zero Posted July 1, 2015 Share Posted July 1, 2015 I might as well toss in another newbie question. I've noted some keep the fridge on while driving, either propane or electric. Didn't know that was an option, but it's great. My question: if the fridge is running on 12v when camped, is level still required or there some leeway in 12v mode? I've got a 100 watt solar panel charging, now, a 12 volt and two series-wired 6 volt deep cycle batteries paired with a 1500 watt inverter, so electric is an option at most times...thanks, great discussions. An absorption refrigerator like you have works exactly same regardless if the heat that makes it cold comes from a propane flame or an electric resistance heater. Problem with electric is it will draw 8-10 amps @ 12 volts and run a lot. That is a lot of amp-draw for a vehicle without the engine running and no alternator charging. A 100 watt solar panel is only going to make around 5 amps of charge in the best sun and no longer then 5 hours in a 24 hour day. So no way is one 100 watt panel going to keep up. Quote Link to comment Share on other sites More sharing options...
zero Posted July 1, 2015 Share Posted July 1, 2015 The start load is what kills you with the inverter. The AC fridge draws a ton more power for a split second when the compressor kicks in. Yes and quite often it is not the inverter that is the issue (from one person's persective). Main problem is - most modern inverters shut themselves off if input voltage drops below 10.5 to 11 volts. Unlike a normal 12 volt system in a car or truck that is intentionally designed to work well at 9 volts. So even a good inverter and too small a battery results in a drop to 10 volts for just a fraction of a second and that's all it takes to shut off an inverter. I've found that a decent 1200 watt inverter (with over 2000 watt surge rating) can run any AC refrigerator as long at the battery is 120 amp-hours or larger. With a mircrowave - you need 240 amp-hours of batteries to keep the voltage drop from the battery above 10.5 volts. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 1, 2015 Share Posted July 1, 2015 An absorption refrigerator like you have works exactly same regardless if the heat that makes it cold comes from a propane flame or an electric resistance heater. Problem with electric is it will draw 8-10 amps @ 12 volts and run a lot. That is a lot of amp-draw for a vehicle without the engine running and no alternator charging. A 100 watt solar panel is only going to make around 5 amps of charge in the best sun and no longer then 5 hours in a 24 hour day. So no way is one 100 watt panel going to keep up. Oh never mind, hard to keep track of where this conversation is going and who is being addressed Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 2, 2015 Author Share Posted July 2, 2015 No thank you to a microwave. Haven't had one in our house or otherwise in 6 years and we're still alive, weird huh? Quote Link to comment Share on other sites More sharing options...
RunningMan Posted July 3, 2015 Share Posted July 3, 2015 can one of these work in a sunrader.? i know maybe its a stretch .. i have old solar and will be putting on new panels and might try to set up a fridge like this with 2 deep cycle Trojan batteries my original dometic 2400 is dead and im looking for an alternative to the propane fridge in a 4x4 that is hardly ever on level ground http://www.suremarineservice.com/R5810ACDC.aspx Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 3, 2015 Share Posted July 3, 2015 It would take a little more than 50 amp hours of power per day according to the specs. There is a great recent thread on this topic and one of the reasons I know anything at all about this. That and some of the great threads on batteries in general. Even if I didn't own a Toyota RV, I've gained a ton here. I think the biggest issue is going to be surface area up top and based on jdemaris' rule of thumb above, 200 watts of panels might get you just enough juice to run it provided you have good sun. I'd plan on something to supplement it like a small generator as a rainy day plan. Anyone chime in and let me know where I'm wrong on my reading of this. Like to get it all ironed out before I try this on my next RV. I've read a bunch of threads but make no claim to be an expert other than I have a very firm grasp on DC and circuit analysis. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 3, 2015 Author Share Posted July 3, 2015 Yeah, I'm actually thinking of going a different direction and getting a high output alternator. I'll probably get something in the 90-100 amp range and idle or drive the rig everyday to charge. I think it'll be quieter and less expensive (initially anyway) to get an alternator for $150 than $500-1000 for a genset or solar and we have no place to haul a genset. All great tips though and all are being considered, THANK YOU!!! Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 3, 2015 Share Posted July 3, 2015 Yeah, I'm actually thinking of going a different direction and getting a high output alternator. I'll probably get something in the 90-100 amp range and idle or drive the rig everyday to charge. I think it'll be quieter and less expensive (initially anyway) to get an alternator for $150 than $500-1000 for a genset or solar and we have no place to haul a genset. All great tips though and all are being considered, THANK YOU!!! We read that. We also like to hijack threads and one post before mine was such a case. Hope it didn't cause any confusion. It's sometimes disorganized but often related and adds to the overall topic base making the sum knowledge greater than the whole or something like that. Doesn't always work out that way but that is the idea. If I were going to take the approach you are planning. I would beef up the wiring overall and add a couple things. My house side had a bad isolator relay and the wiring was pretty much crap when I got mine. There was smallish gauge wire, really bad crimp connections and cheap circuit breakers. Being an electronics guy, I redid everything from under the hood back starting with a new high current isolation relay. Added 100 amp fusible links at each battery end and replaced the small wiring that was there with heavy gauge cable. I even added a bypass relay and switch to