Truck Mounted Camper Batteries

[brianjwilson]

Has anyone else done this, or see a problem with it?

I'm trying to work out the electrical details for the fleet forward dinette that will go on my double cab Tacoma. I want to avoid adding 100lbs of batteries several feet behind the rear axle (the battery compartment is in the rear driver's side), as the forward dinette already has an aft center of gravity. Initially I planned to buy 3 new agm batteries, mounting two under the hood with an automatic charging relay from blue sea, and mounting the 3rd battery in the camper. The aux battery under the hood would be tied to the camper battery with 6 gauge or larger wiring, and charging primarily with solar. However the Tacoma has a thin fender and I don't feel great about mounting 100lbs to the front of the fender, also on the heavy driver's side.

As it turns out, there is a perfect spot behind/below the rear seats to mount two full sized batteries. The tacoma has 40-60 folding seats, and the passenger side is the 60% side. This is where my daughters rear facing seat sits, which makes the compartment nearly inaccessible for practical uses. So now I'm thinking, install the automatic charging relay under the hood, large gauge wiring running to 2 batteries (sealed agm) under the passenger side rear seat. Large gauge wiring to the camper. In the battery compartment I would install a + and - post, and treat them as the battery terminals. Of course each run of wire would be protected with circuit breakers right near the battery, and near the source of charge. Battery switches on each end for when I disconnect the plug in the bed.

Pros;
1) I'm moving 100lbs from several feet behind the tailgate on the heavy driver's side, to several feet in front of the axle, passenger side, lower center of gravity.
2) when the camper is off loaded during the off season, the alternator should maintain all batteries.
3) I gain precious storage inside the camper for lightweight items, and use a difficult to access area inside the truck.
4) I'm leaving more space under the hood, already a little full with a supercharger and that stupid smog pump, soon to have an air compressor too.

So I would love to hear opinions on this. Keep in mind I never intend to use the camper off the truck so I don't see why I need to have batteries on board when off loaded. I can plug the camper in while its garaged to prevent the smoke detectors and such from beeping.

Would this present any issue with the solar charge controller? If the charge controller connects to the posts I install in the camper, it should work the same as having everything direct to the battery, correct? With 4 gauge or larger wiring the voltage loss would be very minimal with a 10' run. I just want to make sure there isn't something I'm missing. The truck has HD OME leaf springs, icon shocks and coilovers and e rated tires so I certainly don't mind an extra 100lbs in the truck when the camper is off anyway.

Thanks for any insight.

 

[brianjwilson]

This is someone else's truck and photo, but shows the space behind the passenger seat. Again I have rear facing car seat on that side so it is not easily accessible anyway.

 

[BFH4N]

I filled that space under the "backseat" of my Tacoma with a compressor and control system for my airbags, but I don't remember the space being big enough for two batteries. Still, I guess the picture doesn't lie!

I agree that where FWC put the batteries in the front-dinette Fleet is too far back (at least they are down low). I am thinking about moving them all the way forward in the camper to new locations, one on each side, under the benches. The cabinetry would have to be modified some, but I think it's doable. The space under the seats is not particularly accessible on a routine basis, whereas the current location is prime accessible storage.

Good luck on whatever you do and post some pictures when it's done.

- Bernard

 

[DesertDave]

I can't think of anything significant that was overlooked in the plan. Relocation of batteries for weight distribution is common amongst my racing friends. My first FWC had no battery in the camper, at that time they offered to place them in the bed of the truck in front of the wheelwells (can you say buried and inaccessible?) and I used a second battery under the hood to power the camper.

 

[photohc]

I had a similar problem with my Hawk. The battery was at the end (near the entry door) of the Hawk. The Hawk installed on my F150 had an overhang of 12 inches pass the tailgate area. Not the best for 110#s (two AGMs') of batteries and center of gravity. I have since replaced the AGM's with a single Lithium LiFePo4 (100AH) battery at 28#'s.

You can checkout my post on this here: http://www.wanderthewest.com/forum/topic/10153-lithium-install-in-my-hawk/

 

[Ethergore]

I would do it if I had the room. I have no such luck with my Tundra. I even considered mounting a battery under the bed to save space but didn't want to try and get a mount fabricated. Have fun with the project.

 

[brianjwilson]

Thanks for the input guys. I'll plan on going forward with this setup. I was going to order what I needed and work on it when I'm home this off hitch, but I have too much planned this time, other things to do, FWC is way behind delivery schedule, etc. Looks like I'll save the project for June since I evidently have lots of waiting time left.

 

[brianjwilson]

Well I finally got around to this project. It was a fairly time consuming one too. Mostly because I'm picky and would route wires, decide on a "better" spot, re-route etc. Lots of head scratching, plastic trimming, last minute runs for hardware. Here is what I came up with, though I have to finish the last run of wire when I'm back home in a week and a half.

Under the hood is an interstate group 34 AGM battery. I used an aluminum sheet to attach the blue sea 7622 automatic charge relay. I'm not a huge fan of how it looks but it is secure. Eventually I may have a custom aluminum tray built. Ideally I would have mounted the ACR behind the fuse box but the heat exchanger coolant reservior for the supercharger resides there now. The 2 gauge wire that runs back to the camper batteries is wrapped in braided sleeve, and the positive wire is additionally covered in nylon split loom. The intent was to run the wire along the frame rail but there was no way to do that without being extremely close to the cat converters on both sides. Due to the fender design I could not run it outside the frame rail. I decided to run the wire above the transfer case and trans where the factory harness was. Access was a pain and I spent many hours for that short run, but it seemed the best option. Currently the stock wiring from alternator to battery and ground is in place as I simply ran out of time before leaving for work.


