Generator vs Battery/Inverter/Solar

ticki2 wrote:
I didn't like the idea of continually pumping 14+v into a fully charged deep cycle battery which is what happens when the solenoid feed is connected to an ignition-on feed. Comments ?

Flooded lead acid batteries will take this without much problem, though it will eventually boil the water out. But that is what is happening to your start battery anyway. AGM batteries are more sensitive, they will take it but it will shorten their life. It will kill gel batteries quickly. There are products made to solve this issue. One is this Balmar product which solves a few problems at once (at a cost). Properly connected, this provides isolation, switching, high current protection, and proper 3 stage charging for the house battery. It limits charge current to about 30 amps, regulates the charging voltages to those appropriate for the battery chemistry (regardless of what is under the truck hood), and can be switched off to isolate the two sides. On my installation, I took the charge wire from the 7 pin and connected it to the control to turn it on. That works on a Ford since the 7 pin charge wire is switched by the ignition. I set the charge parameters in the Duo Charge to the AGM setting for my AGM house batteries.

Compared to a simple large cable and relay, there will be some increase in charge time because the initial charge is limited to 30 amps vs. maybe 60 or more for a short while. It doesn't take very long for the acceptance rate of the batteries to fall to 30 amps though, so the difference isn't all that great.

Is this overkill? Maybe, lots of people just cable the AGMs and don't worry about it. I learned this stuff wiring yachts in which the 12V DC system is much more complex, and much more important to survival, you want to get it right.

Chobe2, look in the Camper University section at the top of page one, there is an electrical subheading with a couple of threads on adding a charge cable.

What I did was to wire a lift gate connector (jack) right next to the camper 7 pin in the bed and on the camper. Then I made a short pigtail with the mating lift gate plug, very similar to the 7 pin pigtail. You have two things to plug in when you load the camper. You should use a least #6 wire throughout for this to keep the voltage losses down when charging heavily, some have gone with #4 or even #2. Since both ends are connected to batteries, both ends should be fused as close as possible to the battery connection point to protect against short circuits. You could also use an Anderson power connector on a cable but it will not be a neat an installation. The most difficult part of the installation may be running the #6 wire inside the camper to the batteries, depending on access.

For fuses on the camper end, it hard to beat this Blue Sea fuse. It requires no mounting and fuses the circuit at the terminal. You can get them on Amazon and many other boat suppiers (West Marine). Since the fuse itself is unusual, buy a couple of extras to carry while you are at it. On the truck end you are going to find a large capacity terminal somewhere and will probably need a mounted fuse or circuit breaker - I like this Blue Sea product as it can be mounted and also incorporates a high current switch.

A problem this creates is that the two electrical systems are tied together so discharging one will discharge the other. You need an isolator to prevent running the start battery down. The old diode isolators are not used much anymore for good reasons. You can use a high current relay activated by any switched ignition source, but the modern way is to use a charge sensing relay such as this one. Yeah I like Blue Sea stuff, it is reliable and higher quality than anything else in your camper. These work by sensing the presence of charging voltage (over 13.6 or so) and connecting the two sides together. When the voltage drops below that, it automatically disconnects. It can be located either on the truck or in the camper (but probably better in the truck), just make sure the sensing side is connected to the truck side.

There will also be some large wire involved in the inverter install, probably #2 to #00 depending on inverter size. Keeping that in mind it may be more convenient to connect the charge cable to that system instead, depending on where things are. In that case the smaller charge cable fuse would be located at the branch to #6, and a much larger fuse at the battery feeding the inverter.

Here is some good reading on charge lines .

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23601503.cfm

I choose to feed the solenoid from a lighted switch on the dash so I could manually control the charging times and the connection between the TC batteries and truck batteries . I didn't like the idea of continually pumping 14+v into a fully charged deep cycle battery which is what happens when the solenoid feed is connected to an ignition-on feed. Comments ?

...Upgrade the charge capability from the truck. This involves running a larger charge cable separate from the 7 pin, through its own connector (a lift gate connector works well). There are many threads on how to do this. The reason for this is it will allow a much quicker charge when you begin driving, if the batteries have been discharged more than 20% or so. The wiring in the 7 pin cable does not allow for a heavy charge...

HMS Beagle - I hate to bug you but I've been searching the web for more information and instructions for running the larger charge cable that you've mentioned. It's all Greek to me! Does this involve any rewiring with larger gauge wire in the camper? Will we still plug the camper into the 7 pin or will we have a different plug or an additional plug? Can you explain a little further or point me in the right direction for instructions?

An inverter is required to have 110V when no other source is available (campsite hookup or generator). They come in all sizes, from little tiny ones to charge your cell phone or computer to many thousands of watts. A lot of us find that having a good quality inverter permanently wired improves the living experience. As they say, "if you don't have 110V outlets at home, you will never miss them camping...". A 2000 watt inverter will run anything you can plug into an outlet. The caveat to all this is that you are limited to the energy that is in the batteries: you can run a low power appliance for a long time, or a high power appliance for a short time, before the batteries need to be recharged.

Dr. Feelgood wrote:
Pardon my ignorance and this might not be the thread but am about to purchase my first TC. When you're talking about adding a 1000W-2000W inverter is that so you can run the heavy wattage appliances? Or will I need to add an inverter anytime I'm using the AC outlets and not hooked up to shore or generator power?
Thanks for your patience

Both, the outlests are 110v and only work with shore power or on genset providing 110v....

Pardon my ignorance and this might not be the thread but am about to purchase my first TC. When you're talking about adding a 1000W-2000W inverter is that so you can run the heavy wattage appliances? Or will I need to add an inverter anytime I'm using the AC outlets and not hooked up to shore or generator power?
Thanks for your patience

Thanks HMS Beagle...that's perfect! That is exactly what we will be doing. Looking forward to the whole thing!

But you said you move everyday. The solar (and truck) charges the batteries while you drive, while you eat lunch, etc.

AGM batteries have better charge acceptance, which makes the larger cable from the truck more valuable. You may want to check that the solar charge controller and the inverter/charger you use has an AGM charge setting (more common these days).

The camper won't use that much more power than the van you had. The biggest consumers are the furnace in a cold climate, lights, and the refrigerator - plus whatever you add in microwave, hairdryer, computer, TV use. (The refrigerator gas solenoid valve consumes a fair amount).

I think the system you outlined in your last post would work well, unless you are constantly under trees and never drive. I have parked in campsites for 3 to 4 days in heavy shade before needing to worry about the batteries. For example Yosemite in winter, nights in the 20s so the furnace was running. That is with two 6V golf cart AGMs (Lifeline brand which are probably the best). We don't go nuts on power use, but we don't put much effort into conserving it either. In a sunny site the batteries are fully charged by mid morning. On a driving day the batteries are fully charged by mid morning. I don't even carry a generator, if I am faced with staying in one place longer than 4 days in the shade or rain, I will just start the truck and idle it for an hour. I think I have had to do that once or twice in 18 years of TC ownership, but not since I put the solar on the roof.

Oh man! Just when I think I have it all figured out, the need for that darn generator is back! We live in Montana (lots of trees) and like to travel to areas that would likely have sun obstructions. We just sold our Sportsmobile Ford van which had one AGM battery, a 1500w inverter, a small microwave and a fridge and we never monitored or even worried about the battery. I could use a hair dryer also with no worries. We always drive everyday on our trips so the battery always had a charge. I'm finding out now that battery usage is going to be a much bigger issue in a truck camper. I better post this quick before this site goes down again!