energize the isolation relay so I can either charge the cab battery when plugged into AC or even jump start the engine with the house battery. This was just with the stock alternator. My thinking is what is the point of a higher power alternator if you can't deliver all the juice back to the battery. You can see what is there, I cannot but my point is to inspect and evaluate what you got currently. Also if you are only going to idle the engine to charge, the higher output might not make that much of a difference. Make sure the alternator you choose delivers higher current at close to idle RPM. Something like a marine Electromaax which will deliver 100 amps at 1000 RPM vs 20 amps of a stock alternator. You need to look at the performance curve data before making your choice to see which will deliver the most current at low engine idle. Which brings me to the last accessory I would suggest. Add a digital volt meter to the house system. That way you can see where the battery level is and what it is charging at when idling. None of these are particularly expensive but do add up. I still think it is worth the effort. Just one crazy guy on the internet opinion. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 4, 2015 Author Share Posted July 4, 2015 Wow, that's a lot, but I am taking notes and adding it to the info bank. How long do you think it will take idling the engine to charge after a a night or day running that fridge and occasional pump use? I know that there are too many variables to answer exactly, just looking for a ballpark. Maybe this, how long to charge a completely dead 110 ah battery to full charge while idling with stock alt.? Hey Don, sorry for all the questions but you seem like a gold mine of info and I have my pick ax and miners helmet on and ready! LOL! Quote Link to comment Share on other sites More sharing options...
WME Posted July 4, 2015 Share Posted July 4, 2015 Rule#1 For max battery life do not discharge your house battery below 50% of capacity. A battery that has a life span of "2000 cycles " @ 20% discharge, will have a life span of 1200 cycles @ 50% and 500 cycles at 90% discharge. YMMV The charge time is simple, alternator amps vs battery amps needed. 20 amp out put and a 100 ah deficit means 5 hr of idle. The MAX SAFE charge rate for a battery that is between 10-85% discharged is C/5, that means 20 amps for a 100ah battery. Doesn't a 200 w solar setup look better all the time? Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 4, 2015 Share Posted July 4, 2015 You give me far too much credit. This place is a collective of knowledge and I was only smart enough to read as much as I could. There were a couple of good battery related threads over the last few years. I needed both batteries this year and so went searching again through the posts. All the battery talk made me curious for some more information. I was looking at things like automatic desulfurization claims of various chargers and such. I found a pretty interesting primer on Lead-Acid Batteries that was a pretty good read. The car stereo guys are also big into power and you will find a ton of stuff there. Caution the car stereo industry has sketchy specifications at times. On high output alternators though the charging rate curves are put out by the parts manufacturers which I trust more. There are a ton of variables with the alternator as well starting with assumption made about the sizes of the pulleys when calculating the charge amperage at RPM. I looked through a few charts online because this discussion was going on. You can google image search alternator performance graph or curve or data and will come up with something similar to this which should give you some idea about where the relationship to RPM is. They all look similar to this with some notable exceptions like some of the marine units designed to output more current at lower RPM. I see WME just added to the discussion. According to the article I linked above it states "The most basic rule is that you can charge at any current you like until the battery reaches 2.4 volts per cell at 25 deg. C (77 deg. F). That's the familiar 7.2v per 6v battery, or 14.4v for a 12v battery. Below this voltage, essentially 100% of the current goes into charging the battery, so there is negligible heating or gassing. The batteries won't reach 2.4v per cell until they are about 70-80% charged. Therefore, to charge the quickest, charge with as much current as your charger or AC line allows. If you keep adjusting to maintain maximum current, or your charger does, you're getting what's called "constant current" or "bulk" charging." Lets add jdemaris into this. He states that once your inverter voltage drops below a certain point, it shuts down. So unless you have other DC loads on the batteries (you state water pump and lights) you will not fully discharge the batteries Using the statement above you will need to charge as much current as possible frome X voltage to Y voltage to get to around 80% charge. I'll let someone else do the calculus or you can just add as much current as you can afford to the design of your system and through trial and error figure it out. The variable will be amp hours of the batteries and charge current going in. I've no way to know any of this. I do not dislike your plan but mainly would consider it as the fore mentioned rainy day plan to a solar set up. An alternator that can deliver high current at low RPM in my book would be a good back up for a boondocking system and unless I needed AC, I'd forgo the generator in place of panels and a high output alternator. That should add to the conversation mix. Got to head out. Got family coming and the wife is looking over my shoulder asking who I'm typing to. Edit: above should read. once your inverter voltage drops below a certain point under compressor start up load, it shuts down. Meaning that there will still be a charge of some amount left with in the battery but the increased starting load spike will shut down the inverter as the battery hits some point of discharge. Looking to correctly represent what jdemaris has said previously. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 4, 2015 Author Share Posted July 4, 2015 lots of good info, thanks! Quote Link to comment Share on other sites More sharing options...
