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MBase avatar image

Have a Victron multi plus 3000/12/120 with a GX colour monitor and BMV 700

Screen shows 96% 12.9 v when going to bed but then in the morning they show 96% 10.4v and alarm warning sets off - when I switch it off and then back on again it goes back to 96% 12.9v can’t understand why this is happening all new batteries and equipment

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3 Answers
MBase avatar image

Put a new shunt on and still having the same problem!!! Any advise? Could it be the inverter?

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Its time to post some photos of your batteries/shunt/wiring/bus.

MBase avatar image MBase klim8skeptic ·

What pics do you require?

Hi MBase,

Post a pic of all 4 of your batteries, including cabling/fusing/disconnect.

A pic of the shunt.

Post a pic of the negative and positive bus.

+1 for photos

Do you see any current flow at the BMV/CCGX?
Is the BMV selected as SOC source at the CCGX?

MBase avatar image

Thanks for your advise firstly I have 4 x 130amp batteries install on a newly built narrowboat and I've set the battery monitor to 520amps the neg to my domestic batteries goes straight to the shunt all other negs are the other side of the shunt - my starter battery is connected to the engine chassis and then I've connected the neg from starter battery to the neg on the domestic bank with a link lead is this correct? Or should I remove the link lead? Everything else you have suggested I have already done. Look forward to any further suggestions

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@MBase, just to clarify, these are 130Ah 12v batteries, yes? Not, for instance, 6v batteries wired in series/parallel...

MBase avatar image MBase Justin Cook - Bay Marine Supply USA ♦ ·

Yes that’s right there 130ah 12 v in parallel

@MBase, one last question... and this may seem silly, but I've seen it happen more than once: are you quite certain that the shunt is oriented correctly? One side is specifically labeled "battery" and the other side is labeled "loads and chargers" and if it's connected in reverse, it will think loads are chargers and vice versa.

MBase avatar image MBase Justin Cook - Bay Marine Supply USA ♦ ·

Definitely correct fitted to the battery side

Nuts, okay... the issue must be with that link lead then. If I get a few minutes today I'll kinda sketch that out so I can visualize how it should be connected.

It's also possible that the shunt PCB is just misbehaving and sending erroneous low-voltage readings to the display head... that does happen from time to time.

Have you gotten in touch with your distributor for tech support on the matter?

MBase avatar image MBase Justin Cook - Bay Marine Supply USA ♦ ·

Hi I purchased all the kit from midland chandlers in Willington fitted the same kit On a Widebeam boat that I built last year and had no problems just thought it must be something small or a faulty part ?

Justin Cook - Bay Marine Supply USA avatar image

@MBase, there are a couple of things that come to mind here... you haven't specified what Ah capacity battery bank you have, but you should check to make sure that you correctly entered the total capacity into the BMV. If you told the BMV that you have a 200Ah battery bank when you only have 100Ah, for instance, the SOC will obviously read 2x what it actually is, which might cause this fault.

The other thing to check is that you've correctly connected the BMV shunt. There should only be ONE thing connected to your battery NEG terminal, and that is the "battery" side of your shunt. ALL other system NEGs, including your MultiPlus NEG, all your DC load NEGs, your chassis grounds, etc etc need to be connected to the "loads and chargers" side of the shunt. If anything is bypassing the shunt and connected straight to the battery, the BMV can't "see" it and therefore can't update the SOC accordingly. The BMV tracks SOC as a function of amps flowing through the shunt, not a function of battery voltage, so if you're seeing a high SOC but a low voltage, the most likely bet is that you have one or more loads that are connected directly to the battery rather than being connected to the shunt.

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