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Surviver76's avatar
Surviver76
Explorer
Apr 04, 2018

96 Lance 3000: Systems Monitor - Battery Monitor Questions?

Hi Guys, I have what seems an odd occurrence I need guidance on soon.
A short or some sort of failure is interrupting the charge signal to my AGM 115ah battery so it gets less & less which I know is damaging to the battery. First, I am in Yuma so getting lots of sun on my solar. So far I have no battery monitor and realize my shortcomings for this lack.
Here is a brief description of my current system. 3 Siemens 50W panels on the roof, ASC Charge Controller, 600W Inverter & FullRiver 12V 115ah AGM Battery. I purchased this battery last week believing my old one was failing and it seems that the old batt may have been ok and my system was where the failure was occurring.

I think the problem may be in the cheesy Lance issue "Systems Monitor" on the wall of the TC. A few weeks ago we had a hot spell and my systems mon showed batt all the way up to the green. Then, with the same basic weather pattern, it went down to one red light at the bottom and the pump was laboring, battery very low. I then thought the problem was the batt. After installing a new batt the same thing is happening and pretty sure I didn't need that new battery after all.
My question is if I install a good Trimetric Batt Mon, how do I deal with the Systems Monitor on the wall? Can I just disconnect it?
If so, how would I do that and I'm thinking the Trimetric could tap into the wiring near my existing charge controller. Also what size shunt should I install and does that go out in the battery bay?
Any help appreciated...

  • BFL13 wrote:

    Mystery is why you are getting 12.8 at the ASC


    AND....12.8 is LESS than a trickle charge and will NOT add anything to the net charge in the battery most likely.
  • Most accurate panel voltmeter I have yet found...

    https://www.ebay.com/itm/Yellow-5-Digit-DC-0-4-3000-33-000V-Precision-Digital-Volt-meter-Voltage-Panel/162859254849?hash=item25eb2b0441:g:I-IAAOSwfVpYqlwE



    Weight: 16g
    Display mode: Five 0.36 LED digital tube
    update rate: > 3s/time
    Physical size: 48 x 29 x 22 mm (L*W* H)
    Opening size: 45 x 26 mm (L*W)
    Supply voltage: 3.5-30V
    Lead wire length: 14 cm?4 lines?
    Measurement range: DC 0-4.3000-33.000V
    Operation temperature: -10 degrees~65 degrees
    Measurement accuracy: (0.3‰+ 2words) {means the table worst case maximum error of less than 10mv normal within error 2mv}

    These meters agree with my



    Some panel voltmeters and battery monitors I have tested exhibit a TWO TENTHs of a volt DC error. A few folks complain that I am too fussy about accuracy. I wonder if they are the same folks who complain about short battery life :)
  • Yes, this is just what I need to replace my handheld meter for at a glance monitoring... Thank you indeed...
  • Ok just about the same time as one great response came in speaking of panel voltage meters from eBay I realized the same. While Trimetric and the like are excellent additions to any system, I was metering the power terminals from the panels & then running outside to the batt bay and metering the batt posts.
    So I ordered 2 of these

    I assume it is "legal" & safe to tap into the controllers' terminals and mount one of them on the wall next to it. I would like to tap the other on the batt posts but would very much like to run a length of wire back inside the camper to also mount the battery mon panel on the wall for frequent viewing.
    Do I need to consider wire size to do this or just get a similar size and feed it through appropriately? Thanks again for all the great help.
  • The solar controller's "battery" terminals and the battery are on the opposite ends of the same wire and will have almost the same voltage, so you can get "battery voltage" from the ASC, inside the rig. You don't really need the voltage at the ASC's "array" terminals.

    Each day, you watch for the solar to bring the battery to 14.3 volts (or as set if variable) and then the controller starts controlling.

    It is a "shunt" type controller, so watching the voltage when it is doing its on and off thing will make you dizzy. (I had an ASC some years ago and could see all that action on the Trimetric)

    You are not telling us the story on why your battery was/is at 11 volts, but that is your privilege :)
  • BFL13: First thanks for clearing that up. Nice to be able to simply connect the panel directly to the controller.
    As for the low batt. This is what I've been telling everyone in this string.
    If you read it from the start, I think you'll get your answer. At some point, my solar must have stopped working and the batt went down. This is what caused me to start metering everything. I had misplaced my meter so at first, it was chaotic being that I do not have a battery monitoring system. The old plug that lets the solar signal go through the fridge vent cover looks a bit fried and I think it came back on when I unplugged it and cleaned it a bit. Working great now. I metered 12.9 coming down from the panels and the batt was at 12.8 today.
  • Surviver76 wrote:
    Working great now. I metered 12.9 coming down from the panels and the batt was at 12.8 today.


    Once again.....12.9 is NOT enough voltage to do any useful charging.
    If that is as high as it ever gets, then it is NOT "working great".

    When you measured "the battery", was it disconnected from all external voltage sources ?? If not you are just fooling yourself.
  • "This is what I've been telling everyone in this string.
    If you read it from the start,"

    I am not seeing all the posts in this thread for some reason. A new one ( 18th supposedly) just came in but not showing on mine. I have 14 replies showing out of 18 listed.

    Anyway, your 12.9/12.8 is normal for the controller before it starts controlling--it lets the battery voltage pass right through to the panels, so "panel voltage" is the same as "battery voltage".

    Your battery will not recover to good health by just leaving it on that solar from now on. It needs a major "recovery" involving desulphation at high voltage (to 16v) and that solar can't do that.

    You can use the solar to do it if you by-pass the controller and go "panel-direct" manually but it is procedure that takes a lot of your time and attention and requires good sunny days. Also needs the battery disconnected from RV 12v systems, so you need another 12v source to run the rig meanwhile.

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