DanRT66 Posted July 4, 2015 Share Posted July 4, 2015 Good info, indeed and thanks to all. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 5, 2015 Share Posted July 5, 2015 Although most of the day was a rain out, had a nice 4th cookout. It's all wet outside and unusually cold this evening. Looks like no tents tonight so most everyone is inside. Even with a large house it gets overwhelming. I've escaped the mayhem by hiding out in my office. So taking a look at some of the numbers we have here. where is this system at? We have a couple of batteries and an inverter. You'll be able to run the fridge off of the batteries for some amount of time before the battery voltage hits the bottom limit when the compressor kicks in. I've addressed some of the charging system issues but here is the rest of the problem. Once you hit about the 80% charge mark, the remaining 20% is the slowest part of the charge and the high current alternator is of less value here as this is the range where too much current can cause damage to the batteries. The regulator in the alternator is going to kick in anyway to lower the current at this point. So you either idle or drive for long periods of time. Otherwise only quick charge to 80% everyday as a temporary solution. If your batteries have enough amp hours you might get by with this for awhile. My thinking is that if your going down this route come up with a staggered plan. Fridge, inverter and batteries first. See how long they last. Later add the high output alternator and upgrade the wiring if what is there will not handle the higher current. Last get at least one solar panel in place. That 5 amps or so a day of charge for 5 hours might make all the difference in keeping the batteries closer to being topped off. For some this staggered approach works better as it is easier to come up with small amounts here and there rather than one big lump sum. I still contend that you are likely to spend about the same amount of money but you are looking for cold now. To me it still doesn't sound like in the end you'll be saving any money. We are a group of people all with varying needs and lifestyles. Some RV full time, others the occasional weekends. The common thread here is the chassis that powers our RV of choice. Quote Link to comment Share on other sites More sharing options...
zero Posted July 5, 2015 Share Posted July 5, 2015 There are a ton of variables with the alternator as well starting with assumption made about the sizes of the pulleys when calculating the charge amperage at RPM. I looked through a few charts online because this discussion was going on. You can google image search alternator performance graph or curve or data and will come up with something similar to this which should give you some idea about where the relationship to RPM is. Alternator charts don't help much in "real world" situations because of all the variables with pulley sizes, internal wiring, etc. Long-story;short - the Nippo Denso 45 amp and 60 amp alternators on a 2.2 or 2.4 engine with a single V belt - can charge around 25 amps with the engine at idle speed. If you put a smaller pulley on the same alternators - they will charge more at idle speed but also be more prone to belt slippage (less belt surface area). This is a major reason why "big" alternators are found in newer cars and trucks. Not for the max rated amperage. More for the higher amperage at engine idle speed. My 2001 Dodge Caravan has a Denso 150 amp alternator and can charge at 55 amps at engine idle speed. It has NO practical use for that 150 amp max rating but does need those high amps at engine idle. There are many alternators designed to have more output at low speeds then the OEM Densos on Toyotas. Delco CS-144 is one of them and a popular swap into a Toyota. That is NOT what you'll more often find though when looking for Delco alternator kits for Toyotas. Most of the kits I've seen have 10SI alternators that don't put out much more then an OEM Denso. A Toyota with a V-belt drive is quite limited to what you can use. A Delco CS-144 is one of what regard as the "best" swaps if you want more charge at low engine speeds. It is rated at 120 amps max and the single V-belt cannot not spin that alternator at that full load. Likely you'll never need it though. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 5, 2015 Author Share Posted July 5, 2015 Are there any direct replacement high output alternators rather than something that has to be modified or customized? I'm kind of limited in tools for modification as we are staying with my in-laws currently. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 5, 2015 Author Share Posted July 5, 2015 Also, what year range can I look at? I see several 95-110 amp alternators for 1985 and newer. Will these fit my 1981 22r 4spd? Quote Link to comment Share on other sites More sharing options...
