Maintenance Q&A
Battling battery woes

Q.This winter, I had family health issues that required I be home each night. My dispatcher switched me from long haul to local pickup and delivery work. I averaged about 15 stops a day. In February, I couldn’t start the truck on five different mornings. Do I need a different alternator for P&D work? Do I need stronger batteries? My mechanic sold me a new set of batteries mid-month and I didn’t have starting problems after that.

A.You probably don’t need a new alternator, and you may not have needed the new batteries. When engines get cold-soaked (left at cold temperatures for prolonged time periods), they require more cranking power. An engine at zero degrees needs 50 percent more cranking power than one at 32 degrees. In your hometown in northern Wisconsin, overnight temperatures often got below zero and daytime temperatures rarely got above freezing.

Your alternator was most likely putting out its designed current, but batteries lose the ability to accept a charge as they get colder. A “full” charge at 0 degrees may be only 75 percent of a charge at 32, and around 60 percent of the measurement standard of 80 degrees.

Those percentages assume there has been enough time for the batteries to get a full charge, but that may not have been the case in your operations. Given a full charge at the start of your day, you averaged 15 starts, 15 short runs around your area, and very little time on the interstate to get your batteries back to a good state of charge. Add in time spent loading or unloading, waiting and doing paperwork with your engine off, and your batteries had time to cool off between actual highway runs.

Bruce Purkey is chief creative engineer at Purkey’s Fleet Electric and TMC’s go-to guy on matters electrical. He cautions that it is important to keep batteries fully charged. Incomplete charging leads to problems that shorten service life. Issues that might lead to incomplete charging are short engine run time especially in extreme cold conditions, incorrect alternator output for conditions, and faulty circuitry.

You can boost alternator output at lower engine rpm by simply changing pulleys to get the alternator to turn faster.

Check battery and alternator cables for corrosion from the road salts used in your area. Make sure to check the strands of braided wires if any cables show signs of corrosion. You can save a bit of money by fabricating your own cables with wire and fittings from an automotive or truck parts supplier. If you do, consider stepping up one size cable and get insulation suitable for commercial use. Spray or brush sealer over any exposed cable ends and fittings to avoid, or at least delay, future corrosion problems.

Finally, if you can, hook up your batteries to a charger overnight. You’ll reduce the amount of discharge your batteries experienced during the day and will raise the batteries’ internal temperature to provide more cranking power in the morning. Make sure your charger has enough amperage to handle all four of your batteries and an automatic shut-off to prevent cooking them after the charge is complete.

Q.This winter, we got pretty cold in Fargo. So when my truck wouldn’t start, I called a road service provider for a jump-start. When he started to hook up the cables, he stopped and said I needed new batteries. He refused to jump-start my truck. He said my batteries had been frozen. I was already late for my pickup so I told him to go ahead and put in four used 750 CCA batteries, and he said he’d credit me against any new batteries I wanted to buy.

My questions: Do batteries actually freeze? What strength batteries should I get?

A. Yes, batteries can and do freeze. The liquid in a fully charged flooded cell battery is 35 percent sulfuric acid and 65 percent water. As the battery discharges, the acid reacts with the plates and releases electrons into the wiring. That gives us the electricity we consume, but depletes the acid in the battery electrolyte.

Fully charged, a battery won’t freeze at even extreme low temperatures. But when a battery is fully discharged, the acid level drops to the point where it can no longer function as an antifreeze. And the electrolyte liquid, which contains about 15 percent sulfuric acid, will freeze at around 20 degrees. It’s similar to a radiator with only 15 percent antifreeze in the coolant instead of the recommended 50 percent.

When coolant freezes, the water in it expands with enough force to split the header tank or, if not for freeze plugs, crack the cast iron block. When the water in a battery freezes, it expands with enough force to bulge or crack the case.

When the alternator charges the battery, it forces electrons back into a battery, converting lead sulfate on the plates back to sulfuric acid and lead. But physical damage is not reversible. Your road service provider was wise to check the battery case for physical damage and to refuse to charge your batteries. It could have been quite dangerous and might have caused an explosion.

Also, the offer to credit you toward the batteries of your choice was quite generous. Some service providers will bring just one set of batteries if any at all. Most just bring their jump-start cart. LL