Community Forums

lthrnk · 09-07-2007, 03:59 PM

Will a multi meter test battery condition as well as AC volts and amps. What would the consensus be on the best all around unit of this type and what should it cost? I know there are always different levels of efficiency and cost that go with it. What would be best all around?

lthrnk · 09-07-2007, 03:59 PM

Will a multi meter test battery condition as well as AC volts and amps. What would the consensus be on the best all around unit of this type and what should it cost? I know there are always different levels of efficiency and cost that go with it. What would be best all around?

KIX · 09-07-2007, 04:44 PM

A volt meter comonly is called a Volt/Ohm Meter (VOM) because that's just what the are capable of checking. Just as the name implies it will check volts or ohms of resistance and that's all it will do. Most can check either AC or DC volts. Some VOMs have an amprobe incorporated. An amprobe is what's used to check amps.
I would suggest that you buy a digital unit.
As far as which one is best and cost goes I'm not going to be much help. the one I have is older and its cost would not be representative of the cost of one today.
To check wet cell battery condition you would need a hydrometer unless there's something new that would be easier to use. Hope all ths helps you out.

Curtis F. · 09-07-2007, 06:58 PM

Harbor Frieght, on sale this month for $2.99. Close enough for camping use. Multi meter

Curt

Paul Heuvelhorst · 09-07-2007, 07:02 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Will a multi meter test battery condition as well as AC volts and amps. </div></BLOCKQUOTE>
Unless the technology has changed in the past dozen years, a VOM will not check:
1. Battery condition
2. Both DC amps and AC amps

In order to check the battery condition, you need a load operating on the battery. The VOM will tell you what the DC voltage is across the terminals when the battery is under load, which will give you an idea of how well the battery and/or charger may be performing. The best tester, in my opinion, is a hydrometer which tells you the specific gravity of each cell and if one or more cells are dead.

For checking the DC current draw on a battery operated appliance, the meter should be capable of testing amperage up to 10-12 amps. For checking the AC current draw on 110VAC appliances, you need an "amprobe" device which encircles the wires going to the appliance. Do not attach probes to the AC wires or their terminals to test amps. Remember, you are dealing with 110VAC and potential deadly shocks.

Of course, any VOM will test both DC and AC voltages. I prefer a selector that allows me to check DC volts on a scale up to 15 volts and AC on a scale up to 125 or 250 volts on an analog scale. If you get a digital display this may not be an issue. I don't own a digital volt meter.

I hope this helps.

Paul Heuvelhorst · 09-07-2007, 07:12 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Curtis F.:
Harbor Frieght, on sale this month for $2.99. Close enough for camping use. </div></BLOCKQUOTE>
Note that this meter does not check DC amps above 200 milliamp, which is completely useless for testing 12VDC circuits in an RV. It doesn't test AC amps. The voltage scales for DC and AC are good. So is the resistance scales for testing continuity.

It would serve me for about 60% of the functions I normally need a meter for.

RV Wizard · 09-08-2007, 12:34 AM

I too prefer a hydrometer to check wet cell batteries that have caps I can remove. As far as a multimeter, I have one I purchased from Sears for about $100 that will check AC & DC Volts, AC & DC Amps (clamp around for both), frequency in Htz., temperature, ohms and is digital. I have had many over the years but I bought this on for the DC amperage that can simply be clamped onto like the AC amperage always has been. Also for the fact that it has a frequency meter that is handy for setting some generator speeds. One thing is for sure, technology has surely advanced and will continue to do so. There is no telling what is available today.

Route 66 · 09-08-2007, 01:51 AM

Another consideration is your inverter.

If it is not a pure sine wave inverter, but a modified sine wave inverter, only a "True RMS" voltmeter will display an accurate voltage reading.

A "True RMS" VOM can be bought for less than $100.

Jeff_in_The_Dalles · 09-08-2007, 03:31 AM

I have an old analog multi-meter, and a cheap Sears digital.

Both will only measure milliamps, which is useful for some applications. A stand alone clamp on amp meter is handy for AC current.

If it is just something to keep on hand in your RV, I think I'd go for an inexpensive multi-meter. It is amazing what $20 or less will buy these days.

Gary RVRoamer · 09-08-2007, 07:31 AM

Many multi-meters, even cheap ones, have a separate circuit for 10A DC measurement. Typically you have to plug the leads into a different socket to get the higher DC amp function.

But the basic question was "will it test battery condition" and the only straight answer is "no". Batteries need to be load tested, which is a voltage measurement under a defined load for a specific amount of time. You can buy an inexpensive battery load tester (e.g Harbor Freight or many auto parts stores) for $30-$40 but they are designed for testing starting batteries moreso than deep cycles and sometimes show "OK" when in fact the battery will fade prematurely under a steady deep cycle load.

The hygrometer the others mentioned is an excellent (and cheap) way to test a wet (flooded) cell battery but cannot be used on maintenance-free, gels or AGMs.

nhgeezer · 09-08-2007, 07:47 AM

The old auto shop teacher hates to disagree about the ability of a plain old DVOM to check the battery condition boys. Use the vehicle at the load to check the battery with a DVOM. I get the same results using the DVOM and leaving the headlights and all chassis accessories on for 10 minutes as I do with my fancy shmancy load tester. If the battery voltage will stay about 10 volts after 10 minutes with all the chassis accessories on, that is ignition on but engine not running and wipers, heater blower, lights, hazards, and whatever else, then the battery is ok. For the hotel battery do the same. The batteries need to come back to about 12.5 volts or higher when the loads are turned off and the batteries are allowed to rest and recover for 10 minutes.

1990 Foretravel

Jeff_in_The_Dalles · 09-09-2007, 12:31 PM

I'd also say that you can get some limited information on battery condition with a volt meter.

For example, if you have batteries that have been performing well, and they have been sitting for a few hours with no load and no charge applied, and the voltage is like 10.6v, you can assume they are deeply discharged... and probably won't run the furnace through a night with temps in the teens.

A hydrometer test would be a more accurate indicator of charge level, but not everyone's batteries are easy to get to.

BryanL · 09-09-2007, 12:39 PM

That old auto shop teacher has wisdom, I think.

There is no direct means to test a battery. That is why, as Brad says, you put the battery under load and see how it behaves to infer what kind of shape it is in.

There are many reasons not to use a hydrometer anymore. With the same amount of due care to make proper measure, you can get an equivalent piece of data with a DVM. The DVM doesn't need you to remove the battery and take appropriate hazmat precautions like the hydrometer does.

A DVM can make load testing more accurate and faster as well. For an example of a low end battery tester that does this, take a look at the smartguage site.

I have seen even fancier ones for commercial use that are faster, smarter, and based on slightly different principles. Even the modern smart battery chargers have battery testers that they use to help them determine the best charge approach. Battery Testing Using Conductance Technology is a powerpoint presentation that might be of interest.

Paul Heuvelhorst · 09-11-2007, 12:18 PM

Yesterday I spent some time in the Sears tool department while DW was shopping for clothes. Sears offers several DVOMs for under $50 that will measure at least 10 amps on both DC & AC, as well as temperature, DC & AC volts, continuity (ohms) as well as other features if you want to spend a little more.

These were not cheap knock-offs. All appeared to be quality test equipment.

From a former electronics technician, now retired school business official.