Shunt/gauge not showing correct amperage

[Tator]

I just finished installing my Victron inverter and my battery gauge is not showing the correct draw. I'm using my Link 1000 that I had with my previous inverter for a battery monitor (disconnected the inverter control cord). I've quadruple checked my wiring and all the connections appear to be correct. I cleaned the terminals and shunt connections. I followed the manual on the order to hookup the fuses. Voltage readings match my VOM readings. I've used my clamp meter and it agrees with the information coming from the inverter/charger. Everything was working on the old system when I left the boat last fall. Do shunts go bad?

Tator

 

[DDW]

Not quite clear what you've done. You are still using the Link 1000 with the Link shunt? the only thing that changed was the inverter?

Shunts are just a very high capacity, low value resistor. They could go bad but it is very rare. If the shunt is very small (usually spec'd in mv/A like 50mV/500A), then the inverter may be exceeding its capacity or the Link's capacity. I'd look up the specs on the shunt, they are often stamped in the side of it.

 

[tpbrady]

Tator,

The Link is measuring current flow in and out of the batteries based on all grounds flowing through the shunt to get to the battery bank negative. The inverter is measuring the load going through the inverter/charger meaning loads whose grounds don’t pass through the shunt won’t be measured. If you turn the charger off the loads should pretty much match. When I replaced the Xantrex last year, I also removed the Link 2000 since I replaced it with the Victron Cerbo GX with the CN-50 display. The display filled the Link 2000 hole and provides a dynamic block diagram of the Victron devices and the “energy” flowing in and out of each device. I say energy because they keep switching between watts and amps so you have to divide or multiply by 12 or 120 to get what you are looking for.

Tom

 

[Tator]

I did not mention that I have changed my house bank to drop-in LPF. I was just reading some reviews that suggested that some battery monitors will not work with lithiums? My shunt is a 500amp shunt and both inverters/chargers are of the same rating. One other modification was the need to use a longer bolt to connect the load side lugs. It probably has a different metal composition than the one it replaced-perhaps more bronze than copper?

 

[twistedtree]

If I'm following you correctly, you are wired such that all negatives flow through the shunt, including the inverter/charger. So you would expect the Link to show all current flow, including that from the inverter/charger. But the Inverter/charger would of course only report it's own current flow.


How much off is the Link? And too high or too low?

 

[CharlieJ]

There are two sides to the shunt; the high side and the low side. It is, after all a resistor.

The only connections to the high side are the negative conductor from the battery bank B-. All other negatives, both sources and loads, are connected to the low side of the shunt.

It is oftentimes easier to lead the battery B- whips to a bus bar and then a single conductor to the high (battery) side of the shunt. Likewise, it is oftentimes to land all of the negatives from the sources and loads on a bus bar and then connect the bus to the low side of the shunt with a single conductor.

 

[SteveK]

Shunt/gauge not showing correct amperage.

What is the correct amperage compared to what is reported?

 

[Tator]

The difference appears to be a constant low reading by about a factor of five. 80amp draw with inverter on measured at the HB negative cable at shunt-Link 1000 reading 16amps. 17.1 draw inverter off measured at same cable-3.77 at Link. Dumb question-does the shunt itself have a load/battery orientation? I haven't seen anything to indicate such.

Tator

 

[CharlieJ]

@Tator #8
Read #6 for content!

 

[Tator]

Thanks for all your help. The shunt was wired correctly except...while on my hands and knees putting on wire ties I noticed that one of the lugs on the load side was barely touching the lug on the battery side-Duh!! Repositioned the lug and all is fine! Thanks again.

Tator

 

[SteveK]

Tator, thanks for that post. Nice to have a resolution posted

 

[Nick F]

Ditto !