Dead Batteries: Winter Kill

Updated Dec 28, 2014

battery art_BWS4409When it’s time for a new battery, shoot for something bigger and better suited for heavy-duty use

By Allan Tarvid

It’s almost as cold in the shop as it is outside. A crew is waiting at the jobsite and you have a million things to get done before quitting time.

But when you turn the key on the company’s five-year-old diesel pickup, the engine barely turns over.

Dead battery. Time wasted. Money lost.

But it shouldn’t have come as a big suprise becasue there were plenty of little warning signs this truck’s batteries were nearing the end of their life cycle.

Hint number one of impending battery demise was the engine turning over more slowly than usual during cold starts.

Hint number two was a noticeable dimming of the headlights when you turned the engine off. Hint number three was the batteries were at  the end of their life as indicated by the labels on their tops.

Unfortunately, some sneaky batteries keep their failing health a secret right up until you turn the ignition key and nothing happens. But this wasn’t the case this morning.

Batteries come in three types suitable for work truck use. The first and oldest design is the flooded-cell, full-maintenance type.

These have removable caps that allow you to check the electrolyte level in each cell and replenish it as necessary by adding distilled water. This antiquated design remains popular because it continues to provide more amp capacity per pound and per dollar than other lead-acid battery types.

The chief downside to these flooded, full-maintenance models is that they must be checked and serviced regularly, including cleaning their tops and posts as necessary to prevent a buildup of crud heavy enough to leak voltage between their positive and negative posts.

Flooded, maintenance-free batteries also have flooded cells with vented caps but the caps are not removable. These batteries are designed to provide a lifetime of normal use without needing additional water.

The third type is the maintenance-free, absorbed glass mat (AGM) battery. The cell plates in these batteries are separated by layers of tightly packed fiberglass material that absorbs all the electrolyte.

There is no free liquid in the cells and an AGM battery won’t leak even if its case is punctured. No maintenance is necessary or possible, other than a seasonal post and top cleaning if required.

The cells are sealed and must maintain a slight amount of positive internal pressure to function.

AGMs have low internal resistance which lets them deliver power and be recharged very quickly. On the downside, AGMs cost a bit more and are a bit heavier than flooded batteries with similar capacity.

The terms “AGM” and “gel” are sometimes used interchangeably, to the peril of battery buyers! I would not recommend gel batteries for heavy duty pickup applications.

Charging voltages above 13.8 volts are generally too hot for gel batteries and can drastically shorten their lives. Most vehicle charging systems reach at least 14.4 volts, and I would not want to risk feeding the most expensive type of lead-acid battery that diet on a daily basis.

Upgrading your truck’s battery or adding an auxiliary battery system can be done safely by anyone with sufficient knowledge of electricity and an appropriate set of tools.

But, if you have reservations about doing it yourself it can also be done (and guaranteed) by your pickup dealer or a good automotive electrical shop.