Best Way to Manage Batteries as a Liveaboard at a Slip

[JK_Boston_Catalina310]

Hey MS. I hope your not getting too overworked with spring commissioning.

I recently installed a new battery bank which consists of four 6 volt golf cart batteries (Duracell ECG-2 from Sam's Club) for a 460 amp hour capacity at 12 volts. I am currently on my second break-in cycle following the Ample Power procedure and plan to do 5 break-in cycles in total. (http://amplepower.com/primer/break-in/index.html)

I currently have a 40A Xantrex TrueCharge2 equipped with a temp sensor. I have a Victron battery monitor (still need to program with the new battery info). My house load draw current when at the dock is about 5-7 amps. So my charger is less than 10% of my battery capacity plus house load but I am not overly concerned about that since we are typically only taking the boat out on weekends and I have time to let the batteries get a full charge. At least until we head out cruising but I will add solar prior to that happening.

My question is what to do during the week when at the dock to best prolong the life of my batteries. Should I just leave the charger on (it's a "smart" charger and will go to float mode once the batteries reach full charge)? Or would it be better for battery life if I turned off the charger after a short period in float and let the house load discharge the batteries down to say 55% SOC?

Of course this would be on top of things like regular equalization, checking the fluid, checking the specific gravity of the fluid, etc. (Anything else I am missing?)

Thanks,

Jesse

 

[Stu Jackson]

Jesse, just when they go into float is NOT a full charge. Use your battery monitor to find out when they are "full" by determining when they reach to 2% of capacity. I think you've read my "Gotcha" article about battery monitor algorithms. If not, let me know and I'll give you the link.

Once fully charged, you can leave them unplugged. After all, that's what skippers do during the winter.

 

[Maine Sail]

Hey MS. I hope your not getting too overworked with spring commissioning.

I recently installed a new battery bank which consists of four 6 volt golf cart batteries (Duracell ECG-2 from Sam's Club) for a 460 amp hour capacity at 12 volts. I am currently on my second break-in cycle following the Ample Power procedure and plan to do 5 break-in cycles in total. (http://amplepower.com/primer/break-in/index.html)

I currently have a 40A Xantrex TrueCharge2 equipped with a temp sensor. I have a Victron battery monitor (still need to program with the new battery info). My house load draw current when at the dock is about 5-7 amps. So my charger is less than 10% of my battery capacity plus house load but I am not overly concerned about that since we are typically only taking the boat out on weekends and I have time to let the batteries get a full charge. At least until we head out cruising but I will add solar prior to that happening.

My question is what to do during the week when at the dock to best prolong the life of my batteries. Should I just leave the charger on (it's a "smart" charger and will go to float mode once the batteries reach full charge)? Or would it be better for battery life if I turned off the charger after a short period in float and let the house load discharge the batteries down to say 55% SOC?

Of course this would be on top of things like regular equalization, checking the fluid, checking the specific gravity of the fluid, etc. (Anything else I am missing?)

Thanks,

Jesse

Jesse,

The TC2 is not a horrible charger, when they work, but they lack the "forced float" mode of the earlier True Charge units. The 40A model should do a good job of holding float under dock side loads. If you find it popping back to absorption frequently, when under load, you can use the GEL setting when at the dock...

 

[Benny17441]

Well too many variables to consider but in general terms, it is advisable to exercise batteries and it is not recommended to leave them on the charger 24/7. To devise an put in practice optimum program might require to much effort with a diminishing beneficial return. It would not hurt to take them off the charger for a 12 hour period once week not exceeding a 45% SOC. You would not want to take them down too deep or too frequently as that would be wasting some of the limited number of charge/discharge cycles in the battery's projected useful life. There are indeed worse battery usage practices than not exercising them and keeping them on the charger.