Weird Battery and Starting Issue

[Wesley Cobb]

Went out this past Saturday...both batteries very low voltage. The blower would come on for about a second or so then go off and there was no gage movement. Took both batteries out and had them tested at Auto Zone -- still good just low voltage. Put them on my charger/tender for about 16 hours. Pulled them off Sunday morning then headed to the boat. Reinstalled...turned the key and the start sequence ran completely. Hit the buttons and nothing happened. Not even an attempt to spin the starter. Both batteries, once the boat is cranked and the CONNEXT display is on, show each is around 13 volts. Tried the emergency parallel switch and the engines started like normally. I am thinking one of the batteries is not holding the charge but why would they show as charged on the display? Any ideas? Right now, I am thinking I need to pull the batteries, have them tested again, then put them back on the tender for longer time.

 

[Judge]

I would get your own battery load tester. I have one like this and there are cheaper and more expensive ones as well. They are worth having and will pay for itself if you have a lot of stuff using batteries.

https://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0/ref=sr_1_6?crid=V5M75X3C6FON&keywords=battery+load+tester&qid=1696409267&sprefix=battery+load+tester%2Caps%2C112&sr=8-6

How old are the batteries?

Are they wet or AGM?

If they are wet / flooded and get get below 50% SOC, the plates can sulfate and that hurts the life and performace of the battery. Good battery chargers will go through an Equalization mode periodically for wet batteries that raises the voltage periodically to 15 - 16V in an attempt to strengthen the electrolyte, and knocking off any loosen sulfate that may be on the battery plates. This is also why it is important not to let the electrolyte to drop below the top of the plates.

If the batteries are good, then I would be checking all of my connections (I would do this anyway). Since you were showing 13V but didn't hear the starter try to engage, you might have a loose or corroded connection in the startng battery circuit. Especially since the Emergecy Start switch allowed it to fire up.

 

[FSH 210 Sport]

I would add…

Do you have an on board charger and keep it plugged in?
What exactly was the charger tender you used to charge your batteries for 16 hours?

in addition to what @Judge said about sulphation of the plates, if your batteries are flooded you need to check the specific gravity of the electrolyte in each cell with a hydrometer and check to see if all the cells are balanced. If the specific gravity is low or unbalanced then an equalization charge is required. As @Judge mentioned, the modern battery chargers will run an equalization charge periodically, but a good charger will have the ability to run a manually activated equalization charge if the hydrometer readings are not good. This is absolutely necessary on a flooded battery to keep it in top condition.

Unless Autozone a true load testing battery tester like @Judge posted a link for then the batteries were not, in my opinion truly tested.

A battery with heavily sulphated plates will / can show good voltage but as soon as load is applied the voltage will crater. Any lead acid battery that is allowed to sit in a discharged state, whether by use or by just sitting will start to have its plates sulphate.

 

[Wesley Cobb]

Gents -- Thanks for the information and advice. They are both wet. I do need a not have a tender on the boat since it is stored in a vertical storage shed on the fourth deck. I do have one at home I use during winter storage to keep them healthy though. It is a ProMariner ProSport dual charger/tender. I think I will remove them and take them to Batteries Plus here in town and have them tested again. I will definitely look at the battery tester @Judge mentioned. Honestly, I think I just got two crappy batteries from the local dealer when I took the boat in for service. I had two distinctly different battery types -- one for start and one for house -- in there before and may just go back to that set up. Worked well for many years. This boat has not given me one single problem in five years (other than bilge pump buffoonery) in over four years but this past weekend was interesting...

Cheers, guys. Thanks for the advice.

 

[Judge]

Gents -- Thanks for the information and advice. They are both wet. I do need a not have a tender on the boat since it is stored in a vertical storage shed on the fourth deck. I do have one at home I use during winter storage to keep them healthy though. It is a ProMariner ProSport dual charger/tender. I think I will remove them and take them to Batteries Plus here in town and have them tested again. I will definitely look at the battery tester @Judge mentioned. Honestly, I think I just got two crappy batteries from the local dealer when I took the boat in for service. I had two distinctly different battery types -- one for start and one for house -- in there before and may just go back to that set up. Worked well for many years. This boat has not given me one single problem in five years (other than bilge pump buffoonery) in over four years but this past weekend was interesting...

Cheers, guys. Thanks for the advice.

Dealers tend to put the cheapest batteries in they can. My dealer put in two Interstate Group 24 Batteries that were wet and only had a 6 month warranty from Interstate. I have a '22 275SD and the heavy system electronics need better batteries to be reliable.

I ditched those batteries and put in two Duracell Deep Cycle AGM Group 27 batteries from Batteries Plus with a 30-month warranty.

https://www.batteriesplus.com/productdetails/battery/marine-and-boat/deep-cycle/sli27magmdc

I had to install new battery trays to accomodate the Group 27 batteries and the AGM's are more expensive but it was well worth it from a reliability perscpective.

 

[Wesley Cobb]

Dealers tend to put the cheapest batteries in they can. My dealer put in two Interstate Group 24 Batteries that were wet and only had a 6 month warranty from Interstate. I have a '22 275SD and the heavy system electronics need better batteries to be reliable.

I ditched those batteries and put in two Duracell Deep Cycle AGM Group 27 batteries from Batteries Plus with a 30-month warranty.

https://www.batteriesplus.com/productdetails/battery/marine-and-boat/deep-cycle/sli27magmdc

I had to install new battery trays to accomodate the Group 27 batteries and the AGM's are more expensive but it was well worth it from a reliability perscpective.

I am here to say you are exactly correct! Had two Duracell AGM batteries in there before. Going back to them!

 

[Marvin willis]

Your starting battery is dead. Connext only reads the house battery unless you do the battery mod that’s on this site. That’s why it starts normal when u use the parallel switch