LVD Alarm and red indicator light not operating

[ski2ways]

Chin_k,

Well I put a lot of load on the batteries. My new little voltage checker did trip its alarm at 12.00 volts and I let the batteries drain until it displayed 11.64 volts, and the LVD did not disconnect - and the alarm did not go on! I plugged in the shore power and the battery voltage jumped right backup to 13+ volts.

So, I accept your gracious offer of sending me your LVD, but I want to buy it from you and certainly reimburse you for shipping. I live in Central CA, a couple of miles from the ocean.

I will try to send you a message outside of the Forum, so we are not giving out personal information on it.

Thanks again!

Jon

[chin_k]

Here is a more modern version of the LVD. I have not have time to look over the entire spec but it is just an example of what is available out there, so be aware of that (it is only good at 20 A, while the original one I expect to be at 45 Amp, so it is not a direct drop-in replacement).

https://www.waytekwire.com/item/80029/E ... e-Switch-/

How urgent do you need to get the LVD figured out? I can try to see if I can come up with a way to test it. Also, if you look at the Reference section, there is a instruction for changing the setpoint with the help of the red LED on the LVD. For my experiment, I just disconnect the SENSE wire to simulate voltage drop. Alternatively, I have some potentimeter that I can use to drop the voltage, and I also have an adjustable power supply that I can use, but do not have time to do it.

[chin_k]

Jon:
See if the following document is helpful for your troubleshooting. I don't think it is the same model, but this is the kind of instruction that a good manufacturer can provide to help user figure out if their LVD needs replacement.

http://ww2.justanswer.com/uploads/budns ... oltage.pdf

I think the flow chart applicable to you is Fig. 1.

Good luck.

[ski2ways]

Chin_k,

Ok I bit the bullet and pretended I was a rodent! I disconnected the Sense wire, at the Sense post of the LVD. Sure enough the red light on the LVD illuminated and when the Coach Batteries switch is turned on, there is no green light and DC power. But the alarm and the red LED at the overhead panel do not operate.

When I set up the new voltage detection device, I connected it to the LVD and did not try to run it down directly to the batteries. I'm thinking that there is a voltage drop in the wires - the red/black wires are 6 feet long. So, the device was reading a lower voltage coming from the batteries than actual and I would have had to keep the load on much longer. That is, it was reading 11.64 volts when there was still more than 11.8 volts that the Sense wire was sensing because it is connected directly to the batteries. Does that make sense to you? Lots of "sense" here. I am thinking of changing the detection voltage on the new unit down to 11.8 volts, because of the voltage drop.

Jon

[caconcourse]

Chin_k,

Well I put a lot of load on the batteries. My new little voltage checker did trip its alarm at 12.00 volts and I let the batteries drain until it displayed 11.64 volts, and the LVD did not disconnect - and the alarm did not go on! I plugged in the shore power and the battery voltage jumped right backup to 13+ volts.

So, I accept your gracious offer of sending me your LVD, but I want to buy it from you and certainly reimburse you for shipping. I live in Central CA, a couple of miles from the ocean.

I will try to send you a message outside of the Forum, so we are not giving out personal information on it.

Thanks again!

Jon

Wow Jon, we must be near to each other. I am in Santa Barbara.

[ski2ways]

Clay,

All three of us are in CA. I live in Aptos, near Santa Cruz.

Jon

[chin_k]

Jon:
I would advise you not to change the voltage cut off from the factory. It is a pain to recalibrate, and it should be a reasonable setting unless you have some unusual setup or configuration.

I have the following table from the previous page:

voltage related to ground when OFF:
V-in 12.47 (12.47 ON)
Sense 12.47 (12.47 ON)
O/R 5.23 (10.09 ON)
alarm 1.07 (0.32 ON)
V-out 0.00 (12.47 ON)

What I should have done is that on the alarm post, I should measure it relative *not* to the ground, but to the V-out because there is a diode or similar component in there. It functions as a ground for the buzzer and the warning LED.

1, Disconnect the gray wire from the LVD so the alarm post is bare.

2, Switch the overhead panel to ON, the LVD should connect if the SENSE wire is good. The green LED ("In use, charging") should be on. There should be 12V between the ground (white wire post) and the V-out. When you measure the alarm post with the black probe of the voltmeter, and put the red probe on the V-out, you should not see much voltage, close to zero. This test to make sure the LVD will turn on when you switch ON.

3, Switch the overhead panel to STORE, the green LED will goes out, and the red LED on the LVD (set point indicator) should be ON. There should be no voltage between ground and the V-out, because you disconnect the batteries with the LVD. If you touch the probes on the alarm post and the V-out again, there is no flow. This test the LVD to shut off when you switch to STORE.

4, Turn the panel switch back to ON. Disconnect your SENSE wire, so that the LVD thinks that your batteries are dead (you don't need to use a long wire to simulate voltage drop, or have to run down your battery on purpose, just disconnect it.) Make sure you cap off the bare wire since if you let it fall and touch the metal frame or the propane line, it will give you a nice spark and set off the 15 A breaker. I would cap it with a wire nut or electrical tape. Anyway, as soon as you disconnect the SENSE wire, the LVD will light up the red set point LED, and you will have 1 minutes to do the following before the LVD cuts off the V-out. Measure the potential between the alarm post and the V-out, you should see 12 V. If you measure the ground (white) and the V-out, you also should see 12 V. After a minute, the voltage on the V-out will be cut by the LVD, and so will be the voltage between the alarm and the V-out. In practice, when the battery got low in the middle of the night, you will hear the alarm buzz for a minute, and then it stops. This test to make sure the LVD will alarms you for a minute when voltage is drop below the set point (simulated by disconnect the SENSE wire).

