New Batteries Don't Last Long

My friend indicates that the batteries being drawn down to 25% (indicated by voltage only) is not the norm, but it has happened several times when he hasn't been able to run the genny. The batteries are the Everstart Maxx group 29 Marine batts from WM with 114 amp hours rating.

Is anyone concerned that the external battery charger and the trailer's converter could be in use at the same time charging the batteries?

I would think that this setup really wouldn't work correctly. If one of the batteries was disconnected from the trailer and the external charger were attached to this battery, it would charge as it should. If both batteries were disconnected from the trailer and the external charger were attached to BOTH batteries, charging would work but would be quite slow. If the generator's power was attached to the trailer, equivalent to shore power, the converter would supply 12V power to everything in the trailer, including any attached batteries. With the converter supplying 12V power to the batteries, what will the external charger see? 'Apparently' charged batteries? If the charging process were started with the trailer NOT plugged into the genny, the external charger would see batteries needing a charge and would attempt to charge them. Now if the trailer is plugged into the genny (shore power) and the trailer's converter is powered, what will happen to the batteries then? They were being charged externally and now another charger is potentially supplying a charge??

I would think that this just wouldn't work correctly and that my friend should charge with either the external charger or the converter, BUT NOT BOTH at the same time.

mena661 wrote:

smkettner wrote:
Charging seems to be adequate IMO.

Really? TWO grp 31 batteries discharged to 25% and fully charged in 6 hrs with a 25A charge rate? I need that charger on my bank then. It's magical. Charging is NOT adequate because the batteries are NOT fully charged. BTW, everyone he has two batteries not one.

25a charger in parallel with the converter. I assume 55 amp WFCO that just runs in normal mode.
I figure 1 to 3 hours together and 3 hours absorption with just the charger. I doubt the 25% is from a real battery monitor.
I assume the portable has a "fully charged" indicator that was reached in the six hours.
Adequate, not perfect.

Check that the frost free switch on the fridge is set to off. Even on gas this feature will draw from your 12 volt system. The switch on my rig is near the top inside of my freezer. It electrically heats the area near the door seals to prevent frost. Good luck.

Ron Nielson wrote:

I have two new marine batteries which have only been used for 5 weeks. I fully charge both batteries at 25 amps, but they run down after two days to 25%.

I just bought a new marine battery. It came with 12.5v, 1.25 sg, I set the smart charger on 15A and when it went to float I measured the specific gravity of the fluid, the same as when I bought it 1.25. I set the charger to 2 amp and it seemed to be holding 2A, voltage indicated on charger was 14.6 but measured with meter was 14.2. Cutt-off to float is some % of charger setting so it cuts off early in 15A mode vs 2A mode. Impatient, I hooked up a manual charger for 15 hrs, final charge voltage was 15.3v and the sg had risen to 1.275. I believe I now have a fully charge battery.

smkettner wrote:
Charging seems to be adequate IMO.

Really? TWO grp 31 batteries discharged to 25% and fully charged in 6 hrs with a 25A charge rate? I need that charger on my bank then. It's magical. Charging is NOT adequate because the batteries are NOT fully charged. BTW, everyone he has two batteries not one.

Hi,

70 amp-hours for parasitic loads over two days, and probably 60 amp-hours to charge the computer.

He might wish to look at solar.

Given the list of loads being run I think the battery capacity seems normal.

Quote:

"Checking with volt meter should be done not "after charge", but 24 hours after charge. Full battery with all cables disconnected should read 12.7V."

Not true in this case. Since a load such as refrigerator and detectors will get rid of a surface charge with minutes. Checking the voltage at the battery-terminals about 15 minutes after charge (all other items left turned off) should work. Fully charged battery-bank should drop to 12.7 volts. Anything higher is still surface charge. Check again in 15 minutes.

If the battery-bank is less than "full charge", the voltage will settle at something lower (i.e. 12.5v -90%, 12.4v -80%, 12.3v -70%). The items I mentioned left on do not cause a voltage drop so reading is good enough for accuracy. I hope he is not starting each cycle 12.3 volts (70%) already or he is in "deep dodo". Heavy sulfating of the batteries already.

is the fridge on 12vdc or on propane

12vdc operation sucks the batteries way down with a 300w electric heating element

how is the inverter wired in, just for the PC and phone charger or the whole house

if whole house make sure the fridge is 'MANUALLY' SET TO LP, other wise it will automatically use the inverter and drain the batteries

Checking with volt meter should be done not "after charge", but 24 hours after charge. Full battery with all cables disconnected should read 12.7V.

Agreed that batteries could have been somewhat damaged already, after repeated discharge to 25%.

SMK is reading my mind - turn the inverter off when not in use. Disable any heaters in the fridge. Also, before bedtime, pull the fuse off the radio clock (you lose station presets but conserve energy).

PS: when something is consuming your power and you want to find out what, you should measure not volts, but current. This is done with a multimeter or ammeter - not "voltmeter". Turn everything off, connect the multimeter in Pos cable between the battery and load cable, and turn devices on and of, one by one. You will probably see some "fantom loads" before you turn anything on. Meter should be able to measure at least 15A.