Mastervolt MICC puzzle

[jenevers]

Getting ready to cruise after boat being moored up for 7 months (on solar). 
“ Ah-time” read out is showing battery percentage 0%, which is not correct as voltage is 14.5v and I’ve been running the fridge/Vax /TV etc on the batteries (12 v, 670Ah Trojans). I can’t work out from the manual, how to change the read out to 100% or is it possible that there’s a lost wire somewhere?

[Jen-in-Wellies]

The AH remaining readings on these sort of things are not terribly accurate and get less so over time since they were last reset. No idea how to reset it on a Mastervolt one. It will be in the destruction manual. Better to go by the voltage reading. Is the solar wire input connected to the battery, or the boat side of the Shunt? If on the battery side, then the solar charging won't be measured and the monitor will only measure current out, hence a reading of 0% battery left.

Jen

[jenevers]

11 minutes ago, Jen-in-Wellies said:

The AH remaining readings on these sort of things are not terribly accurate and get less so over time since they were last reset. No idea how to reset it on a Mastervolt one. It will be in the destruction manual. Better to go by the voltage reading. Is the solar wire input connected to the battery, or the boat side of the Shunt? If on the battery side, then the solar charging won't be measured and the monitor will only measure current out, hence a reading of 0% battery left.

Jen

I’ll check if there’s a loose wire somewhere. Do you mean the solar wire from the panels to the MPPT then to the batteries? Maybe I’ll just do a factory reset and then fine tune to my setup.

[Jen-in-Wellies]

3 minutes ago, jenevers said:

I’ll check if there’s a loose wire somewhere. Do you mean the solar wire from the panels to the MPPT then to the batteries? Maybe I’ll just do a factory reset and then fine tune to my setup.

Assuming the shunt for the Mastervolt thing is in the negative wire to the batteries, does the negative wire to the MPPT solar controller go to the battery side of the shunt, or the boat side? If it is connected to the battery side, then the Mastervolt MICC won't be counting solar amps in.

[jenevers]

9 hours ago, Jen-in-Wellies said:

Assuming the shunt for the Mastervolt thing is in the negative wire to the batteries, does the negative wire to the MPPT solar controller go to the battery side of the shunt, or the boat side? If it is connected to the battery side, then the Mastervolt MICC won't be counting solar amps in.

I’ll have a look. Thanks

[Keith M]

10 hours ago, jenevers said:

Getting ready to cruise after boat being moored up for 7 months (on solar). 
“ Ah-time” read out is showing battery percentage 0%, which is not correct as voltage is 14.5v and I’ve been running the fridge/Vax /TV etc on the batteries (12 v, 670Ah Trojans). I can’t work out from the manual, how to change the read out to 100% or is it possible that there’s a lost wire somewhere?

I have configured and reset MICC many times.

When was the last time the monitor was re-calibrated ?
Is it possible to re-charge the installation using a shoreline so that the system can get into  float mode so that a manual reset can undertaken?

What is your location?

[jenevers]

I checked if the inline 2A fuse was OK. I was surprised to see that the 230 v supply to the ring main was disconnected when I took the fuse out. When I put it back the batttery status read 100%?

[Keith M]

That would be correct.

You have completed a manual reset however what is the battery state? I am assuming they were not at 100% when you removed the fuse.

Ideally you should now recharge the batteries until the battery charger goes into float. 

[jenevers]

1 hour ago, Keith M said:

That would be correct.

You have completed a manual reset however what is the battery state? I am assuming they were not at 100% when you removed the fuse.

Ideally you should now recharge the batteries until the battery charger goes into float. 

I’ll fire the Genny up and see what happens. I’m pretty sure the batteries will be close to 100% as they’re being charged with 400 w of solar panels and no electric is being used.

[jenevers]

Well from a reading of 100% it has gradually dropped down to 70% despite the voltage showing 13.3v. Strange.

[Keith M]

9 hours ago, jenevers said:

Well from a reading of 100% it has gradually dropped down to 70% despite the voltage showing 13.3v. Strange.

Does the solar input go via the shunt of the MICC?

[jenevers]

10 hours ago, Keith M said:

Does the solar input go via the shunt of the MICC?

I think the controllers are wired direct into the batteries. I'll have to check. How should it be wired?

[nicknorman]

55 minutes ago, jenevers said:

I think the controllers are wired direct into the batteries. I'll have to check. How should it be wired?

