Trying to install a Shunt Battery Monitor (LNEX 500A)

[rgnprof]

I have been trying to get this working properly and I'm having trouble.

I have 2 Leoch 224AH 6 volt batteries connected in series and I have installed the LNEX (similar to Renogy) shunt per the instructions (I think - PIC attached). In the pic I have the B- side of the shunt connected to the NEG terminal of the RH battery and the small red power wire connected to the POS terminal of the LH battery (you'll notice the LH NEG is connected to the RH POS). This is now where I'm getting confused - the NEG cable that was previoulsy connected to the NEG terminal on the RH battery is now connected to the other side of the shunt - which you can just see to the left of the small green connector on the shunt). Confusion is that the installation manual shows this connection from the shunt running to a Bus Bar which is then connected to an Inverter and a Charger (I don't have an Inverter but do have a Converter/Charger).

I get power and Monitor lights up, but

PROBLEM: The monitor shows 100% and 224AH, then maybe 99% and 223AH and then jumps to 0 - on both!
Also - the current draw doesn't make sense - in the PIC you'll notice that I'm using 81.1 Watts with a current draw of 6.48 Amps?? Shouldn't that be more like .648 Amps?

I know my batteries are still charged because everything continues to work.

Any help?

ryan

 

[DonTom]

the current draw doesn't make sense - in the PIC you'll notice that I'm using 81.1 Watts with a current draw of 6.48 Amps?? Shouldn't that be more like .648 Amps?

12.5VDC times 6.48 amps= 81.1 watts

-Don- Reno, NV

 

[John From Detroit]

Also - the current draw doesn't make sense - in the PIC you'll notice that I'm using 81.1 Watts with a current draw of 6.48 Amps?? Shouldn't that be more like .648 Amps?

81.1 watts / 6.48 watts = 12.5 volts.. Close enough.. .648 amps would only be about 8 watts. It's 12 volt not 120 volt
In theory the shunt can be in either the negative side as you wired it or the positive but....
Some things need to be reclabrated... I do not know how it measures current for example (Two small wires to the shunt and a 3rd wire for voltage is best.. And current may read backwards.

And in fact it does.

 

[Mark_K5LXP]

It would be standard convention for an ammeter to read a negative value for discharge, and it appears it's reading your load correctly so your shunt is wired correctly. The sudden change from 99% to 0% is a programming/parameter issue, like it thinks you have a 1Ah battery. Some quality time with the manual will probably resolve that.

Mark B.
Albuquerque, NM

 

[OldWEB]

It is your monitor, you should have the manual, read it.

Unless someone has the same unit, we can only guess with the limited info you give us, I know I need more questions answered before I can say why it does what it does... but you want half baked answers so here is mine.
I am sure you have it installed correctly, well for what you want it to do. It monitors power usage and power charging. You have it installed (as per manual) to monitor input and output of the battery. It does not know how much power you use if the converter is also charging. i.e. If you are using 100W on your lights, and you have the converter supplying 80W charging, the monitor will only show the deficit leaving the battery of 20W, the converter (on the other side of the shunt) is supplying some of the light power.

What I think your pictures show is, and this is just a guess, is you have only been charging the battery, it shows ~ -6 amps entering the battery, a negative because you have it installed as a power usage monitor, "what am I using". If current is only going into the battery, then it will show as a negative.
The one picture showing the 0's I am guessing is what power you will use, but with more charge current going into the battery, it has not seen any power leaving the battery.

The first picture can be referred to as the charging profile, the second picture is the usage profile.
I see it has been charging ~6.5 amps for 36hrs, so that is ~234AHs... pretty close to what it shows.
NOW... If you would turn off any charging and then see where the numbers go.
But you have the manual, I am only guessing.

EDIT: HA! I just noticed now that your battery bank is 224AH, and at 99%, that would be ~223AH.... I guess my idea of the charge for 36hrs has missed the mark... or has it?

 

[rgnprof]

Thanks for the replies!
And the manual is useless!!! I'd be happy to scan and email it to any of you - good luck!

I have read it - what there is - a dozen times. I have watched a couple of videos online about this unit but there aren't that many. I have watched several Renogy videos (which is a very similar unit), but none have discussed this issue. I have also emailed the company but haven't heard back from them - hence this post! And YES - I guess I was hoping someone did have the same unit - or one similar.

I get the 12.5 volt and not 120 volt - not sure what I was thinking - oh well.

So it appears that everything is connected properly AND it is reading properly - the -6.5 amps corresponds to the 80 watt +/- draw and the middle number - Volts - is correct as well (I know because I have been measuring voltage directly at the batteries). I have the motorhome plugged in now and it shows +9.90A, 13.3V and 131W... (Pic below).

But when I'm not connected or the Motorhome is not running, everything works for a while until all of a sudden it just drops to 0% and 0 AH...!

 

[Mark_K5LXP]

I have installed the LNEX (similar to Renogy) shunt

Maybe not similar enough...

Mark B.
Albuquerque, NM

 

[rgnprof]

The sudden change from 99% to 0% is a programming/parameter issue, like it thinks you have a 1Ah battery.

Thanks Mark - the manufacturer got back with me this morning and it was a setting. Again - not clear from the manual but there was a "LVP" (battery low voltage setting) that needed correcting. It was set at 12.5v and whenever the value dropped below that level it was automatically resetting to 0v and 0AH. Manufacturer suggested just setting it to 0 volts - which seems to have worked so far.

Thanks.

 

[Gary RV_Wizard]

A 12v lead-acid battery is considered to be "dead" or useless at 10.5v. That's the standard used for the 20-hour test for amp-hour capacity. And that's what I would suggest as the setting for LVP. Using 0V as the low voltage cutoff will fool you into believing all is still ok at 10.5v, whereas most 12v appliances and electronics will simply stop working at that point. About the only thing that still works would be iincandescent lighting, and even that would be very dim.

 

[rgnprof]

Thanks Gary - always appreciate your input!