Just got my new Hawk installed!

[claws]

After waiting 10 months I finally have my new Hawk Shell. FWC installed it yesterday and it's beautiful! Now to start outfitting it. I ordered my Hawk with a propane heater and cook top. I also got the roof mounted 160W solar system to keep my 12V AGM battery topped off and a single MaxAir fan. I'd like to get a small compressor fridge but don't know if my single AGM and solar panel will provide enough Ah to run it. If not, I had planned to buy a 100W Lithium battery but was told by the installer that I can't do that without an extensive, and expensive, electrical upgrade to my camper. He said that while the MPPT controller could handle the Lithium battery, the battery separator couldn't, and that it couldn't be charged from the truck's alternator without the electrical upgrade. This was news to me since I thought the AGM battery could easily be swapped out for a Lithium battery. Was the installer correct or just trying to sell me an expensive upgrade?

Thanks,
Kim

 

[astropuppy]

I have the same setup with dual 12v agm's running a Dometic cfx 75L. Summertime at 43 degrees North latitude, I can go three days without sun. Normally 100% by noon on sunny days.

Late fall and winter lead to plugging in an 100 watt auxiliary panel.

There are precautions when using the stock alternator charge circuit for charging lithium's. Disconnecting it is as easy as removing a fuse. If you do go lithium, I would highly recommend the Victron Dongle ($50) for your stock mppt controller. It makes changing charge parameters much easier. Plus, it will update the firmware.

I bought the Dongle and Shunt for my agm's in preparation going to Lithium when the agm's are spent.

I highly suggest using your camper before spending money. Our reality was very different from our assumptions before using it.

Dongle: https://www.amazon.com/Victron-Energy-ASS030536010-VE-Direct-Bluetooth/dp/B01CGFF8Q2/ref=sr_1_3?keywords=Victron+Energy+VE.Direct+Smart+Dongle&qid=1639871378&sr=8-3

 

[rando]

The installer may be exaggerating a little about the changes needed for lithium. You CAN just switch the AGM batteries to lithium without any changes. The minor draw back to this is that your battery isolator well tend to stay connected as the lithium resting voltage is high enough to trick it into thinking your truck is running. However, if you have solar and park outside this is not a bad thing as it means both your truck battery and camper battery will be nicely charged. You can always pull the fuse on the isolator if you want to disconnect the batteries.

If you don't want the isolator to keep the batteries combined, you have two options - an isolator designed for lithium or a DC-DC charger. The Victron Cyrix isolator is pretty cheap and is a drop in replacement for the one that comes with the camper. The DC-DC charger will improve the charging from the truck, but may require a wiring upgrade that is a little involved.

 

[Charlie]

I think there is some fact to what the installer is telling you. A lithium battery has a much higher charge acceptance than an agm, i.e. it will take a lot more current. But this is an advantage, because you can charge them faster, with less driving.

Also, my experience with the 10 gauge wiring and the simple ACR (automatic charge relay) installed by my FWC dealer was really marginal even for charging the two 80Ah agm batteries that I started with. For one thing, the small wire means that there will be a significant voltage drop between the starter battery and the house battery, which will limit the current going into the agm. Also, the voltages put out by a “smart alternator “ in modern vehicles is constantly moving around, and the vehicle computer is not thinking about your house batteries at all. I got pathetic charging performance; on a cloudy day with significantly discharged agm batteries, it couldn’t charge them up in 6 hours of driving.

But, you want to use a lithium battery. My opinion (caveat emptor) is that one should use a DC/DC charger, which is designed to handle these issues. I just installed a Victron Orion-tr Smart non-isolated 12/12 | 30 and a 100Ah lithium, and did a test run from Colorado to the Olympic NP and back early December. Dark short days, and camping in the forest (“darker than the inside of a cow”). This combo worked really well for me. Each night camping would draw down 30% of the battery. A couple of hours of driving after the second night charged it back up. As @astropuppy said, you could install a lithium capable DC/DC charger without the lithium battery, and save the battery upgrade for later.

It’s a coincidence that I just today did a spreadsheet on the cost of my power system upgrades. It’s significant, but not really too bad. However, I did all of the install work myself. I’ve attached it here.

 

[Jon R]

My cost was also about 2700 for a 200ah lithium battery, 400 watts of solar panels, Victron 30 amp solar and dc to dc chargers, BMV-712, plus wiring and connectors, etc. (installed by me). I saved quite a bit on my camper price by not ordering any electrical power options and selling the base lead acid battery back to the dealer at delivery. The FWC options for similar (but not quite as much solar) capability add up to $7000.

