Test for charging house batt

otrfun wrote:

ktmrfs wrote:

otrfun wrote:
IMO every RV'r should have a cheap, clamp-on ammeter that can read DC current. Most clamp-on ammeters include all the standard functions found on a simple voltmeter, so no real need for a separate, dedicated voltmeter (2 for 1).

A clamp-on ammeter is easier to use than a voltmeter when making current readings. Simply clamp the ammeter jaws around either battery cable to make a reading. It will tell you exactly how much charge current your battery is or is not receiving. It will also tell you much current is being drawn from the battery when it is not being charged. Important readings that a voltmeter cannot provide.

Not all clamp on ammeters are equal. The very inexpensive ones use a toriod (transformer) to sense current and only measure AC current. Not much use for an RV. Luckily the hall effect probes have come way down in price and can measure DC, AC and in some cases DC+AC current.

If the probe does measure DC and does NOT have a button to zero the reading, pass it up. Hall devices look at the magnetic field induced by current flow and also are sensing the earths magnetic field. Orientation affects the fields so there needs to be a way to zero the stray fields. If it does have a zero button check how close to "0" the reading is. should be within 1 or 2 digit(s) of zero. If so you likely have a clamp meter that is good enough for the qualitative measurements needed for most RV troubleshooting.

Another issue is many of the meters have a single range near the 0-200A reading, and pretty large jaws, which isn't real great when looking for readings in the few amp range. But they will at least give you a qualitative indication of current and are far better than having to break the circuit to measure current.

many of the reasonably priced decent useable clamp on hall sensor current probe (and combo current/voltage probes) are made by two companies based in Tiawan. Those meters are sold under various names and OEM'd to some of the more well known brands used and trusted by professionals.

They are a valuable tool, have one in my house toolbox, one in my truck toolbox and one in the trailer toolbox.

Good info, ktmrfs. You've obviously used and have a clamp-on or two!

For our needs, we've found inexpensive, no-name DC/AC current capable clamp-on ammeters (<$50 on Amazon) more than adequate for general RV troubleshooting purposes while we're on the road. We've purchased 2 or 3 over the last few years. Have yet to experience any accuracy issues that hindered any troubleshooting.

Inrush current is the only function we've found to be wildly inaccurate and unusable on many (so-called inrush capable) clamp-on ammeters. Only trust our Fluke 375 for inrush.

yes, $50 ish will get you a hall sensor current probe adequate for many RV and home related troubleshooting task. good ones for inrush current or low current (ma- few amps) another story. low current hall sensor probes exist, but they aren't inexpensive. And lots of the technology around them is protected by "trade secrets" not patents. There is lots of "art" involved in making a low current accurate quantitative hall device current probe.

An inexpensive unit with a smaller detachable smaller jaw would be a welcome addition to my toolkit. The large fixed jaw units can be a PITA to get hooked up in tight spaces.

Fluke 375 is a nice unit.

rickhise wrote:
Can I use a multi meter to see if camper batt is being charged when I’m
Plugged in at Camp ground.

If so how do I set meter thanks

Yes DC VOLTS connect to battery
12.6 is full charge on the battery but not charging anything less than 13 is not charging

13.6 (About) is float (This varies a tenth or so) but still not charging in most chases.
anything over 13.6 is charging

SO.. UNPLUGED hook up meter and note voltage
Plug in.. Did the voltage increase, if the answer is yes then it's charging... NOTE: if the batteries are "Hungry" you will see an increase but it may NOT be as "Dramatic" as the numbers I posted.. That is if you see for example 12.4 and plug in and it goes up tot 12.6.. It's charging wait an hour and look again.. you will continue to see higher and higher voltages up to at least 13.5.

ktmrfs wrote:

otrfun wrote:
IMO every RV'r should have a cheap, clamp-on ammeter that can read DC current. Most clamp-on ammeters include all the standard functions found on a simple voltmeter, so no real need for a separate, dedicated voltmeter (2 for 1).

A clamp-on ammeter is easier to use than a voltmeter when making current readings. Simply clamp the ammeter jaws around either battery cable to make a reading. It will tell you exactly how much charge current your battery is or is not receiving. It will also tell you much current is being drawn from the battery when it is not being charged. Important readings that a voltmeter cannot provide.

Not all clamp on ammeters are equal. The very inexpensive ones use a toriod (transformer) to sense current and only measure AC current. Not much use for an RV. Luckily the hall effect probes have come way down in price and can measure DC, AC and in some cases DC+AC current.

If the probe does measure DC and does NOT have a button to zero the reading, pass it up. Hall devices look at the magnetic field induced by current flow and also are sensing the earths magnetic field. Orientation affects the fields so there needs to be a way to zero the stray fields. If it does have a zero button check how close to "0" the reading is. should be within 1 or 2 digit(s) of zero. If so you likely have a clamp meter that is good enough for the qualitative measurements needed for most RV troubleshooting.

Another issue is many of the meters have a single range near the 0-200A reading, and pretty large jaws, which isn't real great when looking for readings in the few amp range. But they will at least give you a qualitative indication of current and are far better than having to break the circuit to measure current.

many of the reasonably priced decent useable clamp on hall sensor current probe (and combo current/voltage probes) are made by two companies based in Tiawan. Those meters are sold under various names and OEM'd to some of the more well known brands used and trusted by professionals.

They are a valuable tool, have one in my house toolbox, one in my truck toolbox and one in the trailer toolbox.