zero Posted July 5, 2015 Share Posted July 5, 2015 Also, what year range can I look at? I see several 95-110 amp alternators for 1985 and newer. Will these fit my 1981 22r 4spd? Quote Link to comment Share on other sites More sharing options...
zero Posted July 5, 2015 Share Posted July 5, 2015 None that I know of for alternators with external regulators. Late 80s alternators from supras are often used as bolt in upgrades but only for systems with built in regulators. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 5, 2015 Share Posted July 5, 2015 Here in lies the rub in life. One is often limited in what can be done by what one can do. The remedy sometimes for that is being able to afford someone else who can do it. When forced into situations where neither of those are an option, the choice is to make due with what is the best that you can do. I've an engineering mindset but that can only sometime be helpful in a case of determining what is possible. I readily admit to being less than useful in some of the practical parts of the equation. Like what part will fit. As an engineer, my approach is to ask what is the product I want to use and how do I make it work? I have a rig with no AC. If I wanted to set it up the way you want, my approach would likely be to take out the compressor and fabricate a mount for my alternator of choice. I have tools, some skills and the means. I have a small shop to work out of that includes welding and even an old Atlas metal lathe that I've set up with modern tooling. I can measure it out and draw it up in Cad. I can either locate or have fabricated a dual pulley that uses the groove for both the existing alternator and double that up with the AC groove. As a do it yourself guy, I often take it to the extremes. For me the Cad skill is among the handiest. In the absence of doing some of the work, I can draw it up and send the files off to a shop that will fabricate it. All it takes is money. My industrial years taught me some valuable skills even if I don't spend much time these days applying them. Lest anyone begin to accuse this post of being overly harsh. You indicate you are of a stubborn nature. Often in life that rules out. Necessity being the mother of invention and all that. Whatever it takes to move the rock up that hill. This thread includes a lot of information and advice. At some point it is up to you to figure out how you are going to use it and make due the best you can with both what you can afford and do. My theoretical advice is just that. The guy who makes it work is king. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 5, 2015 Share Posted July 5, 2015 Alternator charts don't help much in "real world" situations because of all the variables with pulley sizes, internal wiring, etc. As you probably are already aware, engineers have a great deal of difficulty reconciling with the "real world". The often used phrase is apt, hey, it works on paper. I kid more than just a bit. As an old engineer, I am decidedly math averse. I have software with formula's programmed into it to do so much of my work these days. I'll be replaced by a computer if they ever give them ears and the ability to discern what actually sounds good. The calculation on power transfer and loss via a belt and pulley is one that no doubt would hurt my head. I did have a really odd ball idea that cropped into my head as I was reviewing some of this. (I love solving puzzles). I was reading something where they were doing the calculus of how much horse power to drive an alternator. I was kind of surprised at how little it was. The math someone used didn't calculate losses but the figure came out as less than two hp for a fair amount of amperage. As our friend from Maine says, don't need a 130hp generator. These guys were wanting to set up a alternator on a small engine and the discussion involved the calculus of just that, converting power generation output to HP required. As a electronics guy, I've no love for AC power. First thing we do to it is convert it to DC to make it useful for our ends. So I'm pro DC unless I really want to make something big like my compressor work. You, more than most, seem to have this worked out pretty well. So why not a DC generator rather than AC? An old lawn mower and a single wire high amp alternator with some sort of plug into the RV battery. Transfer station here seems littered with old mowers. A guy down the street collects some of the nicer ones and fixes them up. Says often times a plug and a blade are all they need and many start right up with very little effort. Air conditioning aside, as a boondocking solution, would this have merit as a back up to solar? It'd be cheap and pretty light and fuel consumption should be less than running the rig engine. Probably less than an AC generator which I've no need for. Perhaps others are like minded. Thoughts? Edited: Looked it up. Calculates out at 1.6hp at 100 amps without mechanical and generation losses. Quote Link to comment Share on other sites More sharing options...
