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  1. This is between an off-grid project and a mains electrical project. So, I wasn't really sure where I should post it. The Mains, Solar, Wind & Hydroelectric Power forum won. So, it just so happens that I have 3 - 100 watts panels sitting around collecting dust, and not producing a single watt of power. I also have 135 watts panels doing the same. So, I need to come up with a little project for them. Anyway, the 100 watts panels project, for now. I am going to buy a (cheap Chinese made) 6oo watts grid-tied inverter. I will then connect the 3 - 100 watts panels in parallel, directly to the inverter. Then, I will plug the inverter directly into a mains power point (wall receptacle). That will sync with the mains and start pumping up to 300 watts directly into the electric veins of the farm, depending on the amount of sun they receive, of course. This will help alleviate some of the power needed from the mains to run the farm. Anyway, these inverters run between about $82 USD to $120 USD, each. That would buy you a 500 watts, up to a 1000 watts grid-tied inverter. The reason behind powering a 600 watts grid-tied inverter with only 300 watts of panels, is so as not to overdrive it and possibly cause it to fail, catch fire, etc. The last thing you want to do, is to overdrive a cheaply made inverter, or any inverter for that matter. Besides, you can always buy another inverter, and three more panels to connect to it, then plug it into the mains. The second inverter will sync with the first, as well as the mains voltage. Also, when you experience a mains power failure, these inverters will automatically shut down in order to protect anyone who may be working on the cables. You certainly don't want to be responsible for someone getting electrocuted. I know I don't. Once power is restored, they will come on line again. Anyway, as soon as I get around to ordering one of these, and receive it, I will give you good folks an update on this little project. If this works out okay, I will definitely expand the system so as to reduce our power bill even more, each month. SUMMARY: A grid tied system can help you kill your power bill, by back feeding power into the mains. It is as simple as installing an array of solar panels, connecting them to a grid-tied inverter, and connecting the grid-tied inverter to your mains power in your home.
  2. I hope this thread will help you sort out what it may cost you to install a good starter solar array in Cambodia. First, the visual aid. (It always helps to have an idea as to what you will have once it is installed.) Primary parts (most viewable in the image above): 4 each - 100 watts Just Solar panels - $540 ($135 x 4) 1 each - MorningStar ProStar 30m controller - $250 1 each - MNPV4-MC4 Pre-Wired Combiner with fuse holders - $155 (the combiner comes with 15 amp fuses, but 10 ampere rating is what is needed here.) 8 each - Midnite Solar MNFUSE High Voltage Fuses (10 amp) - $25.00 (four to use, and four spares) 2 each - DB Link MANLFH1 Mini ANL Fuse Holder - $12.18 ($6.09 x 2) 1 each - Install Bay MANL50 - 50 Amp Mini ANL Fuses (2 Pack) - $4.95 1 each - Positive Insulated Battery Power Junction Post Block 3/8 Lug X 16 (Red) - $5.49 1 each - Negative Insulated Battery Power Junction Post Block 3/8 Lug X 16 (Black) - $5.49 1 each - 10' (3 meters) grounding rod with clamp - $20.00 USD 2 each - Yuasa EB-130 Deep Cycle flooded batteries - $240 ($120 x 2) Battery maintenance advice webpage 4 each - MC4 Extension Cables (length varies from panels to combiner) MC4 Informational link Subtotal of $1,258.11 - not including the MC4 extension cables needed, for your primary parts. NOTE: If you have a combiner box that is not prewired, you can buy individual cables, double the length you need, and cut them in half. You can then connect the MC4s to the ones coming from the panels, and trim the opposite (cut) ends to wire directly into the panel bus bars / fuse holders / breakers. Electric Materials List (~$100.00): #6 AWG stranded - red #6 AWG stranded - black #6 AWG solid - green #10 AWG stranded - red - if you do not use MC4 extension cables #10 AWG stranded - black- if you do not use MC4 extension cables 20-22 AWG stranded two conductor - red / black or brown / black 3/8" insulated terminals for #6 AWG wire Various mounting hardware Electric tape - red & black Wire wraps / Cable ties (poly) Maintenance Materials List (~$10.00): 1 each - specific gravity tester 6 each - One Liter bottles de-ionized / distilled water Tools List (cost will vary, depending on what you need): Drill motor Drill bits combination wrenches Allen wrenches Wire crimpers Wire strippers Electrical lineman's pliars Side cutter pliars Hand screw driver set Micro screw driver set PV-MS Disconnect Tool Set - $9.00 Meters (~$100.00): Clamp on DC Ammeter Digital multimeter Rough estimate for all materials and parts, if you have your own tools, thus far, is $1,468.11. This is not including the MC4 extension cables needed. Personal Note: While I like the MorningStar controllers I have, I am very disappointed in MorningStar's customer service, especially when ringing them on my dime from half way around the world. They will be the first two, and the last two that I ever purchase from them. From now on, it will be Midnite Solar, Inc., for controllers. Keep the generator and a 20 to 30 ampere battery charger for days when the clouds in the sky are blocking the suns rays from hitting your panels, and you will be cookin' with gas - errrr sun.
