Dual Battery Basics

[1stDeuce]

Just saw your FB site... Did you already order your camper with a house battery? If so, you might consider leaving it there, adding solar, and not worrying about the 2nd battery in the truck. (Plan B...) Then you haven't connected them, the truck can take care of its own battery, and the solar will charge the camper battery no problemo. And if you do have a battery problem on the truck, you have a spare and can give yourself a jump if you need to.

Lots of ways to do it. All probably will work well for you.

 

[pawleyk]

Just saw your FB site... Did you already order your camper with a house battery? If so, you might consider leaving it there, adding solar, and not worrying about the 2nd battery in the truck. (Plan B...) Then you haven't connected them, the truck can take care of its own battery, and the solar will charge the camper battery no problemo. And if you do have a battery problem on the truck, you have a spare and can give yourself a jump if you need to.

Lots of ways to do it. All probably will work well for you.

I actually ordered the camper without any of FWC's battery wiring or batteries. I'm planning to do my own. For what they charge it looks like I can wire it up myself and get a voltage sensing 2-way isolator while saving some $$ in the process. I'm going to do my own solar also, that's why I was interested in your setup. Those panels look like a pretty good deal.

I think I'm going to do dual's in the truck just as a basic off-road mod to give me the backup when the camper isn't loaded and help run the winch/12v air.

So, for right now, the system looks like this-
1) Parallel's in the truck, on a high-amp constant duty relay wired to 12v+ ign. Basic parallel setup when the truck's running and starting, but isolated when it's off.
http://www.amazon.com/PAC-PAC-500-500-Amp-Battery-Isolator/dp/B001YIPXR2?tag=viglink20599-20

2) Single (?) battery in the camper wired to solar and the truck. Isolated from the truck with a voltage sensing, 2-way relay that'll allow both banks for batteries to be charged by both the solar panel and the alternator depending on conditions.
http://www.westmarine.com/buy/marin...12EBlYYVJ7LrAMNjODMhGt9Gzy4dfD07hghoCcATw_wcB

As always, plans can change, but this is the direction I'm heading.

I like the idea of simplicity combined with redundancy. Sometimes it's hard to make the two work together, but I think this system would be a good compromise.

 

[pawleyk]

Agreed. There are some great simple diagrams at the top of the electrical section. I'm going to install dual batteries with a 600 A constant duty solenoid which will automatically isolate and charge them, as well as allow for self jump starting. I want an "idiot-proof" setup where I can't either forget to charge a battery or end up running both of them down by leaving the lights on in the middle of the woods somewhere.

Do you have fuses installed anywhere in your system?

 

[hawaii]

Do you have fuses installed anywhere in your system?

You definitely want to fuse the lines as close to the battery as possible. Fuse at your aux to isolator, and then main to isolator. Fuse the 12V line used to energize the isolator/solenoid. Nobody ever wished they fused less.

 

[Ducky's Dad]

And put the fuses where they are easy to see. You don't want to be chasing electrical issues on the trail.

 

[pawleyk]

I'm thinking 1/0 AWG for the connection between batteries.. something like this.

http://www.grainger.com/product/CAROL-Bulk-Battery-Cable-1YPZ6?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/1YPY7_AS01?$smthumb$

I don't mind over-building, but as you guys know- this stuff is expensive. I especially don't want to UNDER build and then have to buy more..

 

[Ducky's Dad]

I'm thinking 1/0 AWG for the connection between batteries.. something like this.

http://www.grainger.com/product/CAROL-Bulk-Battery-Cable-1YPZ6?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/1YPY7_AS01?$smthumb$

For relatively short runs with stock alternator, 1/0 should be fine. Best way to buy it is to get welding cable from CraigsList, lots of 1/0 around for cheap. Make sure the specs of the cable you buy match what you need (stranded copper, 105C rating, etc.). If you find black cable and want red, just put red heatshrink on the terminations and wrap in red split loom. I found a bunch of 3/0 for a little over $1/ft, vs $13 at places like Grainger. You might have to look for a couple of weeks, but it's out there. If you are thinking about upgrading the alternator later, just go with 2/0 now.

 

[pawleyk]

Thanks for the craigslist tip, I hadn't even thought of that... I'm not in a huge hurry, so I can wait a few weeks while I keep a lookout. Now that I'm not scouring for campers anymore, I've got to come up with some other excuse to spend way too much time on C/L..

-KP

 

[thebigblue]

I would recommend getting a CTEK D250S DUAL DC to DC charger, I have one in my G, and one in my L608D. Apart from the advantage of the DC to DC part, you can also connect a solar panel to it directly with no separate charger, and it also splits the house from the main batteries.

http://www.ctek.com/dk/en/chargers/D250S DUAL

 

[pawleyk]

Thanks for the tip, I'll check it out. Could simplify the camper charging system a bit.