 

[astropuppy]

Charlie, thanks for the cost breakdown.

The single biggest ampere draw in our Hawk shell is the refrigerator. Our Dometic 75L draws over 5 amps at times. With those facts in mind, I struggle with the cost of upgrading our camper wiring. My current solution is plugging the refrigerator into a portable power source. Then, plugging it into the camper while re-charging the portable power source either outside with solar or in the truck while driving.

We also use portable power outside the camper to charge phones, laptops and run the pump for our shower. Quite handy to have.

Portable power sources are plentiful; Jackery and Goal Zero come to mind. However with little effort, I made my own.

That said: when our AGM batteries reach end of life, Most likely we'll replace them with Lithium batteries.

 

[claws]

The installer may be exaggerating a little about the changes needed for lithium. You CAN just switch the AGM batteries to lithium without any changes. The minor draw back to this is that your battery isolator well tend to stay connected as the lithium resting voltage is high enough to trick it into thinking your truck is running. However, if you have solar and park outside this is not a bad thing as it means both your truck battery and camper battery will be nicely charged. You can always pull the fuse on the isolator if you want to disconnect the batteries.

If you don't want the isolator to keep the batteries combined, you have two options - an isolator designed for lithium or a DC-DC charger. The Victron Cyrix isolator is pretty cheap and is a drop in replacement for the one that comes with the camper. The DC-DC charger will improve the charging from the truck, but may require a wiring upgrade that is a little involved.

Thanks Rando. If I understand correctly, the Victron Cyrix would be the easiest option but would not allow the lithium battery to be charged while driving my truck. Not sure if my rooftop solar could keep up with the power draw from the fridge. Any wiring upgrade is beyond my capabilities. I'll just have to see how my AGM performs for now.

Kim

 

[rando]

The Cyrix will allow your battery to charge while driving your truck, just not particularly fast. On my 2016 Tacoma with a 150Ah lithium battery I typically see 5-7A into the battery when driving, which is about the same as what I was seeing with the stock AGM battery.

That being said, at least in sunny Colorado, 150w of solar provides pretty much all the charge I need. A lithium battery will charge more efficiently of solar than a lead acid battery.

 

[claws]

The Cyrix will allow your battery to charge while driving your truck, just not particularly fast. On my 2016 Tacoma with a 150Ah lithium battery I typically see 5-7A into the battery when driving, which is about the same as what I was seeing with the stock AGM battery.

That being said, at least in sunny Colorado, 150w of solar provides pretty much all the charge I need. A lithium battery will charge more efficiently of solar than a lead acid battery.

Thanks again, Rando. Looks like the Cyrix is a win, win for me if I decide to go Lipo.

 

[fuzzymarindave]

After waiting 10 months I finally have my new Hawk Shell. FWC installed it yesterday and it's beautiful! Now to start outfitting it. I ordered my Hawk with a propane heater and cook top. I also got the roof mounted 160W solar system to keep my 12V AGM battery topped off and a single MaxAir fan. I'd like to get a small compressor fridge but don't know if my single AGM and solar panel will provide enough Ah to run it. If not, I had planned to buy a 100W Lithium battery but was told by the installer that I can't do that without an extensive, and expensive, electrical upgrade to my camper. He said that while the MPPT controller could handle the Lithium battery, the battery separator couldn't, and that it couldn't be charged from the truck's alternator without the electrical upgrade. This was news to me since I thought the AGM battery could easily be swapped out for a Lithium battery. Was the installer correct or just trying to sell me an expensive upgrade?

Thanks,
Kim

Any pics to share? I'm curious how the shell interior looks with minimal cabinet for cooktop and heater. Are you going to outfit it with additional cabinets, seats, etc?

 

[claws]

Any pics to share? I'm curious how the shell interior looks with minimal cabinet for cooktop and heater. Are you going to outfit it with additional cabinets, seats, etc?

I'll try to take some pics if it ever stops raining here. The only "furniture" I'm going to add is a removable 24" wide bench/bunk across the cab side of the camper. I plan to store a Luggable Loo, 30quart chest style refrigerator, and some storage bins under the bench. I can access these things by tilting up the bench and leaning it against the the front window camper wall when at a campsite.