  3. Parrothead

    Phase II Solar Complete

    The second panel came in today. Now, the array will be at 270 watts, 24vdc, more than enough to keep my electronics running during power cuts. Actually, I could keep it running 24 / 7 off this system, with no problems. The panel set aside for mounting after arriving at home. The pole mount, prior to the second panel being added. After the second panel was added. New input voltage with 2 - 12vdc, 135 watts panels in series - 27.0vdc.
  4. Well, they were out of 100 watts modules. They, however, had a limited supply (READ: one) of 135 watts modules. So, we got the 1-135 watts panel and headed home. (I needed something to at least temporarily keep a charge on the batteries.) Fortunately, thanks to a friend, I received my Midnite Kid MPPT charge controller. I had been waiting to arrive for four months. Some things are just worth the wait. His wife came over and brought the controller with her, saving me $100 USD in shipping costs. He will be arriving the last part of the month with some other parts, as well. Hopefully, I will pick up another one of these panels by next month. Two in series would be fine to charge a single 120 AH battery. It's a bit more bulky than the 100 watts panels are, at 11.5 Kg. It measures at 1482 mm tall by 676 mm wide. I bought it for $1.30 / watt.
  5. Parrothead

    A pole - for dancin'?

    Nooooo. It's to mount dual 135 watts solar modules on. They will provide the charge to the battery bank that will run my electronics 24 / 7. (They will be set up for 24vdc @ 7.71 amperes.)
  6. Hey Kid, It took me a while to remember to ask local residents what they are paying for power in that area. But, I did finally get that information. I am referring to the question you asked in my Solar Array Project thread: I found out the current rates for that area are 1,300r (Riel) (.325c US) per kilowatt hour. I estimate we will ultimately use about 100 kilowatt hours per month. At that rate, it would take about twenty-six (26) months to recoup my initial investment. This is with no problems, and with nothing having to be replaced, system wide. Of course, the batteries I am currently using may not last two years. If they do not, the current cost of replacement would be $480 USD. This would be for four (4) 130AH deep cycle flooded cells. If this were to happen, an additional fifteen (15) months would be tacked on. Regardless, forty-one (41) months for a system to start "earning its keep", is not a bad return on investment.
  7. Power cuts? Brownouts? Mains interruptions of any kind? No worries. You can still have lighting around the outside perimeter of your home / property. We do. I bought three (3) 12vdc, 10 watts flood lamps off eBay, late last year. They cost a little over $10.00 each, shipped. Three of them together only draw 2.5 amperes. Taking their compact size into consideration, they actually light up a decent sized area of the property. Installing them, along with a controller that will automatically switch the lights on and off, is a dream. Basically, set it and forget it. Below is a 20amp version of the (10 amp) controller I have. They are offered in both 10 and 20 amp ratings, as well as for both 12v and 24v applications. (20 amperes at 24vdc, would be a LOT of exterior lighting, especially if using LEDs.) The jumper on the last two terminals lets the controller know if the batteries are sealed or flooded lead acid. You remove the jumper for flooded batteries, and leave it in place for sealed batteries. By turning the dial on the right side of the controller (using a small flat blade screwdriver), you will determine the on-off or on-off-on operation of the load (lighting) circuit. There is a distinctive "click" between setting positions. Do note that it takes a couple / few days for the controller to "learn" dawn and dusk times. But, once that is set, it automatically adjusts, daily. NOTE: Days of autonomy will depend on how many watts your lighting is, and how many hours per night you have the lighting switched on.
