Bus conversion Self sufficient.

[Scooternj]

Originally Posted by GreyCoyote

Suggest you dump the hydrionic heating. As others have said, it will be very inefficient and slow. Maybe use that same working fluid in a fluid-to-air heat exchanger instead. Or, at least hedge your bets and install both with valving to run either/both as fact replaces theory. You may also choose to install a regular RV heater as a backup. Believe me, the first time you get into a situation where the high-tech heating system runs cold, you'll appreciate it. Busses, however well insulated, are just lossy sardine cans. They get good (or hot) very, very fast.

I'll third the dumping of hydronic heat as your primary HVAC. When I was a Air Guardsman, my squadron's vehicle maintenance bay (big enough to park 2 40' buses side by side, and still get a humvee behind each one) had radiant floor heating. In the coldest depths of a South NJ winter, it kept the bay maybe in the mid-50s. Warm enough to keep stuff from freezing, but not all that warm to work in.

[kflowers]

Originally Posted by Scooternj

I'll third the dumping of hydronic heat as your primary HVAC. When I was a Air Guardsman, my squadron's vehicle maintenance bay (big enough to park 2 40' buses side by side, and still get a humvee behind each one) had radiant floor heating. In the coldest depths of a South NJ winter, it kept the bay maybe in the mid-50s. Warm enough to keep stuff from freezing, but not all that warm to work in.

I was looking to start with a propane tankless heater to heat the water for the radiant. The solar thermal is later down the road. My girlfriend and I are interested in radiant floor heating but We Do plan to have a backup. Anybody have a good propane air suggestion.

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[kflowers]

Thank you everyone for your amazing suggestions. I am updating my build list. Our objective is to have this live-able by the end of 2017 and complete by 2019. Some of the items will be much later on in the build. Mainly the solar thermal and solar thermal storage.


Electrical

Input

(Primary installed second)
We plan on using solar panels to collect solar power (top front of bus). We are still figuring it out but around 6-9 solar panels depending on model of panel. We plan on using 24 volt panels to work with our batteries bms system. (bottom back of bus)

(secondary installed first)
We plan on connecting a small gas motor from a weedeater to an alternator. This will run to charge the batteries.

Output.
Our battery bank will use 18650 cells. Each battery will have a battery protection circuit to protect the batteries. We are sourcing individual clips for each battery for easy service. The backplane for the batteries will be milled aluminum. Each battery module (holding 96 cells) will have an arduino that monitors temperature, hydrogen, and volatile gases. The battery modules will be housed in a sealed box under the bottom of the bus (back left side)

Heat

Input

(Primary installed second)
We are going to have 6-8 evacuated vacuum tubes in a parabolic trough(top back of bus) We will flow a high temperature liquid (haven't settled on one yet) through the tubes to collect heat. The flow rate will be reliant on a temperature around 600-700f. The liquid will flow through a graphite heat exchanger into a container of salts. The salts will store the heat for the night. Hot water and bus heat will both run off this system through a secondary heat exchanger. (Behind right rear tire).

(Secondary installed first)
we will use a propane tankless heater. It will flow as a closed loop system.

Output

Below the bus we are laying pex tubing along the ribs. There will be 2-3 different zones depending on whose bus it is. Hot water will flow through the tubes for radiant floor heating.

Water

Input
We plan on collecting rainwater from off the roof or in rain trap of some kind. In Massachusetts we are allowed to collect rainwater.

Output
All rainwater would go into a potable water tank after going through a ceramic and activated carbon filter. the storage tank will be a 30 gallon stainless tank with uv sterilization.

Drinking water.
We will have the drinking water come straight from the potable water tank. Excess water will be filtered in a sand and activated carbon filter and added to the shower tank.

Shower
We plan on making a modified version of the showerloop system. The system will be a 20 gallon insulated tank for pre heated water. The water will run through a sand and activated carbon filter to remove contaminates.

Clothes Washing.

Water from the shower tank will be used for clothes washing. This ensures water is drained from the shower. We plan on having a washer/dryer combi.

Sewage
For sewage we plan on having a composting toilet. We want a straight tube that goes into a compartment on the bottom of the bus. We will seperate the urine from the fecal matter.

Insulation
For the sides we are using the existing fiberglass. We will use good fiberglass from the roof to replace any damaged panels. For the roof we will be using closed cell spray insulation. We are going to use closed cell spray foam under the bus as well.

Flooring

We are planning on ripping up the linoleum and replacing it with cherry or oak flooring. the other two buses are keeping the original flooring.

Roof

We are planning on raising the roof this spring. Probably around 20 inches.

Windows

After the raise we are installing blocker panels to keep the weather out. We are building double pain safety glass windows to fit in where our windows will go.

Im sure as time goes on I will repost this with updated information.