The remote switch for the ACR is three position. Manual connect, automatic, and manual disconnect. In auto it is voltage sensing from both battery banks. There is also a start isolate which I wired to the starter solenoid, that will isolate the batteries as soon as you apply power to the starter (in auto mode). In the event they were connected, this prevents the starter from dragging down the camper batteries. Since the ACR can handle 500 amps continuous, it can also be used to jump the starter battery from the camper batteries.


After removing the seats and trimming and refitting the plastic behind the seats, I was finally satisfied with the hack job and the way the other two group 34 AGM batteries fit.


After many more removals of the batteries and plastic, I finally had most of my hardware mounted to the plastic tray, my hull-through fitting installed in the high spot on the floor and got busy making cables. Not the greatest picture but that's what I have so far.


The batteries are of course wired in parallel. On the top right side is a blue sea battery switch, this is where power is coming from the starter battery and ACR. The wire then runs to a 150 amp circuit breaker. The switch is actually wired up as a bypass for the breaker. Normally the switch is off and the current passes through the breaker. If I needed to jump the start battery or run some excessive load (winch etc), I could turn the battery switch on and kick off the circuit breaker. I rarely (if ever) see that happening but it was a function I wanted to have available.

On the left side is a 100 amp circuit breaker that will continue on to the camper. I ran short of wire and braided cover so I will complete when I'm home. I have an anderson powerpole connector mounted inside the bed and a through hull fitting next to if for the wire. Additionally I have another blue sea battery switch and circuit breaker for inside the camper.

When everything is together this should provide a good strong bulk charge from the alternator, and the ability to top off with solar or using the iota smart charger while plugged in at home. The ACR will combine all batteries during a charging state.

 

[Advmoto18]

I don't think I read mention of solar charging? So I will assume you do not have a solar charging system.

However, if you do have a solar panels and a controller installed in the camper, wire length from the controller to batteries greater than 3' is not recommended by most solar controller manufacturers.

I think you need to use a multi-meter and check voltage at the new battery bank with truck at idle and highway speed after the alternator has warmed up.. You may discover the Tacoma OEM alternator is incapable of charging the battery bank after a deep discharge. If the battery bank is full, then perhaps the alternator will maintain the full charge.


From electromax.com

What about the alternator?

Since the acceptance rate described the maximum rate at which a battery bank can be recharged, it stands to reason that the proper size alternator can only be selected once the acceptance rate has been determined. It is wasted money to charge a battery bank that has an acceptance rate of 70 amps with a 165 amp alternator. Likewise, using a 100 amp alternator to charge a battery bank with an acceptance rate of 240 amps is pointlessly slow and inefficient. The goal is to get the output of your alternator (under actual charging conditions) to match the acceptance rate of your battery bank as closely as possible.

Most alternator manufacturers will provide you with the output curve of the alternator you are considering under hot conditions and at a variety of speeds. An alternator rated at 150 amps will likely only put out 130 amps once it gets hot and will only do that running at full speed. Under realistic charging conditions, you may only be running your engine at 1100 – 1200 RPMs. If your alternator is belted at a 2 to 1 ratio it will be spinning at twice that speed, or 2200 – 2400 rpms then it is quite possible that 150 amp alternator is now only going to putting out 80 amps or so.

Given this, how is it possible to get 200 to 300 amps of real charging capability? Sometimes it isn’t possible, but don’t give up too quickly. Very large alternators with outputs of 200+ amps are now quite common. Additionally, it is often very practical to use two or more alternators simultaneously to charge a single bank. Some boats are already set up to have one alternator charge the engine start battery and a second to charge the house bank. Usually the engine start battery needs little if any charging. An automatic battery bank combiner can be used to allow both alternators to charge the house bank.




I had to purchase a new HD alternator for my Super Duty. The factory alternator was unable to provide sufficient charging to the camper batteries after they were discharged; even after drving for 10 hours! There simply were not enough residual amps to after powering truck's systems and two crank battieres. Further, inline voltage drop from truck battery to the camper plug and from the plug through camper wiring harness to battery bank was significant. Even the new HD alternator will not fully charge deeply discharged camper batteries.

I am considering adding a second alternator wired directly to the battery bank since that would produce more consistent charging than solar while driving. I plan on using a Blue Seas selector to isolate the solar controller when driving thus allowing the second alternator's output directed solely to the camper battery bank.

Ford, Chevy and Dodge offer a second alternator option for the diesel engines for the purpose of suppling charging power to additional batteries.

 

[brianjwilson]

The camper will have 300 watts of solar with an MPPT controller. I will be checking voltage drop on the solar charging as well, though I don't expect it to be significant with 2 gauge wire. Also with the blue sky 3000i, I can program what voltage it charges at and make up for any small difference if need be. Maybe not ideal but should be ok.

I checked voltage drop between the starter and camper batteries while the truck was running, shortly after starting and the voltage drop was .05v. Pretty minimal but the batteries weren't highly discharged either.

As I said the alternator is to help with bulk charge. Solar and plug in will top them off. The hope is to have a better aid in charging during the wet, dark cold months. We'll see how it all works. The batteries certainly ought to charge better than they would with the small wiring that FWC uses during install. I could rework the 130 amp alternator but have no reason to believe it is an issue yet.

 

[smlobx]

Brian- where did you get the heavy red braided wire? I've been looking for some.
Thanks

 

[brianjwilson]

I bought the braided sleeve here.
http://www.electricalhub.com/braided-sleeving

Then used adhesive lined heat shrink over the ends.