  8. I won an auction today, one I didn't expect to win. Honestly, I had second thoughts about even attempting it. Money is a tight with what we are putting into the farm. But, I figured if I could keep it under $160 USD, I would give it shot. I just remained apprehensive about getting it, because most on auction sites are more costly than the figure I set as my maximum bid. But, sometimes, you get surprised - you win. I did today. It's a 1,500 watts continuous, 3,000 watts intermittent, 12vdc to 220vac, 50hz, soft start pure sine wave voltage inverter. Chinese made, but most are nowadays. Will see how well this one holds up. Besides, I won't be maxing it out anyway - far from it. I figure 500 watts will be the maximum draw this ol' boy will see for some time to come. Anyway, I won the auction at $156 USD, including shipping, to Cambodia. If you have the option, you will be much better off running a pure sine wave inverter, rather than a modified sine wave inverter. Electric motors, especially aren't crazy about Modified Sine Wave power. They run much more efficiently, and are better for running your appliances. For the record, the most recent prices I got, from a Chinese company nonetheless, are as follows: 1,500 watts - MSW - plus shipping : USD118.30 + USD 53.70 (DHL) = USD172.00 2,000 watts - MSW - plus shipping: USD127.20 + USD 58.80 (DHL) = USD186.00 1,500 watts - PSW - plus shipping : USD193.00 + USD110.00 (DHL) = USD303.00 2,000 watts - PSW - plus shipping: USD221.00 + USD115.00 (DHL) = USD336.00
  9. During my first trip to Battambang, the first week of this month, we sat down with a representative from Khmer Solar. We spoke for a while, and let her know what we wanted installed, concerning our solar array at the farm house. At that time, she seemed fairly knowledgeable about solar power in general. I felt comfortable enough. So, we laid sthe deposit down on the table, and asked her for an official quote on company letterhead, as well as a receipt for the deposit. Stupid me - I would later learn. I should have asked her a few more questions prior to paying the deposit. For example, she should have been queried concerning the difference between PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking) controllers. We ended up going with a PWM controller, well - because it was the ONLY type they had available. Got to love limited choices when trying to set up a tailored solar solar array at your home. Do a lot of research on any solar installation company in Cambodia, prior to doing business with them. By the way, if you are interested, the differences between PWM and MPPT is explained in the following PDF document: Trad-PWM-vs-TrakStar-MPPT-April-2013.pdf The first part of October is well into the rainy season, here in Cambodia. Little did I know, we had arrived in Battambang just before one of the worst monsoons in the past few decades. Knowing my luck, I should have guessed that one the minute the rains started to come down. So, we ended up heading home later that week (after 8 days in the hotel), due to the major flooding caused by the heavy rains that Cambodia was experiencing at the time. Nothing was completed during that trip, with the exception of purchasing the rain water harvesting project parts. That was a shame, really. Lots of water we could have stored, was simply lost. That's okay. Next rainy season we will be cookin' with gas! Fast forward to the third week of October. On Monday, the 14th, we headed back up to Battambang. This time, we decided to do it with a one night layover in Phnom Penh. The next morning, Tuesday the 15th, we headed on to our destination city - in a no-so-comfortable, seven (7) grueling hours ride. Fortunately, the hotel in Battambang was comfortable, as usual. After getting refreshed, we dropped by Khmer Solar's office, and scheduled the installers to show up Wednesday morning, 9am sharp. Yes, Paul, hold your breath for that one. We woke before day light on Wednesday, had breakfast, and off to the farm we went. At 7am, the representative rang us, letting us know the installers would not arrive until 9am. I informed her that we were there waiting, and they needed to get on the ball and get their asses up there. Time to throw a wrench in your plan for the day. Sure enough, about 9:30am, Khmer Solar rang up again, letting us know the installers would not arrive until about 11am. I was not a happy camper, as they didn't have an excuse for being more than two hours later than previously agreed upon. This company was not looking good, in my eyes. Hindsight, people. Hindsight. About 11:00am, they had not arrived. So, we decided to head out to Highway 57, a good 5 kilometers away, to meet them and show them how to get to the farm. (I didn't want any further delays.) We waited along the highway about fifteen minutes before they rang us, letting us know they were 10 kilometers away. They finally arrived to meet us at 11:35am. We led the way back to the house, with them following along. Arriving at the property, we, that was me and most of the male family members, as well as Chan, filled our hands with "solar stuff" and headed toward the house with it all. (Bear in mind, there is a dyke, a not-so-small dyke (about 20 meters across), between the road and the farm property. We had to cross it, and part of the perimeter of