Help please, what is wrong w battery or monitor (Seawind)

[jbinbi]

Trying to help out a buddy on his Seawind 1190.

Mastervolt AGM 130 x 2, going on 6th season. Pronautic 12-20 Battery charger, 2 x 200 solar panels. 2 outboards with 10a alt each. Honda EU2k generator

There is a monitoring system, I am not sure how smart it is, but it shows V, A, and battery capacity. I wasn't there when it was setup and can't find the manual for it. But it says 260Ah, so somehow it was programmed for this.

In the past, it has been pretty accurate.

Then we went on a cruise. When using the Honda, the monitor showed -13 to 18A. I thought since there is no real ground, maybe if it was reversed polarity, it would so neg Amps or something, but hard to believe it was draining the battery. The seawind facebook group theorized that it is because the charger is connected directly to the neg of the battery and not to the shunt? No idea if that would be doing it.

Yesterday, the owner sends me a pic showing that the total capacity is 96Ah. This is after being plugged into dock for 5 days! See pic.

Today, it was depleted on the monitor (see pic).

I went to the boat, charger shows correct state and V. But maybe the monitor is screwed up? So I shut charger, and all loads and it was hovering at about 13.2V for 30 minutes. I figure if the batteries are shot, in a day or 2 it should be down to 12V or lower?

But if anyone has any ideas why the monitor is showing no capacity, I would love to hear it. I do know lots about batteries and know that over time the 260Ah capacity of the banks might only be 130Ah. I don't know if the monitor is smart enough to know this or shows it. But it was odd to have the honda running and showing neg A flowing, and odd now the monitor shows no capacity at all after the batteries should be fully charged.

Sorry the pics are not aligned correctly, not sure how to do that. Pic showing fridge on has same values with fridge off.

[HeywoodJ]

The monitor most likely uses a shunt to measure current into/out of the battery. Somehow either the shunt wiring, or the wiring where the charger connects to the battery are incorrect, so the shunt does not see what it should.

What does the monitor show when the batteries are being used? Negative amps or positive amps? Since you say “in the past, it has been pretty accurate” my guess would be that the charging cables from the charger are connected in such a way that the current flowing through the shunt is not correct. I can’t picture exactly what that would look like, but I’d start by tracing out the connection for the ProNautic, at the same time locating the shunt, and then see what you have.

PS-nothing to do with the negative/ground connection on the AC-side at the generator. Or, if it does, much bigger problems aboard than the monitor not being right.

[jbinbi]

Thanks for the response. I am sure you are correct that there is a shunt that is part of the monitor. However, this has only happened since using the honda to charge while out to sea. I think someone mentioned that the reverse polarity light was on, but I don't think that should stop the charger from working? The only thing I can think of is that maybe if the reverse polarity is on, then the panel doesn't allow AC into the charger, or the charger senses it and it is not charging. That doesn't really make sense to me, but if that were the case, then the neg amps we were seeing was just actually the draw of the loads on the boat.

However, that would not explain why when tied up at the dock after the cruise and plugged into shore power for 5 days that the batteries would show no Ah?!?

[Kiwicrew]

My monitor looks the same (a BEP 600), and I have a similar problem which has only arisen since I moved into a marina and started using shore power. The monitor does not seem to recognise the input from the battery charger. The first time I went back to the boat after being plugged in the monitor was showing 20 amps in the 160 AH bank.

I'd be very interested to know if you have been able to fix your problem.

[jbinbi]

Yeah, as suggested by Heywood, it was shunt related. Original installation of battery charger by first electrician bypassed the shunt. When installing new batteries, he wired correctly and now working the monitor is working correctly.