Fechino Files: A Better Understanding of Batteries

Batteries are used every day in our work, from big trucks to small trucks, equipment, cars and hand tools. They for the most part seem to be maintenance free, but with a better understanding we can help them last longer. If you are not comfortable using battery chargers or voltage meters, please do not attempt the discussion below.

First of all, batteries are Direct Current (DC), which means that the current flows in one constant direction. All of our tools, computers, devices, and vehicles are powered using DC current. Alternating Current (AC) is the power we receive from the power grid, and this is what we use to power our buildings and utility lighting grids. Alternating current will invert its direction, and this is the difference. 

We all use computers, phones, tablets, and a host of other portable rechargeable electronics on a daily basis. Our chargers just plug into the wall and, boom, we are charged; because we charge our devices from the Alternating Current to Direct Current using an AC/DC converter. That block that we connected to the USB cord or the block on the cord of your computer is, in fact, an AC/DC Converter, which will rectify and filter the Current.  

When we charge our vehicle batteries, the battery charger might be a Schumacher brand item. I have used these over the years. Today's battery chargers are basically AC/DC converters; however, offering a non-constant voltage and amperage, they still provide the charging capabilities required for the DC battery used in today's vehicles. Battery chargers are far more advanced than 20 years ago. Today, they have sensors that will not overcharge a battery, as when the internal reading is full charge, the unit will turn off until the proper voltage has dropped and then will restart and provide the proper voltage and amperage to fully charge the battery once again. In the old days, we would use a trickle charger to maintain a battery. With today's technology, they are all part of the larger chargers. If you are still using the older chargers like I am, before you clamp on a battery charger, use a voltage meter to check the voltage of the battery you want to charge and make sure you are greater than 11.8 volts (considered a dead battery) and lower than 14.2 volts (considered a fully charged battery). A battery that has a 10.3 voltage reading potentially has a dead cell, and when a new battery charger is used to charge this battery, it would be common to see it charging for two hours. If the amperage and voltage do not increase, the charger will automatically turn off; this will indicate that battery replacement is in your future, like that day.

The older battery chargers generally do not go bad sitting in your shop. However, you cannot actually test a battery charger by checking the voltage from the terminal clamps. A battery charger will not begin charging until it is connected properly to a battery. At that point, the way to check a battery charger is to check the voltage of the battery after 2 hours. I was always told that a 10-amp battery charger should be turned on the night before, but today, a typical charger will top off a battery by typically 80% in just under 3 hours.

Batteries for our larger equipment are sometimes connected using more than one battery. Multiple batteries can be connected to each other in two different ways: Parallel and Series.

Batteries connected in series are used to increase overall voltage output. When connecting in series, the positive of one battery is connected to the negative of the second battery using a pair of jumper cables. The positive and negative terminals that are not connected at this point are the connections that will be made to the vehicle. The benefit of connecting in series is that the current voltage of the two batteries will be added together. For example, two 12-volt batteries connected in series will develop 24 volts of usable power. Note here that the weaker of the two batteries typically will discharge slightly faster, which is something to troubleshoot if you are having trouble with series voltage.

Batteries in parallel are when you connect the positive of the first battery to the positive terminal of the second battery, then to the connection on the vehicle. The negative of the first battery is connected to the negative of the second battery and then to the ground. This method does not increase the voltage of the battery. The benefit of connecting batteries in parallel is that the voltage remains the same as the individual battery. However, the available amperage is increased and, in some cases, is required for the vehicles' starting systems or operating systems.

When jumping starting a vehicle as a kid, I would always clamp the positive end of the jumper to the positive battery terminal and the negative end of the jumper cable to the positive terminal of the battery. In today's newer vehicles, even some of the newer off-road equipment, it is important to find the ground on the engine as many newer negative battery terminals have a voltage regulator/limiter that may cause additional issues if connected "the old way." As many of you know, when I write these articles, I try to prevent folks from making the mistakes I made. I'm not saying I learned about the negative battery cable regulator/limiter personally, but I can say it cost me $87.69 for the part…I mean, it cost someone I know that much.