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Old 12-10-2005, 15:13   #1
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High Outpur Alternator vs Wind Generator

I was pondering the difference between a high output alternator and a windgenerator. I wondered after some thought why you'd select an alternator for a sailing boat? Some of the thoughts had in comparing them were as follows:

o Cost. By the time one purchased the external regulators for the alternator the cost between a moderate 400 watt alternator and a say 75-100 amp alternator is comprable.

o Installation. The installation of the alternator is less onerous. Perhaps there are issues if you are changing the footing of the alternator such as when going from a small to a large frame unit.

o Output. I assumed that one would run the high output alternator for 1 hour or so daily to keep the batteries topped up. In that one hour 100 amp unit is going to put out about 1300 watts of usable output. the 400 watt wind generator will have to get something like 4 hours of output within the 24 hour period to equal this output.

o Operating cost. The windgerator seem like it would be MUCH less expensive over its life. There is little operating cost that I could think of. I expect the lives of the two system to be comperable. But, 1 hour of fuel is going to cost me about $2.75. So if I am using both daily, the yearly operating cost of the alternator is going to be around $1000. (I assumed $3.00 per gallon for diesel fuel and 365 day running. My engine consumes about .75 gallon per hour)

o Depreciation cost. I assumed the generators life was Identical. I know there is maintenance and depreciation on the marine engine running the alternator. I am adding about 300 hours per year of run time to my engine. If we assumed a useful life of an engine to be 10,000 hours, that would mean I would be fully depreciated in 30 years. If I take the cost of an engine, say $10,000 and spread the run cost over 30 years, I get about $333 per year of depreciate cost to run the alternator solution.

o Invironmental cost. I am ecologically aware, not a zealot. Seems like the impact of running my engine vs the wind generator on the ecology is almost a no brainer.

o Annoyance factor. I get far more annoyed when people are running their diesel engines around me in an anchorage or marina than ANY noise I have ever heard from ANY wind generator. Noise and the SMELL!!! Phew. Not to mention the danger of CO poisoning from our engines.

o Range. I can run my engines for 116 hours before I have to refill. Not a big issue. That gives me 116 days before I have to refill. But I will be competely empty. Not really that big a factor. Unless of course I want to use my engines to move someplace, that will decrease the fuel available for the alternator.

o Loads. I can run bigger loads from the alternator. Still not enough to run the Scuba compressor, but the microwave is not a problem. Hmmm.... Microwave is not a problem for the wind generator and batteries either???


o Charging while running with the wind. The wind generator has poor output when sailing down wind. Well the alternator has the same problem when SAILING down wind, or upwind, or reaching, or running...


o Charging while there is no wind. That's the gotcha. No wind, no power from wind generator. Well, I wasn't thinking of getting rid of the existing alternator. But, I am going with solar panels to resolve that issue.

o System redundancy. If I run down my batteries, for instance my bilge switch gets stuck . I can still get going by waiting for my wind generator to recharge me! I always have the additional system to provide backup energy!

So, what am I missing???? Why do we spend the money on high output alternators.

Fair winds

Keith
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Old 12-10-2005, 17:04   #2
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A typical 100A Alternator, with a good controller, may put our closer 750 Watt/Hours than the 1300W you assume.

”Charging while there is no wind. That's the gotcha!”
You’re absolutely right - the biggest drawback to a Wind Turbine is the absence of adequate wind - which is exactly one of the attributes of a good anchorage. There are other negative factors to wind generators, including:
valuable space utilization, structural issues, dangerously exposed rotating machinery, noise ...

”System redundancy” is good !!!

Big alternator /cw adjustable controller, Solar panels, Wind/Water generator, Shore power, and Nuclear reactor (or at least Hydrox fuel cell). Spend ‘till you drop - you won’t regret it. I’ve never heard anyone complain of too much power.

You’re not missing much, Kieth - it comes down to a matter of priorities.
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Old 12-10-2005, 17:53   #3
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If you're going to go cruising (with a 12v fridge) you have to have a H.O. Alternator and external smart regulator and, of course, the upgraded wiring that should go with it. After that you can fool with solar panels, a wind generator or portable gas generator. (This is for us little guys who don't have diesel generators) It is not an either/or situation. It's a H.O. alternator plus situation. You'll need a house bank of at least 400 amps. The wind doesn't always blow, the sun doesn't always shine but hopefully, you'll always be able to start your engine.
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Old 12-10-2005, 20:04   #4
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The point is, I disagree. You don't need an HO alternator. See above.

