Tell me about trickle chargers

April 1, 2015 | By Jim Richardson

Question:

What are the good and bad aspects of trickle chargers? Are there plusses and minus’ to using them for long-term storage?

Answer:

I have used the automatic, self-regulating types for years, and have found them invaluable. Without them, those of us with what many people would say were too many cars would be buying a bunch of new batteries every year. My favorite is the Deltran Battery Tender because it has its own minicomputer that monitors the battery for you. Deltran has not paid me to say this, but I try to recommend things I know will work. Battery Tenders are a bit more expensive than some brands, but I have had good luck with them https://www.batterytender.com/.

When taking into account older classics from the ‘60s on back, you will need to be careful to use a charger of the correct voltage for your car. You don’t want to hook up a 12-volt charger to a six-volt car, and vice versa. Also, it is critical that you hook the charger up correctly. If a car were positive ground, you would hook the positive (red) cable to a ground, and the black (negative) cable to the hot side of the battery. But on most more-modern cars the red wire goes to positive and the black to ground.

Also, since lead acid batteries give off hydrogen gas as they charge, leave the hood open on the car while charging to prevent any buildup of fumes. On a typical 12-volt system, hook the positive lead to the positive terminal of the battery, and then hook the negative lead to a clean bolt or other part of the chassis. That lessens the rather remote but not unheard of chance of a fire from the gasses when you hook it up to the other battery terminal.

On very old cars that have the battery under the seat, you can hook up the correct lead to the large starter cable at the starter terminal, and then attach the other to a good ground. I do not have any newer cars with computers or preset radios in my collection, and I am old school, so I go to the extra trouble of taking the battery out of the car and putting it on a wooden bench for charging if 1am going to be storing the car for a while, but that is more effort than really necessary.

Whichever brand of trickle charger you buy, make sure it is self-regulating and shuts itself off when the battery is topped up. Even at 1.25 volts, you can eventually damage your battery if a trickle charger without a monitoring system is left on for a long period of time.