Outline · [ Standard ] · Linear+ 12 Volt Electrical System, Please explain this system to me

[Oregonizm]

I have several questions regarding my Host camper's electrical system that I am hoping that someone out there can answer for me. Many of these questions came up during a recent cold weather trip where we were experiencing battery issues:

When the battery finally ran out of enough juice to power the furnace blower in the middle of the night ... why wouldn't the furnace blower operate from the truck's alternator while the truck engine was running?

Same question with the refer but with also why does the refer need power at all when it's operating on propane?

My Host is equipped with a Progressive Power Inc., Intellipower Charger/Converter (725w output). With the battery disconnected at the battery terminals but the camper plugged into shore power, I was unable to operate the camper jacks without reconnecting the battery? Would this mean that if my battery was completely depleted while remote camping that I would be unable to load the camper back up even under generator power?

Does anybody have any suggestions to make starting my propane generator in cold temps more reliable? I have heard that an oversized propane line directly from the storage tank might help. Is there any such thing as some sort of primer that could be installed on the existing line instead??

Thanks in advance for any input that might have!

[Spanky]

Sounds like you may not have a charge line to your camper from your truck and it is not charging your battery. I have always been told not to use my jacks while plugged into shore power. I don't know what kind of gen you have but mine has a primer switch mounted next to the start switch out on the gen itself. Your jacks will not operate on shore power you would have to plug in or run your gen till battery is charged to operate your jacks. At least that is the way my Lance is set up. Someone else may chime in here and set me straight.

[aqualung]

There's a couple of reasons why your truck may not have powered the system. First like Spanky said, there' no connection from the truck alternator to the 12V system in the camper. Second, since the battery was fully discharged, the voltage reaching the camper from the truck alternator was pulled too low for the systems to operate - i.e. too much voltage drop. If you turn on the 12V lights in the camper and they don't come on then there's likely no connection to the truck but if they come on but aren't very bright then its likely a voltage drop. If its a voltage drop then after the battery starts to charge up the voltage will come back up... this could take quite awhile.

Propane fridges have controller panels in them. These operate on 12V so if 12V is not present then the fridge will not operate, even when running on propane. They also have a low voltage shut off so when the input voltage is too low they shut the power off to themselves to protect the circuitry in the controller.

As for the charger, since it an intelligent charger it most likely shuts off its output when it does not see a battery on the terminals. Most "Converters", at least the cheap ones like I have, do not sense the battery presence so they just come on - Mind you they don't charge very well. There should be something in the owners manual on your charger/converter that tells you how it should operate.

Now the jacks likely have a low voltage shut off built in too. If the voltage gets too low then the current goes way up and can burn out the motors. So to protect the motors they prevent them from operating. As Spanky points out, they should not be operated on shore power this is because they draw a lot of current which your charger/converter likely can not supply. When this happens, the voltage drops coming from the charger or shuts off completely - not good for the jack motors. So let your system charge up the battery. Once there's enough charge in the battery it will be able to deliver the needed current to the jacks.

It sounds like with your system you must leave the battery connected for the system to operate because the charger/controller won't provide power out when the battery is not there.

Batteries are notoriously bad at delivering high current in cold temperatures, specially deep cycle batteries. This coupled with age could mean that your battery cannot deliver enough cold cranking Amps to start your generator. A new battery will help solve this problem. If its not this then there could be something wrong with the generator but I know little about them so hopefully someone else can help out here.

Hope this helps.

[skyhammer]

As was pointed out, you need 12 volt power to run the furnace and fridge.
If you ran your batteries down so far that the furnace and fridge would not work, it will take several hours at least to get much of a charge from your trucks alternator. The charge wire from the bed plug is not large enough to deliver a fast charge.
You need to monitor your power usage to avoid running your batteries down to far.
The Host battery monitor is not the best in the world, but when you see that you only have one light on the montior, it is time to charge the batteries.
Lacking a better battery monitor, checking the battery voltage with a multi meter is the next easy thing to do to check the status of the batteries.
The furnace takes a lot amps, especially if you are running it for 10 hours at a time. Plus, if you have an older Host, with no or very few LED lights, they will take a lot of amps.The LRD lights in my Host draw 2.68 watts compared to the 19 watts of the regular bulbs, I can run 7 LED bulbs for the same amount of power that just 1 regular bulb takes.
As far as the jacks go, yes, you do have to have the batteries hooked up for the jacks to work.If you have the generator running, you should have no problem running the jacks, even with a low charge.
The genny will lug down when running jacks, even if your batteries are fully charged.
I usually run a Honda 2k genny rather than running the on board genny. I have to charge the trolling motor batteries on my Jet boat every day, so I run the Honda 2-4 hours a day to charge the tolling mortor batteries and have the genny hooked up to the camper at the same time to top off the campers batteries.
I camp in Central Oregon all the time, coldest has been in the teens and I have never run my batteries down below 50% in a day.
Best thing to do is to figure out how many amps you use per day and make sure that you don't draw your batteries down below 50%. Constantly drawing you batteries below 50% will shorten the life of you batteries, especially if they never get fully recharged, before being drawn down again.

