battery gauge reading low

[CJAuster]

Both batteries on my 20v read 13.4 and 12.4. The gauge reads somewhere around 11. Wondering if corroded or rusted wire ends could cause this? If not, how I should go about trouble shooting the issue?

Thanks,

Chris

[chpthril]

Both batteries on my 20v read 13.4 and 12.4

When is this reading tacken? 1 volt is a huge difference, so work on that also.

next, start right at the back of the gauge with a test meter. Does the meter show the same low reading? If not, its the gauge. If so, work backwards till you find where the voltage drop is. Just remember, the negative is half the circuit. low voltage is not just a positive problem.

[freeheel4life]

Mike is onto something on his readings. 13.4 is usually a sulfated battery if that was open circuit voltage

[CJAuster]

I have a dual battery setup with perks switch. That was with both batteries in the " all " position. Key was off and after a full charge on main battery. Which read 13.4

Sulfated battery would read high? Not low?

[freeheel4life]

I have a dual battery setup with perks switch. That was with both batteries in the " all " position. Key was off and after a full charge on main battery. Which read 13.4

Sulfated battery would read high? Not low?

Maybe I have incorrect terminology. Just been told in the past that batteries with open circuit voktage that high after charging are typically sulfated. Way to confirm is to set you meter in MIN hold mode. Select just that battery on your Perko switch. Crank engine while leads for meter are on that battery. If voltage drops below 9.7 volts then that battery isnt a good battery. Helps to disablr either ignition or fuel pump to give it a good test

[chpthril]

Ok, before getting in deeper. I would suggest charging the batteries individually and with the battery switch off. Yes, it will take longer, but more accurate in the end.

After you feel the battery has been charged long enough, you need to let it rest before taking an voltage reading, other wise, you measure whats called the surface charge. You can let the battery sit for a few hours or disable the ignition and do 3 sets or 5 second engine cranks. Again, dont combine the batteries with BOTH, we need them separate.

I think you may find that the one reading 13.4 was the surface charge as it was fresh off the charger. The one reading 12.4 likely did not get fully charged or is bad. With the switch in BOTH, they should read the same after charging.

[freeheel4life]

^^ nice call Mike. Assumed no surface charge as obviously helm power/ignition was on.