Should I buy a solar trickle charger?

February 8, 2007 8:34 PM

Car battery solar trickle charger -- fact or fiction?

So I don't drive for like 2 weeks at a time. In the winter, this means dead battery. Googling around indicates that there are these solar "trickle charger" devices sit on your dash, plug into your lighter socket, and slowly charge your battery. Has anyone actually used one of these things? Did it work? I'm skeptical.

Example here.

posted by Mid to technology (16 comments total)

Replace the battery? There shouldn't be a reason for a car battery to be dead after only two weeks without being run

In addition, the winter time period is the worst for solar power, and I can't imagine it would be enough power being pushed in to be worthwhile to do. On the other hand, I've never tried.
posted by cschneid at 9:11 PM on February 8, 2007

Dead after two weeks? Invest in a battery, not a charge.
posted by caddis at 9:15 PM on February 8, 2007

also, check to see whether you have some low drain going on, like say a light in the glove box not going off when it is shut.
posted by caddis at 9:15 PM on February 8, 2007

i've never used one of those exact devices, but the theory of it is perfectly sound. and i have seen trickle charging setups working with lead-acid batteries, that while they weren't in a car, were basically car batteries. so i think it would work just fine.

that said, trickle charging your battery isn't going to help much if it's old and it's too cold for the chemistry to do its thing.
posted by sergeant sandwich at 9:34 PM on February 8, 2007

While I have not used the solar powered ones, I have used one of those that plug into your cigarette lighter/12v plug - they are fine if you left your door ajar for a few hours - for instance if the key is in the ignition and when the door is open, your car will buzz but not enough juice to start, one of those mini things will work and presumably the solar powered ones will do the same but if your car is like an old truck I had that would go dead after two weeks, even a full battery charger would not work - wouldn't efven get a click. I actually had to connect my other car - run that for at least 10 minutes so anything less than another car was too weak ... and yea, my truck had a leak because the moron before me hooked up the radio to the interior lights so that would drain ... you can cheat by trying to figure where the drain might be and removing that fuse ...
posted by jbelkin at 10:03 PM on February 8, 2007

I have one like this. It came with my 2003 VW Beetle.

My son likes to sit in the car and play the radio really loud. He gets to do this as long as he likes, provided there are a few hours of sunlight until I next need to drive the car. It works great. It is a very handy thing to have.
posted by Methylviolet at 10:09 PM on February 8, 2007

Third-ing (or fourth-ing) the battery replacement. We had a mild winter *last* year, but my Chevy V-8 (with high compression) turned right over after months sitting.
posted by notsnot at 5:30 AM on February 9, 2007

you might have a short in your electrical system - check if your trunk light goes out when you turn off the car, mine doesn't. It's been too cold to try to find the problem so I've been disconnecting the negative terminal on my battery in between starts. No worries about a dead battery if I don't drive my car for a couple of days. Just open the hood and slip the terminal back on.
posted by any major dude at 5:48 AM on February 9, 2007

I have one that looks very similar to the one you are looking at and it is pretty worthless for anything but very small charging needs. If you look at the technical specs these devices only put out a few hundred milliamps-enough for a cell phone but less than half of the 2 amps a standard trickle charger puts out and a far cry from the 30-50 amps a regular charger puts out. With those kinds of outputs it would take several hundred hours to fully charge an automotive battery. And those numbers are for the panel in full, direct sunlight; the power output falls off pretty quickly if there are clouds or shade. There are solar chargers out there that provide more power, but those are typically in the hundreds of dollars.

If you have access to an electrical outlet near your car, something like this Battery Tender is a much better investment.
posted by TedW at 6:14 AM on February 9, 2007

Actually, looking at the Battery Tenders, I see they only put out 750-1250 mA. However, they do it constantly, at night and in the shade, so they are still far better than the solar panels. I have and use one on my motorcycles.
posted by TedW at 6:17 AM on February 9, 2007

My father-in-law is a car dealer and he uses them in nearly all the cars on his lot to keep the batteries from dying. But as others have said, a battery should last two weeks. You might need a new one.
posted by GuyZero at 6:53 AM on February 9, 2007

the lighter sockets in my car shut don't work when the car is off so I don't think one of these should work for me. Might want to check your car for this before you invest in one.
posted by subtle_squid at 8:26 AM on February 9, 2007

A plug-in trickle charger that connects to the battery (not the 12V power point) is what you want. Either that or run the car for 15 minutes every few days.
posted by bonehead at 9:34 AM on February 9, 2007

Replace the battery. You have a new $60 dollar battery in one hand, and a $30 recharger in the other. With the recharger, you'll have to plug it in and hope for sun, and hope it works with your 12v socket.

Batteries have a lifespan of 4-6 years. You WILL replace your battery. You have a choice as to if it happens at the worst possible moment when you really need your car to start, or a moment of your own choosing.

The same goes for water heaters. You're going to replace it in 10-12 years. Whether you do it now, or with 3" of water in your basement is your choice.
posted by duncantuna at 1:10 PM on February 9, 2007

Thanks, all. I was crazy at work today or I would have checked in and added the following: it's not the battery, this happens to me every year. My car must have some small short somewhere that is only a problem in the winter (this only manifests in the winter). But I've needed a new battery every winter for the past 3-4 winters.

The car is old (11 years), so I figured a $30 trickle charger might be better than trying to find the short and fix it, especially because the short seems like a very small deal -- only causes a problem in the dead of winter if I don't drive for a week or two.
posted by Mid at 8:19 PM on February 9, 2007

The solar chargers come in a range of sizes, and obviously, the smaller it is, the less power it produces. It will work if it's not too small, but the $30 one is at the small end of the range. (Also, the windshield will reduce efficiency of the already cheap-ass cells). So yes, I would think a solar charger is a good solution for you, but whether you need a more expensive one a few sizes larger or whether that little wee one would be enough, I have no idea.
posted by -harlequin- at 10:36 PM on February 10, 2007