How do you check an inverter to see if it is putting out the proper DC voltage? My lights in my Tioga worked when I lived in Oregon then when I drove it back to Texas they quit working.......any ideas or insight on what and how to check?


Tioga Sportsman

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check converter you take the positive terminal off the battery plug rv into 115v supply take your test light and put negative to the battery and positive to the lead that go's to the battery/ the one you took off if the light comes on your good

I don't quite understand what you are trying to check.....12v or 115v?

So did you take your battery out of the loop at some point? There has to be a battery somewhere in the circuit. What finally cooked my old converter was the bad house batteries - the old style needed good batteries in the loop in order to function properly. 

I don't think any further testing is required based on your initial description. Your converter is not putting out 12V any longer. It's old and inefficient and due for a change anyway. The big question is whether you need a battery in the circuit.

After I check out the remaining possibilities for my current converter and there is a need for me to get a new one and it requires a battery in the circuit then I will get a battery. Otherwise I don't need or intend to get a battery.

Is there a battery in the circuit now? If so, and it's dead, that might be your problem. As I said, mine was so busy trying to charge my 2 dead house batteries that there was very little juice left for the 12 vdc house stuff. It wasn't totally dead, but everything was dim. When I replaced the batteries things were better, but still not up to snuff. Still pretty dim. New converter fixed it.

I was just Googling some videos on the power max and it appears you don't need the batteries in the circuit because some of the videos shows the PowerMax powering up ham radios and car amps. I will contact Power Max tech support just to be sure if I can hook up the converter just to supply power to the house lights etc.

I would think you could do that without a problem, I just haven't done it. Might have to make sure wherever your battery(ies) was/were doesn't have dangling (+) connection that can ground out.

   If its basically a DC Power Supply which the data makes it appear YES it can be used to power 12 volts DC Loads (lights, small appliances, etc)  REGARDLESS if one of the loads happens to be a battery. If a battery were attached and its voltage is greater then the batteries voltage, then it would charge it, even though it does NOT appear to be any sort of a 3 or 4 stage progressive "Smart" Charger.

 John T


Good morning, Tioga Sportsman; 

You said that you have and use a voltmeter.  I have some questions:

What kind of a volt meter is it?  Is it a DVM (Digital Volt Meter)?  Does it have a "Peak Reading" function, perhaps with a positive (+) and a negative (-) choice selection?  If it does, it will probably also say that it is a "True RMS Reading" type of DVM.

I will explain why I have these questions:

You can use that peak reading function to also check to see if your "RV 12 VDC power converter" really does put out a true straight line DC (Direct Current) voltage level like what we expect to get from a battery, when they say that it is "12 VDC." 

The problem is that most of the older ones, and many of the currently available ones (sorry about that), are not true DC power sources, and you do not get "12 VDC" out of them when plugged into "shore power" or operating off the generator.  In the never ending quest to maximize profits, they built things that will "just do the job," and are barely able to claim the title of the equipment that performs that function.  I learned about this just this Summer when I was seeing some problems with the LED lighting conversion I was making with the incandescent bulb lights in the Winnebago Elandan. 

While many LED lights will claim a life expectancy of 25,000 or even 50,000 hours of operation, a lot of the lower cost lights I was trying were not making it to even 6 or 7 WEEKS.  It turns out that the problem was my old B-W 6345 power converter with the C-01 battery charger option.  When I put one of my oscilloscopes on the output of the B-W 6345 to look at the "12 VDC output" waveform, the problem was immediately obvious:  The B-W 6345 does not put out a "12 VDC" voltage.  It is not a true straight line 12 VDC voltage level like what we would see from a battery, but instead it is a "pulsating 12 VDC" waveform, or more accurately described as a "rectified 60 cycle 12 Volt AC (Alternating Current) sine wave."  

The problem is that this wave form has an average value of about 12 VDC that works fine with the old incandescent light bulbs, but it is not so good with LED lights and other electronic devices.  The waveform ranges from 0 volts up to about plus 18 volts peak. 

It is that +18 VDC peak voltage that was causing problems with some of my LED lights.  They were burning out. 

I am replacing the old B-W 6345 with a Progressive Dynamics PD-9245V or PD-9255V "power supply" which has filtering and voltage regulation.  The specifications have a tolerance range of +/- 0.3 VDC for the 13.6 VDC voltage output and a ripple and noise level of < 50 mv RMS on the output.  This says to me that it is filtered and regulated, unlike my old B-W 6345.  And the Parallax Power "slide-in-replacement-upgrade" that goes right into the original power distribution panel has exactly the same simple transformer and rectifier circuit as my old B-W 6345.  I am keeping the Parallax Power unit as a reminder to me and a monument to the effectiveness of the  phraseology from the guys at Madison Avenue. 

You can use your voltmeter, if it is a true RMS reading type, and it has a Peak Reading function, to look at the output of your RV 12 VDC power converter.  If the peak reading is about +18 VDC, then your RV 12 VDC power converter probably is the older simple transformer and rectifier design with no filtering nor regulation.  Your voltmeter is a good valid indication if it reads a peak of +18 VDC, while using an oscilloscope and seeing the waveform will provide absolute proof. 

If your "RV 12 VDC power converter" is the older extremely simple design, and you want to use LED lights, or you want to plug into your 12 VDC power system any electronics or devices to recharge your cellular telephone battery and other similar things, then the idea of upgrading to a true modern power supply type of "12 VDC" power source for your motor home or other RV when plugged into "shore power" or running off the generator begins to look much more attractive. 



Latte Land, Washington 

Does anyone have a fuse nameplate for the fuse panel right behind the cab driver side wall? 1976 Dodge Tioga or at least somewhere close to that year? The cover was missing when I bought the RV and could not find the fuse box cover.




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