Author Topic: WBjr & MNBCM & Inverter DISAGREE wildly. HELP ? OR Not !  (Read 69 times)

Steve_S

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WBjr & MNBCM & Inverter DISAGREE wildly. HELP ? OR Not !
« on: August 09, 2019, 09:50:37 AM »
OK Folks, posting in General as this is a general Observation / Question.

My Configuration is simple enough, Classic-200 + WBJr in e-panel. Then I have an MNBCM wired directly to the battery terminals.
Last night I walked into notice the MNBCM saying I was at 80% yet WBjr reporting 99% 25.5 V (24V system) and the Samlex inverter reporting similar to WBjr.   

I appreciate the MNBCM is not a terribly accurate device and should only be used as a "quick glance" reference tool BUT this is a significant 20% difference...   At this stage, I only look at the MNBCM as a quick reference but if I had been relying on it to tell me the state of the batteries, I'd be quite unsettled (being nice).

Classic-200, Samlex EVO-4024 Inverter/Charger, 2080W of Canadian Solar CS-260P in 2 strings of 4,  8x Rolls Surette S-550 24V/856Ah battery bank.
System Detail: http://midniteftp.com/forum/index.php?topic=4643.0

boB

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Re: WBjr & MNBCM & Inverter DISAGREE wildly. HELP ? OR Not !
« Reply #1 on: August 09, 2019, 11:05:47 AM »

I would trust the WB Jr. in this case...  The WB Jr. is based in amp-hours which "should" be more accurate than the MNBCM which is based on voltage AND is supposed to work over a wider battery type.

Also, the WB Jr. will try to tell you the need for an Absorb cycle.

Either way, sounds like your batteries are being charged OK even if you were to take an average of around 90% SOC using both units.

Battery state of charge is a tough one but as far as we know, amp-hours in and out combined with a semi-accurate amp-hour efficiency is the way to go.
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