Electrical Good News?

I came home this evening to a voltage in the low 11s and a battery monitor that claimed I was at 98% capacity…

I had a theory. I shut off the fridge… and voltage leaped to 12.5. I repeated the exercise after being home for about an hour and running a light that long. Still 12.5.

So the culprit is the fridge. For some reason, it’s drawing a ton of voltage.

If I need power at night to do whatever, I can just shut down the fridge, wait a couple of minutes, and do whatever. I still need to figure out why the fridge is drawing that much voltage, and I’ll start by tracing the lines to and from it. But it seems that I really don’t have the huge problem I seemed to have on Wednesday and I have a good clue on where to start troubleshooting.

Thank you to everyone who has been hanging in there with me and trying to help me resolve this issue. I’m getting close! 😀

 

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7 Comments

  • OK, if you want to see how much a device is using the easiest way I know is to use one of these:

    http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P

    I have one and it can read .010 amp draw from an LED light. This tool is what I use to determine how much each fixture / appliance is using and to determine what my parasitic draw is when I think everything is shut off.

    It is not a Fluke, but it works very well for the price. More good luck and hang in there……

  • Gary, the battery monitor tells me exactly how many amps things are drawing. I’m not having an amp problem, but rather a voltage issue. I have more than enough power, but not enough pressure to get that power to me. There’s something wrong with the pipes (ie. wiring). That’s actually good news in that I do have a very realistic notion of what my daily power consumption rate is.

  • Rae – Amps, Volts and Resistance are inextricably linked. If your battery voltage is fine but you’re showing low voltage, then either you’re drawing too much current and the voltage is sagging or there’s a resistance in the line ( bad connection, too small a supply wire – 1 gauge is plenty big ) and that’s dropping the voltage.

    This relationship is called ohms law and it’s one of the most fundamental to understanding how electricity works. Here’s some of the basics, explained better than I can. http://www.youtube.com/watch?v=b3XS4lAxvrc also see http://en.wikipedia.org/wiki/Ohm's_law

    So if the fridge is lowering the voltage, it’s drawing too much current, not voltage. Or there’s something wrong in the line that it can’t deliver the current, thus lowering the voltage. But devices don’t use too much voltage.

    However, you are right that excessive current would show up on your LinkPRO, so I don’t think you need a clamp on ammeter, despite their usefulness in easily measuring current on a single circuit without putting a meter inline.

    Thinking through it, at the moment, I can see three potential failure points that you could track down that might help you resolve the problem.

    1. Your meter isn’t reading voltage correctly, either through a failure in the meter or in where it’s measuring the voltage. It should be directly connected to the battery and only showing lowered voltage if the battery is lowering as well.

    I believe that you’re reading your system voltage from your linkPRO. Is this correct? Are those LinkPRO power leads directly connected to the battery ( or the shunt ) as displayed in the instructions?

    I have two meters in my RV. One came with the RV and is often inaccurate ( just sorta wanders around ), the other is on my LinkPRO and is very accurate. I’m thinking of putting black tape over the bad one until I can find a replacement so I stop panicking when I see 11.4V in the middle of the day.

    Have you measured the voltage with a separate hand held voltmeter ( on the battery terminals! ) to confirm the system voltage?

    If you don’t already have one, get a digital voltmeter. Cheap is better than nothing at all, I have several really cheap ones ( as cheap as $3 at a flea market ) and they all seem to read pretty accurately for my needs. Here’s one from Amazon that looks very capable for not a lot of bucks. And it’s available PRIME.

    http://www.amazon.com/Digital-VOLT-Meter-Voltmeter-Multimeter/dp/B005EK3NRS/ref=sr_1_3?ie=UTF8&qid=1360418410&sr=8-3&keywords=digital+volt+ohm+meter

    But a local hardware store, or a big box store with a tool section ( Kmart, Walmart, Target, Home Depot ) should be able to sell you passable meter for under $20. If you don’t have one, get one.

    Put it on the battery terminals and compare what it says to what your RV meter says. They should agree or be close. Don’t worry about the hundreths digit if the cheap meter has one.

    If the meter is wrong it could be faulty or it could be hooked up incorrectly in some way.

    2. Your system voltage is actually low and your meter is reading it correctly.

    This would be the case if the handheld meter confirms the system reading and they both read the batteries as low. This would probably indicate bad batteries, since the wide variances in voltage for very little load seem unlikely with full-capacity batteries.

    If that’s the case, measure each battery individually. If they are the same, the pack is probably just wearing out. If they are significantly different ( more than a tenth or two ) you have a bad battery or cell.

    3. Your battery voltage is fine, but the power that gets through to your RV is low because of a bad connection and for some reason, your meter is reading that voltage rather than the battery voltage.

    If the meter you’ve been reading system voltage on isn’t directly connected to the batteries, and you have some sort of resistance to the current flow which is lowering the voltage in your RV, this would show as reduced voltage in the RV when under a load, but good ( or at least better ) voltage at the batteries. Ohm’s law…

    To resolve this, you may have to use that handy handheld meter and measure voltage at various points on your RV. The batteries, the fusebox, the fridge.

    To summarize, at this point, I think the most important thing to do is measure the battery voltage with a handheld meter and confirm or disprove the low voltage reading.

    Feel free to email me directly if you wish.

  • Airmon, I feel really bad that you took the time to write all of this this morning just as I was writing the post where I explain the solution to my problem. I’ve got this. It’s all fixed now. Give me a few more minutes to hit post.

    Thank you SO much for your help.

  • Rae, what you are alluding to is that the fridge is drawing too much power. The only way for the voltage to drop in a healthy battery system is for the amperage to increase to a point where the battery cannot keep up with the draw and as a result, the voltage drops. IMHO the volts cannot drop without the amps going up or the load increasing. This is the relationship expressed in Ohm’s Law.

    What you are experiencing sounds like a problem with the electrical board in the fridge and the result of it drawing too much current should result in the board heating up. The fact that the fridge appears to be acting normally seems to introduce another problem into the equation. This may in fact be a wiring problem and as Gary says, the only good way to check the amperage being drawn it is with a device like he illustrated.

    The 12 volt wire that powers the fridge should come directly from the 12 volt fuse panel. It could be replaced for testing purposes with a wire directly from the + terminal of the battery. The negative wire could also be the problem and it should be checked as well. It should go to a screw in the frame or to the body of the fridge, assuming it is grounded.

    The first thing to check for is heat from the wires and the board in the fridge. I am just trying to work through the theory here, not cause alarm. The fact that the fridge seems to be functioning fine makes trouble shooting more difficult. Come on experts, help!

  • Croft, like I said to Airmon, check out my latest post. Very simple problem, very simple solution. 🙂

  • WhooHooo!!! 🙂

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