Good info, ktmrfs. You've obviously used and have a clamp-on or two!

For our needs, we've found inexpensive, no-name DC/AC current capable clamp-on ammeters (<$50 on Amazon) more than adequate for general RV troubleshooting purposes while we're on the road. We've purchased 2 or 3 over the last few years. Have yet to experience any accuracy issues that hindered any troubleshooting.

Inrush current is the only function we've found to be wildly inaccurate and unusable on many (so-called inrush capable) clamp-on ammeters. Only trust our Fluke 375 for inrush.

otrfun wrote:
IMO every RV'r should have a cheap, clamp-on ammeter that can read DC current. Most clamp-on ammeters include all the standard functions found on a simple voltmeter, so real need for a separate, dedicated voltmeter (2 for 1).

A clamp-on ammeter is easier to use than a voltmeter when making current readings. Simply clamp the ammeter jaws around either battery cable to make a reading. It will tell you exactly how much charge current your battery is or is not receiving. It will also tell you much current is being drawn from the battery when it is not being charged. Important readings that a voltmeter cannot provide.

Not all clamp on ammeters are equal. The very inexpensive ones use a toriod (transformer) to sense current and only measure AC current. Not much use for an RV. Luckily the hall effect probes have come way down in price and can measure DC, AC and in some cases DC+AC current.

If the probe does measure DC and does NOT have a button to zero the reading, pass it up. Hall devices look at the magnetic field induced by current flow and also are sensing the earths magnetic field. Orientation affects the fields so there needs to be a way to zero the stray fields. If it does have a zero button check how close to "0" the reading is. should be within 1 or 2 digit(s) of zero. If so you likely have a clamp meter that is good enough for the qualitative measurements needed for most RV troubleshooting.

Another issue is many of the meters have a single range near the 0-200A reading, and pretty large jaws, which isn't real great when looking for readings in the few amp range. But they will at least give you a qualitative indication of current and are far better than having to break the circuit to measure current.

many of the reasonably priced decent useable clamp on hall sensor current probe (and combo current/voltage probes) are made by two companies based in Tiawan. Those meters are sold under various names and OEM'd to some of the more well known brands used and trusted by professionals.

They are a valuable tool, have one in my house toolbox, one in my truck toolbox and one in the trailer toolbox.

IMO every RV'r should have a cheap, clamp-on ammeter that can read DC current. Most clamp-on ammeters include all the standard functions found on a simple voltmeter, so no real need for a separate, dedicated voltmeter (2 for 1).

A clamp-on ammeter is easier to use than a voltmeter when making current readings. Simply clamp the ammeter jaws around either battery cable to make a reading. It will tell you exactly how much charge current your battery is or is not receiving. It will also tell you much current is being drawn from the battery when it is not being charged. Important readings that a voltmeter cannot provide.

opnspaces wrote:
This is a simple test that will tell you if your charger works. But not how well or efficiently the charger works. Unplug your shore power and run the furnace blower for 2 minutes to pull any surface charge off the batteries.

Put the volt meter on DC volts. The DC volts symbol looks like a solid line on top with a dotted line under it. If there are multiple selections for DC volts then put it on 20v or the closest reading that is more than 12.

Measure the voltage at the batteries. Then plug the RV in and measure the voltage again. If the voltage increases you are charging.

finally an accurate post.

Looking for 14+V when charging is NOT repeat NOT a good indicator. Battery voltage won't reach near 14V until it is fully charged. Voltage could be as low as 13V on initial charge depending on the charger and battery. And the typical WFCO charger will almost NEVER get to 14+V, maybe 13.8

This is a simple test that will tell you if your charger works. But not how well or efficiently the charger works. Unplug your shore power and run the furnace blower for 2 minutes to pull any surface charge off the batteries.

Put the volt meter on DC volts. The DC volts symbol looks like a solid line on top with a dotted line under it. If there are multiple selections for DC volts then put it on 20v or the closest reading that is more than 12.

Measure the voltage at the batteries. Then plug the RV in and measure the voltage again. If the voltage increases you are charging.

rickhise wrote:

JaxDad wrote:
Set the voltmeter to DC volts, neg to neg, pos to pos and you should see about 14.5 volts if it’s charging, 12 volts if not charging.

Thanks simple enough.

I’m assuming I could do the same thing to check if
Truck running an power cord for brakes and lights
Is charging as well??

Yes but be aware that there is often long and smaller gauge wires to the RV which will lower the voltage.

A better check is to measure both amps and voltage. I have a DC clampon ampmeter that is simple to use and also measures voltage.

JaxDad wrote:
Set the voltmeter to DC volts, neg to neg, pos to pos and you should see about 14.5 volts if it’s charging, 12 volts if not charging.

Thanks simple enough.

I’m assuming I could do the same thing to check if
Truck running an power cord for brakes and lights
Is charging as well??

theoldwizard1 wrote:
Yes ! A lead acid battery will be charging if it is receiving 13.8V or more.

To clarify, what it is receiving is amps. The voltage seen at the battery could be way less than 13.8, so the OP should not think his charger is not working if he sees less than that

If the battery bank is low, the initial voltage when a charger is turned on set to 14.8 could be more like 13.4 or even lower and then rise from there. You have voltage drop as seen at the battery bank depending on the charging amps amount.

BTW this is related to the dreaded under 13.2v a WFCO needs to see at first in order to go into boost