Parallel Batteries Don't Add part2: When 1+1 = 2.7
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- čas přidán 29. 08. 2024
- In this video series I demonstrate how putting batteries in parallel, or series, results in more than 2x the capacity of just one battery. This is a very poorly understood concept that is not well explained on common internet sources, and this is a demonstration on how that internet lore is misleading.
The affect you're discussing is because you have two batters to draw more current from. As I noticed the recovery voltage wasn't as high as the single one. As you're still only going to get the 100 ah from each battery in parallel before you fall below 10.7 volts for good.
discharge rate directly affect voltage drop. one battery in 130 amp load vs two batteries in 130amp load will have a different voltage drop because the discharge rate of those two batteries is only half of 130 amp, so the discharge rate of those two batteries is only 65 amps each. so try discharge 65 amp in one battery and I think it will last the same as the two batteries discharging 130amp. thanks, sorry for my english
Peukert equation or Peukert curve. Higher discharge reduces capacity of the battery. Mostly due to chemistry and some due to additional heat from overcoming the internal resistance. knurlgnar mentioned the curve. A given battery has it's own curve that has to be developed using multiple rates of discharge and doing the discharge a number of times at each level.
Some time ago I asked the obvious question, ”If 1 + 1 = 2.7, then what does 1 + 1 + 1 equal?” I don’t have 3 lead acid batteries I can parallel, but I ran the test with identical Panasonic NCR18650B li-ion cells, charged to 4.20 volts. I used a Haweel Power Bank, model 4x18650 with cells wired in parallel. The load was a USB powered fan, model HVRA 1-4UMT drawing 650 milliamps. Discharge ended at 3.20 volts. It’s not a perfect experimental setup, but it’s the best I can do. My results were:
1 cell = 217 minutes, 2 cells = 464 minutes, 3 cells = 750 minutes, yielding 1 + 1 = 2.14 and 1 + 1 + 1 = 3.46.
Take it for what it’s worth, probably not much.
Interesting results! Thanks for posting.
In fact, you are a gifted teacher, greatly appreciated!!!
I used 30A because discharge current increases as voltage decreases. By the end the current was well over 30A, so 30A was a good average.
This has important implications for building a boat with electric motors. Thanks.
"Of course, you won't be able to figure out how to make this yourself. It's way too complicated." Hahaha...love that.
This is precisely the reason why I read the ratings on the batteries I purchase and buy enough batteries in parallel to make the load I intend to run fall below the discharge rating stated on the battery. Many of the bigger name brand batteries do tend to put fairly accurate info on the battery capacity label but it really does depend on the quality of the battery.
You're a wise individual! Not many battery purchasers do so.
Great video...
I have obtained quite a few 12 volt UPS batteries that were removed from service due to none use (six months) These have recent date codes of about two years old.
I had thought of making up multiples of ten to create "one" battery. The terminals are of the flag style and while the terminals can accept 10ga wire, coming up with a common bus for them proves to be a challenge.
That is an interesting effect! I am not that familiar with lead acid batteries like those, but am familiar with LiPos and lithium ions, good ones will often have discharge curves for constant current at different C rates, and it is clear that discharging, say, a high capacity lithium ion battery, it will deliver a considerable bit more capacity when discharged at really low rates, and often the capacity will be less than half at the full rated output.
As lithium batteries die, the internal ionic resistance increases exponentially, and if you discharge them to below 3V per cell the high internal resistance starts to become permanent.
+Power Max Once the load is disconnected though, although the voltage will still climb back up, the internal resistance stays largely same, and the batteries do not really recover. But that is when they are connected to the same load again. I was fooled this way with a 3S, 3AH, 30C lithium battery pack for my quadcopter, the unloaded voltage was 12V, so I assumed the pack was mostly charged, but it did not last but 10% of the expected flight times, I thought the battery was damaged from the time I had flown too long and caused the pack to fall to 10.5V unloaded. Though a healthy long charge and I was able to fly 80% of how long when the battery was brand new.
