Battery Charging Adventures

image source: West Marine

 

 

WEST MARINE–Group 31 Dual-Purpose AGM Battery, 105 Amp Hours  

I've been slowly trying to nurse the main starting battery back to health over the last few days. 

 

I've had the charger disconnected since I installed the microwave in the galley last May. 

 

I was going to run the engine this past weekend - and discovered the battery was only showing 10.5+ volts. 

 

The first few days - I kept the charger on for 4-6 hours. But each time, immediately afterwards - the battery failed to hold a charge.

 

Tonight, after disconnecting - it still showed 12.3 volts. 

 

I am hopeful. But, we'll see how it looks in the morning. 

 

These are AGM batteries - and were purchased in July 2013 (paid $259.99 each). AGM batteries are very robust - usually good for 3-5 years, or 6-8 years if properly maintained. 

 

I have two on the house side, and one for starting. 

 

They are rated for 300 cycles ("Recharging cycles are the number of times a fully charged battery can be discharged to 10.5 volts at 80 degrees F. then then fully recharged an hold the charge.")

 

These are the same type of batteries I had in my previous boat. 

 

I spend quite a bit more for this quality of battery - but they are rock-solid reliable - and I think much safer. I sleep much better having them aboard. 

 

Once I get this sorted - I plan to add solar panels to keep the batteries charged.  

Battery Articles

• https://en.wikipedia.org/wiki/VRLA_battery 
• https://en.wikipedia.org/wiki/VRLA_battery#Absorbent_glass_mat_(AGM)
  
• https://en.wikipedia.org/wiki/Depth_of_discharge
  
• https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm
• https://www.discountmarinebatteries.com/west-marine-dual-purpose-agm-review/
• https://www.tripsavvy.com/best-marine-batteries-4579773
  
• https://www.practical-sailor.com/systems-propulsion/electrical/deep-cycle-marine-battery-test
• https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/
• A fascinating article...  

 

2021-04-29 update:

•  Back to 10.5 volts this morning. 

 

2021-07-29 update:

• (3) New AGM batteries installed (paid: $279.99 each) - once again, my vessel is operational.