a rice field, to get to the farm house. Talk about rural living. Green Acres ain't got anything on us! FINALLY! Everything was there and ready to be installed - except the damned installers. They were out by their car, hood (bonnet) popped up, and using a voltage inverter and power tools to cut up some angle iron, which appeared to be 1" x 1", or perhaps 1.5" by 1.5". (They apparently, had been constructing the bracket to which the panels would be mounted.) A while later, they finally crossed the dyke, and with the balance of the parts in hand - the frame, a ladder, and one solar panel. By now, we were bumping on 2pm. Needless to say, I was definitely NOT happy with these people. I mean, Khmer Time is fine for most things. However, when it comes to work engagement, especially after you have agreed to a specific time, that is just rude and disrespectful as hell to your customer. Not to mention the money we were paying these guys to get this done - $110 USD, just in labor and deliver fees! They were not worth 10% of that! It gets worse. Once inside, one installer, the one in charge, began taking out his little handy dandy combination wrench, and started tightening down the already tightened (snug, as they should be, by me!) battery terminal bolts on one of my batteries! The fecker thought he was Arnold Schwarzenegger. Bear in mind, these are battery terminals that were ALREADY torqued to appropriate specifications. It doesn't take a rocket scientist to determine what a half turn past snug means. I immediately stopped him from continuing on, and hollered for Chan to come into the house to translate for me. She was some distance away from the house. So, I had to get my big boy voice out to get her to go there - fast - before I ended up killin' this guy and burying him in the rice field! Basically, and I am sure, by using much nicer words than I had, she convinced him to leave my batteries alone, get out of the house, and climb his happy arse on the roof to start the panel install. I later found out that the installer had told Chan that the batteries would not charge properly, unless the terminals were "tight". Well, apparently, his idea of "tight" was measured in inch-tons of pressure, not foot-pounds. The idiot. After I saved the batteries from being tightened into oblivion and ruined, I grabbed the charge controller, a MorningStar ProStar 30m (with meter) and began installing it. Khmer Solar was very limited in their stocks, having only one other controller on hand. It was also a PWM. So, I chose, what I felt to be, the best option - the ProStar 30. The meter on the ProStar 30 rotates reading Battery Bank Voltage (the voltage at the batteries), PV Amperes (charging amperes from the panels), and Load Amperes (what your circuits are drawing from the batteries), continuously. Below, you can see the controller is showing the panels are charging the batteries at 13.8vdc, and in the second image, charging at a rate of 10.1 amperes. If you are interested in a rural project similar to ours, and want a decent controller that is fairly reasonably priced and packed with features, I can recommend the MorningStar ProStar 30M Charge Controller. I would recommend buying one from the states, though, as you can import one cheaper than you can buy one locally. Here is information you may find beneficial about this particular unit: PS2.IOM.English.EN.021.pdf PSdatasheet.pdf Now, to keep this story from getting much longer - yeah, I know, too late for that, Paul. Well, the bottom line here is, everything these guys worked on ended up shotty. I wish I could have taken a photo of the bracket they mounted the panels to. (EDIT: I have since purchased a camera and taken images. A photo of the controller and one of the controller and current combiner box is above. A photo of the (installed) bracket is below this paragraph.) Oh, yeah, the panels. They cut the FACTORY INSTALLED MC4 plugs off brand new PV panels so the installer could junction the wires on the panels. This was done rather than buying the proper MC extension cables to add length for the wires to the combiner box. There goes the 20 year warranty on three PV panels. Oh, when they mounted the bracket and panels, they didn't bother to see what angle the roof was at, which would determine the proper elevation (just under 13.00 degrees) for the panels. (I have an azimuth / elevation gauge I will take back with me, to make sure the elevation is correct.) I am glad I changed the setting on the controller to lead acid (flooded) batteries. (There are three settings, depending upon which type of battery you will be using for the array.) The installer didn't even bother to check it to make sure it was on the appropriate setting, when he connected it! To top it all off, they didn't finish the install until that evening - long AFTER sun down. Soooo, we couldn't even check to see how well the panels were performing until the next morning. So, folks, if you are looking for a solar array to be built on your property, definitely, do NOT EVER use Khmer Solar. I cannot believe a professional business could be so shotty. But, they are. As far as I am concerned, the next install / upgrade we do concerning the solar array, will be done entirely by me and Chan's family. An extra $110 USD would buy us a lot of beer for the after install party.
