Batteries not holding charges

[Mhorowitz]

We have been having trouble keeping a charge on our house batteries. I have a Coacmen Freelander 29 QB. With 2 grp 24 deep cycle batteries we have to charge 2 to 3 times a day. This seems unreasonable since we are not using much off the batteries. When I run the genset for an hour or so the batteries register full but within 8 to 12 hours they are flat again. I Suspect the batteries are worn out or damaged so I am planning to replace them.

Secondarily, how difficult would it be to add additional batteries? On my boat I have 4 grp 31's plus solar panels and never need to run the genset.

Suggestions.

[Bordercollie]

If both batteries have been tested and are in good chargeable condition, and converter/charger is supplying 13.6 volts charging voltage measured at battery terminals, and you are allowing enough time for converter to charge both batteries, there may be a short in the 12 volt wiring system or some item that is drawing excessive amps and needs to be disconnected/replaced. Check for lights left on in the storage compartment, etc. If there is a short, it should blow a fuse or circuit breaker if one is in the circuit, if not, a short could cause a fire. You might try feeling for heat in 12 volt wiring. If you had an amp meter, you could check on how much current is being drawn from batteries with everything shut off.

[RoyB]

Batteries take much more time than one hour to charge. It depends on the DC Charge voltage you are using and how much DC the batteries are allowed to draw.

The rule of thumb is you will want to have around 18-20AMPs of DC CURRENT available for each battery you are charging in your battery bank. i.e. if you hit a discharged deep cycle battery with 14.4VDC the battery will demand around 18-20AMPS of DC CURRENT from the source charger to start its re-charge mode.

Consider this report from PROGRESSIVE Dynamics on how long it takes to charge a deep cycle battery when discharged down to 10.5VDC

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

This is battery charging science at play here - not many ways to get around it...

Just some of my thoughts here...

Roy Ken