Off Grid Expedition LMTV

[ohiobenz]

I'm in the research process for my LMTV conversion.
The truck has a 12/24VDC alternator, the primary bank consists of 4 12vdc TL batteries wired for 12 and 24vdc output.
A 28vdc diesel 3.5KW generator is mounted on the rear box for backup.
The plan is to put four 300-350W mono solar panels on the roof for 24vdc primary power to an inverter.

An 8000btu 110vac AC (10A max) and small fridge/freezer 110vac plus a convection cook top will be the major consumers.
Would also like a "shore power" input in case of staying somewhere with power for extended time, winter storage etc.

Seeking recommendations for inverters, controllers, switching etc.

Someone recommended a Tesla auto battery as the aux battery bank for more storage/$ than the battleborn units.

Any input and advice is appreciated.

 

[luthj]

What is your daily kwhr usage? How long do you need to go without charging? What is your expected temp range to operate in? This is a complete system design, and should not be approached piecemeal.

 

[DiploStrat]

What is your daily kwhr usage? How long do you need to go without charging? What is your expected temp range to operate in? This is a complete system design, and should not be approached piecemeal.

Amen! If you look under "Documents" on my site, you will find things that may be useful.

Further on, you will need to think about 24/12v integration. There are various ways to do this and a lot will depend on whether you use lead acid batteries, in which case you will want to optimize for high voltages, or lithium, in which case you will want to do the reverse. I have scars!

 

[ohiobenz]

KWH Usage hasn't been determined yet because I don't have all the appliances selected.
Temp range... Continental US...
Like I said, the research phase. Not looking at this piecemeal, rather looking at/for components and concepts that work well together and will allow me to be able to be off grid as long as I have fuel. If the weather is bad, the generator should recharge the battery.
I'm looking at something very similar to this setup, except the truck is already 12/24, and the diesel generator is 28vdc not 120vac.
Used Tesla battery packs are getting good reviews in many applications and (for now) readily available

https://www.mortonsonthemove.com/toms-tech-stuff/

It looks like the major compromise will be that hot water for showers is going to require propane assist. I had hoped to avoid a 2nd expendable fuel source, but cold/tepid showers are survivable if I run out of propane...

 

[DiploStrat]

KWH Usage hasn't been determined yet because I don't have all the appliances selected.
Temp range... Continental US...
Like I said, the research phase. Not looking at this piecemeal, rather looking at/for components and concepts that work well together and will allow me to be able to be off grid as long as I have fuel. If the weather is bad, the generator should recharge the battery.
I'm looking at something very similar to this setup, except the truck is already 12/24, and the diesel generator is 28vdc not 120vac.
Used Tesla battery packs are getting good reviews in many applications and (for now) readily available

https://www.mortonsonthemove.com/toms-tech-stuff/

It looks like the major compromise will be that hot water for showers is going to require propane assist. I had hoped to avoid a 2nd expendable fuel source, but cold/tepid showers are survivable if I run out of propane...

FWIW: 28v is 14v x2, or just a bit low for 24v lead acid battery bank and probably perfect for lithium. But put a meter on that beast to be sure. Use a 24v solar controller and inverter/charger and then use a converter to produce 12v for your appliances. May actually give you slightly better performance for your 110v stuff.

Why would you need propane for a shower? Lots of diesel and even gasoline options. My truck has no propane and we take hot showers down to around 5F.

 

[DiploStrat]

Nothing wrong with diesel heating water. Its not instantly hot like LPG, but if hung up on using single fuel...

??? Mine certainly is. (Webasto Dual Top) YMMV.

 

[luthj]

My hydronic takes 10 minutes from dead cold.

Victron is a great place to start looking. They have full system integration down.

 

[DiploStrat]

My hydronic takes 10 minutes from dead cold.
...

Interesting. The Dual Top has about the same time, but we almost never turn it off, certainly never in the winter. So about the only time there would be a wait is in the summer, but that is never a problem as we turn it on when we wake and it is hot by the time we need to wash up or shower.

 

[luthj]

Diesel on demand is about 2 min or so. My set up heats a 4 gallon tank, so is not on demand. The dual top is usually left running for cabin heat in the winter, and is quite fast.

My tank stays warm for 24 hr, so I just heat it while driving, and have hot water all day.

 

[DiploStrat]

Jon beat me to it.

The point is that a diesel system uses so little fuel that you can leave it on all the time.

 

[ohiobenz]

It sounds like the diesel heaters are not on demand? My experience with even a 5 gal reservoir heater has been rather negative. Maybe with a pre-heater roof panel it would work, but I always ran out.
So I would like more info....
My build is literally in it's infancy.... Going from my FJ with OBA and OBW with an RTT to a converted military LMTV is a huge change...
Right now I'm gathering info, researching etc while focusing on revamping the cab.
That's more than enough to keep me busy..

 

[ohiobenz]

??? Mine certainly is. (Webasto Dual Top) YMMV.

I looked at the Webasto site, interesting.
My search for a local dealer did not work tho.
Pricing? Where did you get yours?

 

[luthj]

My D5 hydronic diesel heater outputs 5kw, and takes a couple minutes to start heating. With a 4gal water tank, I can make about 10 gallons of shower temp water. If I need more I just turn the Espar D5 on for 15 minutes to get the water tank back to 180F. With an in-line heat exchanger, this system can be made into an on-demand type.

With diesel heaters it takes a minute or two to heat the glow plug in order to ignite and diesel, so they do not turn on "instantly" like LPG units. Of course they also don't need an extra LPG tank, and diesel is available everywhere trucks drive.

 

[luthj]

One source.

https://www.heatso.com/webasto-dual-top-evo-8-standard-heater-kit/

 

[DiploStrat]

Dual Top notes.

Had/have two of them, one on a Tiger and now in the XP. Both were bought and installed by the camper manufactuers.

-- Don't make too much of the "on demand" idea. Most hot water systems heat around 5 USG and supplement as needed. This is easily enough for two adults to take hot showers. Recovery time is not a big deal.
-- The Dual Top is great when it works but they have a high failure rate. Tiger no longer use them and XP is looking at alternatives.
-- Webasto has sales in the US but most Webasto depots will not touch a Dual Top. (As a friend found out only after driving several hundred mikes!) This leaves you to your own efforts.

Were I building anew, I would probably go with a Rixen system. (http://rixens.com/products-services/sprinter-class-b-and-c-rv/) Tiger and Advanced RV now use Rixen's as OEM.

A hydronic system adds some complexity, but in my particular case, with an old diesel that has no glow plugs and smokes like an SOB, the ability to build in an engine pre-heat alone might be worth it.