumacher-SE...ef=sr_1_10?s=automotive&ie=UTF8&qid=1413373551&sr=1-10&keywords=battery+charger

 

[Michael Bush]

>but I screwed up and bought a cheap charger, that doesn't indicate when the battery is charged or how much. It also does not cut off automatically. I am afraid to use it.

You bought the right charger. It will actually charge a dead battery where the automatic ones just refuse to do anything for a dead battery... Charge it for an hour and start the thing. The alternator will take care of the rest. Besides a couple of hours of charging isn't going to hurt anything. It's when you go a very long time with no shutoff that it's an issue. Most of the manual ones have two settings also. Once you've charged about a hour on the high one, you can set it to the lowest one and leave it for quite a long time with no damage if you really want to. But nothing is more worthless than a charger that won't charge a battery if it's dead...