As noted in our recent article on lift truck batteries ("Battery room confidential"), batteries that appear to be interchangeable can have subtle differences that make them unsuitable for certain applications. What works in dry, moderate temperatures, for example, may be ineffective in a cold storage warehouse. A battery that performs well with a DC (direct current) motor may not last a full shift in an AC (alternating current) truck.

Those examples aren't exactly surprising. But here's one you might not have thought of: A battery can be the wrong weight for a particular truck.

Electric lift trucks rely to varying degrees on the weight of the battery to safely counterbalance loads. But operators who are swapping out batteries sometimes focus solely on the replacement's physical dimensions and output capacity while giving little thought to its weight. That oversight can lead to unsafe lifting conditions that could cause a truck to tip over. "Just because a battery physically fits into a [compartment] doesn't mean it will be heavy enough," Tony Amato, executive vice president of battery distributor Industrial Battery Products Inc., told us. And just because it's heavy enough for one truck doesn't mean it will meet the standard for another model, even if that truck is from the same manufacturer.

Some batteries weigh more than others of the same physical size. To ensure the battery you plan to use is heavy enough, Amato recommends checking the lift truck manufacturer's "minimum battery weight" specification, which is often listed on the truck's data plate. (If not, you can get it from your local dealer.) Be sure, too, to verify the battery's weight, which is usually stamped on the outside of its case.