Maintenance Free Battery!

[J Burns]

Long ago I read that sulfate left on battery plates eventually hardens. In addition, it?s good to have a battery well charged before hitting the starter because the surge can knock sulfate off the plates, shortening battery life.

I?ve been putting a charger on my car battery if it gets down to 12.55 V or less. I take it off when the current tapers to a certain point. A few days ago, I checked to voltage 8 hours after taking the charger off. It was 12.78. It must be a Maintenance Free battery!

Because the cell covers appeared to be removable, I assumed it was Low Maintenance (Sb/Ca) and not Maintenance Free (Ca/Ca). The two are charged differently. Nowhere on the case does it say what kind it is. Online, manufacturers of lead/acid batteries no longer seem to say which model is which. (Nowadays, Maintenance Free batteries often have removable covers.)

On the farm, cars used to have Low Maintenance. I used a Standard battery (Sb/Sb) in the truck because they were supposed to stand up better to vibration. I used a Maintenance Free with cushioning for the tractor because a Standard battery can self-discharge at 2% a day in hot weather. The tractor could sit for weeks and be far from an outlet.

I?d charge any battery if I found the voltage down. The automatic charger had a switch for Maintenance Free.

Somewhere, I got hold of the Battery Council International?s 1978 Battery Service Manual. It devotes 6 pages to Maintenance Free batteries. A graph of ?typical charge voltage characteristics? shows a Standard battery being topped off at 14.6 volts and a Maintenance Free battery at 15.7 volts.

My car?s regulator delivers 14.4 volts at normal temperatures. If it were set higher, it would be bad for a Low Maintenance or Standard battery. That explains why I need a charger to top my battery off. The Service Manual says Maintenance Free batteries charge on a taper. That explains why it takes hours to bring it up a little to 100%.

The charger I use now, has 2-millisecond pulses. It doesn?t say so on the case, but I checked it with an oscilloscope. It seems that the microprocessor determines the spacing of the pulses according to the voltage between pulses. Apparently, this allows it to charge any kind of car battery without a ?Maintenance Free? switch.

[Stormin Mormon]

If the battery is maint free, doesn't that mean you put it in your machine, and don't need the charger and volt check every few hours? Seems like a lot of attention and action (maint) for a maint free battery. Did I miss some thing?

[Tony Hwang]

Hi, I wonder, after all that trouble how much longer OP's batteries last? I usually replace my car battery on or about 5 year mark.

[J Burns]

Now I see why they quit labeling them maintenance free. Some consumers took it literally. Good for sales, bad for a brand's reputation.

I suppose I put meter probes on the terminals every 1500-3000 hours. It will probably be down, and I'll probably charge it.

[J Burns]

My last was a 2-year battery that worked reliably for 13. As it was being discarded when I picked it up, I was surprised.

I started checking batteries not to extend their lives but to avoid trouble, like being unable to start a tractor 1/4 mile from any road.

[Stormin Mormon]

Have you tried or used jumper packs? I saw one used, and was so totally impressed, I promptly bought one for each vehicle. Don't waste money on Harbor Freight, the one I got with the big 22 amp hour battery didn't jump my truck, but the older Winchester with

17 amp hour did nicely. The HF was new, and had charged overnight with the provided charger. The day before I needed it.

[J Burns]

I don't remember when I last needed a jump, but if I wanted to keep a charged battery on hand, I think I'd get an AGM.

Last year, I took a chance and bought one for my riding mower. Then I read an online recommendation not to charge an AGM over 120 F. Mine was getting nearly that hot until I put in an insulating board.

I've occasionally checked the voltage and never had to charge it. AGM takes a charge pretty fast, loses only 1-2% per month, and doesn't grow sulfate crystals if kept charged. It's resistant to vibration, fairly light, and doesn't leak.

I'll have to look into the possibility that my mower is overcharging it. If the electrolyte dries up, that's all she wrote.

[Tony Hwang]

Hi, Often charging circuit/component is not well.

[J Burns]

One time I boiled my battery dry on a motorcycle in Canada. The regulator points had stuck.

I had a car that sometimes had a dead battery. I never figured out what had been left on. I suspected that sometimes a door wasn't fully closed, but when I'd walked past the before, the doors looked closed and I didn't see any lights.

One morning when I jumped it, I connected the cables wrong. There was something unusual about color coding of the positive and negative sides, and I was sleepy. As soon as I clamped the cable to the ground of the car, I knew it was wrong, but it was too late. The alternator didn't work after that. It could have been worse.

As I recall, other than that, the problems were corrosion on posts, batteries that hadn't been run enough, and batteries that should be replaced. It was better to find out sooner, with a meter, than a few weeks later, when it might fail to start.