 

[1stDeuce]

I wire everything up with welding cable from Tractor Supply. It's actually copper, and they have 2ga and 4ga by the foot, as well as copper terminals. I push the cable into a terminal, whack it with a crimper (Or squash it in the vise) and then heat it and add some solder to make it solid. Shrink with black for neg, red for pos. Easy battery cables any length I need. I've found that 4ga is fine for most use. I use 2ga to the winch, or 1/0 for longer runs, like power to the back of the vehicle for a multi-mount.

With a 100A+ alternator, and the engine running, I have yet to really need two batteries for winching, even with my current Optima in the Jeep. (Optima batteries have pretty low reserve power compared to similar size batteries because of the round cell design.) I think that generally, the two battery hype was generated when everyone had a 67A alternator that barely put out at idle, and they spent hours winching through mudholes for the sake of "making it through". Most newer alternators are capable of putting out huge amperage, even at idle. If you raise the idle to even 1000rpm, they'll hit 80-90% of rated output. If you have to winch a long way under a hard pull, you'll need to let the winch motor cool anyway, and while that's going on, your alternator will have plenty of time to juice the battery back up for another pull.

What was my point? Oh, since you'll have a house battery for the camper as an emergency backup anyway, I think I'd skip adding the 2nd battery to the truck. Its just more weight, more expense, and more points to fail. You'll find that making your truck heavy is easy, but keeping it light is worth more effort... Just put a good Group 27 battery under the hood, and a 27 or 31 in the camper, and you should be set! I'm a big fan of KISS, and the older I get, the more I think that's what works the best... Opinions obviously vary though, and you're well on your way to forming your own! Just trying to help out by sharing my experiences.

Good Luck!
Chris

 

[Ducky's Dad]

the two battery hype was generated when everyone had a 67A alternator that barely put out at idle, and they spent hours winching through mudholes for the sake of "making it through". Most newer alternators are capable of putting out huge amperage, even at idle. If you raise the idle to even 1000rpm, they'll hit 80-90% of rated output. If you have to winch a long way under a hard pull, you'll need to let the winch motor cool anyway, and while that's going on, your alternator will have plenty of time to juice the battery back up for another pull.

Well, sorta...
If you try a long pull with a big winch and a "normal" battery/alternator combination, the winch will heat up quickly as the voltage delivered from the battery drops. It's a vicious cycle, and the more voltage you can maintain, the better the winch will run. At a given load, as voltage drops, amperage increases and that heats up the cables too. A stock alternator on a vehicle not designed for heavy use will have a hard time keeping up with winch draw. The 3G Power Wagons came with a Grp 65 battery and a 160 amp alternator, and those who actually use them typically upgrade to bigger batteries or dual batteries with good results. I don't remember the exact specs, but that factory winch draws something like 460 amps at max pull. Simple is good, but stuff needs to be configured to work together.

 

[Nullifier]

i used a napa,isolator on my tacoma. 8 years no problems like $60. on my new 80 series i am going to wire them parrallel with a auick disconnect. I will have the same quick disconnect on my solar panel so I can seperate betteries at night, and also plug in solar when not traveling.

 

[pawleyk]

Hey guys,

So I got my batteries wired up finally, it can take a while to co-ordinate a craigslist deal.

Like I was planning, basically just wired up parallel, but with a 500 amp continuous duty solenoid between them.

I found a 10 amp fuse labled "IGN E". Tested it and found that it was hot IGN AND during starting, which I need so both batteries can/will start the truck.

I found the wire that corresponded to the fuse inside the under-hood fuse block and connected it to the solenoid.

Everything worked great, started truck, both batteries show the same charge voltage. Turn the truck off, they're just slightly different (since one hasn't been connected to anything and hadn't charged up yet).

Success right?

Here's the weird part- Everything worked fine until I put the truck in gear. Put the truck in gear and it sounds like the starter tries to engage for just a second. As that happens, all the accessories go dead and then flash back on. Except for the factory amp apparently as just the sound from the radio never comes back until the truck's been restarted.

Unplugged the lead to the solenoid for the batteries and everything goes back to normal.

Obviously I need to find a different source, but was just curious if anyone had an idea what was going on.. why putting the truck into gear would try and start it seems odd to me.

It does this into drive and reverse, from both N and P.

If anyone's got a go-to suggestion for IGN+ that stays hot during start, I'd take that too..

Thanks,

 

[Buddha.]

I'm not sure why the truck would try to start when put in gear. Maybe you have a weird grounding problem? Did you recently change the starter wires? I was once working on a truck were the starter would randomly engage. Long story short the solenoid stud at the starter wore through the poorly positioned starter wire and would cause the starter to engage randomly.

But anyway, this is where I'd start:

Take the wire off of IGN E and temporarily put it directly to battery positive without changing anything else does the problem remain the same?