We have been cruising for several months and have done without HO. I have a 12v Frigoboat refer and a 12v Frigoboat freezer.

It is really about understanding how much energy you use and having a power source to keep up with that use. My normal alternator puts out 55 amps, high out put is 75 or 100 amps. So, under worse case, I'd have to make up 45 amps. That is easy to do. It is only 45 amp hours. 5 hours of sunlight with a 125 watt panel will replace it. 2 hours of moderate wind will replace it.

So far the wind generator keeps up with all my DC loads. I am not in a high wind area, we do get a blow now and again. I have been in ancorages that have had so much more wind.

But, we'll see after I get the solar panels whether running an engine is necessary to supply the needed power.

Keith
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Old 12-10-2005, 20:45   #5
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Hi Keith, I agree with you 100% and have fitted out Cat Tales the same way. Since you have two engines, you have 2 X 55 Amp/hrs which is already "high output" when you are underway. The additional power needs can be added by wind gen and solar. On our previous boat we had 260 watts of solar and an Air Marine 400 watt wind gen. With that setup, we rarely had to run the diesel for electric power despite 12V fridge, SSB and water maker. On Cat Tales, we installed 330 watts of solar and an Air-X wind gen and we think this will keep us from running the diesels at anchor. The cost of making electricity from the diesels is very high when you factor in reduced engine life, "bad hours" due to light loading of engines, more frequent oil/filter changes, etc. Besides, who wants to add more heat to your cabins in the tropics and listen to the noise?? One thing you might consider, if you haven't done it yet, is to add three stage external voltage regulators to your existing alternators. The 3-stage regs give you a lot more charging power than internal regulators. I started with internal regulators on both my diesels, but I took the alternators to an "auto electric" shop and they modified the wiring for external regulators for $20. each. I added Xantrex 3 stage regulators with temp sensors to throttle back the charge rate if the batts or alternator get too hot.

...break.. what are your cruising plans? We are still in the "boat building" stage, but plan to leave for the Bahamas in January.
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Old 13-10-2005, 03:53   #6
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Keith, if you've only been off the grid for a few months, you don't yet know what you're long-term daily amp loading will be because your cruising lifestyle is still being determined. And since it's now fall, you may also be moving the boat with some regularity, which won't be true each time you 'arrive' in cruising grounds that lure you to stop & smell the roses. Your batteries' efficiency will also drop, over time - another factor folks forget about. I also notice you make assumptions about those 55 A alternators that aren't true, since without 'managed' regulation, they will put out f-a-r less than 55 amps, more on the order of 10A once the engines have run for a few minutes.

I would phrase your fundamental question differently: If I have a windgen, why should I externally regulate my alternator? The answer is that you get far more electrical generation for the same fuel consumption (who could argue with that?) for very little add'l expense. This can be done with your stock alternators, if you wish; crack the case and jump the excitation circuit to outside the frame for connection to a simple regulator. Whether you choose to spend more money on a high-output alternator (which really does produce 75+ A when bulk charging) is a separate decision.

And I concur with Vasco insofar as where most boats that are full-time cruising end up: it becomes a 'HO Alternator, Plus' scenario. As Gord points out, nothing puts more energy into a house bank, more reliably and quickly, than an engine-driven HO Alternator source. Also don't overlook the fact an intermediate cost/benefit choice exists: upgrading to a higher stock alternator. E.g. If your alternators are Hitachis, you can purchase a 90A alternator right off the Parts shelf at a Nissan (or whomever) dealer which is intended for their high-end luxury cars. (Take your Hitachi with you to mate up the form factor). I did this on a previous boat and ended up carrying a spare and charging at a much higher rate with a simple external controller, all for far less than the 'marine' solution. Alternatively, have an auto electric shop build up a HO Alternator for you; I did this for our current boat and the cost was half a typical (e.g. Amptech) marine HO alternator. (Having said that, its performance at near idle speeds is far less than the Amptech I normally rely on. You really do get what you pay for).

