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BambiBirder · 11-08-2012, 08:29 AM

When boon docking, my battery always runs out of juice, setting off various alarms and clicking sounds. I have a generator and use it during the allowed hours (usually for 15 mins or so, to minimize disturbance to other campers). I usually only run the refrigerator (propane) at night. I have heard that linking two batteries may solve the problem - is that the best way?

**azflycaster** · 11-08-2012, 08:36 AM

Running a generator for 15 minutes is not going to put much of a charge back into the battery.

If the battery is fully charged you should be able to go all night unless you are running the furnace for an extended time. Either your battery is not fully charged or it has lost the ability to hold a charge.

A W Warn · 11-08-2012, 08:42 AM

I thought about adding a second battery too. Instead I bought the largest battery that would fit in my battery box. Then I changed about half my interior lighting to LED, at least one bulb in each two bulb fixture. I only turn on the second bulb in each fixture only when I need task lighting at that specific location. I've been like this for more than a year now and this works for me. I have not cold weather camped unless I had shore power, so I do not know if this will maintain enough charge to run the furnace all night.

15 minutes run time on your generator will not fully charge your battery. You need around 2 to 2 1/2 hours at least to maintain daily. If it's completely dead more time.

Protagonist · 11-08-2012, 08:49 AM

Quote:

Originally Posted by BambiBirder

When boon docking, my battery always runs out of juice, setting off various alarms and clicking sounds. I have a generator and use it during the allowed hours (usually for 15 mins or so, to minimize disturbance to other campers). I usually only run the refrigerator (propane) at night. I have heard that linking two batteries may solve the problem - is that the best way?

You may need to charge the battery for more than 15 minutes if it's as depleted as you say.

Also, make sure the battery charger matches the type of battery. A charger meant for wet-cell starting batteries will not do so well for either wet-cell deep-cycle batteries or AGM batteries.

Connecting a second (identical) battery will double your amp-hours, but also double your charging time.

perryg114 · 11-08-2012, 08:59 AM

I don't think he is getting the battery fully charged as others have suspected. The battery voltage as measured at the terminals with no load should be around 12.5 V. Measure your voltage a few mins after turning off the generator and see what you get. I would try to measure at the battery terminals if possible.

Automotive battery - Wikipedia, the free encyclopedia

Perry

68 TWind · 11-08-2012, 09:01 AM

It's all about amps in amps out. You must "put back" amps that you take out. This is a very simplistic way of thinking but it is what is going on. The output of your converter and the size of the battery will determine just how long you have to run the generator to bring the battery back up to full charge. There is a lot of really good info on maintaining 12V systems on many RV web sites. Look at the capacity of the battery (amp hours) and the capacity of your converter, do a little math and you can get the approx. time to run the generator. Bear in mind that there are losses so a little longer is better. This is assuming the battery is still in good condition. A good digital volt meter is very helpful.

perryg114 · 11-08-2012, 09:04 AM

He is right. If you have a 70-100 AH battery it will take several hours at a 20A charge rate to recharge that battery.

Perry

Mexray · 11-08-2012, 10:58 AM

I use the 150% rule when trying to estimate the recharge time...

If your gr-24, 80 amp hr battery was completely discharged, and you have an 40 amp rated converter/charger...

80 AH / by 40 amp chgr = 2 hours x 1.50 = 3 hours total to complete the charge...

This is only an approximate estimate, as actual conditions vary...

We have a 3-stage chgr & a volt minder so I know when to quit charging when the volt meter shows the charger has reduced voltage to the 'float' mode, about 13.6 volts...

Protagonist · 11-08-2012, 11:06 AM

WHEN to charge can make a difference, too. Try to charge your battery when you're using the most AC current anyway, so that you're running your AC appliances off the generator and not the inverter. The generator should put out enough juice to run both the appliances and the charger at the same time.

If you charge your battery around dinnertime, so that your lights, microwave, etc, are running off the generator and not the inverter, you also start the "quiet hours" with a fully-topped-off battery, and you will find that it lasts longer than if you charged it in the morning and it's already half-depeted by evening time.

polarlyse · 11-08-2012, 11:42 AM

We have 2 group 27 batteries. We stayed 3 nights on battery this past summer with no problem. Of course the heater is a big drain and we weren't using it. But for refrig and lighting it was good. One fully charged battery should last more than one night without using the heavy consumers.

jdalrymple · 11-08-2012, 12:18 PM

You know how your cell phone takes longer than 15 minutes to charge?
So do the batteries in your trailer.