Great choice on the Samlex.
I love batteries! Good job on the video!
It is a mathematical fact: Batteries = happiness
(This identity is only applicable for battery dorks)
***** I got a good deal on the high end of batteries not as good of a deal as you but still much cheaper then retail, they are 135Ah each and our AWESOME!!! should theck em out and you will laugh at my 12 volt generator.
fliping720
Love the 'hokey' 12V generator you have! I attempted to make a 12V generator many years ago out of an old lawnmower and it didn't work out too well. Now I know better and know how to make it work. ;)
@@knurlgnar24 why would you only reply to 1 person... reply and refute the others comments too
@@estmars When I was more active on this channel I would spend at least an hour every day going through comments. I only check them occasionally anymore.
Very informative video. I would like to see what results you will get if you were to connect just the 3 bulbs right away and see how long of amp/hours you will get from a single light load.
So many videos people put the load wires on the same battery. I saw where you put a positive on one battery and a negative on another Period that always seem to make sense to me for some reason, but I don’t know the technical reasons. I’m just about ready to put my batteries in parallel, again thank you for this video. Something tells me you really know your shhhhhhtuff
I often put both leads on the same battery for convenience, service, and physical reality reasons. When the real world doesn't get in the way it's best to put positive on one side and negative on the other. This way the voltage drop to each battery is approximately equal and they drain and charge at the same rate, otherwise the one battery you connected directly to gets stressed more than the ones further down the line.
finally someone who makes the information USABLE
Very interesting ! Can't wait for part III
Knurlgnar...I have a question about a inverter...What watt resistor do you use to bleed the battery off when hooking up a inverter to avoid a large arc? I have a lithium ion battery pack for a cordless drill.. do you recommend charging with a modified or pure sine wave inverter and does it matter? PS.. Love your videos...
Simple. No resistor to bleed it. ( isn't bleeding the battery anyways, it is charging the inverter's capacitor bank. ) Use a proper circuit breaker. Then the arc is properly contained.
Great video. But why did you use 30A in your calculations at 4:29? It should've been 28A!
Both videos were totally awesome! Thank you
Thanks, glad you found them useful!
Outstanding Video. Great explanation.
Since those batteries are so new (as far as # of cycles), you should have waited until they were each cycled maybe 10 times before running this test. Then I suspect 1 + 1 would be something more like 2.2 or 2.3, which is about normal for AGM type batteries.
This is because the internal resistance of the batteries increases as they are depleted.
That is a good one sentence summary. There is much misunderstanding of the subject on the internet.
Great detailed information, where can we buy industrial batteries of the kind you are using in Australia?
Thank you.
Franklin
but isnt this effect load dependent and due in some way to ''internal resistance'' heating/losses, as your effectively increasing the surface area of plate, with the same draw from the same heater, wouldnt a 200ah batter have lasted just as long as the 2 100 ah batterys??? i think it would...
I guess if you paralleled two batteries and used 2 heaters we would not have seen 2.7, but more likely 1.9 due to increased inverter losses
Could it have something to do with the internal resistance of the batteries? Imagine that the internal resistance of the battery as an actual resistor in series with the battery. putting 2x batteries in parallel effectively halves the internal resistance. There is also the resistance of the 2 gauge wire, I would be interested to hear your thoughts.
i know if i over size the load i will not get the correct discharge of the battery so there for in my eyes i have to have more batterys in parallel to supply the power for the load but not going over the c rating of the battery bank to get full usage of the capacity
By letting the battery recover after the 1300-1500 watt load, it seems like it could run that same load for more time. You didn't illustrate this. Generally speaking, when paralleling 2 identical batteries with a fixed (constant) load, you can expect to get about 10% more than double the runtime so 2.2x where 1x is the duration a single battery can run that load. This is well known and published already by major battery manufacturers. For example, a deep cycle battery with a C10 rating of 200Ah should have a C20 rating of about 10% more or about 220 Ah. C10 meaning the 10 hour drain rate and C20 meaning 20 hour drain rate (likely to 1.75vpc (volts per cell)).