It needs to be wired with the negative connected to the boat side of the shunt, such that the only thing connected to the battery side of the shunt are the domestic battery negatives.

 

What is probably happening is that the shunt is registering discharge from the boat’s services, but the recharging from the solar is not registering due to the wiring error. Hence the gradual decline in displayed SoC.

[jenevers]

17 hours ago, nicknorman said:

It needs to be wired with the negative connected to the boat side of the shunt, such that the only thing connected to the battery side of the shunt are the domestic battery negatives.

 

What is probably happening is that the shunt is registering discharge from the boat’s services, but the recharging from the solar is not registering due to the wiring error. Hence the gradual decline in displayed SoC.

Had a look at the shunt. One end is connected to the battery negative, the other to the negative busbar which has 

the solar negatives connected too. But there are two small cables as well, one connected to each side of the shunt blocks?

Edited May 28, 2021 by jenevers

[nicknorman]

6 minutes ago, jenevers said:

Had a look at the shunt. One end is connected to the battery negative, the other to the negative busbar which has 

the solar negatives connected too. But there are two small cables as well, one connected to each side of the shunt blocks?

There should be two thin wires from the screw terminals on the side of the shunt, going to the MICC panel. These are the sense wires that the MICC uses to measure current. Is this what you are talking about? If so that is as it should be.

 

the other thing to check is that the domestic battery negative isn’t connected directly to engine battery negative. That would allow eg alternator current to partially bypass the shunt and thus not register properly. The engine/starter battery negative must be connected to the boat services side of the shunt, not directly to the domestic battery negative.

[jenevers]

31 minutes ago, nicknorman said:

There should be two thin wires from the screw terminals on the side of the shunt, going to the MICC panel. These are the sense wires that the MICC uses to measure current. Is this what you are talking about? If so that is as it should be.

 

the other thing to check is that the domestic battery negative isn’t connected directly to engine battery negative. That would allow eg alternator current to partially bypass the shunt and thus not register properly. The engine/starter battery negative must be connected to the boat services side of the shunt, not directly to the domestic battery negative.

Yes to your first paragraph?

I'll check re the starter battery. Thanks.

[jenevers]

4 hours ago, nicknorman said:

There should be two thin wires from the screw terminals on the side of the shunt, going to the MICC panel. These are the sense wires that the MICC uses to measure current. Is this what you are talking about? If so that is as it should be.

 

the other thing to check is that the domestic battery negative isn’t connected directly to engine battery negative. That would allow eg alternator current to partially bypass the shunt and thus not register properly. The engine/starter battery negative must be connected to the boat services side of the shunt, not directly to the domestic battery negative.

Actually, I’ve just remembered, the starter battery is charged by a separate solar panel and not connected to the alternator at all. The alternator only charges the leisure battery bank.

[nicknorman]

1 hour ago, jenevers said:

Actually, I’ve just remembered, the starter battery is charged by a separate solar panel and not connected to the alternator at all. The alternator only charges the leisure battery bank.

Nevertheless the starter battery negative will be connected to engine /hull/alternator negative. And thus presents an alternative current path bypassing the shunt if connected directly to domestic battery negative. Remember that shunts and Ah counting battery monitors are all about what happens in the negative line and nothing to do with what happens in the positives, so if the engine battery positive is connected to something independent from, or connected to, something on the domestic positive, that has no bearing on the situation.

[Detling]

There should only be one connection to the battery negatives that coming from the shunt nothing else should be connected on that side of the shunt or to the battery negatives v(interconnects to other domestic batteries are allowed. Every other connection must go to the 'boat' side of the shunt. The connection to the starter negative, any solar controllers, inverter chargers and all the lightd pumps etc all must be on the boat side so that every bit of current has to go through the shunt.

[Tony Brooks]

10 hours ago, Detling said:

There should only be one connection to the battery negatives that coming from the shunt nothing else should be connected on that side of the shunt or to the battery negatives v(interconnects to other domestic batteries are allowed. Every other connection must go to the 'boat' side of the shunt. The connection to the starter negative, any solar controllers, inverter chargers and all the lightd pumps etc all must be on the boat side so that every bit of current has to go through the shunt.

 

So no one misunderstands. There will typically be two connections on the boat side of the shunt. A thick feed to all the items Detling lists plus a thin or very thin connection running to the meter (as the OP has). This is usually on a different terminal to the thick wire. Nicknorman explained what this thin wirei s for.

[jenevers]

Thanks everyone ?