Tool Review: Schumacher Electric Battery Extender

July 5, 2013
Easy-read display and automatic charging top reviewer's list

The Schumacher SP3 Battery Extender is a fully automatic microprocessor-controlled battery charger that maintains both 6V and 12V batteries, keeping them at full charge using float-mode monitoring. Perfect for charging small batteries. Great for maintaining small and large batteries kept in storage, including motorcycles, classic cars, RVs, boats. This 3 amp charger and maintainer provides a scrolling messaging display, and can automatically switch from full charge to float-mode monitoring. Other features include a quick-connect harness, the ability to snap either connector into place in seconds, rreverse-hookup protection, auto-voltage detection and a hook attachment to hang the unit outside the work area for safety and convenience.

The review

Tom Karagianis, owner of Tarkus Automotive in Milwaukee, WI, is no stranger to seeing batteries going dead on his rack or in his customers' garages. Sometimes, what his customers really need is a solid battery trickle charger to keep the battery fresh.

"(This tool) works like a dream," Karagianis said succinctly. "It's totally idiot-proof."

He found that the SP3 was intuitive and self-explanatory. "Yellow is charging, green is totally charged," he notes.

Karagianis observed that the tool was so simple to use that it appeared that they could be used by his customers.

"It's more intended for the consumer, like guys that park motorcycles and snowmobiles for multiple seasons," he says.

In fact, the first batteries he wanted to use it on were on his recreational equipment.

"I used battery tenders before on my snowmobiles and all it has is a red light and a green light," Karagianis continues. "This (tool) gives more detail so you can see what's going on. It tells you exactly what its charging, it has an LED display that tells you exactly what percent charge a battery has."

He also liked that the tool was set up with accessories that made it easy to connect in several different ways. 

"It comes with an adapter with ring connectors so it is easier to plug in to the battery and it has a DC connector that goes into the cigarette lighter," Karagianis noted.

There were several things he was unsure about. For example, he knew it had a 3 amp rating, but he was not sure if he could use it to retain computer memory when changing car batteries. He also did not know if it could be used on glassmat batteries.

"Basically, it's just a small battery tender," Karagianis says. "For the money, it's nice, it tells you if the battery is charged and automatically charges the battery.

When asked to rate the tool, Karagianis said "It's a 10. I like it for a battery tender. It basically 'talks' to you, it tells you the condition of the battery as soon as you hook it up."

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