How Do You Prevent Battery Sulfation?

Will multiple battery chargers solve the problem for this owner of seven bikes?

deltran, battery tenders, battery chargers, sulfation
Low charge, or a complete discharge, over time leads to sulfation and a dead battery; sulfation can kill a sealed battery, too, if it’s insufficiently charged or allowed to go flat.©Motorcyclist

Q. There are four riders in my family, and we have a total of seven motorcycles —two vintage bikes, five modern. Since there aren't enough of us to ride all the bikes at the same time we alternate taking them out to keep the gas fresh and the batteries charged.

Recently two of the batteries, one in a vintage bike and another in a modern one, went flat, and when I took them to the shop to have them recharged I was told they were no good and would have to be replaced. The vintage one showed what the mechanic called sulfation—white chalky stuff in the bottom of the battery. He said the load test showed the modern sealed battery was probably sulfated too. So I bought two new batteries and a couple of battery chargers to put on the bikes that don't get ridden much. Will this solve the problem, or am I looking at buying five more batteries soon?

Tyler Drake
San Diego, CA

A. Our advice is to buy a few more battery chargers—or maybe just create a routine where every bike gets on the charger for two to four weeks at a time. And make sure they're float chargers that bring the battery to a full charge and then go into a "sleep" mode until the voltage drops enough to turn the charger back on. This prevents overcharging, and thus overheating, the battery; it's especially important with a wet or flooded battery (the kind you add electrolyte to occasionally, as opposed to a sealed battery).

According to Deltran’s Larry Gordon, there are common causes of battery failure. Low charge, or a complete discharge, over time leads to the sulfation you saw; sulfation can kill a sealed battery, too, if it’s insufficiently charged or allowed to go flat.

Vibration or impact can separate the plates in the battery or break the connection between them. If one of those vintage bikes is a big single, this is the first thing to look for. Take a moment to check the voltage across the battery terminals with the engine running to get a read on each bike’s charging system. The voltmeter should read 13.8 to 14.2 volts with the engine above idle. More and you’re probably cooking the battery. Less and it’s unlikely to be getting a full charge while you ride.

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