5, Reconnect the SENSE wire, and turn the panel switch back to STORE. The LED on the setpoint should be lit. The V-out should be off, verify by voltage 0 between the V-out and the ground. The alarm should be off, verify by V-out and the alarm post. Turn your converter on by plug your rig to shore power. You should see the V-out and the ground (white) have ~13+ volt from the converter. Now, here is the important part. Measure the voltage between the alarm post and the V-out, you should see 13+ v there too, since the alarm post is acting as a ground. This test to make sure your LVD is grounding the alarm post and cause the buzzer to sound to alert you to connect the battery if the genset or the shore power is available.

Let us know how your LVD did when you do the procedure above.
Here is the updated table:

voltage with buzzer and warning light on the overhead panel disconnected (gray wire).
ground (white) vs. V-in 12.47 OFF (12.47 ON)
ground (white) vs. Sense (red) 12.47 OFF (12.47 ON)
ground (white) vs. O/R 5.23 OFF (10.09 ON)
V-out vs alarm (gray) 12.47 OFF* (0.00 ON) <----- *V-out only going to be on for ~ 1minute if the SENSE wire got disconnected, unless the converter is on.
ground (white) vs. V-out 0.00 OFF (12.47 ON)

[ski2ways]

Chin_k,

Here's my test results:

Gray wire from LVD disconnected – alarm post is bare.

Switch overhead panel to ON:
• Voltage: Ground (white) to V-Out: 13.12
• Voltage: Alarm Post to V-Out: 0.00

Switch overhead panel to STORE:
• Voltage: Ground (white) to V-Out: 0.00
• Voltage: Alarm Post to V-Out: -0.20

Switch overhead panel back ON with SENSE wire disconnected:
• Voltage: Ground (white) to V-Out: 13.08, 0.00 (After 1-2+ minutes)
• Voltage: Alarm Post to V-Out: 11.95, 1.10 (After 1-2+ minutes)

Switch overhead panel back to STORE with SENSE wire connected:
Shore power not connected:
• Voltage: Ground (white) to V-Out: 0.00
• Voltage: Alarm Post to V-Out: -0.20

Shore power connected:
• Voltage: Ground (white) to V-Out: 13.76
• Voltage: Alarm Post to V-Out: 0.00

I have no idea what all of this means, other than the alarm and the red LED on the overhead do not sound when 1) Shore power applied and Coach Batteries are in the STORE position; and, 2) SENSE wire disconnected (The LED on the LVD does turn red).

You are the MAN, Chin_k!

Jon

[chin_k]

Here's my test results:

Shore power connected:
• Voltage: Ground (white) to V-Out: 13.76
• Voltage: Alarm Post to V-Out: 0.00

I have no idea what all of this means, other than the alarm and the red LED on the overhead do not sound when 1) Shore power applied and Coach Batteries are in the STORE position; and, 2) SENSE wire disconnected (The LED on the LVD does turn red).

OK, that is good work there. Here is the problem: When the shore power is on, the voltage between the alarm post and the V-out should be 13+. you measured the ground to V-out as 13.76, so you should also get 13.76 for when you measure the alarm relative to the V-out. You got ... nothing. This is very puzzling to me since in the section you did "Switch overhead panel back ON with SENSE wire disconnected" it was working. (If you connect your gray wire on there, you should hear the alarm when you disconnect the SENSE wire). So do me a favor and repeat the experiment on "Shore power connected" again, and confirm the value. In addition, find the voltage between the alarm to V-in too. You have to read something like 12+ on that. (When your LVD is off, and you plug your shore power on, it is the converter that makes your buzzer and LED work, nothing related to your LVD or your coach batteries).

Without seeing the result from the procedure I asked you to repeat, here is my guess. You buzzer and warning light works fine (they should work when you disconnect the SENSE wire). Your LVD works fine (all but the last time it passed!). The issue lies in the connection between the converter and the V-out. Do the procedure first, and it you see 12+ between the alarm post to V-in, but nothing between the alarm to the V-out, go take a look at the brown box (the converter/charger by the bathroom) and make sure the wiring on the BATT posts (both positive and negative) are good. You will also need to verify the continuity between the BATT- to the ground as well as the continuity between the BATT+ to the V-out.

You should have other symptoms like you have not been able to charge your battery at all (edited to removed incorrect statement about not able to run DC appliances.)

I must have missed these, but I do not remember you mentioned either 1, or 2, so I have always assume the connection between your converter to your LVD is good. Now, maybe we need to take a look at that and see if the rodent chowed up more wiring.

At any rate, I think you do not need a LVD, but there are more thing for us to learn here.

[ski2ways]

Chin_k,

I redid the test with shore power connected, with the batteries on STORE and ON. On STORE I get Vout @ 13.76 Volts, Alarm @ 0.00 Volts and Vin @ 13.26 Volts. With batteries ON, I get similar results: Vout @ 13.70, Alarm @ 0.00 and Vin @ 13.69.

I'm not sure I told you this, but when I connect shore power AND the batteries are on STORE, the green light turns on and I get DC power. No alarm and no red LED, and it doesn't matter if I push the batteries ON. When I push the batteries on, the green LED continues to illuminate and I still have DC power. I'm assuming that the batteries are being charged when the switch is ON. Prior to all of this calamity, I think the green light wasn't on when I connected shore power. I seem to remember that It went on when I pressed the switch ON and the alarm and red LED went off.

I'm now thinking you are right that the LVD is functioning correctly, because I reconnected the gray wire and disconnected the SENSE wire and the alarm sounded!

Okay, I looked at the brown box and the wiring to the BATT posts appear fine, at least from a layman's point of view. But, I have no idea how to check the continuity between the BATT- (The white wire) to ground and especially between the BATT+ (Red wire) to V-Out...

Jon