[Oregonizm]

Thanks all, you are a wealth of information. Skyhammer, I too have come to rely on my 2KW Honda rather than my onboard propane generator but I only have it along when I have a trailer because of storage space issues. My onboard propane generator usually will start in the summertime but I can rarely get it started on winter camping trips. I too have LED lights throughout but our sattelite TV system probably eats up anything that we save from the LED lights. I usually don't have any battery problems until the 2nd or 3ed night out and when the monitor finally hits the "one light" status, it's late at night and I don't know it till I start getting cold. I do a lot of snowpark camping with my sleds so it gets pretty cold sometimes. Another question that this all brings up is how long should the batteries last? Considering the fact that I have run them down close to nothing several times during cold weather nights, how long would you expect two 6v Interstate RV batteries to last? Also, please clarify the remark about not running the camper jacks while plugged into shore power. I have always done just the opposite ... if I have shore power available I plug in until I am finished running the jacks so that I am not utilizing my stored battery power. What would be the difference between runnign the jacks while plugged into shore power and running the jacks while the generator is on? Either way you would be using 120v through the converter to power the jacks instead of draining your batteries of stored power, wouldn't you? Thanks you guys, it's awesome to have a place to ask these questions and get these answers!

[aqualung]

The problem with operating the jacks when on shore power is only when you're on shore power alone with no batteries. The converter/charger does not supply enough current on its own to run the jacks properly. If the battery is attached and charged then it supplies most of the current during jack operation while the converter supplements the battery.

There's no difference between shore power and generator with respect to the jacks since they run on 12V. The generator is only another source of 120Vac, your converter/charger and battery are still the power sources for the jacks. The difference is where the converter/charger gets its power from.

How long the batteries will last is a tough question to answer with any degree of accuracy. It all depends on what storage the batteries have (i.e how many Amp Hours). My Trojan batteries are 220 AH batteries and when fully charged will last 4 days on average. Of course charge condition and battery age affect how much charge is actually in the batteries which will affect how long they last. Temperature also affects the batteries ability to provide current to the loads - the colder it is the less current a battery can deliver (batteries work on chemical reactions. Chemical reactions are slowed or stopped the colder it gets). How much power you use on a daily basis also greatly affects how long the batteries will last (ok this ones obvious). The only way to accurately determine battery charge and charge useage is with a proper battery monitor that measures current in and out of the battery not voltage. LED bar graphs are pretty much useless in this regard, votage monitors aren't much better. To measure it properly you need a monitor like a Xantrex LinkLite (there are many manufacturers of these type of monitors):

http://www.xantrex.com/power-products/powe...ry-monitor.aspx

One more thing about Lead Acid batteries, they should never be taken below 50% charge. Going below this damages them. Would I run out and buy new batteries if this happens? No, you may have reduced the life of the battery a bit but its still ok to use.

In your case since you're camping up high in the mountains and in the cold, I would sell your propane generator and invest in a solar system. This will keep your batteries charged for daily use. Since you're in Oregon, the best supplier of solar power for RV's that I've found in North America is in your neck of the woods - AM Solar. I did just that two years ago and have since never needed a generator and only hook up to shore power to keep the fridge running without using up propane or to use the air conditioning. If you're a doit yourself'er and electrically inclined they sell kits. If not then they will do the install too. From what i can tell, they know what they're doing. Here's a link:

http://www.amsolar.com/

When I installed my solar system I went with 2 of their 100GS solar panels, a SunSaver 15 MPPT Charge Controller and one of their system kits that included all of the wiring, roof connection box etc plus I added the remote panel for the charge controller and I added a Xantrex LinkLite to monitor the batteries. On average I use 45AH per day and the panels supply about 30AH per day each (on sunny days) so I'm ahead of the game. Up high in the mountains you can expect more charge from the panels per day. Oh and when solar panels are cold, they work better.

Anyways, I'm done rambling on for now, I could go on for hours on this topic but there's work to do. If I were you I would give these guys at AM Solar a call and at least see what they can do for you. There's no obligation to buy and its definitely worth a phone call. No I don't work for them, I'm just a happy customer.

[Oregonizm]

Thanks Aqualung!

[Mayday]

Another thing to remember: Some newer units have isolators that isolate the camper batts from the truck batts. Unless the truck battery is above a certain voltage. Most isolators will not allow the truck electrical system to charge the camper batteries if they drop below the threshold of the isolator. Some isolators cut off at 11.4v, some at 10, some do not cut off at all. (this is to protect the truck batteries AND to avoid putting a fast charge on your batteries).

Example: Your camper batteries are at 9volts. You start your truck. If your isolator is as described above, you probably won't be charging your camper. If this happens, you have two alternatives: 1). run jumper cables from your truck to your batteries. If you do this MAKE SURE YOU ISOLATE THE BATTERIES FROM THE CAMPER. Once your batteries are above the threshold level of your isolator, you can remove the jumpers and re-connect the camper batteries to the camper power system. Once above the threshold voltage, the running truck should charge the batteries. 2). Jumper across the two large wires on the isolator. Unless you know what you're doing, I'd avoid this.

Hope this helps.

[Oregonizm]

Thanks Mayday .... that definitely explains why the refer and furnace wouldn't work with the truck running after draining the camper battery so low. Somewhere in the back of my head I knew that there was some built-in protection so that I couldn't draw down the truck battery but that certainly puts it into laymen's terms.