Hawk Flatbed Build Thread

[elmo_4_vt]

For my next mod, I shamelessly borrowed this wonderful idea from elmo_4_vt: making a rear rack out of 80/20 extruded aluminum.

Wow, this stuff is fun to work with. I need to think of more excuses to use it. Here's a shot of the finished product:


...
Thanks again to elmo_4_vt for the idea! I had to take the camper in to FWC for some minor repairs, and the factory guys were duly impressed with your design. I made sure to give you full credit.

Looks awesome Carl, and I love that 80/20 stuff. It's still holding up very well for me. I just added a roto-pax mount as well to make i easier to fill up the on-board tank from distant sources, although it would take a long time. Mostly, we'll probably use it for camp/cooking water when cooking outside.




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[rando]

It is a cell phone booster antenna. This is the beauty of 80/20 - it is so easy to experiment with different options. The idea with that mount is that you can loosen the knobs and slide the antenna above roof line for better coverage, or drop it below roofline to be more stealth (pictured). So far it has worked pretty well.

 

[CarlG]

Nothing like the pressure of a big trip to get stuff done! This rig is heading out for 8 weeks today!

When I got the truck converted to a flatbed, the guys who put the bed on re-mounted the stock back-up camera into the skirt of the flatbed, pointing straight out. This wasn't great, for two reasons:

1. The angle was all wacky. Because the stock bed had the backup camera mounted up in the tailgate handle, pointing downwards, having it point straight made the optics weird - it was like you were looking up into the sky.

2. For this long trip we have coming up, we're going to have a hitch mounted cargo basket, which would have blocked the view from the camera entirely.

So in typical fashion, I came to this forum for ideas, and found them!

Here's my take on the electrical-junction-box camera re-mount:

Step 1: Cut the cable. NOT PICTURED: copious amounts of self-doubt.

Step 2: Made a new 6-strand wire, soldered it to the camera, and mounted the camera in a 3/4in LB style electrical conduit body. What a great idea this is, and cheap! Thanks WTW!

Step 3: Threaded the wire through one of the stake holes in the flatbed, soldered the other end into the other side of the snipped cable.

Step 4: Breath a huge sigh of relief when it all works again. Screwed it into the bottom of the 80/20 using a bent simpson strong-tie.

Now the angle is fixed, and you can see over the cargo basket!

 

[DieselShack]

Some good info in this thread. I really like the bunk and the 80/20 stuff, it opens up a lot of possibilities.

I'm curious to hear how your bunk bed has been holding up, if there's any side effects or anything? My flatbed hawk should be done shortly and we're planning on putting our family of 5 in there (12, 10 & 4 year old boys)

 

[CarlG]

Some good info in this thread. I really like the bunk and the 80/20 stuff, it opens up a lot of possibilities.

I'm curious to hear how your bunk bed has been holding up, if there's any side effects or anything? My flatbed hawk should be done shortly and we're planning on putting our family of 5 in there (12, 10 & 4 year old boys)

The bunk bed is holding up just fine, those cam-o-bunks are built very sturdy.

At first I had it sized a bit too tight and driving with it up caused some chafing on the curtains. I took off 1-2 cm and now it's just fine. It's a bit of a chore to set up and tear down, so we tend to keep it up, but then you lose the use of the rear dinette, of course. We carry a few camp tables with is and just try and spend our time out of the camper anyhow.

 

[super doody]

Great idea on the camera. Look forward to reading your trip report.

 

[CarlG]

Hi all. Sorry for the lapse in updating this thread. But fear not - I haven't stopped using or improving the camper. Time to catch up!

First up is my all-time most cost-effective mod: A paint stick mounted to a scrap angle bracket to create a brace for holding the bed up when rummaging through clothes!

 

[CarlG]

The stock USB outlets that FWC installs in these campers are complete garbage. Twice these things shorted and tripped their fuse, so I picked up some blue sea fast charge 3.8-amp outlets. This was an easy replacement, and while I was at it I mounted a hacksaw-modified junction box behind them because the wires hooked up to the USB outlets were just loose in that storage cabinet. This protects the backs of the USB outlets from the camp chairs and other heavy stuff that I cram into that space.

 

[CarlG]

Got some new shoes for her. Replaced the stock tires with Toyo Open Country RT 285/75R18, effectively 35", up from stock 33"

New wheels too 'cause they look cool

 

[klahanie]

Hey CarlG, great looking rig. Thanks for posting up.

btw I don't mind a follow up comment, if it's convenient, on how you like the new tires. I like that they are a 'tweener. Am on the second set of AT2s in the same (great) size but looking for something a bit more aggressive. Was told by a tire shop guy the RTs wear "too fast" whereas the MTs "wear like iron". Am skeptical on the last part. Am thinking that rig weight is the biggest factor any would effect each pattern type fairly equally but, IDK.

Thx

 

[CarlG]

I love'm so far. I have about 10k miles on them, wear seems minimal, but of course that's not a ton of mileage.

 

[CarlG]

Next mod was to add airbags and onboard air. This one was a bit out of my skill range so I had a local 4x4 shop do it.

I found that I needed the airbags for the new 35" tires to clear the aluminum flatbed's skirt. I don't really like the design of the AlumLine flatbed: un-necessary clearance issues. The airbags help the ride quality a bit also.

