For a sense of the numbers/variation, the table below lists measured values. I think he means effectively isolating each string. That a “slight wrong doing” in any charging or setup procedure shouldn’t cause such a catastrophic failure. The batteries the salesman was pushing were nickel-cadmium. In almost all cases the car starts in the morning and then the battery fails completely that evening (or vice-versa). I suspect that I am missing something here, and that a new battery in an otherwise old set may work itself out in some non-destructive way. But 15% efficiency would be a great improvement over the 0% efficiency Murphy now gets when the sun is shining while his lead batteries are full. What numbers are you looking at? Theoretically, you could connect an infinite number of cells in parallel simply by lining up the cells and connecting all of their positive termin… 15% is actually remarkably food, beating biology (photosynthesis) by a large margin. 4.3 out of 5 stars 40. During most of the ensuing day (Friday, Nov. 23), Battery E/F accepted far less than its fair share of charge. The B-LFP12V 12AH configuration, 13.2V / 12.4Ah, is shown in Figure 2. With a transistor or thyristor type of device, you could for example forbid any loading of the batteries when there is no PV production, or disconnect the batteries that are empty and keep going with the one that are still loaded, or limit the amps going in or out of the batteries. But on the topic of batteries, with a very quick google search I saw some references to remedies for desulfating with epsom salts, but this is likely not your issue. Not sure about this Tom….. Wiring Batteries in Parallel. (Wikipedia). If you feel like spending several times the price of the lead-acid solution, you stand a chance of enjoying a 10 to 15 year battery. Is it scaling? This topology can cope with bad cells far better than the series/parallel configuration. The results are published in the June 26 issue of the journal Nature Communications. As we said earlier, the cells in a battery can also be connected in mixture of both series and parallel. For example you can connect six 6V 100Ah batteries together to give you a 24V 200Ah battery, this is achieved by configuring two strings of four batteries. Parallel Batteries. They only persist in the market because they are cheap(ish) compared with alternatives. Probably easy to find details in search. To avoid the series problem, I could buy two new batteries, but this seems an unfortunate waste of battery F. For all I know, Battery E is an anomaly and I can expect another several years out of the other batteries. November 18 was a partly cloudy day, as seen by the spiky nature in the red (solar input) curve. Remember, electricity flows through a parallel connection just the same as it does in a single battery. my condolences for your loss… The nice thing about NiFe is their extremely long life (some Edison-manufactured batteries from the Twenties are still being used today). This time, after sunset, we see a net transfer of energy from battery C/D into battery E/F (yellow points in negative territory). If Murphy simply had more or bigger batteries (without even approaching the limits of what he could fit in his house), he could avoid ever letting sunlight go to waste. Battery is an electrical element where electrical potential is produced due to chemical reaction. As a CS phd student living a life constantly on the move, I’m both amazed by the battery performance of modern laptops compared to their ancestors and still perpetually upset at their neverending problems. Hi Tom, Once you get past the populist appeals and self-comparisons to Volta, Mendeleev, etc., I thought the talk was interesting although bereft of the kinds of numbers that would make me feel better about the technology–like comparative performance to the “expert” batteries of sodium-sulfur, lead-acid, etc. This can eventually form a sort of unwanted metallic plating on both. But I’ll try to avoid this in the future. Actually when load is connected with the battery, there will be load current flowing through it. I’ve left the system essentially unattended for months while away (though checking remotely), and nothing went off the rails. $7.99 $ 7. Or even none at all. A parallel connection is not meant to allow your batteries to power anything above its standard voltage output, but rather increase the duration for which it could power equipment. A parallel connection between battery cells is a connection where all of the positive terminals of the cells are connected together, and all of the negative terminals are also connected together, but separately from the positive terminals. And the flooded ones, I believe, are the worst of the bunch. With an energy payback time of 3-4 years and a lifetime of 30-40 years, you’re looking at a 10:1 gain (energy returned on energy invested, or EROEI). There’s one thing I wanted to ask about in response to your earlier