Battery/generator project

[Fordguy64]

And more info/thoughts on the ac/heat pump idea. I don't use much ac in the summer as I have a whole house can that draws just over one amp at 120v. It does a really good job of keeping the house cool as long as the humidity isn't high. So I would probably use it more in heat pump mode then anything and that actually works out because that's when I have the least amount of solar input to the batteries. So the generator will be running more anyway. I've thought about making a 200 gallon thermal storage/buffer tank for the heating/cooling and just pump that water thru a water to air heat exchanger in my central hvac system. I know that the water would have to be kept very cold (below 40*f) to get any kind of good dehumidification and cooling. On the heating end of things I could use the engine heat on the cold side of the ac system to increase the efficiency and the overall heat output of the ac system..

Anything I'm missing?

[thomasonw]

... On the heating end of things I could use the engine heat on the cold side of the ac system to increase the efficiency and the overall heat output of the ac system..

Anything I'm missing?

Just some thoughts / ideas:  It seems to me that a Heat Pump can be thought of as a Heat Concentrator, taking a lower temp side (Air, water, ground coupled at say 40-50f) and concentrating it to something higher that can be used to comfortable provide space heating (say 100f or higher??)  Given you will be starting with engine heat there is a likelihood the temperature will already be elevated enough that it can be used directly for space heating needs, so not sure you will gain anything running it through a heat pump.


If you do want to do some active heat transfer type setup, myself I would 1st look at modern self-contained units.  Aside from the issues of trying to get licenses and sources for freon (Not really that hard, truth be told), it occurs to me that modern AC units are very efficient, and the likelihood of being able to come close to that with a component approach would be tough...

Oh, and on 2 alts vs. 1.   As the controller actively manages Amps you can easily 'dial in' the max number of Amps you want the system to deliver.  If you use two alts and their total capacity is too large the controller will be able to rein them in.  Not sure if there is more efficiency using two lightly loaded alternators vs. one heavily loaded one...  Am thinking you could save doing the mechanics up twice if you decide down the road you need two alts..

And my thinking is, assuming the two alts are like model, just wire them in parallel.  The Field Drive can handle many Amps, easily driving two Alts.  Or heck, if the fields are 12v, wire the two fields in series?? (12v fields from your 24v battery)  Do wonder if there would be some issues with the two commutators/brush sets in series ...   Would be very interested in hearing what the likes of Bob has  to say on all this.

-al-

[Fordguy64]

Well I'm just not sure if the engine will provide enough btu to keep the house warm.. So the heat pump was just to add some btu to the tank. But my main goal is to have the alt set up and working on the motor by winter time and have a new larger inverter running.. At that point ill be able to get a better idea of the btus that I can harvest from te motor

Speaking of inverters my original plan was to use the outback vfx3524 inverter. But I'm thinking now of going with the magnum ms4024pae as it has the ability to use the inverter power and the gen power at the same time to increase power handling. Also it outputs true 240v power basically 2 2kw inverters. My only fear with that is 2kw is kind of small. Now my intention was to be able to run as many of the normal electrical loads as possible so that's where the magnum inverter idea comes in.

[thomasonw]

Were you also looking to get some way to harvest heat from the exhaust?  Kind of interested in seeing how folks to that, as I understand most waste heat actually goes 'out the pipe' 

[Fordguy64]

Thinking something like this for the exhaust ex

http://www.pirate4x4.com/forum/general-4x4-discussion/324151-another-homemade-onboard-shower.html


Anyone know if copper does anything weird with exhaust gases?

[mike90045]

....Anyone know if copper does anything weird with exhaust gases?

Nope, copper does nothing to exhaust gas.   

But exhaust gas is going to eat holes in copper pretty quick.    Steel has been the standard for a long time.

[thomasonw]

IIRC something about re-using stainless 'EGR-coolers' from auto/light truck diesel engines..

-al-

[Fordguy64]

ill look into it.. ive been trying to get the ac generator that doesnt output the correct voltage working.. ive replaced the capacitor and tried to re charge the field with no luck.. still outputting 4.7v. its just a 120v unit. its spinning at 3700 rpm. its a little fast i know but it should be outputting more then 120v. guess the next step is look at the brushes? also the neutral wire was connected to the chassis of the gen head when i got it is that correct? seems funny to me. this apu is a carrier pc6000. i cant find to much info short of a few pdf that show the normal what to check and how to install it info.. nothing i need..

[glort]

4. This is the one that I know least about and have only seen people talk about but have yet to see a system actually in use. That would be to drive an ac compressor to heat/cool. I've seen a few people talk about it on here but I have not seen any systems in use? Correct me if I'm wrong. Anyone seen any on another site? Links?

Thoughts?

I pulled a working AC out of a car a couple of weeks ago just for such a project, diesel engine, verg fueled AC. No, I haven't seen anyone do it either and i'm surprised at that.
Unfortunately after testing the AC in the car before I dismantled it. ( the whole car and the AC) I left the reciever/ dryer line behind so I'll have to get another one this week when I go back up.  I''m also going to cut some hard lines out of other cars while I'm there so I can make up extended lines so I can position the Motor/ compressor and the Evap unit further away as I'll need them than in a car installation.  Only thing I'm not quite sure of yet is how the Compressor is switched in and out from the temp/ icing switch on the evaporator.  That may be via relay but I suspect on teh vehicle I got it from, it could be incorporated into the car or body control computer. If it is, shouldn't be hard to work around. At worst, I can slightly undercharge the system so it runs all the time but that will depend on the heat going into the unit, IE, how hot the weather is.