[cowlitzcoach]

A weedeater engine will not have enough HP to turn any sort of alternator big enough to charge up even a small car battery.

Back in the day we were playing around to see how much HP it would take to turn a 35 amp car alternator. A 3.5 HP lawn mower engine would stall out with a load as small as just one headlight.

I will grant you that alternator technology has greatly improved over what we were using back in the day. But it still takes a certain amount of HP to turn an alternator. I have an old Dayton genset that has a 6000 watt power head on it. It has a Briggs and Stratton 11 HP engine on it. It will surge up to 7,500 watts but only for a very short period of time. When it gets hit by the full load it will start to slow the engine down. It either surges enough to get the load started or it will stall out. When it is working the full 6,000 watts you can tell the engine is laboring.

Again, I think you need to rethink the putting warming coils under the floor. I really do not think you will get enough heat up into the floor without putting a lot of insulation below the warming coils to encourage the heat to go up into the floor rather than radiate out into the atmosphere. The job of running the coils and insulating from the bottom is going to be a very difficult job as you work around what is already hung underneath the bus. It will work a lot better if you lay the warming coils on top of the bus floor and then building a new floor over the warming coils.

[kflowers]

Originally Posted by cowlitzcoach

A weedeater engine will not have enough HP to turn any sort of alternator big enough to charge up even a small car battery.

Back in the day we were playing around to see how much HP it would take to turn a 35 amp car alternator. A 3.5 HP lawn mower engine would stall out with a load as small as just one headlight.

I will grant you that alternator technology has greatly improved over what we were using back in the day. But it still takes a certain amount of HP to turn an alternator. I have an old Dayton genset that has a 6000 watt power head on it. It has a Briggs and Stratton 11 HP engine on it. It will surge up to 7,500 watts but only for a very short period of time. When it gets hit by the full load it will start to slow the engine down. It either surges enough to get the load started or it will stall out. When it is working the full 6,000 watts you can tell the engine is laboring.

Again, I think you need to rethink the putting warming coils under the floor. I really do not think you will get enough heat up into the floor without putting a lot of insulation below the warming coils to encourage the heat to go up into the floor rather than radiate out into the atmosphere. The job of running the coils and insulating from the bottom is going to be a very difficult job as you work around what is already hung underneath the bus. It will work a lot better if you lay the warming coils on top of the bus floor and then building a new floor over the warming coils.

We are looking to generate a small output (around 700 watts) to charge the batteries over a several hour period. This isnt my expertise so I cant really speak to if the motor is large enough. Thank you so much and I will pass this information along.

[kflowers]

This monday we are meeting with our EE who is helping with the project. Here is a rough design of the battery packs. We plan on using 18650 lithium ion batteries.

[TAOLIK]

18650 lithium ion batteries: Like AA rechargeable batteries? What are you planning to use 96 of them for?


A lot of radical ideas in this build. Sounds like you have quite the braintrust so I'll just sit back and enjoy the show.

[kflowers]

Originally Posted by TAOLIK

18650 lithium ion batteries: Like AA rechargeable batteries? What are you planning to use 96 of them for?


A lot of radical ideas in this build. Sounds like you have quite the braintrust so I'll just sit back and enjoy the show.

They are larger than aa batteries. These batteries are commonly found in laptops and e-cig machines. I have a very close friend who runs a precious metal recycling company. We will be using used batteries that we individually test. 96 batteries is just how the design ended up for each contained "battery box". We plan on having several boxes for the build. Im sure once we have a initial design review it will change a bit.

[kflowers]

Here is the rough design of the solar thermal collectors. Each tube is 70" long. Eventually this will be on a single axis motorized gimbal for sun tracking.

[TAOLIK]

Originally Posted by kflowers

They are larger than aa batteries. These batteries are commonly found in laptops and e-cig machines. I have a very close friend who runs a precious metal recycling company. We will be using used batteries that we individually test. 96 batteries is just how the design ended up for each contained "battery box". We plan on having several boxes for the build. Im sure once we have a initial design review it will change a bit.

3.7v each says amazon, my bad. Best of luck and I look forward to your report back with your results!

[joeblack5]

For the generator based on a weed eater motor. Harbor Freight sells a whole generator , about 700 watts for $80 to $90. Same idea only already done and with warranty.

While the 18650 lithium battery is nice you will have to match rated capacities and actual capacities / age / brand to come up with a decent setup. What voltage / capacity ? Ah are shooting for.

I built a coupe of block using that cell for a motorcycle battery and also an electric lawnmower but it get very very time consuming.
To put so many in parallel you have to design an impressive BMS to keep charging and discharging under control.