battery-system post (Blow-by-blow), but didn’t have ready in time. You could enquire of SAFT, as one manufacturer of them. You’ve been able to measure each cell, and identify that only one is failing. I don’t know too much about the subject, but I am surprised that you don’t have any system to control the loading and unloading of the batteries. Simply connect all the negative battery terminals to each other, and all the positive battery terminals to each other. Batteries may consist of a combination of series and parallel connections. But all this with the caveat that I have seen nothing more on it other than a TED talk. normally on smaller systems these are not issues. My controller does equalization. Putting each battery on one of these for 24 hours or longer periodically will desulfate and bring all the cells to very close to the same charge. But then, I simply don’t understand what is the proposed advancement. these batteries have some disadvantages but many more advantages and can and have lasted several decades with minimal maintenance. Just before disconnecting, E and F measured 11.29 and 13.81 V, propped up by batteries C and D (drawing power out of the good batteries). Really. There’s a group at Stanford who are working on Edison Nickel-Iron batteries and are claiming substantial progress using graphene as a substrate. Associated products can be found in the automotive terminals, automotive cable and wiring products and battery shop products sections. If I plot the fraction of juice accepted (blue) and sourced (red) from Battery E/F during 2012, We see the dramatic endgame. They are not reliable. A cobalt-oxide sandwich and a bunch of graphitic carbon acting as electrodes for lithium? The friendly battery salesman assured us that lead-acid batteries would be hopeless. That evening I measured batteries C through F to be 12.33, 12.39, 11.12, and 13.59 V, respectively (both chains must add to the same voltage). If you are doing high voltage charging with the idea of equalizing then that is hard on your battery (creates heat, and gas discharge that can explode). (Supervisory Control and Data Acquisition), Programmable Logic Controllers (PLCs): Basics, Types & Applications, Diode: Definition, Symbol, and Types of Diodes, Thermistor: Definition, Uses & How They Work, Half Wave Rectifier Circuit Diagram & Working Principle, Lenz’s Law of Electromagnetic Induction: Definition & Formula. The failed battery proved itself to be practically useless the following night, and only really started accepting appreciable charge once Battery C/D reached its absorb potential and began refusing current. Whether or not battery repair is possible/effective, I judge it to be a near certainty that the revived battery would be poorly matched to its brethren. Oh, well.). I would confirm if the oscillation is due to clouds or shadowing, otherwise you may have an issue with the solar array as well. Based on cycle depth, I expected another 2.5 years out of the present set of batteries. Terminal voltage of battery is the potential difference across its terminals when the current is being drawn from it. It decided that 10% was enough. And it seemed that if you’re going to make a shipping-container-sized battery, why populate with lots of trays of individual units, each with a lot of material in the metal casing, inefficient use of space, etc.? I’d be curious to see an update to your earlier post about how awesome PV is as a solution, adjusting battery replacement cost to be aligned with your actual experience (whether typical or not). Below is a typical plot of the five-minute resolution data. The total length of the wiring for each battery should be the same. Empirically, I found that my batteries have always behaved as if their capacity was 125 Ah, from day one. This system is called PACER, and the LLNL version of this fusion power plant was designed by Dr. Ralph Moir, who was the senior nuclear designer at the Lawrence Livermore National Laboratory during the years of my career service. We’re running out of time before commenting on this post closes. Best of luck. :-/. One way of acheiving this is to use two steering diodes on each bank. You will need at least four batteries to build this complex configuration. In series, when one battery is in worse condition than its partner, it will sit at a lower voltage in both charging and discharging scenarios. Hydrogen isn’t as easy to store as other forms of chemical energy, but the more useful things you can make with electrolysis (aluminum and alkali metals) require extreme temperatures and are thus obviously infeasible. Why should it be your problem to disconnect the battery? Let me say up front that I am not a battery expert. In this post, I’ll show the metrics on my system detailing the demise of “Battery E.” The gruesome graphics are intended for mature audiences. Am I mistaken? The fresh one would get a higher charge than the old one and that ages the newer one