Testing Marine Battery Monitors


Our test gear comprised a ProMariner ProNautic 12-40P battery charger; West Marine-branded, flooded-cell, deep-cycle battery with a 75-amp hour rating; and two 120-volt, 70-watt incandescent light bulbs powered through a Heart 140-watt DC to AC inverter. This setup created a 12-amp DC load on the battery. We confirmed voltage and current draw using a Fluke Model 867B graphical meter and a Blue Sea Systems Model 8110-amp clamp/multimeter.

Victron monitor

We ensured that for each product tested, our battery was at full charge, and we monitored both amp draw and voltage levels as we discharged the battery. We compared these values as we timed the constant 12-amp draw. We found that all of the units were quite accurate, but understand that this was a very controlled test using new equipment, most importantly, a new battery. The need to recalibrate this equipment as batteries age cannot be overstated, if extreme accuracy is desired.

Testers spent time analyzing the potential difficulties with installation and what the manufacturer provided to facilitate installation, including a wiring diagram and calibration instructions. It was in these areas where we found a rather broad disparity between the different manufacturers. Some units were clearly too challenging for most boat owners to install and calibrate themselves, and the units were so poorly supported that the average do-it-yourselfer would soon become frustrated. Other monitors were much easier to manage, and could be installed and calibrated by any handy boater who is capable of closely following instructions.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at darrellnicholson.com.


  1. Here it is. I’m sorry about the inconvenience. We post all test protocols separately because those are public domain for the science community to replicate our tests. Many of these protocols do not have back links to the original subscription-only articles. This is something we are working on. In the meantime, it should be easy to search the archives. The original article came up by entering “battery monitor test” in the search box. https://www.practical-sailor.com/marine-electronics/best-battery-monitor-test-update. Searching by brand or model helps narrow the search more quickly. Newer articles should rise to the top, but many of the older articles are still very relevant and to into more detail.