Are these options 'necessary'? No...but then neither are most other things with which we load up our boats. It's not the black/white choice you suggest.

Jack
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Old 13-10-2005, 06:27   #7
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Stock set-up

Keith,

Your Hitachis will put out 55 amps (maybe) for about 15 minutes and then fall back to 10 amps or less. If you ever anchor for four or five days you will certainly run your 400amp bank down say 50%. You will then have to run your engine for 20 hours to bring it up to 85%. Believe me it's what happens in the real world. As I think I said in an earlier post in another thread my Powerline HO alternator went on me and I relaced it with the stock 55amp Hitachi for a short period. There was no way this would bring my bank back up. Just do the math. A good resource on these matters is Ample Power. http://www.amplepower.com/
When I started cruising I knew nothing about 12 v management but I did buy the 2 Ample Power books which I would not go anywhere without. On Breathless I have a small case Balmar, a spare Balmar and the stock Hitachi . On La Belle Aurore (which is retired from long term cruising) I have a 15 year old Powerline which has been overhauled a couple of times and the stock Hitachi. You also need an external smart regulator. It is a rare cruiser these days that still has a stock charging set-up. I go through about 70 amps in a 24 hour period, most of this is from the fridge. We have halogen lights and switch one off when we switch another on, my anchor light draws 250 milliamps (homemade from GM sidelight bulb and saltshaker), we always turn the solenoid (1 amp) off when finished with the stove, and use the inverter and microwave sparingly. Microwave draws 90 amps!
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Old 13-10-2005, 07:02   #8
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Rick’s use of only about 70A/H per day is predicated on his careful attention to energy conservation (see his post).
With a refrigerator running, I’d say his performance is excellent - and others might use well over 100A/H per day (always depending upon the major consumer - the refer’).
It’s not uncommon for the refer’ to run 50% of the time (and more), in warmer climes. At about 5A load, this results in a consumption of about/over 60A/H (5A x ½ x 24 Hrs), just for refrigeration.
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Old 13-10-2005, 09:50   #9
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Gord:

Definately agree. I was giving the Alternators 100% efficiency. Definately inaccurate.

I guess I should state that my cruising is in the tropics. I like a "little" wind in the anchorage. Gets too hot otherwise.

I don't quite understand the space issue. It seems like most generators are mounted in space that is not utilized. I must admit, that I am having to mount my SSB antenna on the otherside of the boat though?? Structural issues, agreed. Rotating blades, agreed. I mounted my wind generator just about so I could reach and secure the blades if I had to. I am 6' 4" with long arms! I would have to work at it to accidently get hit by blades. Blades could definately fly off though.

My engine make far more noise than any generator I have heard.

One of my major points is it cost about the same for a wind generator as swapping to a high output alternator. There is little cost trade-off there. So in terms of priority you don't have to make an implementation decision based on $$$'s, perhaps just time.

Greg:

I don't want to use the engines for electrical generation at all. My design objective is to supply my average daily need from a combination of wind and solar. I have to admit, in bringing up the boat from Florida to North Carolina, we used the engine far more than I expected. (Anyone want to hear how much I dislike the intercoastal!) But, we used it so much more that it wasn't a matter of squeezing power from the available time. It was an issue of generating power with no place to use it.

We will be coming back down to Florida in Mid November. We'll head over to the Bahamas and Turks in December. I'd love to finally hook up with you then.



Jack:

Yes; I agree about the 100% efficiency assumptions about alternators. I should have made an assumption of something like 50%. That makes the case for eliminating alternators as a primary source of power all the more compelling. No?

Perhaps the question should have been, should I use my engines as a primary or even secondary electrical generation source? I originally had no wind generator or high output alternator and had to decide what was the appropriate solution to my energy needs. To install my wind generator cost me $800 or so. To get a Balmar 100 amp alternator with 3 step regulator was going to cost me $800 or so. Initially I did not realize the HO alternator was so expensive. That caused me to do the aforementioned analysis. That led to the conclussion that using my $10,000 engines to do something I could pay $800 was perhaps, how do I say this, stupid?