For heat storage search Tamera in portugal and stirling engine. They use vegetable oil that an be brought to higher temperatures then hot water.

good luck, J

[GreyCoyote]

If you are looking at this bus as a mobile experiment, then you are on the right path for learning. Lots of design choices are being made against conventional wisdom, but perhaps they will work for you. Certainly you are pushing the edge of the envelope... and maybe thats a good thing.

But one thing I am particularly concerned about is your heat storage method. Even using a salt that undergoes a phase change (solid to liquid), you are looking at nearly a ton of working media to get this bus through a cold night. And the thought of a 500-700F working fluid on a bus is a serious cause for concern. These kind of temperatures are not easily handled by common materials, and assuming you manage that, you are faced with a very lossy system.

By all means do try it, but dont put all your eggs in this basket. I think after a few months of numb fingers, you may see some wisdom in using less "experimental"'modalities such as propane, heat pumps, lead-acid, etc.

[retiredChemist]

With access to reasonable amount of lithium batteries, you may have a far safer system going the peltier heating / cooling path.

Trying to store molten salt as a battery is never going to be successful in such small volumes.

[kflowers]

Originally Posted by GreyCoyote

If you are looking at this bus as a mobile experiment, then you are on the right path for learning. Lots of design choices are being made against conventional wisdom, but perhaps they will work for you. Certainly you are pushing the edge of the envelope... and maybe thats a good thing.

But one thing I am particularly concerned about is your heat storage method. Even using a salt that undergoes a phase change (solid to liquid), you are looking at nearly a ton of working media to get this bus through a cold night. And the thought of a 500-700F working fluid on a bus is a serious cause for concern. These kind of temperatures are not easily handled by common materials, and assuming you manage that, you are faced with a very lossy system.

By all means do try it, but dont put all your eggs in this basket. I think after a few months of numb fingers, you may see some wisdom in using less "experimental"'modalities such as propane, heat pumps, lead-acid, etc.

After talking with several people and tons of suggestions on this forum I think we are going to abandon the thermal storage. We are still planning on using the solar thermal for heat during the day. For the night we will use a propane water heater.

[kflowers]

Three snow finally melted and we are getting moving. This week we extended the battery box. It can now hold 5 batteries. We also finalized the design of the couch.







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[Brewerbob]

Originally Posted by kflowers

Three snow finally melted and we are getting moving. This week we extended the battery box. It can now hold 5 batteries. We also finalized the design of the couch.

Why 5 batteries? I haven't looked into solar, electrical, or any of that jazz (yet). Two is normal for a "regular" bus. I can see wanting 3 for extreme weather and long rest periods. I don't know the norm for living completely unplugged.

[cadillackid]

I have my 2 main starting batteries.. and then have an isolated set of 2 AGM deep cycle batteries... since they are isolated the main bus batteries wont get run down when using my AGM's..

if I do decide i want all 4 batteries to do the job, either for helping to start the bus, or in the event I want all 4 running inside equipment, I can throw a manual switch to tie all 4 together...

I could easily see where you might want 5 batteries.. im guessing they will isolate some of them to not kill all 5..
-Christopher

[Brewerbob]

Originally Posted by cadillackid

I have my 2 main starting batteries.. and then have an isolated set of 2 AGM deep cycle batteries... since they are isolated the main bus batteries wont get run down when using my AGM's..

if I do decide i want all 4 batteries to do the job, either for helping to start the bus, or in the event I want all 4 running inside equipment, I can throw a manual switch to tie all 4 together...

I could easily see where you might want 5 batteries.. im guessing they will isolate some of them to not kill all 5..
-Christopher

On your shortie you have 4? Again, I haven't looked into it AT ALL but 5 just seems overkill. Or there would be a better size/packaging etc. for a solar bank. Whatever the house systems use. No clue if they (the house systems) will tolerate the vibrations, temps, etc.

[cadillackid]

Originally Posted by Brewerbob

On your shortie you have 4? Again, I haven't looked into it AT ALL but 5 just seems overkill. Or there would be a better size/packaging etc. for a solar bank. Whatever the house systems use. No clue if they (the house systems) will tolerate the vibrations, temps, etc.

on my DEV bus I have 2 mains in the normal battery box, and then my house batteries inside are my 2 AGM's.. they can be tied together for use. and when my bus is running they are tied together so my 200 amp alternator can recharge the house batteries when im running the bus.

-Christopher

[Brewerbob]

Originally Posted by cadillackid

on my DEV bus

I dunno what that means.

I have 2 mains in the normal battery box, and then my house batteries inside are my 2 AGM's.. they can be tied together for use. and when my bus is running they are tied together so my 200 amp alternator can recharge the house batteries when im running the bus.

You're not off grid are you? Does it make a difference?

You're always on the road and using that alternator. Is 200 amp big enough? Is there bigger? To do it over again, ...