DC panel power drop on battery bank 1 only

[jvoorhies]

I am not sure why this happening.

When I try and run my refrigerator on bank 1, I get a low voltage alarm. When I switch to bank 2, the refrigerator works fine. I have a tank level indicator display that also reads voltage. When I’m on bank 1 it reads 9.6 volts and when I’m on bank 2 it reads 12.7 volts. That almost makes sense.

However, when I check the battery voltage at the panel voltmeter, both banks read 12.7 volts, when I check the voltage at the batteries they to measure 12.7 volts.

What do you think could be the problem?

 

[drew-]

Does the meter show 12.7 when the suspect battery is under load? I suspect the voltage drop might only manifest itself under load. I would have someone turn on the fridge while I hold the test leads. If so I would swap battery locations and complete the same test. I have worked in automotive retail and seen a healthy voltage that quickly drops when brought under a load, but that didnt self discharge like commonly seen. Just my opinion.

 

[heritage]

Drew is right that under load voltage can drop to a very low level if the battery is shot. The same thing can happen if there is a loose connection to the battery or corrosion on the battery post.

 

[Benny17441]

Voltage by itself means nothing. Like it has been previously said a bad battery can show good voltage but when subjected to a load it may quickly bring a Bank down. Go to harbor Freight and purchase an automotive battery load tester ($19,99) and test each battery individually and replace the dud. keep the tool, it will come in handy many times in the future.

 

[Don Lucas]

clean connections and measure voltage at battery, there really is only 2 causes here 1-bad connections 2- bad battery

 

[jvoorhies]

Tested the load on both batteries and they were good, no loose connections or corrosion on battery terminals, bought new gell batteries two years ago

Could there be a short in the panel? If so, how would I test for that?

 

[splax]

bad cable- the cable can get a non- conductive corrosion on the surface, which happens to be where the majority current happens. This leads to nominal voltage under no load and low current when loaded.

 

[jvoorhies]

Thanks for everybody’s input. I believe I fixed the problem. First, I swapped the batteries and same thing, low volts on 1 and normal on 2. Next, I pulled the battery switch out and noticed battery 1 switch to dc panel main was loose. Tightened it and problem went away.

Time for a margarita!!

Before I too many, I need to inspect my boat speed transducer because it stopped working. As with most boats, I have a speed and depth transducer, is there a way of telling which one is the speed short of going for a swim in frigid Lake Michigan water? are?

I sail a hunter 356. One is on starboard and the other on port.