chargin battery via 7-pin RV connector

[E U G]

How long does it take to charge? Just bought a deep cycle battery a Costco and going on my first trip this weekend. I know it comes already charged but I'm wondering how long it takes to charge so I'm ready for my next camping trip. Do I need to buy a separate charger?

[eamarquardt]

I dunno. It depends upon the output of your alternator, the size of the wire from you alternator to the battery, the type of battery you have, and maybe other factors.

You might drain the battery down, make a dummy plug with the battery charge lead and ground stubbed out. Put the battery in your trunk and drive around as usual keeping a log of how long you drive and how long it takes to bring you battery back up to charge.

If you're gonna be camping where there is shore power a 4 amp (or more) charger, running 24 hours/day will provide you all the power you need (unless yer a real power hog) as it will keep your battery topped off all of the time and when you need more than 4 amps (or whatever the capacity of your charger is) your battery will supply the excess demand.

Given a battery and a reasonable charger I have never seen the need for one of the converters. They do, though, charge the battery but their capacity is far in excess, IMHO, for what I'd ever need.

Hope this helps.

Cheers,

Gus

[E U G]

I dunno. It depends upon the output of your alternator, the size of the wire from you alternator to the battery, the type of battery you have, and maybe other factors.

You might drain the battery down, make a dummy plug with the battery charge lead and ground stubbed out. Put the battery in your trunk and drive around as usual keeping a log of how long you drive and how long it takes to bring you battery back up to charge.

If you're gonna be camping where there is shore power a 4 amp (or more) charger, running 24 hours/day will provide you all the power you need (unless yer a real power hog) as it will keep your battery topped off all of the time and when you need more than 4 amps (or whatever the capacity of your charger is) your battery will supply the excess demand.

Given a battery and a reasonable charger I have never seen the need for one of the converters. They do, though, charge the battery but their capacity is far in excess, IMHO, for what I'd ever need.

Hope this helps.

Cheers,

Gus

Thanks for the reply! Could you elaborate more on the charger/offshore power? This is my first time camping in a trailer/RV. Just tents in the past. My trailer has a 3 prong plug in, does this mean a charger is built in? If I have something plugged into the outlets inside while trailer is plugged in will this use battery power or shore power? I guess I'm wondering if shore power is for charging only. Thanks!

[Techguy]

Thanks for the reply! Could you elaborate more on the charger/offshore power? This is my first time camping in a trailer/RV. Just tents in the past. My trailer has a 3 prong plug in, does this mean a charger is built in? If I have something plugged into the outlets inside while trailer is plugged in will this use battery power or shore power? I guess I'm wondering if shore power is for charging only. Thanks!

Your shore connector MAY only power the 110 outlets in your rig.
Your shore connector MAY charge your battery via a charger plugged into the 110 circuit of the trailer.
You shore connector MAY connect to a converter that produces 12V but switches over to 110 when connected via the shore connector
You shore connector MAY connect to a converter that produces 12V AND switches over to 110 when connected AND provides 110 from the batteries when disconnected.

I can't really see that if your builder added a 110 shore connector that they didn't also add outlets.

I would say you need to determine what is in YOUR rig. Each one is different either based on customizations requested by the original dealer or purchaser or it may vary based on "manufacturing improvements" by the builder and each rig being slightly different. Some of this is due to actual improvements other times it will be that the builder could not get the "normal" batter/converter/... in the right time frame or price range for the current build.

This is one way to test, connect your shore connector and plug in a radio or lamp to each of the 110 outlets to see if you have power at the outlets. Test your 12 V lamps to see if they are working when connected via shore connector, then unplug the shore line and see if the 110 outlets still work. Also, when you connect or disconnect your shore line, you may see the 12 lamps "dim" or "get brighter" when the shore is connected or disconnected. You may also be able to hear a slight buzz if you have a converter built in. Some converter will charge your trailer batter, other don't. Some have a stand-alone trickle charger plugged into the trailers 110 circuit.

Sorry for the long winded... it depends.

[eamarquardt]

Thanks for the reply! Could you elaborate more on the charger/offshore power? This is my first time camping in a trailer/RV. Just tents in the past. My trailer has a 3 prong plug in, does this mean a charger is built in? If I have something plugged into the outlets inside while trailer is plugged in will this use battery power or shore power? I guess I'm wondering if shore power is for charging only. Thanks!

