Xantrex LinkPro Charging Amps Discrepancy

Caroline and her hubby are exercising their generator tonight by letting me plug in. I thought, woohoo! I’ll have a fully charged house battery bank tonight AND a fully charged computer!

Reality according to my LinkPro has been somewhat… disappointing.

Since yesterday, when I actually hit full charging amps from my solar panel for a bit, I’ve noticed that my LinkPro is only showing half the amps going in that my solar charger claims is going. And, yes, this reading is taken with everything off.

I’m getting the same deal from my dedicated battery charger! I’m on the 15A setting and only getting a measly 7.5A in. If I plug in the computer, I only get 2A. 7.5A is barely worth running the genny for and 2A is a waste of gas.

Who do I trust? The solar array monitor and battery charger or the LinkPro, which has been 100% accurate in recording the amp hours going out?

Xantrex hasn’t been any help regarding this and I’m not finding any anecdotal evidence about it. I’m convinced (ie. hopeful) that I’m wired correctly since I’m getting an accurate record of amps going out.

The only thing I can fathom with the current situation, being on the genny, is that the charger realises that I’m above 80% and is only doing the tapering charge. That would make sense when I’m on solar, too, I guess, but if that’s the case, then there’s no sense getting another panel because I wouldn’t squeeze any more juice out of it than I already am.

Do any of my experts want to give their theories on yet another mystery?

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  • I would bet on the Xantrex, but I’d want to verify it. In and out amperage are measured the same way and take the same path.

    If your Volt-ohm meter has an amps setting ( many have one that’ll read up to 10A ) you can double-check the LinkPRO by putting it in series with one end of your battery pack. Your meter should have an easily accessible fuse that will protect it if the load goes over its ability to handle.

    Does your battery charger have an ammeter on it? If its just a 15A setting on a switch, that is maximum current it can put out. As you surmised, it’ll go down as the battery charges, so being on the 15A setting doesn’t mean it always puts out 15A.

    While another solar panel won’t make charging over 80% any faster, I believe that you’ve spent a lot of your time lately under that point. So another panel will get you up to that point faster and you can then spend more of your time above 80%. 80% to 100% takes time, so getting to 80% while the sun is still shining is important.

    Also, while your amp reading goes down from 7.5 to 2 when your computer is on/charging, those 5.5A are still not being pulled out of your batteries and are doing useful work for you via the computer.

    If you had more panels, you’d have more “left over” power to charge your house batteries while operating or charging your computers. 15A of solar power minus 5.5A of computer drain would leave you 9.5A of current to go into your house batteries ( assuming they’re under 80% ) rather than 2A.

    It means that at the end of a sunny day, you’re more likely to have full house batteries and charged computers for the night or the next couple of days.

  • Hi Rae
    I have been mulling over your question re charging discrepancy. Looking at the Link Pro installation diagram as shown it will only read the NET CURRENT into or out of the battery. I am assuming that you have installed it according to their diagram.

    Other assumptions:
    1) all loads, charger, solar panel alternator are connected as followns; (+) to battery erminal, (-) to the (-) side of the shunt; {system ground}
    2) there is not a meter in the dedicated charger to display its output current
    3) Solar panel and Link Pro agree on the charging current when there are no loads on the system
    4) 5 Amps is required by the computer charger

    Given the above you must consider the charging current supplied by any charging device to be like a river. Only a limited amount of water (amps) is available If you devide the flow between 2 (or more) devices the sum is not changed.

    If the “charger” supplies 7.5 amps and the computer requires 5 amps (assumption # 4) then the battery only gets 2.5 amps as shown by the Link Pro.

    You state the 110 V dedicated charger is on the 15 Amp setting (a switch ? ) this would be the maximum Anps available from the charge on that setting. The actual current supplied will depend on the resistance in the charging circut. In most cases this will be determined by the battery’s current state of charge (as shown by its no load voltage reading).

    Hope the above helps. Ken

  • Ken and Airmon,

    1) Everything is wired correctly as per both AM Solar and Xantrex who have reviewed my wiring diagram;

    2) This huge discrepancy is with everything off so I’m comparing apples to apples.

    3) Right now, my solar array is saying that I have 6.8A coming in while the battery monitor says 4.5A.

    4) I just plugged in my computer. Solar still says 6.8A, monitor says 1.3A. So I am NOT able to use the full amount the solar array monitor is coming in. The monitor says I have X coming in, that the computer is pulling Y, and I am left with Z, regardless of what the solar array is saying.

    5) The LinkPro does show the net current in and out and also keeps track of the total amp hours in or out.

    6) I don’t really trust what my charger says.

    7) My batteries got really low at the beginning of February, up until my return from Mexico. Since I got a full charger after that, I have not gone below 85% charge and even that was an exception. Most nights, I go to bed at 90% to 95% charge according to the monitor. So I’m not anywhere close to running out of power, I just want a full charge for my batteries’ health.

    Thanks for your input.

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