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Concentration of CO2 in the Atmosphere

The TriMetric Monitor: A Gift for “Off-gridders”

The author’s TriMetric monitor, TM 2030 A, shows 58.8 volts at 3 pm, February 13, 2016.


By N. R. Mallery

Solar power has become a mainstream option today. Battery backup systems are necessary, if you are “off-grid,” and an option if you are grid-tied. A generator is recommended, if you are off-grid, to be able to keep batteries charged when necessary. This generally requires the use of fossil fuels.

At present, the most widely-used battery systems still use lead-acid technology, which requires maintenance. Neglect will compromise the health and life of the batteries and your investment.

Neglect can happen if the batteries are charged excessively, or if they are allowed to discharge too far. Batteries can suffer because they are allowed to sit with a partial charge too long or from repeated failure to bring them to full charge when necessary.

Maintenance is made much simpler and better by using the proper tools. If the system has lead-acid wet-cell batteries, the electrolyte solution needs to be topped off in each cell, as necessary; a hydrometer should be used to check the gravity.

It is important to get a complete picture of the battery’s charge state. A battery that may seem to be at a full state of charge may actually not be. There’s more to the picture.

This is where the TriMetric comes into use. It is probably the most important tool available to understand what is going on with your batteries. (Your power is dependent on the health of your battery bank. It is how you are able to have electricity when the sun is not shining.) This handy tool tells the full charge of a battery system by measuring both the voltage and the amp-hours. It is compatible with lead-acid wet-cell, gel, and AGM batteries, as well as some other types, including some lithium batteries.

It’s awesome to look at the TriMetric and see that your battery system is 100% full after just a few hours of sunshine. But, the TriMetric is designed to give you a more in-depth reading and understanding of what is behind the scene. When a battery is charged the amp-hours need to be somewhat higher than what had been discharged. Without keeping track of this information, recharging correctly is guesswork, to a good degree. Because the TriMetric measures the number of amp-hours, in conjunction with the voltage, the information can be used to be able to recharge batteries to the correct amount.

The TriMetric also keeps track of a lot of other useful data such as the time that has passed since the last charging. It can record the length of the charge-discharge cycle. It keeps track of when certain other maintenance procedures were last done. It has audible alarms, a display that can be read in the dark, and more features that are helpful for technicians.

I don’t know what I would do without it. It not only helps to know how the batteries are doing, but it also tells you how much energy you are using at any given moment. This awareness naturally leads to not wasting the energy that is stored in your batteries, which is what you live by when you are off-grid. It can also help to keep your dependence on fossil fuels to a minimum.

The TriMetric is a product of Bogart Engineering. The web site is


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