linda s Posted July 5, 2015 Share Posted July 5, 2015 I know a place that sells high amp alternators for your 81 rig but by the time your done it would have cost more than a brand new refrigerator and then you wouldn't need it. Ya know a small generator, 1000wts, would charge your battery just fine. Won't run a roof AC unit though Linda S Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 5, 2015 Share Posted July 5, 2015 I know a place that sells high amp alternators for your 81 rig but by the time your done it would have cost more than a brand new refrigerator and then you wouldn't need it. Ya know a small generator, 1000wts, would charge your battery just fine. Won't run a roof AC unit though Linda S My posts of late are very much in the vein of thought exercises as I am bored not having any work to apply my energies to. I hate slow periods at work but we get stretches of them. At least this one is during the summer. I know cost was one factor the original poster had but also seems determined to move in a particular direction. Not speculating but have some experience with a niece who lives out in WA who lives off the grid in a cabin and shares a communal space with other like minded folk. Spent the first couple years building the common areas. No electricity or refrigeration. Did a lot of reading by lamp at night in her tiny shed sized cabin. It is a lifestyle choice and she is doggedly stubborn about how everything gets approached. They now have power and more people. Not my thing but hey they are happy with their lives. Economics on this one defy logic so I am only adding some technical information as I understand it and let others chime in on some of the practical. Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 As a electronics guy, I've no love for AC power. Edited: Looked it up. Calculates out at 1.6hp at 100 amps without mechanical and generation losses. All our electricity made in our RVs comes from rotation and magnets and that always begins as AC power. So, kind of hard to avoid it. DC is more-or-less derived from the alternating current. AC has the benefit of not arcing and burning switch contacts like DC does. It takes approx. one horsepower (from a gas or diesel engine) to make 40 amps of charge current @ 14 volts. Back to Toyotas and alternators. Toyota uses a 5 7/8" crank pulley driving a 2 3/4" alternator pulley. I.e. a 2.1 to 1 ratio. When the engine idles at 800 RPM, the alternator spins at 1700 RPM. If the engine idles at 1000 RPM, the alternator spins at 2100 RPM. Just about all alternators must spin at least 1600 RPM to do anything. A stock Denso 45 or 60 amp alternator with stock pulleys makes around 25 amps with the engine idling @ 800 RPM. Here are some alternators that do better. The Delco 10SI often sold in Toyota "upgrade" kits barely does more then the stock Denso. But a CS-144 easily makes 75 amps at engine idle speed. At 1600 shaft RPM – Delco 10SI = 23 amps, 12SI= 30 amps, 15SI = 40 amps. 17 SI = 50 amps, CS-144 = 75 amps (140 amp model) Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 6, 2015 Share Posted July 6, 2015 All our electricity made in our RVs comes from rotation and magnets and that always begins as AC power. So, kind of hard to avoid it. DC is more-or-less derived from the alternating current. AC has the benefit of not arcing and burning switch contacts like DC does. Yes I get that. Hence the name alternator. There is a series of rectifier diodes to make it DC. It was kind of a joke that didn't land. Point was many everyday devices we use today run off of DC. The TV, computer, printer, radio, stereo. You know, the important stuff (insert uncomfortable laughter). In my RV, I have little that runs off of AC except the toaster oven and microwave. I can live without the microwave (it doesn't get used already) and suppose I can use one of those stove top things to make my toast. From there it is all DC. So supposed I wanted to set up an RV for getting away from it all? If I am running on batteries, why not build a DC generator rather than go with an AC one to supplement solar which the top of the RV would have little space for? With batteries as a buffer and the ability to produce some decent current, coupled with a decent sized inverter wouldn't even a 5k btu household air conditioner be possible for those who want to go that route? I mean at the cost of running a gas motor but that is what many do now. I'm just intrigued by the question and wonder where the holes are. Your thoughts? Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 6, 2015 Share Posted July 6, 2015 Poking around the web got part of the answer. Found some that are building DC power units. First one was a guy who said they used to build these for their drag racers to charge the batteries and give them a boost for starting at the track. The drag racer motors wouldn't have alternators installed. The other was some non-RV off grid types who build them to supplement their solar when they have extended weather sun blockage. The advantage seems to be cheap. Old lawn mower and a junk yard alternator pull. I might have to try this. Mechanical isolation I can come up with. Now does anyone know how to calculate back pressure for a muffler? Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 With batteries as a buffer and the ability to produce some decent current, coupled with a decent sized inverter wouldn't even a 5k btu household air conditioner be possible for those who want to go that route? I mean at the cost of running a gas motor but that is what many do now. I'm just intrigued by the question and wonder where the holes are. Your thoughts? RoadTrek E-Trek. Solar, lots of batteries, no propane, no separate generator. Kind of a neat rig. Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 The advantage seems to be cheap. Old lawn mower and a junk yard alternator pull. I might have to try this. I've built many. A 3-5 horse engine coupled to an automotive alternator makes a great battery-bank "bulk" charger. Just need to build a custom voltage regulator. Used to be very common with off-grid solar users. There were also a few factory-built versions. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 6, 2015 Share Posted July 6, 2015 $90k used to $150K new. Sure, I'll take two. Neat rig indeed. Might need to ask to borrow a couple bucks. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 6, 2015 Share Posted July 6, 2015 I've built many. A 3-5 horse engine coupled to an automotive alternator makes a great battery-bank "bulk" charger. Just need to build a custom voltage regulator. Used to be very common with off-grid solar users. There were also a few factory-built versions. There are a few circuit diagrams for the regulator on the web. I only glanced at them but not much to them. Transistor biased via a zener diode with a couple caps and resistors. Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 $90k used to $150K new. Sure, I'll take two. Neat rig indeed. Might need to ask to borrow a couple bucks. I've never spent more then $3300 in my life for any car, truck, or RV. But it's fun to see some of these newer rigs and what systems might work. I suppose a brand new Toyota RV would be $75K now if they were still made in the USA. The new ones cost a fortune in Europe and Australia. Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 There are a few circuit diagrams for the regulator on the web. I only glanced at them but not much to them. Transistor biased via a zener diode with a couple caps and resistors. This is one I've seen copied and used. Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 6, 2015 Share Posted July 6, 2015 Many years ago everything had DC generators except things like ambulances and fire trucks that used AC generators and huge selenium rectifiers (not real efficient). The DC ones did not charge at idle they needed speed, however by design they could not turn very fast because they had a tendency to sort of self-destruct at high speed because they was no way to contain the winding in the armature. They were heavy, the brushes carried the load and the regulators were a complex network of relays. Along came alternators that made AC and could turn a high speed with the winding contained in the rotating field. In the Case of the Toyota MH the pulley is small so that the alternator could turn fast at idle speed so being over driven the small belt drive is being over taxed at high output and will slip. Generally the high output alternators are driven with a flat belt or in case of earlier high output alternators two belts. There is no reason one could not make a portable alternator DC set up the biggest drawback would be the size and storage issue. 2000 watt generators now (yeah the little open frame one) are cheap like under $200 and are enough to power DC 45 amp on board chargers. Quote Link to comment Share on other sites More sharing options...
zero Posted July 6, 2015 Share Posted July 6, 2015 We've had this discussion before so I'm well aware of your disagreement. Regardless, many cheap AC gensets will not power conventional battery chargers very well. It is a well documented fact. Thus the reason why many off-grid solar users built gas-driven bulk-chargers with automotive alternators and lawn-mower engines. Also the reason why many solar equipment dealers sell higher-end electronic battery chargers that work well on poor AC power like made from cheap portable AC generators. In addition it is also why most companies that sell inverter/charger combos likeTrace/Xantrex/Duracell stopped using conventional battery chargers and are including more sophisticated electronic chargers in the combo units. Generally speaking, the old cast-iron generators used in cars, trucks and tractors mid-60s and back, were a big pain in the a**. Prone to brush problems, and very inefficient for their size since much of the power potential is thrown away and not used. Quote Link to comment Share on other sites More sharing options...
Back East Don Posted July 6, 2015 Share Posted July 6, 2015 My main issue with the idea of using an AC generator is going to be charge rate. Bigger motor, likely more fuel and longer run times. I am also only thinking in terms of supplementing power and not being the main power source. Bulk charge the batteries when needed and let a solar panel top them off. Not so much of a disagreement as a difference in use, approach and philosophy. Quote Link to comment Share on other sites More sharing options...
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