more quickly. I know it’s not cold where you live (and it’s even warmer where I am) but concrete can keep batteries too cold through its thermal mass. In the very least you should get them up onto something insulating so the entire battery can operate at the same temperature from top to bottom. Switching to a single chain of 6 x 6 volt deep cycle batteries to make 36 volts should be sufficient. Given that batteries are usually the biggest expense in a typical system it makes sense to use a good quality charge controller and inverters and load controllers with low-voltage cutouts to protect the batteries. I would bet that a serial only solution would be more robust, especially if you used Not a lot of data out there on them, seem to be only made in China these days but available to buy (while oil stocks last, imagination not included). So a 12 volt battery will have total 6 number of cells connected in series. So, if any one measures the terminal voltage of the load i.e. Tom, if you figure out what happened to the cell, let us know! Looks like your charging rates are kinda high….C/2 to C/3…? We have a 48V battery bank using Deka brand AGM batteries. For example: let’s consider 2 sets of batteries 12-volt 150Ah wired in parallel and put them in series. I’m thinking of telephone system applications where a bank of flooded cells in an air-conditioned room sits waiting for a mains power failure, whereupon they automatically maintain the exchange’s DC bus voltage. At least: from what I understand, we have two orders of magnitude more antimony than lead (good news? But overall discharged current of the battery does not exceed the discharged current of individual cells. I’ve had nothing but trouble with smaller batteries, none of them have lasted even 2.7 years! (I’ll look back at prior blog posts to better visualize the wiring when I have more time. There is series-parallel connected batteries. In a stationary situation, if you want to go with flooded cells then purchase true deep cycle batteries with really “meaty” electrodes. that would be: http://www.zappworks.com for information and pricing. The post on PV efficiency details the curves, but in brief: red is solar input; cyan is the load (refrigerator cycle spikes evident), black is battery voltage (right-hand scale), green is battery state of charge (percent full), and the yellow dots indicate what fraction of battery current is flowing to battery chain E/F. The purpose of parallel connection of lithium batteries is to increase the capacity. Limiting the depth of discharge which in your situation can be done with a low voltage shut off. Batteries A and B are in parallel. A general comment: please, to the extent possible, avoid use of red vs. green as color codes in charts or anything else! At most, I throw about 900 W into the batteries, which comes to about 33 A (into 27 volt charging batt), split between the parallel tracks for about 15 A each. The terms series circuit and parallel circuit are sometimes used, but only the simplest of circuits are entirely one type or the other. Every day, an automated script grabs data off of my solar recording apparatus, and most nights I check the day’s performance. I calculated my average daily cycle depth to be 31%, and from cycle curves, expected 2000 cycles at this depth. I think you would appreciate the quality long after the price has been forgotten! Hi Tom. Let me first recount the status of my battery system as detailed in a post from September of this year. I Love your work hope to more of it as I live at Sea level and I think it is time to move a bit higher but i can’t “Do The Math”. Of course the classical solution of using a resistance wastes power. I don’t think his earlier post was really that PV is that awesome. Now we have to arrange the 15 cells properly for making the electrical connection … We would be better off consuming less, than trying to find a free lunch. A piece of wood is a pretty cheap safeguard. But 995 days after installation, battery E fell off the cliff. Isolating your two battery packs is a really good idea. So what’s the conundrum? Parallel battery terminals are used for connecting multiple batteries together in a series or parallel configuration. If emf of each cell is identical, then the emf of the battery combined by n numbers of cells connected in parallel, is equal to the emf of each cell. To combine batteries in parallel, connect positive to positive and negative to negative as shown in Figure 4 right. Reading your blog it becomes very clear that batteries [stink] big time. If emfof each cell is identical, then the emf of the battery combined by n numbers of cells connected in parallel is equal to the emf of each cell. 22. The parallel problem is that if one chain is weaker than the other chain, a similar phenomenon happens. the 2 or 6 volt batteries Trojan says are optimized for renewable energy. The process of “equalization” is supposed to reduce stratification by