  10. I am continuing with a project I have been researching and wanting to complete for some time. After calculating everything I would need to power, including lighting, I have determined a 300 watts solar array is what I would need to start with. To begin with, the array will be made up of 3 - 100 watts solar panels. I will add additional panels to expand the total array output. I was going to order a single 285 watts Yingli, but recently decided against it due to a couple of reasons. One reason was time constraints. I want to finish this system this up coming week. It would take me about two months to get the panel here. Another reason was no guarantee of the panel being received in good condition. After all that waiting, I could end up with an issue with the panel. Knowing my luck, I figured I would go with the safer option - let the company I buy from replace a non-working panel at his cost, not mine. Not to mention, the local supplier has all the panels I need in stock, and then some. If I want to expand the system, it will be as simple as dropping by his office, picking one up and taking it to the site and installing it in the current array. I will start with four (4) deep cycle batteries, 120 amperes each, on a 12vdc system. I am leaving room for expansion panels as well. I will probably add three to five more panels, over the next several months, as power requirements increase. The batteries are connected as below, to help guarantee equal charging among each battery in the bank: I am going with a MorningStar Solar Controller for the array. The model controller is a Morningstar ProStar-30 (meter version). They have a great reputation among solar power enthusiasts, and from reviews I have read online. Take a look at their 2012-2013 catalog: Morningstar-catalog-2013.pdf UPDATE: Here is their 2013-2014 catalog: 2013-2014-MS-Catalog-Oct-EN-small.pdf I haven't decided on a voltage inverter yet, primarily because I have one already that I can use, until I have decided what to do there. All lighting will be 12vdc. The bulbs will screw into standard lighting sockets. Total cost, a modest $835 USD. I will have a complete 300 watts solar array installed and running, for this cost.
  11. On the way back to the hotel tonight, I began thinking of a business where only one guy seems to be making money in the rural (READ: The yet-to-be powered area) of Battambang. Down the - rather lengthy road where I am working on my projects, and considering there are no mains power lines anywhere along this road, residents are using 12 vdc car and deep cycle batteries to run 12vdc lighting, charging units to power their cell phones, etc., daily. This fellow charges the residents $1.75 per two days, to put these batteries on a charger and build them back up - although I don't think he knows what he is doing. He will put, no joking here, 40 or 50 batteries on a single battery charger. I can only imagine how few amperes are actually getting to these batteries. Then, without checking them, he simply returns the batteries to their owners. This was fine and good, until he made it a point to state that a (new) battery I had was "no good", due to it being old. However, when first used in an unpowered area, this same battery lasted more than a week, providing all the family needed. Not to mention, I had fully charged that very same battery for a week, prior to load testing it myself. So, I call BULLSHIT on that, without a second thought. So, I took one of my battery chargers along for a trip with me to Battambang. Today, after purchasing all the plumbing parts needed for the new Rain Water Harvesting System I designed, I asked the store owner if we could partake of some of his power, for a small, reasonable fee? Sure! He was fine with it, in fact. I will get him to leave it on the charger for three or four days, then take it home and test it again. At least I will personally know the battery was fully charged, prior to returning it to service. Anyway, I am way out on this tangent. Let me reel myself back in a bit. The idea I have is to add a second solar array, completely separated from my primary one I am installing on Tuesday. I will make one that will handle about four (4) batteries at a time, and will completely recharge them. I figure a fee of 2,000r ($.50c US), per day would be a fair rate. Many people who live on that road have batteries. We could do about $60 USD per month, consistently, possibly more. Nothing to sneeze at as a supplemental income for a Cambodian farming family. My total outlay would only be for a single controller and the panel(s) necessary. Perhaps, $400 to $600 USD, total investment?