The shop routed the valves for the airbags to the license plate. They're individually fillable, which is sort of useful in leveling the camper as well.

Underneath the flatbed there was plenty of room for an air tank. Super happy with the way the shop figured out how to mount this thing up - it uses space that was completely wasted otherwise. Pretty clean and clever.

The best part is that they mounted the air chucks inside my flatbed's utility boxes. One on each side of the truck. This is the shot of the box with the fuse and controls for the compressor. The other side just has an air chuck in it. This makes airing the truck up and down a breeze, big improvement over the portable compressor I was using before.

 

[CarlG]

And now for the big one. Over the past season, we started having a number of electrical problems. Basically, the batteries were holding less and less charge, to the point where we could barely go a day without full blazing sun or hours of driving without losing the voltage overnight to the point where we'd lose power to the fridge. The whole concept of "don't drain your batteries too far" is something we never followed, and given the kind of remote camping we do, I don't see how you could do that. It's not usually a good option to lose your perishable food. So guess what? We killed our AGMs in just over 2 years.

It got so bad that the voltage would get so low (~10.5V - now that's dead) that the (terrible) battery separator that FWC installs wouldn't even let us charge the batteries off the alternator because the house side was too low. There is no override switch, which I think is a bit of an oversight.

So my project over the past few weeks has been to retrofit the system for LiFePO4 batteries. Much thanks to the folks at Batteborn for helping me think through this project. As many of you probably have already figured out, these batteries are not a "drop-in replacement". At least, not if you really want to maximize the benefit of your brand new $2k batteries.

My plan was to replace the two AGM 75 amp hour group-24 batteries with two BattleBorn 100Ah LiFePO4 GC2 (golf-cart form factor) batteries.

In order to maximize the solar system, switched out the Zamp ZS 30A with a Victron MPPT solar charge controller. I also installed a switch that would let me pick which solar panel I was drawing from: Roof, external rear plug, or both combined. I did this because I think the system doesn't perform well when one panel is in full sun and the other is in full shade, so I wanted to be able to select panels.

The battleborn folks recommended that instead of a simple battery separator or ACR, that I install a Battery to Battery charger to charge the batteries from the truck's alternator or from shore power. This was to prevent the LiFePO4 batteries from drawing too much current into themselves too quickly, which apparently shortens their life span.

And lastly I wanted to install a modern power monitor so I could see what was really going on with my system and not just rely on voltage readouts, so I installed a Victron BMV 712.

Here is the diagram of the final system I put together:

 

[CarlG]

To begin the project, I pulled off the lid to the cabinet where the electronics are stored. This is no easy job, as it is screwed in from inside the cabinet. Tricky to do. There are fuses inside this cabinet too! Good thing one of them never went, I never would have found it.

Once inside, I was greeted to this rather intimidating view:

Yikes. I called FWC for the wiring diagram, and was sheepishly told that they don't have one.
Cue about 3 days of me tracing each wire with a multi-meter to figure out what everything was. At least it's all labeled now.

The GC2 batteries fit absolutely perfectly in the battery caddy that the old group 24 batteries were in, except that they're taller so the velcro doesn't go over the top.

The velcro is easily repositioned though:

Ta-da: this part was easy!

 

[CarlG]

First I removed the Zamp solar controller. Since the new solar controller is not exterior-facing, I later re-used the slot that the Zamp was installed in to mount the blue sea switch.

Then came out the battery separator:

And this circuit breaker got re-position to make some room:

It's hard to take pictures in this cabinet, but I managed to mount the BMV712 shunt right beneath the negative 12v busbar. This was lucky, because the negative cable coming from the battery didn't have much slack on it.

I used some scrap wood to fill in the space where the Zamp controller was and mount the new Blue Sea switch:

Here's the best shot I have where you can see how I fit the Sterling battery to battery charger into the cabinet. This thing is pretty big, but there is space for it, it's just a bit tricky to mount.

 

[CarlG]

And here's the shot of it all (almost) put back together.

And the batteries in their new home, snug as a bug:

It's alive!

We took it out for a shakedown this past weekend. I am really excited by just how well this stuff worked. The MPPT captured an impressive amount of energy in overcast conditions. The batteries weren't even the slightest bit taxed by 2 stationary days off grid + mixed condition solar. I'm super impressed by the quality of the Victron parts and their bluetooth integration. I usually find that hardware manufacturers treat smartphone integration as a marketing point, and then the experience is usually crap. Not these things - the bluetooth connectivity is really useful, the apps are professionally done, and provide a wealth of information.

Let the season begin!

 

[smlobx]

Great write up on the new battery installation and going with Battleborn.
Are they 6 volt batteries?

I had the same thing happen to my two 6 volt lead acid golf cart batteries and replaced it with one 100 AH Battle Born battery and so far am very happy...

 

[CarlG]

Are they 6 volt batteries?

They are 12V batteries in parallel.

 

[Vic Harder]

Nice write up and work! 200AH of LiFePo... that is a lot of juice. ;-)

 

[CarlG]

Nice write up and work! 200AH of LiFePo... that is a lot of juice. ;-)

Thanks. Yeah I hope it solves my capacity issues once and for all. Off-grid camping in dense shady forests was pretty dicey before.