Charging house batt. with charger - time

An RV battery at 80F will only START bubbling vigorously at FOURTEEN POINT EIGHT VOLTS after it reaches about 70% state of charge. Next time after a long freeway run measure your motorhome house battery while the engine is still running. Sur-prise!

I charge my batteries at 14.8 volts from the second the charger starts until the electrolyte starts to bubble three or four bubbles a second then I reduce the charge rate.

"Smart" chargers are like state highway workers. Cut them slack and they lean on a shovel. A battery charger allows the "smart" charger to start leaning right off the bat. This is exactly why I recommended the power supply units. I've got better things to do than play games with a smart charger that has an IQ of around 60.

OMG, camping has turned into a mar's landing mission.

2 batteries, charge when low, camp & have fun. It's actually pretty simple.

OK, thanks or the good info. Last year I took two batts. and charge one at a time in garage and change them every other day, a little work, but only if it gets cold and need heat. thanks again.

Following.

"how long it would take to charge batt."

IMPOSSIBLE to say, with no info provided.

Things to consider:

Battery Capacity, Battery SOC, overall battery health, Charge Rate, Charge Voltage, Temperature, Wiring, Loads, etc.

MR MAC wrote:
Staying at Sons house in NC about a wk., too far from ele. plugin, any one how long it would take to charge batt. with a charger plugged in to MH with gen. running. May need to use furnace at night.. Also would charging cause any damage to converter as both would be sending current to batt. and is this a bad thing to do. Or do I have to disconnect batt to charge with a charger?

Second question: Would converter be damaged: NO, not at all, there are devices that act as electric check valves that protect both the charger and the converter.

How long will it take.. Now that is complex,, For Bulk charging you need to know the output of the converter, the output of the charger, the amount of load on the system and the capacity of the battery and the state of charge.. Then You add the charger and converter, subtract the loads, Multiply battery capacity by state of DISCHARGE (IE: if batteries are 60 percent SOC you multiply by 0.4) divide product of multiplication by the sum of addition/subtraction and that is hours to 90% in theory,, then it's 2-4 hours to top it off.

How far are you gonna be parked from his house? You only need to charge batteries and such right. No major AC draw?

I would try this. Put the refrigerator on gas as it I will draw a fair amount of amps. Then if you only have a very long light duty electrical chord it should be able to handle the light load to power converter and keep batteries charged. Just don't use any other 120 volt electrical devices.

There are well documented battery charging rules.

Consider what PROGRESSIVE DYNAMICS says in just about all of their converter/charger manuals on how long it takes a typical deep cycle battery to re-charge.

"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. You can charge your battery quicker by raising the 14.4VDC to a higher DC VOLTAGE and the battery will then demand more charging current. The downside to doing this is you will start boiling out the battery fluids if you are charging with more than approximately 14.4VDC at a higher DC CURRENT demand. I can re-charge my 12VDC batteries back up to their 90% charge state in about three hours charging time and can expect almost full performance capacity out of my battery. I can do this 50% to 90% charge cycle for 12-14 times where I must do a full 100% charge state. Continuing to re-charge only up to the 90% charge state without doing a full 100% charge cycle will do harm to your batteries.

IN your case you would want to provide 14.4VDC with the capacity of 40AMPS DC Current using a portable smart mode battery charger like the Black and Decker VEC1093DBD battery charger to re-charge a 12VDC DEEP CYCLE battery to its 90% charge state in a three hour time frame.

This will re-charge a 50% discharged battery back to 90% charge state in about three hours time.

Just running your trailer generator for three hours should do this as well without adding a portable charger. If your on-board CONVERTER is a smart mode type it will charge your batteries in a three hour generator run time. If your on-board converter only puts out 13.6VDC all the time then it will take around 40 hours to return you 50% charge state battery to 90% charge state.

Just running a charger for a couple of hours in the morning and another couple of hours in the afternoon will work good if you have a smart mode charging system. If you are charging each time with only 13.6VDC this will make you think it is going to work but the performance of the battery will fall off real quick. Continuing to do this short cycle will eventually do harm to the battery...

If you wanted to run out a good HD 10-Gauge (10-3) extension cord from the house plug-in the trailer pedestal using the RV30A-15AMP ADAPTER that would work also. In this case you would have to turn off several high current circuit breaker zones in the trailer with just using the low wattage circuits including the on-board converter. We use this method all the time here at our house.

Running totally off the battery won't last very long. Maybe one night with running the furnace. Plugging in a portable oil filled type heater to the 120VAC extension cord from the house will help out big time keeping things warm inside the trailer. Then maybe you can cut back on the furnace with low thermostat setting.

Keep in mind you will do harm to your battery if it gets discharged below 12.0VDC or around 50% charge state and not get re-charged back up to its 90% charge state in a short time period.

All of this comes from experience so if this is the first time you are doing something like this it may not turn out good for you haha...

I did all of my driveway camping at home the first two or three times... Its all second nature now since we know what do and what to monitor to make sure it is working...

Roy Ken

Multiple chargers is fine, no issues. Give it four hours. Two in the morning and two more toward bedtime. Adjust as needed.

I would have a couple 100' extension cords from house to portable charger if I could. Leave it on 24/7.