  12. How to correctly interconnect multiple batteries to form one larger bank. Reprinted by written permission from David Small. www.smartguage.co.uk Two things I have noticed in my (more than) 20 years in this business are that:- A. Many "specialists" simply tell you..... "do it this way, this is the correct way" without ever showing why they consider it to be the correct way, and often it isn't, which is perhaps why they couldn't show you why it is(!) B. Some things have been done for so long, in a certain manner, that it seems they must be the best way of doing it. Otherwise why hasn't another method appeared? Here at SmartGauge Electronics we always show you why one method is better. We don't expect you to take our word for it. We will happily use practical examples, theory, maths or whatever else it takes to show the results of various ways of doing things. Interconnecting multiple batteries to form one larger bank is one case in point. Though in this case, newer methods have emerged over the years. Unfortunatley they still aren't perfect. Here is a diagram showing the old way of interconnecting 4 batteries to form one larger bank. This is a method that we still see in many installations. Method 1 Notice that the connections to the main installation are all taken from one end, i.e. from the end battery. The interconnecting leads will have some resistance. It will be low, but it still exists, and at the level of charge and discharge currents we see in these installations, the resistance will be significant in that it will have a measurable effect. Typically the batteries are linked together with 35mm cable in a good installation (often much smaller in a poor installation). 35mm copper cable has a resistance of around 0.0006 Ohms per metre so the 20cm length between each battery will have a resistance of 0.00012 Ohms. This, admittedly, is close to nothing. But add onto this the 0.0002 Ohms for each connection interface (i.e. cable to crimp, crimp to battery post etc) and we find that the resistance between each battery post is around 0.0015 Ohms. If we draw 100 amps from this battery bank we will effectively be drawing 25 amps from each battery. Or so we think. In actual fact what we find is that more current is drawn from the bottom battery, with the current draw getting progressively less as we get towards the top of the diagram. The effect is greater than would be expected. Whilst this diagram looks simple, the calculation is incredibly difficult to do completely because the internal resistance of the batteries affects the outcome so much. However look at where the load would be connected. It is clear that the power coming from the bottom battery only has to travel through the main connection leads. The power from the next battery up has to travel through the same main connection leads but in addition also has to travel through the 2 interconnecting leads to the next battery. The next battery up has to go through 4 sets of interconnecting leads. The top one has to go through 6 sets of interconnecting leads. So the top battery will be providing much less current than the bottom battery. During charging exactly the same thing happens, the bottom battery gets charged with a higher current than the top battery. The result is that the bottom battery is worked harder, discharged harder, charged harder. It fails earlier. The batteries are not being treated equally. Now in all fairness, many people say "but the difference is negligible, the resistances are so small, so the effect will also be small". The problem is that in very low resistance circuits (as we have here) huge differences in current can be produced by tiny variations in battery voltage. I'm not going to produce the calculations here because they really are quite horrific. I actually used a PC based simulator to produce these results because it is simply too time consuming to do them by hand. Battery internal resistance = 0.02 Ohms Interconnecting lead resistance = 0.0015 Ohms per link Total load on batteries = 100 amps The bottom battery provides 35.9 amps of this. The next battery up provides 26.2 amps. The next battery up provides 20.4 amps. The top battery provides 17.8 amps. So the bottom battery provides over twice the current of the top battery. This is an enormous imbalance between the batteries. The bottom battery is being worked over twice as hard as the top battery. The effects of this are rather complex and do not mean that the life of the bottom battery will be half that of the top battery, because as the bottom battery loses capacity quicker (due to it being worked harder) the other three batteries will start to take more of the load. But the nett effect is that the battery bank, as a whole, ages much quicker than with proper balancing. I have to be honest now and say that when I first did this calculation in about 1990 I completely refused to believe the results. The results seemed so exaggerated. So much so that I wired up a battery bank and did the experiment for real, taking real measurements. The calculations were indeed correct. Method 2 All that has changed in this diagram is that the main feeds to the rest of the installation are now taken from diagonally opposite posts. It is simple to achieve but the difference in the results are truly astounding for such a simple modification. The connecting leads, in fact, everything else in the installation remains identical. Also, it doesn't matter which lead (positive or negative) is moved, Whichever is easiest is the correct one to move. The results of this modification, when compared to the original diagram are shown below. Only that one single connection has been moved. After this simple modification, with the same 100 amp load.... The bottom battery provides 26.7 amps of this. The next battery up provides 23.2 amps. The next battery up provides 23.2 amps. The top battery provides 26.7 amps. This is quite clearly a massive improvement over the first method. The batteries are much closer to being correctly balanced. However they are still not perfectly balanced. How far is it necessary to go to get the matching equal? Well, the better the quality of the batteries, the more important it becomes. The lower the internal resistance of the batteries, the more important it is to get them properly balanced. So that now leaves the question of whether or not there is a wiring method to perfectly balance the batteries. Before getting to that, it should be pointed out that doing the calculation is not actually required in order to arrive at the ultimate interconnection method. I simply did them to show the magnitude of the problem. In order to get a better balancing it is simply necessary to get the number of interconnecting links as close as equal between each battery and the final loads. In the first example the power from the bottom battery passed through no interconnecting links. The top battery passed through 6 links. In the 2nd example (the much improved one), the power from the top and bottom battery both passed through a total of 3 links. That from the middle 2 batteries also both passed through 3 links which begs the question "why were they not therefore perfectly balanced?". The answer is that some of the links have to pass more total current and this therefore increases the voltage drop along their length. And now we get to the correctly wired version where all the batteries are perfectly balanced. All images and text content Copyright 2005, 2013 - SmartGauge Electronics. Reprinted by written permission from David Small.
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