Your shore connector MAY only power the 110 outlets in your rig.
Your shore connector MAY charge your battery via a charger plugged into the 110 circuit of the trailer.
You shore connector MAY connect to a converter that produces 12V but switches over to 110 when connected via the shore connector
You shore connector MAY connect to a converter that produces 12V AND switches over to 110 when connected AND provides 110 from the batteries when disconnected.

I can't really see that if your builder added a 110 shore connector that they didn't also add outlets.

I would say you need to determine what is in YOUR rig. Each one is different either based on customizations requested by the original dealer or purchaser or it may vary based on "manufacturing improvements" by the builder and each rig being slightly different. Some of this is due to actual improvements other times it will be that the builder could not get the "normal" batter/converter/... in the right time frame or price range for the current build.

This is one way to test, connect your shore connector and plug in a radio or lamp to each of the 110 outlets to see if you have power at the outlets. Test your 12 V lamps to see if they are working when connected via shore connector, then unplug the shore line and see if the 110 outlets still work. Also, when you connect or disconnect your shore line, you may see the 12 lamps "dim" or "get brighter" when the shore is connected or disconnected. You may also be able to hear a slight buzz if you have a converter built in. Some converter will charge your trailer batter, other don't. Some have a stand-alone trickle charger plugged into the trailers 110 circuit.

Sorry for the long winded... it depends.

Ditto. Cheers, Gus

[MtnDon]

Like was said, it depends. There is no hard and fats rule that is followed by manufacturers. It takes some simple experimenting as mentioned above to figure things out. Poking around under the counters, seats, etc you should find any hidden devices.

To help avoid confusion remember there may be two different devices. RV's with a shore power connection should also have a converter. A converter takes 120 VAC (north america) and makes 12 VDC. Some RV's may come with inverters as well. An inverter is the opposite and uses 12 volt DC battery power to make 1110-20 VAC power. There may also be an automatic transfer switch. This will automatically switch the power going to the internal AC outlets from inverter supplied AC to shore power AC whenever the RV is plugged into external AC power.

Note that the converters that come with many RV's are not very good at keeping batteries charged. Many do not have a high enoough output to quickly charge a depleted battery and yet their float charge is too high and if left plugged in for prolonged periods they cause the battery water to be "boiled" away leaving you with a bad battery. There are converter chargers that have a proper three stage charge; bulk, absorb and float.


Regarding the 7 pin connector power supply. Is that an OEM setup? OEM's should be wired so the connector power pin is only hot when the vehicle is running. Some folks wire their own and make it hot all the time which is a mistake. That can result in the trailer drawing down the vehicle battery. There are devices called isolators that can be used to prevent the trailer battery from drawing on the vehicle battery unless the engine is running. If it's OEM check to see what the mfg rates as the maximum current. It may not be sufficient to do a fast charge. Depends.

Myself, I have always used a separate charger with a high enough output to make charging as short as possible. I also have an isolator in the vehicle power system. When driving the vehicle system will vary the charge. That may be enough to charge the battery and it may not. Check the total battery capacity, the amp-hour rating. Ideally the maximum charge current should be equal to C/8 or C/10, depending on who you listen to, where C= the battery amp-hours. A three stage charger will start at that rate and then taper down through the 3 stages as the battery charge builds.

Also note that battery voltage can be a poor guide to the state of the battery charge. A hydrometer gives an accurate indication if corrected for temperature. Unfortunately one can not be used on a sealed battery; one reason I do not like sealed batteries.

[len19070]

If I drive somewhere that's over an hour away....My Battery is in good shape.

I just left foe a music Fest last week with a dead battery. It didn't bother me because when I got there I would have 110V.

Got there and no 110V.

From just the hour and 10 Min. drive, my battery was good for 4 days +

Happy Trails

Len

[E U G]

Thanks for the replies. Just called the manufacturer and got some info. He didn't know how long it would take to charge, says it's the first time anyone asked in 30 years. Seems odd, that's almost the first question I had for the saleman who sold it to me. He didn't know either... So that's good to know a 2-hour drive would charge it up pretty good. Looks like I would need shore power to work my 110 outlets, and it won't charge the battery.

