The least expensive way to keep track of what’s happening in your boat’s electrical system is with a voltmeter. The best way is with a system monitor. A voltmeter tells you the battery voltage, which gives a general idea of the state of charge (SOC) and charging and discharge. However, in order for the voltmeter to give you an accurate measure of SOC, the batteries have to sit for at least several hours (some manufacturers recommend 24 hours), before you can read the “at rest voltage”. This is hard to do when you are living aboard and the battery is constantly being charged or discharged. Your electrical panel probably includes a voltmeter. However, if it has a needle and scale (called analog), then it only gives a rough estimate. A fully charged battery at-rest voltage is about 12.8 volts. A battery at 50% discharge is about 12 volts. It is unlikely that you can see the voltage to an accuracy of 0.1 volts, unless you have a digital voltmeter, and even a digital voltmeter only gives you an approximation.
If you have an ammeter, it shows current flow in your system but cannot keep track of the total energy used from the battery bank(s).
The best way to keep track of your boat’s electrical system is with a system monitor. This has a display will tell you the battery voltage, amps, and battery state of charge (as well as a number of other things that are not as important, like maximum voltage, days since equalization, etc). We sell the TriMetric system monitor that has proven to be very reliable, as well as being the least expensive monitor.
We’ve also come up with a couple of tricks that can be used with the TriMetric (or other system monitors) so that you can monitor the wind and solar output. Call for more info.
TriMetric 2030 $190 BUY NOW
What the Trimetric 2030 can tell you:
- “Percent Full” (“State of charge”) of your batteries, so you can see if you need to charge them more, or check that overall usage is less than your charging resources.
- Volts of the batteries, for example to check that they are being charged at proper voltage.
- Energy going in, or out of your batteries, measured in amps or watts, so you can see that your charging sources are charging properly, or how much current your loads are using.
- How many days since the batteries were fully charged: to remind you to not wait too long between fully charging your batteries to maximize their life.
The TM2030 is easier for you to program the necessary system parameters.
- The TM2030 has some minimal data logging, which can be useful for a technician to diagnose some common setup or operational problems with battery systems.
- The TM-2030 will operate with (nominal) battery systems from 12 to 48V. The TM-2020 will operate with 12 or 24 V systems, but requires the addition of the “TM-48VA” Adapter and lightning protection board when using it with 48V battery systems. This also provides lightning protection for the TM-2020.
- The TM-2030 can also monitor the voltage only of a second battery, such as a starting battery, or possibly also the input voltage of a solar array (if less than 100 volts.)
- The TM-2030 has a “simplified” level of operation suitable for most users, but can be configured for more flexibility (and complexity) where occasionally required.
- (For the technically knowledgeable only) The TM-2030 has a serial data output of all the “real time” data—which could be used to access data for other control or output in, for example OEM applications.
- The newer TM-2030 includes better lightning protection compared with the TM-2020.
- It is easier to view and enter programmed parameters..
- It is about typically about $15 more than the TM-2020. For 48V systems it is less expensive than the TM-2020 because it does not require an extra 48 volt adapter.