One interesting this is if you double the # of identical batteries in parallel but also double the load, the expected run time should remain constant.
Why would these batteries not show the 1+1 is not equal to 2 property of paralleled batteries as well as some other batteries? You said that cheap batteries have terrible quality control so it is possible that this test would have 1+1=2.2 if you had 2 cheap batteries where the quality control of the single battery was bad, thus giving you a bad baseline. It seems like higher quality batteries (as used here) would INCREASE the accuracy of the test. It seems you have it backwards!
This only really applies to Lead Acid. Peukert effect is not really present in Lithium to this degree.
so 2 100ah batteries at a moderate load will give longer run time than 1 200ah ?
If so I need to factor this into my battery buying calculations for my inverter batteries in my van....
Which also begs the question of how charge time is affected....
if you wana run long get a few truck/marine battery. iam going for them there 1100 amps mca with that capacity it will last as just 1 per cycle chain that way i have found charging and discharge is equal if 100 amp in 1 hr is used then to recover 100% you need to charge at 100 amps how ever its never a 100%use of a battery if it where it would be zero volts. and inverters cut out at 10-11volt but yes 1 thing true when volts fall amps go up however when a charge is put in as its drawing off battery even half of drain it will keep volts higher and use less amps same way its done on solar or a cars alternator the wise thing to do is dont let the battery go past 50%drain and use more like 2s or 4s in a loop this way it never runs down and only need to charge half the amps in half the time
The knurlgnar load tester. What other high tech creations do we owe to knurlgnar?
Extremely knowledgeable video will subscribe to this channel now
You keep lowering the load.
What are the ramifications of just putting the higher load on it instead of lowering it?
Tks.
It is clearly demonstrated in the video.
Are you stupid?
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I hope you stocked up on those 100W filament bulbs!
You said that commercial car batteries don't have very good quality control. I'm thinking of replacing my own car battery. Are there any makes that you'd recommend as being better than the other dross? I was considering an Exide battery.
I did stock up on 100W bulbs. Got a whole big box full of 'em. :)
I don't particularly like Exide but some of their top quality batteries are good - same as most other manufacturers. I like the Exide Nascar Extreme for example, but stay away from the lower and middle end Exides and most other brands made by Exide. I prefer batteries made by Johnson Controls myself as they seem to 'drool' less and have better made casings. I've seen many exides that leak around the supposedly sealed seams.
***** Thanks for the prompt reply! The Varta Silver Dynamic is in the same general price range as the Exide I was considering. I take it the Optima batteries are 'overkill' for my needs? They're three times the price!
dalriada842
I would not get an AGM battery for a vehicle unless you have specific needs for one. Flooded is more appropriate for automotive applications unless price is of no consequence.
Price is always of consequence. :(
It looks like a Blue Dynamic EFB then. I need reliability first and foremost, as there is no public transport when I travel to work.
The pros and cons of different battery technologies would make for an interesting video. :)
dalriada842
It would be a good topic for a video - thanks for the suggestion. I have been wanting to make more videos like that but haven't had the time recently. (Or more accurately I've been using my time to do other things)
looking forward to next video
In the minute 11:36 you said that it last one hour and one minute but the the timer shows only 57.3 minutes. Can you explain why ?
When using a too small wire for a high amp load, will this destory the battery? And if it dous ,why?
I recently used a way to smaal calbe bc i mixed up diameter in mm , with surface in mm2 while using the diswasher, the cable completly destroyd itself.
The battery will be fine as long as the battery terminals don't get too hot. The wire will have a bad, and probably its last, day.
@@knurlgnar24 Thank you so much for your responce!
Unfortunatly i have to inform you that the wire died that day, it burned itself in the line of duty. It transformed itself into molten isulated plastic and pieces of carbon from the steel.