I read on this forum that it's best not to run the battery below half power. Is this correct? If so, how do you know where "half" is? Is it safe to assume that for a one or two day camping trip I can use the battery as much as I want as long as I'm not running a heater or fan all night, or watching movies all day long?

[MtnDon]

I read on this forum that it's best not to run the battery below half power. Is this correct?

If you want to get decent life from the battery, yes, 50% discharge should be the maximum before recharging soon. More discharge will noticeably shorten battery life if done all the time. Once in a while is ok but not ideal.


On a 12 volt battery full charge is 12.7 volts.
70% is 12.32
60% is 12.06
30% is 11.75 and getting into the danger zone
dead is 10.5
Those voltages are what would be measured at the battery after sitting idle, no charging and no discharging for 3 or so hours. (info from AZ Wind-sun... scroll down to find chart on voltages and state of charge.


Use as much as you want? Without knowing the loads you'd run and for how long, nobody can really give you a reliable answer to that. The best thing is to use your system and monitor the state of charge. Either the voltages as noted or best, using a hydrometer.

[bc toys]

really don't know how long it will take to charge going down the road But I keep mine on a green lighting charger it keeps it a 100% and want let it drain to low before it brings it back up to top it off. I've been doing it this way for years and we only run inside lights at night on battery so we are good to go for a while about 5 days before they start getting dim.

[E U G]

Thanks for the info. I guess I don't know enough about amps/volts to know what my loads are going to be. I would be just doing the typical family camping stuff though. Maybe use the electric gril for a couple meals, interior lights for 2-3 hrs at night, and a couple cell phones on chargers thru the night.

I did find out that my 110 outlets only work if I'm plugged in though. Seems kind of silly to me. Why would all the interior and exterior lights work off the battery and the 110 outlets be wired this way? The trailer does have 12v "car charger" outlets right next to the 110 outlets, but I just don't get why they wouldn't just include it in the build.

Is it okay to leave a battery partially charged? I'm thinking a charge on the way back home plus another charge on the way out to my next trip would completely charge the battery on short little trips just outside of town here.

I read on this forum that it's best not to run the battery below half power. Is this correct?

If you want to get decent life from the battery, yes, 50% discharge should be the maximum before recharging soon. More discharge will noticeably shorten battery life if done all the time. Once in a while is ok but not ideal.


On a 12 volt battery full charge is 12.7 volts.
70% is 12.32
60% is 12.06
30% is 11.75 and getting into the danger zone
dead is 10.5
Those voltages are what would be measured at the battery after sitting idle, no charging and no discharging for 3 or so hours. (info from AZ Wind-sun... scroll down to find chart on voltages and state of charge.


Use as much as you want? Without knowing the loads you'd run and for how long, nobody can really give you a reliable answer to that. The best thing is to use your system and monitor the state of charge. Either the voltages as noted or best, using a hydrometer.

[MtnDon]

I did find out that my 110 outlets only work if I'm plugged in though. Seems kind of silly to me. Why would all the interior and exterior lights work off the battery and the 110 outlets be wired this way?

There could be an inverter to supply 120 VAC to the outlets. The inverter would be powered by the battery. Loads like a coffee maker, hair dryer, etc are very large compared to a light or two. You would need hundreds of pounds of batteries to operate a lot of the usual household appliances.


Batteries are best stored fully charged and best recharged as soon as possible after depleting the charge. Most folks with RV's that are not used at least every few weeks would be advised to have a good float charger to maintain the charge, as the previous poster mentioned.

[E U G]

Thanks, googling float chargers now...

[Dale M.]

Perhaps your question is already answered here....

viewtopic.php?f=30&t=28620

And about batteries...

viewtopic.php?f=30&t=18904

In fact lots of TD electrical to be found here....

viewforum.php?f=30

Dale

[len19070]

So that's good to know a 2-hour drive would charge it up pretty good.

Yes it will.

I think that what everyone who intends on using a 12V battery for dry camping should do is get a fully charged battery and hook a light, or better yet a fan to it.

Turn it on and count how many days it takes before it stops.

Then you will have a realistic idea of what a 12V battery will do.......You will be amazed!! As well as abandon a lot of fears.

Happy Trails

Len