New battery monitor wonky--powers up but reads all 8's

[SIsolar]

Hello everyone and thanks in advance!

I have previously mentioned that I am building a 20 AH LiFePo4 battery generator as a sort of prototype for the real thing. I am about 85% finished and have a battery monitor attached, but when I power the device up, the battery meter reads all 8's. Every single LCD on the display is activated. This leaves me with no useable data.

The literature is not helpful, even worse than vague. The literature states that the exact condition I described indicates a full battery, but this is confusing as I can't even get a voltage reading. The literature even contains a picture of the monitor in this exact condition, but I can't seem to figure out a way to get it out of that condition so I can get useable information.

Is this a normal condition for a battery meter? Is there some setting I am missing? Do I have a faulty meter? I am about at wit's end and I would just replace the meter were it not for the fact that the literature seems to say that this is normal for a full battery. I have even gone so far as to put the device under a load and very carefully watch the voltage to see if the battery meter seemed to pick up on any change, but nothing had happened. As it stands right now, the battery sits at about 70% state of charge, based on voltage (and after having been charged by removing the battery and charging with a separate, dedicated Lithium charger).

This is a shunt-type device and I have hooked it up correctly as per directions.

So after all of that, my basic questions are:

1) Is this normal for a battery monitor?

2) Is there something I need to do to get meaningful data?

3) Does this indicate a faulty battery meter?

I can provide pictures if that would be helpful.

Thank you very much!

SIsolar

 

[sunshine_eggo]

If you included the brand/model, those with the same unit would be able to assist.

 

[SIsolar]

Well, you are not wrong. Unfortunately, I bought the meter from Amazon and it was some nameless, brandless battery monitor. I will see if I can dig up the original one on Amazon.

 

[SIsolar]

This one--

https://www.amazon.com/bayite-6-5-100V-Display-Multimeter-Voltmeter/dp/B013PKYILS/ref=sxin_14_ac_d_rm?ac_md=0-0-YmF0dGVyeSBtb25pdG9y-ac_d_rm_rm_rm&content-id=amzn1.sym.568df61d-e115-4cb1-a96a-ba070b8f0935%3Aamzn1.sym.568df61d-e115-4cb1-a96a-ba070b8f0935&cv_ct_cx=battery+monitor&keywords=battery+monitor&pd_rd_i=B013PKYILS&pd_rd_r=abf3ad82-1aec-47ba-90b6-17123bf571b6&pd_rd_w=bl2Ep&pd_rd_wg=5nwOe&pf_rd_p=568df61d-e115-4cb1-a96a-ba070b8f0935&pf_rd_r=GF67N5C1MD8DKZZYWNQB&psc=1&qid=1664203327&qu=eyJxc2MiOiI1LjU5IiwicXNhIjoiNS4wNiIsInFzcCI6IjQuODQifQ%3D%3D&sr=1-1-7d9bfb42-6e38-4445-b604-42cab39e191b

 

[SIsolar]

I entered the wrong item. Please look at the next post.

 

[SIsolar]

AHHHH!! Never Mind. I meant this one.

https://www.amazon.com/MNJ-Multifunction-Battery-Multimeter-Voltmeter/dp/B07W7XXKVF/ref=sr_1_6?keywords=battery+monitor&qid=1664203327&qu=eyJxc2MiOiI1LjU5IiwicXNhIjoiNS4wNiIsInFzcCI6IjQuODQifQ%3D%3D&sr=8-6

 

[Mattb4]

Let's go through how you have it wired up. Taking the picture from Amazon of the back of the unit connections as guide your top two connection are likely not wired unless you have an external power supply. You should have a wire that go to the small screw on load return side of the shunt for positive voltage and a lead to the small screw on the negative battery side of shunt as negative voltage reading. If these are reversed you would get a negative voltage reading or perhaps all 8's. Than is the shunt current reading where a wire from the bottom of the shunt and a final wire from the positive side of the battery.

BTW: I am using the first shunt and monitor you posted to keep track of my solar panel input to my AIO. Works great except at night when there is no voltage to keep it alive. Your unit with the external power supply would be a better choice for that usage.

 

[SIsolar]

Mattb4,

That is really useful information and I can easily test it. I would never have guessed it myself. As I said, I did hook it up according to the directions, but I have already had one bad set of instructions on this project—the brass terminal on some switches had the wrong polarity.

I will try swapping out the connectors this afternoon.

 

[SIsolar]

OK, I tried switching the wires from the shunt around--I still only got all 8's. That was a useful suggestion, it just did not bear any fruit. Does this sound like a dead unit or does anyone have some idea that I am missing?

Thanks for the suggestion Mattb4

 

[Mattb4]

Sorry it did not help. Sure looks like you got a borked unit. The only thing else I can think of is it might need the external power source to function properly.

 

[SIsolar]

Yeah, borked unit sounds likely at this point. I might have to try another. I am not certain why it would need a separate power supply as it clearly has power. Thanks anyways.