Using a trickle charger all the time?

So I've got a battery tender jr. (12v 750mA), and was wondering what your thoughts were about connecting it to my car battery on a regular basis. I just to a new battery (04 Mazdaspeed Miata), and since the battery is in the trunk, I can easily attach the pigtail permanently to the battery making it easy to connect the battery tender every time I park it. During the summer it is my daily driver, and it is also in the winter except if there is snow on the roads. Just wondering if it is good or bad to always hook the battery up to a trickle charger? I know it's probably unnecessary unless I'm leaving it parked for more than a week or so, just wondering if it would do any harm.

While it won't hurt your battery, I'd advise against using ALL THE TIME. during harsh winter months, its great to have the battery fully charged, ex specially when the cold zaps the hell out of the CCA on a battery. In the summer, might want to keep it off. Heat kills batteries, and the charging process creates heat. Soon, you'll start to experience diminishing returns on your charger and battery.

Also, since most alternators go bad during the summer, you may be masking the alternator failing by keeping the battery charged during summer. You won't know you've got a bad alt until your battery is toast.


If your driving this everyday in summer, then a battery tender is not necessary.

So, lets recap.

Winter: charger is good idea.
Summer: charger is bad idea.

17 years as an auto tech.

Hope that helps.

While it won't hurt your battery, I'd advise against using ALL THE TIME. during harsh winter months, its great to have the battery fully charged, ex specially when the cold zaps the hell out of the CCA on a battery. In the summer, might want to keep it off. Heat kills batteries, and the charging process creates heat. Soon, you'll start to experience diminishing returns on your charger and battery.

Also, since most alternators go bad during the summer, you may be masking the alternator failing by keeping the battery charged during summer. You won't know you've got a bad alt until your battery is toast.


If your driving this everyday in summer, then a battery tender is not necessary.

So, lets recap.

Winter: charger is good idea.
Summer: charger is bad idea.

17 years as an auto tech.

Hope that helps.
Yeah that makes complete sense. I guess I really was just thinking of the winter anyway. Great info, thanks.

its my experiance useing a trickle charger is always the best way to charge I have older plow trucks and there hard on the batteries large alternators help 500 up&side to side is hard on batterys trickle charging help this and keep them fully chargred for the next snowfall

its my experiance useing a trickle charger is always the best way to charge I have older plow trucks and there hard on the batteries large alternators help 500 up&side to side is hard on batterys trickle charging help this and keep them fully chargred for the next snowfall

Yeah I think what I'll do is never really use it in the summer, unless I know for some reason that I'm not going to be driving it for a couple weeks. Then in the winter iI'll just plug it in on the nights I know I'm not driving it the next day. I think that should keep it happy. I've got the pigtail hooked up permanently to the battery, although I had to cut the sleeve over the positive post a bit for the wire to fit, and it's not as clean as I would like but it's nice just having the little plug there anytime I want to plug it in. I don't have to pull up the carpet or anything. You think I need to worry about any power draw from the pig tail when it's not plugged in?

Shield the pigtail in a cover to avoid sparks or other problems.

Shield the pigtail in a cover to avoid sparks or other problems.

Yeah it has a little cap that goes over the plug on the end.

Then you are all set!