But I absolutely agree. Any system that is on board should be optimized. I will look into the external regulation. But, from what I saw initially, the external regulation options seem to run about $300 or so.

I wonder if most cruisers understand it is costing them $80 or more a month to use their alternators for power generation? I am sitting here thinking of this cost, and it seem SO HIGH. Are my figures right???? Probably. I was speaking with the service guy who had pulled the head off the engine in the boat next to me. He said water had somehow got into the engine of the Genset. It was frozen. He estimates it is going to cost $10,000 for a new genset engine! Ouch! They may be able to rebuild the existing engine, but he said that would cost about $7,500. He was going to recommend the $10,000 option. That comes with a 2 year warrenty. the $7,500 only came with 60 days.

How about the fuel cost figures? I assumed about .75 gallons per hour. How does that compare? If it is .5 gallons per hour and you run 1 hour per day, in 30 days that's 15 gallons. At $3 per gallon that is only $45 per month. Lots better! Only $547 in fuel cost per year.

So the point is, do most cruisers think it through, or are we just falling on the train like some others? I am trying to understand what I am missing? Why is not black or white? What criteria makes the questions fuzzy? The only undetermined variable I can see is the amount of wind available for energy generation. One can get x amount of energy by running an engine/alternator for n hours in a 24 hour period. Can one get x amount of energy from the wind in the same 24 hours? If one can get x amount of energy from the wind solution, are there safety? space? or structural issues? that mitigate the decision. If one can't get x amount of energy from the wind solution, is the cost, fuel, ecology issues worth making other solutions work? So far, I am getting about 4x out of my wind generator. That may change. Could be 6x could be 0x.

Now there are some additional points. I do have a catamaran, so there are some differences. I can put 5 125 watt solar panels above my dinghy davits with no space issues. I don't carry as much fuel as many mono's. Mounting a wind generator is not a space issue. I don't rock a lot at anchorages so, windy areas don't bother me much. Hey, I didn't think this was going to turn into a discussion of the additional merrits of catamarans!

Anyway, gotta run, gotta finish the watermaker install!

Fair winds,

Keith
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Old 13-10-2005, 12:31   #10
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Keith:
”... most generators are mounted in space that is not utilized ...”
Wow - un-utilized space on a boat! What a concept ...
Those Privilege 37's must be a lot bigger that the 42's I’ve worked on.
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Old 13-10-2005, 16:50   #11
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I mounted my wind generator on a pole on the back of the transome. The only thing I put back there is my Dinghy, there is space for a life raft and the name of the boat? As I said, I want to mount my SSB antenna back there too, so I'll have to put it on the other side. I do have about 20 feet or so to play with, but, I can't think of anything else to put in that space. Besides, it is only about 3 inches by 5 inches that I am taking up. The top of the generator does not get in the way of the boom, or sail, or toping lift. I'd really have to work to use the sky up there.

Inside I do have 6 AWG cable routed in the engine room and connecting to my battery distribution panel. There is a total of about 20 feet of cable. I had to make the green one longer because I wanted to tie it directly to my bonding system. Otherwise it is only 6 feet for each of the black and red cables. I did mount a fuse and relay on that panel. But, the fuse and relay can't take up more than 4 square inches or so. There is also a control switch on my nav station. It is about 1.5 x .75 inces. I wouldn't use that space anyway.

Yes, some space, but none of it really usable for anything else I'd have in mind. Far more of an issue is the weight. Didn't weigh it, but I imagine it can't weight more that about 10 gallons of diesel.



PS. I messed up installation of the watermaker and had to reinstall the pumps. For some reason I can't drive the pumps backwards. Fancy that!
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Old 14-10-2005, 10:06   #12
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Discussions on the cost effectiveness of electrical generation options (and claimed self-sufficiency) can go in lots of directions. Because I don't have the time, let me just make a couple of brief follow-up observations:

