Link 20 battery monitor

[pullark]

Hello All,
My Catalina 30 has a Link 20 installed. Recently I've noticed that if the boat is unused for a couple of weeks the battery status LEDS flash orange indicating battery is discharged. However when I check the battery/batteries with a meter I find the battery is in a good state of charge. This is also indicated on the digital voltage reading on the Link 20 itself. If I momentarily disconnect the monitor sense wire from the battery, the battery status display will go back to green indicating battery is full. I can live with this except that I also find on occasions it's difficult to crank the engine as if the battery is low in cranking capacity. This happened recently. Tried a few minutes later and all good. Engine turned over and started as usual. I also noticed that battery status LEDs changed from orange to green. My instinct was to check connections especially ground connections on the monitor's shunt and also the engine block. Also checked starter motor terminals.These all seemed good with nothing loose or corroded. My electrical setup includes two 120W solar panels feeding in through a MPPT regulator and a high output Amptech alternator with an external regulator.
I'm guessing the Link 20 is about the same age as the boat (1989 MK 11). Maybe it's just overwhelmed or confused by all the other stuff added into the system. Maybe I need to upgrade to a newer monitor? Any thoughts for troubleshooting or replacement would be appreciated.

 

[LeslieTroyer]

Sounds like a bad ground connection somewhere.

 

[Stu Jackson]

I agree with Les. Looking at wiring connections is really useless. You have to TUG on them, and sometimes remove, clean and replace them.

There's also this about battery monitors, don't know if you'd ever seen it:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

http://c34.org/bbs/index.php/topic,4922.0.html

DEFAULTS are factory settings that are made to be modified to suit your setup.

Also read this one:

Programming a Battery Monitor (by Maine Sail)

http://www.pbase.com/mainecruising/programming_a_battery_monitor

and his newer 'site

https://marinehowto.com/programming-a-battery-monitor/

 

[SG]

As others have indicated, I'd look for a bad connection (or a deteriorated wire?). It's amazing that the "ground" seems to the likely culprit so often. :^)))

It's possible to have continuity but not enough capacity due to either a corroded connection or wire. e.g., You can get 13.2 volts (or whatever), but not have the ability to actually get much amperage (watts) through connection. I've been frustrated with inverters and other high amperage connection over the years because the initial "test" looks like no problem when you really have a bad connection.

Older wires (especially those that weren't marine grade, tinned ones) can be like a old supply pipe with scale on the inside -- impossible to get much through, even though the show adequate "pressure", just a tinkle comes out.

 

[Stu Jackson]

You can get 13.2 volts (or whatever), but not have the ability to actually get much amperage (watts) through connection.

That's a good point, and why one wants to (needs to) measure voltage under load, not static.

 

[pullark]

Thanks Guys. You have given me plenty to think about. I agree with your point about testing under load Stu. This is when I'm seeing the problem. I think I need to go right back to start switch and work in from there. Exposed position and long wire run to the engine is problematic. I believe the 1989 Mk 11 did not have instrument panel wiring issues highlighted on earlier boats?

 

[Ward H]

I believe the 1989 Mk 11 did not have instrument panel wiring issues highlighted on earlier boats?

I have a 93. The trailer plugs had been removed and a euro connection strip was used behind the panel. Butt connectors were used at the engine but they were badly corroded and burned from overheating. There is a volt meter instead of amp meter on the engine panel but the alternator output still ran to the engine panel and back to the starter.
Not sure if it was done this way by the factory or a prior owner.