Since obviously the wire was very hot, the terminals also where very hot and the battery`s (i think) lost a lot of capacibilty.
so that gives me the opportunity to try to fix them! New project :) :)
um, how do you 61 minutes out of the 57 minutes on the timer?
i kno9w right
time space continuum
1 hour timer
I wondered the same (but trusted him) still, I went back and watched when he started timing
4 digit display, 59 min 59 sec is max
Then starts over, so the 57 shown was 3 seconds short of 1 full cycle (1hr) plus 1 min
Thanks, i guess two batteries in parallel offer twice the current (hence twice the time to run a certain load/device), and reduce the battery effective internal resistance to 1/2 of that of only one similar battery (hence long run time since less power losses within the battery itself). I must say if anyone hooks batteries in parallel, make sure they are already at the same voltage so that there is no rush of current from one to the other.
Thanks for the demo very we'll explained
say knurignar24 .how much was that inverter you got and how much power is it pure sine ?or mod? whos site thks.
Dear knurlgnar24, thanks very much for your interesting videos. I've watched many and find them very informative and helpful.
Regarding this video. I currently have one 125Ah AGM battery that was shipped to me last week and I just ordered another one so I'll have two 125Ah AGM batteries by next week. I want to ask if the benefits you describe in this video work only for parallel linked batteries or will series linked batteries benefit likewise? Is the benefit maximized in parallel connected batteries?
I just purchased a Cotex 1500W Pure Sine Wave 24v inverter, so I'm hoping your described benefits can be achieved in series connections as well as parallel connections. Otherwise I'm going to have two buy two more additional batteries to achieve two parallel banks of 24v battery chained in series. That's going to be costly as these batteries are $250 each.
Thanks again for your interesting and informative -- and often irreverent -- videos. :-)
The exact same effect happens whether the batteries are connected in series or parallel so this video applies to both connection methods. Think of it this way: Either way you are cutting the current in half so the batteries have no knowledge of whether they are connected in series or parallel.
***** Thanks for the explanation. After my previous post, I subsequently watched this series again and I noticed you did mention that this phenomenon worked for series connected battery banks as well.
Why is that Samlex fan going at only 300 watts????
Using 2 "untested" batteries is not a good scientific way to test this multiplication factor. You would have to find 3 of those orange batteries that have about the same individual performance, then do your test.
In reality, paralleling identical batteries should give you 220% of the runtime of a single battery assuming the same load is kept on both banks (the single and the double bank). However, the total Ah of the pair is a simple addition of the individual Ah of each battery. The reason you get the extra 10% is because by paralleling 2 batteries, you get both more efficiency (each battery is working less hard so less energy is lost as heat), and you effectively lowered the load as seen by each battery individually, thus allowing you to "squeeze" a few more Ah out of them.
Also, you didn't finish that final leg of the test at 100 watt (or so) saying that it is bad for the battery to get drained down that low but that is not an accurate statement since the battery is rated at 100Ah at the C/10 rating which is 10 amps which is very close to the load from a 100W light bulb (plus the power needed to run the inverter). You should have finished that last leg of the test.
So this test has 2 significant "mistakes" in it which somewhat invalidates the results. Just because 3 batteries look the same doesn't mean they are the same.
You did illustrate a good point that lowering the load after each segment of the discharge test helps you "squeeze" the last few Ah out of the batteries.
Also, there are some exceptional cases where paralleling 2 identical batteries might NOT get you 220% of the runtime of a single... an example is on an electric scooter where the 2nd battery adds significantly more weight (such as a child driving the scooter and the extra battery adds 15% more total weight such as going from 100 pounds to 115 pounds total). This is especially true if there are hills. In this case, you might only get about 5% more range over the double so maybe 210% total vs. 220% total that was expected.
My thoughts exactly.
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I have the same batteries in my battery bank but they are labelled as super safe SBS not power safe SBS are mine fake or is there a copyright issue between USA and Australia?