As mentioned above, you need to run a generator 3-6 hours a day to get a complete recharge. More batteries mean more storage and longer run times, but will take longer to charge, too.

Regards,

JD

perryg114 · 11-08-2012, 01:02 PM

Some generators have a 12V output at several amps that may charge the batteries faster than going through the converter. Just because your converter puts out 55A MAX does not mean that much is going to the battery. When the battery is dead you might get 55A but when it is half charged you may only be getting 10A.

Perry

Bill M. · 11-08-2012, 02:02 PM

Are you running the furnace? I think one good battery fully charged out to be good for 3 or 4 days for lights, fan, refrig. You probably ought to buy one of the little $20 battery voltage meters and keep it plugged into your trailer. Pretty soon you will learn to tell how well the battery is charged and how far it discharges. Depleting the battery all the way and recharging is very hard on the battery. I suspect at this point you need a new battery and a longer run on the generator. Also not that driving the car and pulling the trailer will not fully charge the battery. It really needs to be charged on shore power to get it to full capacity.
We have some LED lights and a fantastic fan. We run the refrig all the time. We can go 4 days or longer on a half draw down on 2 batteries. But if it is cold and we run the furnace we have to charge almost every day.

DanielB · 11-08-2012, 02:58 PM

You have a 2005.. do you have one of those buttons with a meter that you can push to see the status of your battery?

HiHoAgRV · 11-08-2012, 02:59 PM

Quote:

Originally Posted by perryg114

Some generators have a 12V output at several amps that may charge the batteries faster than going through the converter. Just because your converter puts out 55A MAX does not mean that much is going to the battery. When the battery is dead you might get 55A but when it is half charged you may only be getting 10A.

Perry

On a Honda 2000, the DC Charging circuit is unregulated and only 8 amps max. It's much better to use the AC side to charge batteries.

I have noted that my setup, 3 group 27 batteries (+-240 AH) when discharged to 80% will only load a 65A 3 stage charger on it's Bulk Mode to 13-15 amps. In other words, the last 20% will take hours to approach a full chargel.

Jammer · 11-08-2012, 03:10 PM

Quote:

Originally Posted by BambiBirder

When boon docking, my battery always runs out of juice, setting off various alarms and clicking sounds. I have a generator and use it during the allowed hours (usually for 15 mins or so, to minimize disturbance to other campers). I usually only run the refrigerator (propane) at night. I have heard that linking two batteries may solve the problem - is that the best way?

Since you have a 2005, if you have the original battery, it's time to replace it. Even if it's not the original battery could still be beyond it's useful life (rule of thumb: four years).

If you have the original converter in your Airstream, it takes an overnight charge (or longer) to get the battery completely topped off. With a multi-stage converter it would still take at least four hours to recharge a completely discharged (or nearly so) battery.

Running the fantastic fan or furnace are the two quickest ways to run the battery down at night. Avoid those if your situation permits.

perryg114 · 11-08-2012, 03:46 PM

Well if you have a tow vehicle with a big alternator in it you could charge it off that in a shorter time if you use jumper cables to get maximum current.

Perry

Protagonist · 11-08-2012, 03:52 PM

Quote:

Originally Posted by perryg114

Well if you have a tow vehicle with a big alternator in it you could charge it off that in a shorter time if you use jumper cables to get maximum current.

Perry

You could, but preferably if the trailer battery is a wet-cell starting battery (which is entirely the wrong type of a trailer, but you never know what the previous owner used), and not a deep-cycle battery. The voltage regulator on the engine alternator is optimized for recharging starting batteries.

perryg114 · 11-08-2012, 04:35 PM

Voltage is voltage. Current is Current. Try it and if it does not work try something else. I don't know of another way to get that kind of current to recharge a battery fast. Charging a battery fast is not optimum no matter what type the battery is. Running a quiet generator for several hours is probably the best solution.

Perry

FreshAir · 11-08-2012, 04:46 PM

When we dry camp I run my Honda 2000 an hour in the morning to recharge from to past evening...tv w/satellite or movie (dvd) and/or late night book reading etc. When we sleep NOTHING (electrical) is on. Heat if needed is portable propane...no fan but never when sleeping. Then I run the charger 1 hour again late afternoon if my volt meter says that the battery is a little low. Works for us.

Neil