Is a negative current reading relevant?

We have to perform some monitoring functions that require us to record some current and voltage readings on a SBM. The current value is displayed as negative. My belief is that the sign displayed for current has no real-world significance unlike voltage. Am I correct?

I guess u re talking about a DC circuit, where the current flow is in one direction. I suspect the Negative symbol that's shown may be due to the opposite flow. i.e., if u have placed the negative multimeter needle to +ve and positive needle to -ve, it will show a minus before the value.
Please, Correct me if i'm wrong...

What is "SBM"? Small Burnt Meatball?

BTW: The sign shows the direction of current flow through the meter/probe/datalogger/whatever the flop is giving you that reading [hmmm... does "SBM" refer to the measuring device or the device being measured?]

Likewise - I don't see how this can possibly be answered meanifully without knowing what an "SBM" is.

SBM stands for Superior Battery Management. It's related to UPS. For example: http://tinyurl.com/a7p7tyu

Small Bronzed Mementos?
Savory Butter Mints?
Slow Boat to Morocco?
Small Butch Munchkins?
Sandy Beach Mates?
Seventy Billion Mosquitoes?
Super Bad Manners?

Oops...didn't see your reply :p

Well, then, like I said before, the negative sign indicates the direction the current is flowing through the meter/sensor/detector/whatever you're using to measure and indicate the current value (still haven't divulged). So, if your current logging device has polarity labeling, then a negative sign in the reading means the electrons are flowing from the positive labeled terminal, to the negative labeled terminal. Since your application involves battery management, then one polarity on the reading probably means "discharge" and the other polarity means "charge", assuming the current logging device is connected in the charge/discharge path of the battery. Can't say for sure which polarity is what since I don't know how the what-ever-the-heck-you-are-using is connected where-ever-the-heck-it's-connected.

Are you catching the undertone of frustration

Thanks for your response.

I'm just reading values from an integrated lcd that is part of a large piece of power equipment, the connections are all internal. The whole point of the question was that one of my colleagues thinks recording the sign of the current is important while I don't think it matters since its DC and never changes sign.

I WOULD record the sign, if I were you. You never know if it will be significant in the future, such as when there is a need to troubleshoot and an accurate history is required--especially if the current "crew" moves on.

Suppose at some future date, someone looks at the reading and asks the question, "Has that always been negative?" or "Didn't that used to read as 'negative'?" If the integrity of the historical record is in question, it fails as a troubleshooting tool.

In other words, never say "never"

If I may summarise in a nutshell: a UPS is a battery-powered back-up power supply to keep important equipment working when there is a temporary mains supply power cut.

If the current indication is positive, the battery is charging.
If the current indication is negative, the battery is being discharged and will eventually run flat.
Then the equipment will have no protection against power cuts, until the battery is recharged.

Now do you see the "real world" significance ?

Please don't take this as an insult, but what company is sending people with zero electrical knowledge to test vital electronic equipment ?

Insult taken. You conclude that I have "zero electrical knowledge" based on asking one question? Given that the current reading has been negative for months I suspect you don't understand as much as you think you do. In any case, had you been reading carefully you would realize that I'm not testing anything, I'm merely monitoring.

Hi Jeff, please accept my apology for any offence you feel I have given you.

Your question indicated that you did not know the difference between current going into a battery and current coming out off it. This suggested an extremely low level of knowledge of the most basic concepts taught in a school science class.

But I have to confess, that I paid very little attention at school, and gained all my training after leaving school. Sorry.

Your apology doesn't seem to be very sincere since you're still suggesting a lack of knowledge on my part. Looking at some of your other postings I can see that you are a bit of a troll. It's OK, but I won't be feeding you anymore. Cheers.

Jeff, my apology is sincere, and I have clearly explained the reasoning behind my surprised comment, and I have given you a clear explanation of the reason for the negative reading. What else can I do ?

Yes, but, what would the reading be if the system were supplying power rather than storing it (i.e. during an interruption of power). To assume a negative sign is insignificant because it has "been negative for months" is ridiculous. The sun has been up for hours, guess it'll always be that way. So, whom is it that doesn't understand? I mean, it was you that was arguing against noting down the negative sign, right?

In other words, I support Frank. And I think his apology is just fine and that he was calling a spade a "spade".

But, then, I guess you won't see this...oh well...

Steve, Frank said "if the current indication is negative, the battery is being discharged" So I guess you think the battery is been discharging for months? That's some battery!

Jeff, just take you "lumps" like a man...man

Steve, by "take your lumps" I guess you mean "I can't counter your argument". It's OK, it happens all the time on internet forums.

"The battery current (negative values correspond to
the discharge of the battery)."

http://www.gedigitalenergy.com/products/manuals/PowerQuality/OPM_SGS_USM_M40_M50_2US_V010.pdf

this is from a related site that you linked to, it may or may not be the same product

this download is the relevant page:

Thanks Gary.

I'm just sayin' you took the stance that the negative sign is inconsequential, and you were wrong -- get over it.

Pointing fingers at other people and bad mouthing them are the actions of immature little children. I'm assuming you're an adult. If you're not, then I understand--when you grow older, hopefully you will, too.