Keith, your Hitachis are such a poor source of DC battery charging that it's a good thing you aren't counting on them. But OTOH when that approach is someone's goal, it can certainly be effective. On WHOOSH, on the hook but also moving about a bit (e.g. this summer we were in the Spanish Rias, didn't plug in much, and we have a first generation AirMarine wind gen), we ended up running the engine about 20-30 mins/day, beginning on Day #2. The primary reason for this was hot shower water (ocean water temps were 50F). I burn about .5 gals/hr at high idle while heating water & charging at 70+ amps. The HO alternator & external regulator have been in use for 6 years, no repair costs. Factoring in a $60 USD oil change @ 100 hrs but excluding a prorata repowering cost, in a given month on the hook we were spending roughly $2/day to be electrically sufficient...and that's at diesel = $5/gal. I'm not including a repowering cost (or more likely, add'l engine service costs) because that depends on several assumptions that can go lots of different ways, but you can see the cost even so isn't extreme.

Your wind gen vs. HO alternator cost comparison may be valid to your experience but it doesn't need to be like that. First, wind gen (plus tax or shipping) plus cable run plus mount plus breaker & defeat switch...how much did that whole system cost? My guess is perhaps $1200, altho' I'm just guessing... Since we have a Link 2000R aboard, I can monitor wind gen output easily; that $1200 cost will probably bring you, day in/day out over the course of a year, probably 1/3 of your total electrical consumption. I could surely be off on that but I don't think it will err by much.

If you had visited an auto-marine electrical shop with one of your stock Hitachis in hand and asked them to build up a HO alternator of that form factor for you, it would probably have cost you $200-250. (I paid $200 for my 108A hot rated unit, tho' that was a few years ago). You could install that on one of your engines and get a free spare for that $200. To that you will need to add an external regulator; I notice Jack Rabbit Marine offers a 12V Xantrex regulator with lots of onboard intelligence for $187. As you can see, I'm working towards a cost comparison that makes some form of engine-driven HO charging regimen financially reasonable, and certainly less than a wind gen. Couple that with it providing all the electricity you need when you can't get it from anywhere else, and that explains why HO alternators are so popular.

I think you're absolutely right that folks rush right out and buy lots of gedunk for their boats without thinking things thru; that seems to include solar panels (terribly expensive on a watts/day basis) and wind gens, not just alternators. You're thinking all this through thoughtfully, so you're not part of that crowd. Good for you.

I don't mean to suggest you're doing anything wrong; your choices may be just the ticket for you. But there are reasons why so many boats start with a HO alternator...or end up there, after a while.

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Old 14-10-2005, 13:08   #13
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Hitachi alternators; the good, the bad

The bad: The internal regulators have a negative temperature coefficient that tapers off the output current well before any excessive temperature build-up occurs internally. The regulator actually attempts to control the internal ac, not the external dc output. As a result, the greater the dc output current the lower the dc output voltage due to the diode drops not being compensated for. The overall net effect is a very conservative operation which works fine to recharge a start battery and maintain the engine "electrics" during operation. Performance in recharging deeply discharged batteries is not merely poor, it is unacceptable.

The good: With the internal diode "trio" and regulator disconnected, with one field wire internally connected to the negative output ("ground") and the other field wire brought externally for external "P-type" regulation the Hitachi alternators can be operated at 113% of their "nominal" values with good results. Yanmar documentation is very good to reveal to any competent electrical person how to perfom the operation. As mentioned earlier in this thread it is a boon to use a good regulator having an alternator temperature sensor (like Balmar) if YOUR batteries pull sufficient current for sufficient time so as to drive operation towards excessive heating, otherwise a non-temperature sensor regulator is fine. By "upgrading" to an 80 A Hitachi you can get slightly more than 90A, the limit that I consider will give you reasonable single-belt life, water pump bearing life, and small-frame efficiency.

The ugly: Keep attention to the belt tension. Too tight and you will prematurely wear the water pump bearings on the shared Yanmar belt. Too loose and you get excessive belt wear and heating on the alternator pulley which transmits to the alternator. Use this test: When the engine is cool and off (my disclaimer for fools) place a rag on the alternator fan and rotate the pulley so that the engine crank rotates (yes, the pulley ratio mechanical advantage will enable you to do this). If the belt slips the tension is too loose. Tighten the pulley JUST so that it doesn't slip with this test and you will be fine. Keep checking the tension over time.
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Old 14-10-2005, 13:16   #14
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Interesting discussion. Cat Tales, my 35 Tobago cat, has 2 Yanmars with 55 amp alternators. They charge the 3 banks of batteries (house plus 2 starter batteries) through a diode block with 2 "in" screws and 3 "out" screws. We ran a little frig with both a 12 volt chiller and a 220 volt cold plate with a dedicated inverter. Other energy needs are rather regular, but we do like our music. Before leaving Canada for the Caribbean last year, I installed a wind generator (Air-X Marine)on the starboard stern.

