This puts a much higher load on engine just like A/C compressor running reduces MPG. Nothing is FREE. It takes energy to produce it in one form or another. Based on the reduced fuel mileage to charge the batt. along with the extra load on alternator which could shorten it's $200 life, would you agree that is still the least expensive way to charge your batt. vs gen. or solar considering the cost of gen. and fuel.
You are still converting gasoline into watts. Using a big engine to charge batteries while just sitting in camp is going to be horribly inefficient, but if you are tooling down the highway at 60mph then adding a bit of extra load to the engine to charge batteries isn't going to make much difference.
I would guess (without doing the math) that charging the batteries while on the highway costs about the same as running a generator in terms of fuel used. As far as the life of the alternator...you could buy 5 $200 alternators for the cost of one Honda EU2000i.
So, yes I would agree that's probably the least expensive way...while on the highway. Definitely not while parked or in stop-and-go traffic.
Also, You still have the added batt. weight of 200-300 lb. which will also cost you some MPG. These small 2000 watt. gen may not run everything and if you run A/C unit there is not enough to charge batt. while A/C is running. You may not have enough remaining to run lights / electronics (parked) and would have to depend on batt. bank. Bigger, heavier gen would cost more and use more fuel but if you didnt have to buy as many batt. and haul the extra weight that would save up front cost and MPG in reduced weight. You may carry bigger gen that uses mroe fuel and not spend any more if you averaged it all out. Compare all the variables. Bigger heavier gen, smaller gen, solar, batt. bank, combined fuel use. Comes down to how much Elec. you need and for how long before you start driving like you said before. I am thinking it might be hard to justify more than 2 batt. considering all the variables.
Another thing to keep in mind when figuring the bigger gen. Inverter gens can throttle down when appropriate, regular gens can't. So a regular gen that is loaded at say...under 50% is going to be inefficient and wasting fuel.
As for battery charging and running the a/c. A charger that puts out 15a to the battery, is going to draw around 2a from the 120v of the generator. I use a 10a charger that draws 1.6a from the gen at full load, but it normally never goes over 8a to the battery. Even then, it tapers off in a few minutes to around 5a-6a and so it's normally only drawing 1a or so from the gen's 120v.
But it's a constant voltage charger, not a constant current charger. A constant current charger, like a 2-stage or 3-stage, would keep the amps up till bulk was done and thus keep the load on the gen up.
So, for trying to run a small a/c and also charge the battery, it may be better to use a constant voltage charger which is slower to charge the battery, but also draws less from the gen.
For me, it's not an issue. When I bought a generator for the camper I have now, I was already planning to use a 5k a/c -and- charge batteries, so I bought the Honeywell because it has a 125cc engine and is rated 2000w continuous. (And if anyone is wondering - is it a good gen? I think it's fine if you don't get a lemon...but there are lot of lemons.)
Most will prob. say if your only using van for 1-2 mo. per year just go with gen and be done with it. I am not living in van nor do I use it enough to justify RV type heater and power but wanted the best set up for reg. camping trips. If I am in the middle of forest where you can hear a pin drop I don't want to start gen to charge batt. but I don't want to park out in the sun to use solar panels either. I always park under trees in shade if possible and that combo doesn't work with solar panels on roof. That brings me back to charging while driving or gen. It would be a lot of work running wires and solar panels out into open sun then packing them back up again for the amount of power they would offer if only parked a couple days. Your ideas ?
For me, I don't care about the noise. I normally don't camp near other people, and in that case, running the gen doesn't bother anyone but me, and I'll tolerate the noise to get the power.
But I haven't put a/c in my camper yet, and I don't have a microwave in it. I have an 8 hour battery for my netbook and a 12v power supply for it, and I bought a low power netbook anyway that only draws 9w in power saving mode, 14w when charging the battery. My DVD player is a little one that also runs from 12v. I don't use a lot of power. If I'm not running my heater at night, I usually only run my generator every three days to recharge the battery.
I also abuse my battery. I take it down below 50% quite often. But there is a place where I can buy a decent no-name 100ah deep cycle (not rv/marine) battery for $45 so I don't mind abusing it. I can buy a dozen of those batteries for the same price as a 200w solar setup.
Myself, I camp often in the desert, and there are no trees, so putting solar on the roof is not a problem. But even with trees I don't think putting the solar panel out in the sun and running one extension cord would be so much work. 5 minutes really. Also - if you do that, you can set the solar panel to southeast in the morning, and southwest in the afternoon and harvest maybe double the watts. So I think that having movable solar panels is actually an excellent idea.
For you...
Well, you mentioned about a trailer, so you could put the batteries and solar there and only use them when you need them.
The other Q I am trying to figure out is the cheapest method to heat van ? From what I understand any elec. heating method is the same because it gives you heat based on the energy used. Some people try to claim one is better than the other but based on the facts you get back only what you put in. So which method offers the most for less ? (Gen. Elec. space heater)
Catalytic propane is very efficient, since no heat is wasted as exhaust. You can't really consider what you lose from leaving a window open a little - you have to that for fresh air no matter what, so you will lose heat from that no matter what heating system you go with.
