RV Electric Power for Dry Camping

Blog Index

Technical Issues and Projects

Home Page





Electrical Test Equipment


For Working with RV Electrical Systems


I have a few very basic Meters and testers.  You don't need to have all these, but it sure helps.  None of them are expensive. 


Clamp-On Volt / Amp meter


The clamp on volt/amp meter is likely the most versatile and useful tester you can buy.  This Sears model 82369 measures DC Amps as well as AC and is a steal at under $60.  Few meters in this price range will measure DC Amps.  Most will only measure AC Amps.  So I highly recommend this one.


No, it isn't a Fluke - but it also doesn't cost $300! You'll find some other options HERE









Digital Multi-meter


This is a good quality digital multi-meter, but not expensive.   You can get this model on sale at Radio Shack for under $30.  DC Volts scale is very accurate in the 12 to 15 volt range for testing battery charge status.  Reads to 3 decimal points. 


My only complaint; I'm an old electronics tech from the 70's, and I really hate digital meter's for continuity testing.  Sure, they're more accurate, but it's so simple with an analog meter to touch the ends and watch the needle swing instantly across.  Digital meters have a little lag, and I find it hard to adapt.  Just my little gripe


You can find many other multimeters here















AC Outlet Tester

AC Outlet Adapter


Here's the latest addition to my collection.  Shown here with a simple AC outlet tester plugged into it.  For less than $35 the Kill-A-Watt allows you to accurately measure Amps, Volts, and Watts, Frequency, and KWH used for any AC appliance of 15 amps or less.


This has several uses.  Serious boondockers use it for doing an "energy audit".  You can see how many watts each appliance uses, and figure usage time allowable with your particular solar/wind/battery combination.


I also use it when we arrive at a new hookup campsite.  I plug the KAW into a 30 amp adapter.  Then I plug a circuit tester into the KAW.  Finally, I plug it all into the power post and throw the breaker.  In a matter of a few seconds I know if the post is wired right, and what the voltage is.


Other models and styles are available and you can see them all here




What am I Missing?


A couple of things.  First, if you have regular flooded-cell lead acid batteries you need a good hydrometer.  We have AGM batteries, which are sealed, so we don't need one.


Battery Hydrometer


You use a hydrometer measures specific gravity of the electrolyte in each cell of your battery.  This is the most accurate way to determine your battery's condition.  Voltage measurements are useful, and important, and you monitor voltage each day; however, a volt meter can't tell you the condition of each CELL of a battery.  The hydrometer can. 


Your hydrometer will come with instructions, so I won't go into detail on how to use it.  I will recommend frequency of use -- once every three months when dry camping.  If storing the RV you should check batteries before putting it away, and as soon as you take it out.  If you take frequent trips, you could switch over to the 3 months schedule.  Keep all the readings in your maintenance log for future comparison.


Which hydrometer to buy?  DON'T buy one that looks like a plastic anti-freeze tester.  This is junk, you may as well not bother. What you need is a professional tool that will accurately measure specific gravity so you can detect small changes, and so you can see differences between cells.  These used to be expensive, but these days you can get a good one for under $20.  Some battery shops carry them, but I've found that most do not.  It will be glass, not plastic.  It will have instructions for use, and a scale for correcting the measured values for temperature correction.  Some hydrometers include a built in thermometer, although many people use air temperature if the batteries are in shade and have not been charging (and therefore heating up).  Here are a lot of options


Battery Monitor


Another item I'm missing is a good battery monitor system, like a Trimetric from Bogart Engineering.  Without getting technical, these are like "fuel gauges" for your battery bank.  They'll tell you how many amp hours you've used, battery % of charge, and much more.  You can buy these, and similar meters, from about $140 up to $350.  More advanced units run well over $400, but for a basic battery bank they're overkill.  Some people swear by their TriMetric and feel it's an indispensable component of their system.  I believe they're very useful, but not an absolute requirement.   I may get one some day. 


Continue on to Battery Types -- or choose another topic from the menu in the left sidebar at the top of this page.