Monitors for Starting Batteries

There are very few solutions available for monitoring the health of engine starting batteries.  Only Crankcheck testing provides the information necessary to know when to replace a battery before it fails.

Battery volt meters:

Many cars and electric vehicles already include some type of battery volt meter, and many battery volt meters are available for aftermarket installation for use in boats, RVs and other vehicles. A voltmeter often has an analog needle ranging from 10 to 14 volts, or they will have a series of LED lights that turn on or off as the battery voltage changes. 

Poor 'Fuel Gauge' / State of Charge information

Unfortunately voltage is not a very useful battery attribute to monitor to understand battery charge level. Battery voltage is related to battery charge level only when the battery is completely at rest (not being charged or discharged). However, it is most important to know the charge level while you are using the battery, not after you have stopped.  

No Battery Life / State of Health information

Battery voltage is not at all related to battery health.  A voltmeter does not provide any battery life or state of health information. Without battery life information you have no idea what condition your batteries are in. You will not know if they are up to the task or if they have reached end of life and should be replaced. 

Low voltage disconnects:

A low voltage disconnect device can be purchased in the aftermarket and added to a battery wiring harness. The device will measure battery voltage and if the voltage drops below a specific level the device will disconnect the battery from the vehicle.

While these devices can reduce the consequences of an accidental deep discharge, these solutions are not really monitors as they do not provide any information at all.

A low voltage disconnect is not the solution if you are looking for information that can help extend the life of your battery or information about when to replace a battery nearing end of life.

Crank effort testing

Crank effort testing is one exception to the general rule that "you get what you pay for." All other methods discussed above offer little direct information about how the battery is able to perform a specific job. The crank effort testing method is designed specifically for batteries used in engine starting applications. By measuring the effort required by the battery to crank the engine, the battery's cranking health can be determined and plotted along a scale of 0 to 100. This result is the most direct and useful indication of performance because it is based purely on the battery and its demonstrated ability to perform the specific task it is needed to perform. 

For a more detailed description of Argus' Crank effort testing, please read about CrankCheck.