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.

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

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.

The answer to your issue is in the above post on how long it takes to recharge a battery. One hour of charge is only going to show a surface charge voltage which is not the true state of charge. A high output converter and time is what your recharge system needs to get the batteries back to a 90% state of charge quickly. Getting to 90% SOC should be your goal. The last 10% takes a loong time.Jim

Motorhome house battery charging is essential to operating any motor home. Getting to know the location and understanding basic functions of the converter/charger, the house battery disconnect switch and relay, fuse and breaker boxes, how to check battery voltages with a simple multi-meter, and how to maintain battery electrolyte levels, is basic to having house battery power when you need it on the road, away from home. 12 volt DC supply connections at the converter/charger, batteries and at appliances, and other 12vdc devices must be clean, tight and make good contact. Most appliances need a combination of 12 volts DC for controls and 110 volts AC or Propane for main power. There are some helpful You Tube videos and generic "how-to" RV books. Nothing beats exploring and getting to know your own rig's 12 volt systems.

As you realize by now it takes much longer to charge your batteries than an hour or two.If you can measure the voltage the batteries are getting when being charged, or post the model name and number of your converter we could be of more help.How difficult is it to add more batteries? That depends on your RV and the available space. It is more a physical than a wiring challenge.

Batteries not holding charges | Good Sam Community

maillemaker
Explorer
Jun 09, 2014
Tons of advice already on charging. I have also heard that many converters are not optimal battery chargers. I make sure my toggle switch is in charge mode when I am driving to and from the camp sight so the engine's alternator does the charging.

As for adding a battery, I added one to my 1990 Winnebago Warrior. It only had room for a small house battery up under the hood. So I added one in the storage bay right behind the generator. I purchased a long set of jumper cables and used it to wire back to the original battery. It was cheaper than buying the same gauge wire and building my own cable.

Steve

Steve
jauguston
Explorer
Jun 08, 2014
Something else to think about. If your converter voltage is adjustable and many modern ones are the best setting is 14.8v. Most are set at 14.4v and it is proven to not be high enough. That setting will speed up your recharge time.

Jim
Bordercollie
Explorer
Jun 08, 2014
Typical converter chargers charge very slowly to avoid boiling batteries out of electrolyte. All converter chargers will deplete electrolyte levels a certain amount rquiring periodic replenishment. Modern ones may have faster intitial charge rates but still take hours to charge house batteries, charge time also depends on condition of batteries and how discharged batteries are to start with. The chassis alternator should charge house batteries more quickly while driving to the next campsite.Charging house batteries using the RV generator near other campers is not practical. Hooked to shore power, charger should charge house batteries during daytime unless 12 volt power is being used to run the furnace, wonder fans, etc.

I read about a couple who ran their generator all night long because they liked running the air conditioner and having it cold for sleeping snugly covered up. That could be dangerous to your health or at least make you unpopular with other campers.
jauguston
Explorer
Jun 08, 2014
Roy B gave you the answer.
ksg5000
Explorer
Jun 08, 2014
How are you measuring whether batteries are full or discharged? Many new RVers use the idiot lights on the control panel and they worse than useless when it comes to determining the condition of a battery.
Bobbo
Explorer II
Jun 08, 2014
3 hours minimum
Mhorowitz
Explorer
Jun 08, 2014
Alright guys so my hour of generator morning and night isn't enough charging even with a 55 amp converter/charger running at 14 volts. So how many hours do indeed to disturb the peace when boom docking ? On my boat I have 4xgrp31 with 350 wards of solar. Looks like I will/should be adding solar to the RV but seems like in RV application clear sunshine is harder to come by.
Harvey51
Explorer
Jun 08, 2014
"One hour of charge is only going to show a surface charge voltage which is not the true state of charge"
It happened to me! I trusted the lights on the monitor panel but those lights greatly exaggerate the battery charge until a few hours after charging ends. And damage to the batteries results because they are not designed to be used below half charge (12 volts measured 4 hours after charging).

With little use of the batteries and LED lights, many of us manage with just charging from the engine as we drive for an hour or so per day. But this risks going below half charge and damaging the batteries, particularly in cold weather when the furnace is used a bit in the morning.
jauguston
Explorer
Jun 07, 2014
YES
Dakzuki
Explorer
Jun 07, 2014
Shadow Catcher wrote:
This brings up the, only way to truly know the SOC (state of charge) of your batteries is with a battery monitor that measures the current going into and coming out of your battery. The two choices are basically Trimetric and Vectron.

A fully charged battery is measured with a voltmeter and compared to the manufacturer's spec after the prescribed amount of "rest" after charging. The devices that use current base it on initial full charge and estimated capacity. Capacity changes with age.