Okay, I'll ask the obvious question. If 1+1=2.7, then what does 1+1+1 equal?(
That's a good question maybe 4.1.. at least but since the 2.7 outcome..it should be greater than 4.1.. I was trying to figure that out myself but actually I'm using 9 batteries... So I've got some calculating to do LOL.. or just enjoy having extra time on my BATTERIES.. and more time to sip on a cold one. 🙃haha
@@CJames-gw9xj I only have two deep cycles, but I'm going to try this experiment using three 18650 batteries. I'll report back.
Can two dissimilar Ah capacity batteries (say 80 Ah and 100 Ah batteries) be hooked together, either in series or in parallel, without damaging the batteries of course,?
You might overcharge the lower ah one which can cause problems, It is always better to get the same ah or very close values to be safe because overcharging a battery can be very dangerous.
So two 100ah batteries are better than a single 200ah battery? Tnx!
10:00 22 minutes, not 23 minutes. 12:00 should be 57 / 22 = 2.6 times as long. Why so many errors?
All of this information can be determined from the batteries datasheet.
yes it can, people just don't bother to read it, there is 10x more info in the battery datasheet then in the video. one big point he missed is battery cut voltage with current draw which is a graph in the datasheet. e.g discharging a 12v lead acid battery to 9 volts? all ok, just look at the datasheet
LoL mama always said... When all else fails... Read the darn instructions LOL... And quit hitting your little brother haha that's what mama said anyway..😝
No man no, the thing in batteries is that some times a battery it's not the same as the other even if it's new and the same exactly one, some discharge more rapidly tan others, and some times some have more capacity than others... the chemestry isn't the same exact in any battery, some deteriorate faster even without use.
So will 1+1+1 over 4 and if so can I sell that extra batrery
Cool video, but how does 57.3 on the stopwatch get read as 1 hour and one minute? Greater than 46 minutes, but am I missing something?
57.3 seconds. That particular app rolls over to zero after 1 hour.
***** you don't get that on an iPhone
Another problem with android
***** yeah but i can buy 3 descent android phones for the price of one iphone...
Or you could buy one really nice iPhone and jailbreak it and get the best of both worlds
is the first battery made it run for 39:23 minute/second?
The bank of two did not last 2.7 times longer than a single battery. Your terminology is "whacked".
2.7 times as long or 1.7 times longer is what you meant but you did not say that.
Can it be use for solar set up? Tnx!
You need to let your viewers know that when batteries are hooked in parallel the voltage is the same and the amps are doubled. When the batteries are hooked in series the voltage is doubled and the amps are the same.
The amps are not doubled. The amp-hour capacities are summed (doubled if batteries are the same) - but the current (amps) drawn by the load will be the same.
So that means is best to buy 2 six volts batteries than 1 twelve volts batteries?
That depends on the application and batteries available. Either configuration can work well, but for most deep cycle needs when using common off-the-shelf batteries two 6V batteries are better.
Thanks for you help, love your videos!
Great Video, that's exactly what I meant its nice seeing it done practically.
My next video will be specifically on Peukert's Law and a mildly technical explanation of how it actually works. As you said, this is a demonstration of that effect without the details as to why it is the way it is. Thanks for the comment!
***** off topic but I have a samlex 1500 that I fried trying to hook a wireless remote any chance that I could pay you to fix it for me?
The ? Everyone want to know can you parallel 2 same type 12v lipo battery with different amp in to the Test
This video applies to all batteries including Lithium technologies. Lithium tends to have lower ESR at low charge levels and has less of a Peukert effect, but the exact same effect is still there regardless of battery type.
what's the device are you using for voltage display?
czcams.com/video/5Dp8tr4EhT4/video.html
you maths are way off and as you sais 1 hour somthing when the stop watch said 57 minutes and the 2 batterys parallel the c rating was no longer ten but 20 if you had of drawn power off at 10 amp then you would of got full 100 amp hours so when you went to 2 then the c rating was 20 meaning the battery bank could handle the load better if your bank was large enough that your load matched the c rate then you would get 100 % of capacity
the term youre looking for is Peukert effect.
which would last longer, 24v 100Ah or 12v 200Ah??