bringing the battery to the point of off-gassing and causing the electrolyte to “stir” but as soon as it stops, the ground is going to start to stratify it again. Sunny weather, plenty of time spent in absorb state (battery voltage plateau, while solar utilization scales back to accommodate), loads cranking away doing their thing, and the yellow dots behaving reasonably. My batteries float at 54.4V, or 27.2V for your 24V setup…. Wouldn’t that be a lot safer for the remaining batteries in case of a failure like this? I worked from home the on the 27th and made occasional checks of battery voltages, to learn what I could about the dynamic charge state. Practical D-D fusion that produces net energy – If you stick with AGM or Gel cell construction then you don’t have to worry about a lot of the usual maintenance routines including topping up, equalising (the gassing of which also ensures that the flooded electrolyte is stirred up preventing sulphation), etc. But it does depend on your environment of course. Up to my knowledge, batteries should not be connected in parallel. All the metrics looked great. There’s no way of knowing if it works, but so far so good… http://www.megapulse.net/products.html. (However I think I would remember such a price for quite a while!). No heat, no worries or am I missing something? A colleague and I looked hard at PV this year as we had an awesome deal on some panels but the batteries remain a dissappointment. This voltage is generally referred as electromotive force or emf of battery. Avoiding over charging which is what it sounds like you are doing with your equalizing process. You would send your vehicle out without being completely confident that the endurance would measure up to the previous run. The cells within the panel also relate, with the weakest, or shaded cell dragging the rest down and even potentially killing it’s brothers and sisters in series. In series-parallel batteries combination, one pack of batteries connected in series is joined in parallel with another pack of batteries connected in series. And the solution is to get a really efficient fridge like this… http://damnthematrix.wordpress.com/2009/09/06/heres-a-really-cool-idea/. In our illustration we show two 6V batteries with 225AH wired together. [So what use is a battery you don’t discharge?!] Aside from “de-tuning” a new battery by diluting the electrolyte, so that it matches the old one it will be in series with (just a speculative thought), dropping in a new one and accepting the imbalance seems like the least wasteful option, and your reliable equalizations should prevent any major imbalance from getting out of control. It might be the best option for keeping the rest of your batteries going for their hopeful life. Don’t forget however that you *are* already using the internal resistance to compensate the mismatch and it’s probably not that good for the life-span. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh. I used to work for the chap who sold them to me, he’s been in the solar industry for over 33 years now. But perhaps it is possible to turn an otherwise heavy block of junk into a useful battery again. I’m making some assumptions about the wiring, but the thought is valid even if my assumptions not. I’d differ with the physicist quoted in your last post. I think you’re describing the role of the charge controller. Using 4 6v batteries in series will solve your series/parallel mismatch problems. The resultant internal resistance of the combination is, The current delivered by the battery is the sum of currents delivered by individual … That looses the benefit of the redundancy which has kept you going when one of 4 batteries failed. In the diagram above, we have a battery bank that produces 12 volts and has 20 amp hours. Who knows. More destructively, the repeated and constant chemical reactions inside the battery leave dissolved metal on the cathode and, to a lesser extent, the anode. not knowing much about batteries, I am left to wonder why your parallel/series combination isn’t shorted across the middle? Excessive depth of discharge, undercharging and overcharging all cause significant reduction in battery life. Inertial Confinement Fusion reactors that use a tiny amount of fissile U-233 to reliably create the conditions for Deuterium-Deuterium (D-D) fusion can be built today. Battery E/F was effectively a drain all night. And compared to century-scale challenges like fusion, it’s outstandingly easy. Up to two batteries can be put in parallel. 9 Batteries in … He told me he had a customer who also bought a used set of these batteries of the same age, and they lasted him 21 years…! This is probably not a practical issue. T Plug Parallel Battery Connector Cable Deans Style Parallel Y-Harness For RC LiPo Battery Male and Female Connectors. double the current capacity and the output voltage remains the same as a single battery.
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