Unlike what most people assume you do not want 0oc air coming off the evap unit or it will freeze up. When that happens efficency falls through the floor. The fins of the unit are blocked by ice and can't pass enough air.  Also instead of evaporating and cooling, the high side of the gas goes back still in superheat and damages the compressor nor results in extended off cycles whilst it cools.

If you wanted to have a reverse system, you'd simply have to put a TX valve in the circuit.  You could get an old one from a scrapped domestic system or buy a new one as a spare part.  Plumb that in and all should be well.

The advantage of using the heat from the engine would be to keep the system way more on the efficency curve. Reverse cycle AC is only good down to a certain temp, around 5 oC. After that the efficency falls right off the curve because the condensor freezes up and the unit will spend more time in defrost mode than it will in heat mode.  By drawing off engine heat, The problem should be largely offset or completely avoided.  AS mentioned, the availability of more heat in the first place means there is more for the system to more or less pass straight on anyway.  If there is insufficent heat then the balance will be made up from the surrounding air. As long as you keep the condensor coil from freezing, You'l be able to pull the max heat.

Car aircon units are roughly around the higher end of medium output home split systems in capacity .  Some would be more, some less obviously depending on the vehicle to which they were initially installed.  They are going to give a quite creditable output compared to normal Home AC units so be far from a waste of time.  Setting them up should be simple enough. They are a simple plumbing circuit with only 2 electrical controlls. The Compressor in/ out and the evap temp sensor for the compressor on/ off control.
You would need power for the Condensor fans, the TX switching if installed, the compressor clutch and the evap blower fan. The fans could easily be replaced with mains powered units if that was easier.  Other than that, run the lines, vac them down, fill them with refrigerant on pressure to take into account extended line runs instead of weight and it's all up and running. I'm planning to set it up all on a frame to test the engine power requirements and control setup and then I'll cut the lines and extend them by using copper insulated pipe the some on domestic  installs then using flare fitting to put it all together.

For cooling, one thing that really helps AC units particularly on hot days where they again fall off the efficency/ effectiveness curve is a water mist on the condensor unit.  The evap effect f that even in quite high humiditys can drop the effective air temp quite well and make the output a lot cooler. A good spray will absorb and remove a LOT of heat from the core and make things a lot less stressful on the already hard working compressor unit.
As far as I can see, a car type ac unit could also be given a boost by running dual condensor units. May not make a big diff in normal operation but the increased ability to shed heat at the tougher ends of the scale certainly wouldn't hurt. The only difference is the amount of refrigerant in the system would need to be increased to make up for the volume of the 2nd condensor and keep the pressures where they needed to be on both sides.

[Fordguy64]

Thanks for the info.. Keep me posted on your project..

[Fordguy64]

So I'm torn between 3 inverters.. Outback vfx3524 magnum ms4024pae and the Schneider conext sw4024..

Leaning more towards the magnum or Schneider do to the pass through ability with an ac generator. And further leaning towards the schnieder do to it's price point..

[mike90045]

I have the XW-6048, and it's been pretty solid.  I use the generator support  {Gen Support} all the time while charging in winter.  I'm not sure about the SW series, if it has the same features as the XW's.   XW's come from the factory, jumpered to only support split phase 240V power, and need 240VAC for battery charging and pass-through.

[thomasonw]

ill look into it.. ive been trying to get the ac generator that doesnt output the correct voltage working.. ive replaced the capacitor and tried to re charge the field with no luck.. still outputting 4.7v. its just a 120v unit. its spinning at 3700 rpm. its a little fast i know but it should be outputting more then 120v. guess the next step is look at the brushes? also the neutral wire was connected to the chassis of the gen head when i got it is that correct? seems funny to me. this apu is a carrier pc6000. i cant find to much info short of a few pdf that show the normal what to check and how to install it info.. nothing i need..

Hi, it would be normal for the Neutral wire to be connected to the chassis.  In North America's wiring practices the bonding between the green safety wire and the white neutral wire to occur at the source - the generator in this case.

I don't know too much about self exciting AC generators, ala the ones with basically a Cap and that is it for regulation.  But reading it appears there are actually two components:  the Cap, and a Diode embedded somewhere in the rotor.  A tuned ckt is formed (to the 3rd harmonic of 60hz) which not only is dependent on the cap, but also the the RPMs turned.  Also read a caution about making sure the cap does not have a built in beading resister as is common for run-caps.  Seems the built-in resister can destabilize the tuned ckt..  But I thought these were brush-less designs, does yours have brushes?

-al-

[Fordguy64]

Hmm ill have to look at the specs a little closer on the new cap I got. But I was just soon some more digging for parts and I can't find anything worth while for this gen head. So to be completely honest I don't know if it has Brushes or not.. Couldn't get it apart far enough to tell. I looked in all the wholes I could and didn't see any.. But I did find some info that suggested trying to re charge the capacitor field in a service manual. Basically disconect the cap and start gen connect 12v to leads for 2 sec turn gen off reconnect cap and start again.. Ill try that when I ge home

[Fordguy64]

Ugh still 5.4 volts..