The answer depends on many factors but if use the 'all else being equal' qualification then I would reply by saying that they will both last the same amount of time. For example, if we use two identical 12V batteries and connect them either in series or in parallel then they will last the same amount of time.
would the reduced voltage drop in the 24v configuration have a noticeable effect on the system, and perhaps make it last a bit longer?
Bradley Klein
If appropriate cabling is used then voltage won't make a noticeable difference. 12V also has the advantage of having all series cells 'matching' which increases battery lifespan and is easier for battery maintenance. (Unless you can find true 24V batteries) The primary efficiency benefit for 24V will probably be the inverter. 24V inverters tend to be a little more efficient than an equivalent 12V unit.
Sir, thank you very much. I've learn a lot from your demostration.
Very helpful !
Your test is not very accurate since you did not test all 3 batteries solo first to make sure they are the same solo actual Ah capacity. Once you did that , then you could advance to the next step which is paralleling them. You skipped a few steps therefore your results are invalid for the 1+1 (parallel) test. It could be that the 2nd battery solo had more capacity than the first one so it could have been something like 1 +1.3 relatively speaking.
This mite be a dumb question for you geeks so im sorry but the amps thing, 300 watts of light bulbs at 115 volts is about 3 amps AC so why is the inverter drawing 28 amps DC? Do you loose that much converting DC to AC? I'll watch the rest of the video too lol
rappsks Watts = Volts * Amps. At 115V 3 Amps is 115*3 = 345W. At 12V 28 Amps * 12V = 336W. These numbers aren't exact because there are a lot of variables but you can see that the two are similar. Inverters typically lose 10% to 20% of the power in the conversion process.
my walmart 12 v/109 ah deep cycle batteries lasted 3 years and were never even close to 109 ah. maybe at .5 amp load or something crazy like that. they were about $100 each. i looked for the made in china label but did not see it. but the math for its rating was definitely done in china.
Wal-Mart rates there battery at 1amp rather than the standard 20 hour rate, they're saying a 100 amphour battery will last 100 hours on a one amp draw, the standard 20 hour rate is saying at a 5 amp draw your battery will last 20 hours, 5x20 = 100
Just wanted to add I always use the term labelled at rather than rated at
what i will agree on is Peukert's Law does not work and the math to work it out makes no sence
Light wired up in parallel. I'M A GENUINENESS!!!
What's a *_"GENUINENESS" ?_*
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well you better get another inverter and batteries because i do fleamarketing and i live in my van and i run my 1500 watt heater just like the one you used and my one 100 ah battery ran it for two nights and my cobra 3000 watt work just fine so stop blowing smoke people try it for yourself you will see it will run more then an hour off one battery thank you but no thank you
You are misunderstanding something critical here - a 100ah battery only contains about 1kwh of energy so it simply cannot do what you claim.
Nice video. Thanks for making it. I would think that you would not be able to get the full 100 amp hours out of the battery when you start with such big loads. I squared R losses due to internal resistance and the connectors were many times that associated with the rated draw. And even thought the duration of the high I squared R is much less with the high load, that high current really creates a lot of heat.
Very nice demo.
You are doubling the capacity of the batteries but not doubling the load.
This is just the same as halving the load on a single battery.
Of course you're going to be able to pull more out of the battery at half the load.
Sorry, but I'm not impressed.
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That is another way of looking at the same issue. We are saying the same thing here and I should have included this perspective also. Thanks for the feedback!
Why not just look what the load rating is at the 100Ah advertised capacity, duplicate that exact load , and do a fixed load test instead? You are taking something simple and making it more complicated.
Amp it up, and you have all the wrong shit too.
you forgot to include power factor Of Inverter Dear and that's y you got wrong results.