Don't Trust Connext Battery Readings

[RobbieO]

Tomorrow I'm taking my maiden voyage, so I can start my 10 hour break-in. I put the new batteries back in the boat today. They have been on my ProMariner ProSports HD 12A Dual Bank battery maintainer (which is brand new) for the last 2 months. After hooking them up, I went to start the engines and both battery gauges showed 12.2v with a red arrow pointing at the low voltage. What? I can't go out with these batteries. Got the DVOM out, and both batteries were 12.65. Don't trust the Connext screen, the readings are bogus. Tomorrow when I hit the lake, I'll see what the charging voltage is. I can understand some variance, but what gives with the red arrows.

 

[haknslash]

Wait, I’m confused. The promariner battery tenders are onboard smart chargers / maintainers. Why would you be putting your batteries back in the boat? They should stay in there and connected to the maintainer when the boat is not in use. There’s no need to remove batteries unless you live in very cold climates and if that is the case it’s possible your batteries died from the cold if they were not kept somewhere insulated, warm and on a tender.

The batteries are going to read 12v if the engine is not running. With the engine running they should show 13+ volts.

 

[Dave burke]

On similar vein to @haknslash, I thought your readings seemed fine. Coming off the charger, around 12.5V is pretty normal and when putting it in the boat under load dropping to 12.2 seems about normal because the ignition is on.

My boat reads about 12.1-12.3 when I turn on the ignition and then about 13.5-14.2 when the engines are running.

 

[adrianp89]

My SX always showed almost a .5 voltage drop from meter on battery from connext screen.

 

[anmut]

Tomorrow I'm taking my maiden voyage, so I can start my 10 hour break-in. I put the new batteries back in the boat today. They have been on my ProMariner ProSports HD 12A Dual Bank battery maintainer (which is brand new) for the last 2 months. After hooking them up, I went to start the engines and both battery gauges showed 12.2v with a red arrow pointing at the low voltage. What? I can't go out with these batteries. Got the DVOM out, and both batteries were 12.65. Don't trust the Connext screen, the readings are bogus. Tomorrow when I hit the lake, I'll see what the charging voltage is. I can understand some variance, but what gives with the red arrows.

Did you by chance have not have your battery switch on house and start? I know that in the past if I've just turned the start battery on for running the boat in the driveway, i'll get a low battery warning on the house, simply because it's off.

 

[RobbieO]

Wait, I’m confused. The promariner battery tenders are onboard smart chargers / maintainers. Why would you be putting your batteries back in the boat? They should stay in there and connected to the maintainer when the boat is not in use. There’s no need to remove batteries unless you live in very cold climates and if that is the case it’s possible your batteries died from the cold if they were not kept somewhere insulated, warm and on a tender.

The batteries are going to read 12v if the engine is not running. With the engine running they should show 13+ volts.

There are no outlets at my storage facility. Once I have a storage place with an outlet, I'll mount it in the boat.

 

[RobbieO]

Did you by chance have not have your battery switch on house and start? I know that in the past if I've just turned the start battery on for running the boat in the driveway, i'll get a low battery warning on the house, simply because it's off.

No, I double checked. And that's why I originally pulled the batteries. The indicators said the batteries were low.

 

[haknslash]

Also ensure the small black cable that’s often attached to these batteries is connected since you removed and reinstalled the batteries. That little cable (can’t remember if it goes on ground or positive terminal) can cause issues for people. Honestly though 12.x volts without the engines on is about normal. Not sure why connectx is freaking out but not surprised either tbh lol

 

[FSH 210 Sport]

I inquired about this a few months ago and was told that it could be the zener diode that is in the connext module. My voltage reading on the connext screen is low by .4 VDC.

 

[tdonoughue]

Would be instructive to have the voltage reading at the Connext (like measuring it there behind the screen) versus at the battery, as well. It may be that your Connext is not measuring correctly or it may be that you have a different voltage at the Connext point in the circuit.

 

[212s]

Not sure what the issue is exactly, but read about similar issues with older models reading low but everything was ok at the batteries. I think the issue was very small gauge wires adding resistance and dropping the voltage reading in the Connext? Luckily my Connext is very accurate with the voltage readings. I confirmed they read the same with my volt-meter. I'm wondering if it's a wiring issue, something not connected at the right place, or a connector not fully plugged in behind the helm, etc.

 

[RobbieO]

I inquired about this a few months ago and was told that it could be the zener diode that is in the connext module. My voltage reading on the connext screen is low by .4 VDC.

Exactly...my gauges read .4v low....

 

[Canuckjetboater]

@RobbieO ..... are all your associated grounds making good contact and tight. I have seen sooooo many electrical problems, over the years, attributed to poor grounds. BTW I like @212s suggestion regarding resistance. Wiring gauge is another marine issue or rather too "thin" as in higher gauge wire.

 

[RobbieO]

@RobbieO ..... are all your associated grounds making good contact and tight. I have seen sooooo many electrical problems, over the years, attributed to poor grounds. BTW I like @212s suggestion regarding resistance. Wiring gauge is another marine issue or rather too "thin" as in higher gauge wire.

I’m going to disregard the Connext readings and go off my DVO . It’s charging good