How long are you holding the switch??? I hope no more than 5 seconds or so?. If I remember right the manual says 10 seconds. Done that one time and smelt like fried wires coming out of the tester. Another thing battery loose some ampree if they set awhile. I suggest you charge them up then run the test. I've tested several and the bad ones won't load test over 2 or three seconds with out meter diving to the bad side. Course we know they will show 12Vs even dead so the multimeter will only show volts and not ampree or amps, that's why you need the load tester to pull power off all the plates.

If you still don't believe it take the tested battery out and go to parts store compare with their load meter

A good battery will start the car after an afternoon of playing cassettes. What more do you need? ;)

Cassettes..What the heck , they still make those things Roflmbo ! :)

Hmmmmm. A battery tester from Harbor Freight? At 49 cents apiece, I wonder if they could be from a bad batch?

With that load tester the load only 100 amp. hold switch to load until see wire inside turning red volts on on meter should read 10 volts while holding load switch if does battery is good.
Most these tester will need needle zeroed small plastic screw on cover about where needle pivots very little movement on screw change needle.

Thanks for the input. I think Gator has the right idea. If it'll hold at 10 volts while supplying a 100 amp load it should be good. Contrawise, (is that a word?) if the battery is sulfated or otherwise unable to source that current it's bad. Also, that's a good reminder to check the "zero" on this or any other dial meter. I'd forgotten that....:-(

Guess it's a "wonderful thing" which I've now added to a barn full of "wonderful things" I've accumulated over the years.

Thanks again,

Ev

The HF price of $24.99 is about the same as a Schumacher load tester ... of course, the Schumacher might be made in China, too. But ExMar's price was $0.00; I'd take one at that price, but at $25 I'd go with the Schumacher.

Very few products are made in america. From air conditioners, electronic's, car parts, to hand tools. It's the american way to outsorce, cut labor, and management and owners to rake in the cash. But, at a price of the american comsumer which soon are running out of blue collar jobs which what made this country great. Bottom line we can't compete with near slave labor that products are alowed to be shipped into this country with no tarriffs so who suffers? I think I don't have to answer that. HF and about 95% of all products are made elsewhere or there components are. I predict (Hope NOT) in another 10 years we will be 3rd world country and NOBODY will donate billions of dollars to our policktisions or maybe a dictator by then so they can steal it. If you got gun better keep it you will need it to protect what little you have left by then. What can you do Vote any policktision out of office that's been there more than 8 years IMO they are crooks and liars by then and are not looking out for the voter but a slim ball liar stealing your vote with there lies.

The Schumacher BT-100 box says "Made In China to Schumacher Specifications." Just looking at the picture of the Harbor Freight model, looks like it and the Schumacher are first cousins.

Don Schumacher made millions off his electronic's and able to play around on the drag strip with all the teams he owns he would think atleast make his products in USA employing america workers. But, maybe that's how he got so rich?. I don't know if he even owns his electronic's company anymore???