My 55 amp alternators certainly can put out 55 amps, but only into batteries that need it, and never with both alternators running. I therefore run only one engine when only charging. I have also installed special wiring to ensure the internal regulators put out the extra volt to negate the one lost through the diode block. I did not realize that internal regulators drop output to control the heat of the alternator. That is a significant issue in insulated engine spaces in the Caribbean.

I keep reading about HOA's and smart regulators, but continue to have difficulty understanding their capability. It seems to me that another cause of the reduction of output from my 55 amp alternator has to do with the battery(s)' ability to take and store it; i.e.: friction builds up in the batteries as they approach full charge. I am unsure how a smart regulator overcomes that or deals with the internal heat of an alternator. I'll keep reading until I get it, and the comments written in this thread help. I am not stupid, but even as I became a successful civil engineer, I somehow never fully got over a subconscious feeling that electricity incorporates a fair bit of magic.

I am also aware that the best way to get a battery up to full charge, and to fight the sulphation that comes from constantly undercharged batteries and steals their capacities, is to charge them longer at lower rates (at least when near full charge). That is something that solar panels do fabulously (and I understand a smart regulator can do, but not without burning some diesel). I was considering another windmill for the other stern, but when the wind is blowing, I soon have more energy than I can use, and when it isn't, well, two times nothing is still nothing. I wonder why I see small boats with two wind generators.

I return to Trinidad next Wednesday to continue cruising. Three 123 watt solar panels are waiting for me. These will complement the stock alternators and the wind generator, and make up for the 20 amp DC watermaker (Echo-Tech) that is also waiting for me.

Love to hear your comments.
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Old 14-10-2005, 14:42   #15
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My experience is that alteration of the stock wiring, like modifying the input voltage to the R terminal of the alternator in order to compensate for an external diode, results in unstable ouput at the lower engine rpms and battery voltages. So, I'm interested in just what you have there if you have stable operation.

It is distasteful to tolerate the external diode losses....have you considered using battery combiners instead? Combiners also have advantages when using inverter/charger sources to charge the batteries with ac present as they do not lend themselves at all to the use of diode isolators.

It is not true that low current and long times for recharging deeply discharged batteries are better at recovering lost capacity than using higher currents (which result in faster charging anyway). See some of the history in this section for explanation. What you refer to as "friction builds up in the batteries as they approach full charge..." is called charge acceptance. Charge acceptance is high when deeply discharged and low when approaching full or at full.

If charge currents are too low during the charge accept mode the sulphation will not uniformly reverse chemistry into lead oxide and overall capacity will suffer cycle after cycle. This is not true for all lead-acid battery designs yet is true for the ones which are designed to tolerate deep-discharge with high current loads, such as we cruisers require. One analogy to this phenomenon is to imagine spray painting a wall using low-volume output spray cans versus a commercial sprayer with high paint volume. With the little spray cans you eventually get the wall painted yet it looks terrible in that the paint is very non-uniform over the surface. If you don't have at least a minimum threshold of charge current (proportional to the surface area of all of the plates being charged) the charge process will be non-uniform. That is why it is recommended to have a charge source capable of delivering an acceptance current of over 10% of the Amp-hour rating of the battery being charged.

There IS a benefit to spending as much time as possible in the float mode on a charge source to fully form the final "coat of paint" yet it has been shown that by following the Amp-hour law of charging that a completely dead battery can be fully charged within 3.5 to 4 hours with very little difference after spending a lot of time on float. If low voltage charging is used then it will take a very long time on float to get "full" and, guess what, "full" does not mean that the capacity lost has been recovered it means that the battery exhibits a lack of charge acceptance attendant with a standing voltage indicative of full.
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