A 1600w generator running a 1500w radiant heater is also pretty good. As you said, 5000 btu of heat. But running that on a Honda or Yamaha will be right at the max, so it won't be saving any fuel on econo. I'm not sure how long your generator runs on a gallon of gas at full load, but if you run it 24/7 you could use a few gallons a day.
The best would be the nice diesel powered Espar units. The D2 unit on high puts out 7,500 btu on 0.07g of diesel and 2.8a of 12v per hour. So 5g of diesel would last 70 hours or so and 200ah of battery would go 30 hours before it hit 50%. You could put it in a box and leave it outside and just run supply/return hoses to the van.
http://www.espar.com/html/products/airtronic2.html
But those aren't cheap - over $1000. Like you said, you can buy a lot of propane for that price.
So would you say based on my use a 2000 watt. gen with 2 golf cart batt. something like 250 ah and 1500 watt. inverter would be the best set up ? I could always start vehicle engine while running some of the bigger things like microwave for a few min. if I didn't want to shut down A/C or Elec. heat,etc. from gen.
2000w gen? Or 1600w gen? 2 golf cart batteries would be 6v ea. Trojan T105s are 225ah, so 2 in series for 12v would be 225ah. I know that sounds nit-picky, "yet there is method in't". Most people tend to over-estimate the available power. 2000w when really it's less, 250ah when really it's less.
You won't be running a/c or electric heat from the inverter/batteries - only from the gen. But you will probably run the microwave from the inverter, and that gets power from the battery, so you probably won't need to start the engine. If you are splitting the heat between electric and buddy, then you can spend some gen time for battery charging.
Do remember, a microwave's rating is the rating of the magnetron inside the machine, not not how much power the whole machine draws. A "600w" microwave usually draws > 1000w.
I was also looking for step by step install instructions for the best batt. set up. Seems there are diff. opinions on what works best based on cost and since you seem to have some back ground in that areana figured I would ask. (Best inverter and batt. brands for the money) Was considering mounting 1-2 batt. under pass. side area. But we are talking about $500+ and couple hundred pounds added weight. Geeeeez, I could almost buy another Yamaha gen for that and link them together running anything I wanted. decisions, decisions.
There are a few issues.
If you use 2x6v in series, you don't have to worry about balancing the batteries' resistance, so that's good. If you wired 2x12v in parallel, you would have to do it balanced.
Don't run positive wires and then use the vehicle frame for negative. That is fine for small amp circuits, but not for high amp batteries/chargers/inverters. You need dedicated positive -and- negative cables.
Battery to Inverter cables have to be LARGE. 1500w@12v is 125a! You need cable rated -over- 125a and a fuse to protect that cable.
To charge from the vehicle engine, don't use a diode type isolator (like you find in auto parts stores with a big heat sink) always use a "split charge relay". For an excellent document about why, look here:
http://www.smartgauge.co.uk/diodes.html
Some people will say that a split-charge relay is not good, because of a big surge when the batteries are connected together. Not true. Here is the math:
http://www.smartgauge.co.uk/nosurge2.html
Inside the vehicle, DO NOT use regular flooded batteries. They vent hydrogen when being charged. Use AGM which are sealed and don't vent unless you seriously overcharge them and blow the seals. I like AGM better than GEL because they aren't as finicky about voltage - they almost all use the same voltage settings as a regular flooded battery. Also usually cheaper than GEL.
3-stage charging is best if there is no load on the battery when charging, but if there is a load, it can trick the charger into thinking that the battery is low and cause it to overcharge. If you are going to charge while there is a load on the battery, better to use a 2-stage charger like Iota or Samlex. Samlex have a dip switch and can do either 2-stage or 3-stage.
If you get AGM batteries, make sure you get a charger that either does not equalize, or can have the EQ function disabled. Most AGM are not supposed to be EQ'd.
Pure Sine Wave (PSW) inverters are the best, but more expensive. Modified Square Wave (MSW) have a bad rap since PSW came out, but the truth is that 99% of everything will work fine on MSW. The 1% that won't - will usually burn out immediately. Some electronic control boards will instantly fail when connected to MSW. They are very uncommon. You won't know which one will burn out until you try it. Surprise! All electric motors will hum a little on MSW - some won't work at all. Again, those are uncommon. Better quality MSW inverters have a lot of steps in the fake sine wave. Cheap ones only have one step.
EDIT: One thing that is pretty much guaranteed to fail eventually on MSW are battery tool chargers - Ryobi, DeWalt, Makita, etc. Better to get the charger that plugs in the cigar lighter.
Power Jack products are junk. BZ solar products are junk. AIMS inverters are...well a lot of people say they are junk. Personally, I never looked at one, but I wouldn't buy one. I would buy Xantrex or Samlex.
I would not buy an inverter/charger combo, because the charger will likely be too big. Like 40a up to 100a. For 225ah of 12v battery and a 1600w gen - 15a or 30a is enough.
Iota chargers are tough and not expensive. Don't buy the smart charge module for it if you have AGM, because you can't disable the EQ (besides, they are 2-stage without the module and that's what you want when charging if there is a load).
Buy deep cycle, not "rv/marine". Deka, Concorde, Surrette, Crown or Trojan all make excellent deep cycle batteries.
Buying batteries is best done locally. They cost a lot to ship. Plus you want to check the manufacture dates before you pay. Try not to buy batteries that have been sitting on the shelf for six months.
