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Batrium Shunt inaccurate current measurment
#1
My batrium shunt is reading inaccurate current. Both my charger and clamp on meter will show 100A charge current, the batrium reports 85A. This of course throws off the SoC counter. 

Is there a calibration procedure for this? Googling doesn't reveal any.
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#2
I'm not aware of any way to calibrate the shunt reading. I would recommend contacting support > info@batrium.com.
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#3
Bit of a stretch but if the charger has a lot of electrical noise on it, some meters might read incorrectly.

More likely you might have another path for current around the shunt.
The battery -ve (0V) terminal should not have anything other than the shunt & a cellmon/longmon -ve connected.
ALL other -ve wires should go to the other side of the shunt.

Another cause might be if you have a load using some of the input current from the charger.
Running off solar, DIY & electronics fan :-)
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#4
Mine's been working fine for a year now.    Its very close (less than <1% difference) with my Midnite Classic Whiz Bang Jr (shunt) that is in series with it on the negative side of the battery bank.
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#5
A clamp meter is generally not accurate.
How is your charger meassuring? Clamp meter or direct?
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#6
Woah, lots of people attacking my question and not answering it ( Except Mike, thanks Mike I emailed them as soon as I saw your reply. ). Don't mean to be unappreciative, I bet there's lots of inexperienced asking these types of questions. For reference I'm an Electrical Engineer so I'm not your average enthusiast.

I'm using a Sunny Island 6048 to charge. I'd hope a $5k MSRP inverter has a good idea of the current leaving it, and my expensive and calibrated clamp meter agrees with it exactly, only the batrium is off. And it's only off on charge, on discharge they all agree.

AND the result is my SoC is constantly shifting down quickly and having to be reset on discharge (because it under-tracks energy going in but correctly tracks energy going out.)

I've made sure there's no possible explanation for current flow other than a mis-calibrated or defective shunt. Even disconnected my DC solar charge controller to make sure it wasn't trying to sink 500W magically somehow. Batrium requested detailed design of my system and their telelmetry logs which i sent them to review. Waiting back to hear what they say.

I agree its odd for a shunt to be inaccurate, and only in one direction. But I'm staring at one that is, I can't explain it. And I don't want to open it up till Batrium decides to cover this as a DoA and replace it. Someone on facebook said loose screws between the shunt PCB and the shunt itself could cause this, but I don't want to open it up till I hear from Batrium.
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#7
Wow,....
All i saw was people trying to help.
Volks
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#8
Not attacking at all, just trying to help - we only had minimal info to go on from your post & no idea about your setup or experience level, etc ;-)
Glad you've got the bases covered.

The (new info) clue might be in how it's only happening on charge but discharge reports normally.
Like suggested already, this might be from the Sunny Island unit making some electrical noise & this is hiccuping the shunt's readings.
The noise would only be there when charging....

Q: if you watch the current readings on screen reported by batrium when charging, are they steady (assuming of course input is steady...), or jumping around?
Q2: if you reduce the current output of the charger (assuming you can via s/w, switching out some PV, etc) does the inaccuracy track the reduction or do something else?
Q3: can you post a system diagram &/or pics?
Running off solar, DIY & electronics fan :-)
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#9
As Said you should have given all that info from start what and howbyoubdid check Smile that would have helped alot in answering.

Try to tighten the screws Tiny bit. They should dit right but not dead hard

I just myself had a shunt with 2 solder joints flawed so had to open mine. But my scenario was different.

That it should meassure wrong only One way seem very Odd to be true. That sounds like wrongly callibrated.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#10
The error scales linearly based on charge current. No jumping around, dead steady. And since it's under-reporting instead of over-reporting, I doubt it's a bad solder joint on the shunt itself.

Really looks like a calibration error, hence my original simple question if there was a user calibration routine for it. Googling and their documentation did not reveal any.

I could buy a bad connection between the shunt and it's control PCB, as some impedance between the two could cause under-reporting, but I'm going to get Batrium's permission to not void my warrant before opening it up.

I do appreciate anyone that took the time to respond, thanks. As an engineer I get jaded when I'm bombarded with rookie level questions, but I'm sure most of the members in this hobby warrant such a response until proven otherwise. Sorry for being crass.
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