January 17, 20179 yr 5 minutes ago, incagarcilaso said: Yes, and if balancing solves the problem than that's great. I was also trying to find out exactly why this happens, although it now seems that it is not uncommon. If it's just a question of balancing that's find but if it's a bad cell I certainly don't know which one because there are all showing a very similar voltage. It's true that the readings show one or two tenths of a voltage lower across the board on the 12 that are not charging so high, which adds up to the 1.4 volts difference between the two banks. What confused me is why it didn't always show this, only on the last bit of the charge and only if the charging amps were high. Here is a snapshot of what's happening today. Not much voltage input when reaching almost fully charged so the difference between the top and bottom is not so high. But if there was sufficient charge to push them up to the 56.4 bulk charge level the mid-point deviation jumps to 3.5%. About 8 months ago the worst mid-point deviation reading was 2.3%, so they are getting worse. The only fool proof way to find a bad cell would be to log / record each one's voltage and temperature individually over time. And use a hydrometer to measure each battery's "specific gravity". My neighbor's been doing it for years and it helped him weed out bad cells very quickly.
January 17, 20179 yr 12 minutes ago, SilverNodashi said: The only fool proof way to find a bad cell would be to log / record each one's voltage and temperature individually over time. Not true. Bad cell = bad battery so if batteries are fully charged, you can also test each one using a Hawkins Battery tester or similar. Can handle 6v/12v batteries. Take them to a shop or borrow one and do it at home.
January 17, 20179 yr Just now, The Terrible Triplett said: Not true. Bad cell = bad battery so if batteries are fully charged, you can also test each one using a Hawkins Battery tester or similar. Can handle 6v/12v batteries. Take them to a shop or borrow one and do it at home. those testers are very expensive and I don't think the OP wants to load those 2V cells in his car to go test them.
January 17, 20179 yr Just now, SilverNodashi said: those testers are very expensive Nope, I bought one out of pure frustration. Paid R2500 for it. But, you can try and rent one or a supplier buys one and hires it out. Yes, picking a bank apart is a huge story but it is dire straits - there is an issue and if you want to find it quick, like in right now, test them. So for general knowledge and another idea over and above yours, I added my 2cents.
January 17, 20179 yr Just now, The Terrible Triplett said: Nope, I bought one out of pure frustration. Paid R2500 for it. But, you can try and rent one or a supplier buys one and hires it out. Yes, picking a bank apart is a huge story but it is dire straits - there is an issue and if you want to find it quick, like in right now, test them. So for general knowledge and another idea over and above yours, I added my 2cents. which model do you have? and how many Ampere can it test? And what's it's voltage range? The one I looked at was R8k
January 17, 20179 yr Author 2 hours ago, superdiy said: Have you googled yet, I've already posted a link earlier and there are other products available as well. Thanks for the link. Yes I have been trying to find stuff but keep getting two pages on the HA02's (which might work fine) on alibaba and e-bay. I'll have to change search terms as I need more authoritative pages with good detailed descriptions of specs and functions of the balancers so I can find the best ones for my 2V cells.
January 17, 20179 yr Author 2 hours ago, SilverNodashi said: those testers are very expensive and I don't think the OP wants to load those 2V cells in his car to go test them. Yes, this is a problem - each cell weighs in at 110 kilos. I've even got a major job on my hands if I want to try and move cells around between banks. That's why I'd like to know exactly what I need to do, to avoid unnecessary manipulation of the cells.
January 17, 20179 yr Author 2 hours ago, The Terrible Triplett said: Nope, I bought one out of pure frustration. Paid R2500 for it. But, you can try and rent one or a supplier buys one and hires it out. Yes, picking a bank apart is a huge story but it is dire straits - there is an issue and if you want to find it quick, like in right now, test them. So for general knowledge and another idea over and above yours, I added my 2cents. Appreciated. I'll see if I can find a tester to hire, but I still feel out of my depth with diagnosing the exact issue with these batteries and getting hold of the right equipment or strategy to do it.
January 17, 20179 yr Author 2 hours ago, SilverNodashi said: The only fool proof way to find a bad cell would be to log / record each one's voltage and temperature individually over time. And use a hydrometer to measure each battery's "specific gravity". My neighbor's been doing it for years and it helped him weed out bad cells very quickly. Over how much time do you need to take the measurements, approximately? Or is it just until you notice an anomaly?
January 17, 20179 yr The HA02 series of battery equalisers cannot work on 2v cells. Sorry guys. I would think that one should be able to use them over 2 x 2v cells, but I think either Chris or Plonkster must help here! Hi Chris, Yes, 18 pcs HA02 are available, you can check the updated invoice please. The HA02 equalizer cannot work with 2v batteries, the smallest voltage is 2.4V. We are still trying to develop equalizer that can balance 2V battery, I can inform you if there is any updated news. Best regards, Iris
January 17, 20179 yr 7 minutes ago, incagarcilaso said: Over how much time do you need to take the measurements, approximately? Or is it just until you notice an anomaly? I would have measured three or four days. Something like an Arduino could be used to measure each cell's voltage and temperature (it's a lot of wires and DS18B20 temperature sensors) and then see what "anomalies" you get. A Hydrometer cost about R150 (R300? for the nicer ones) and can be used to measure each cell's weight in the morning and afternoon. Write it down on a piece of paper, or Excell spreadsheet and you'll pickup the differences over a couple of days. Number your batteries to make it easy. IF you had to swap them around (i.e. 11 -> 1 and 12 -> 24, for example) you'll be able to pickup of those two batteries charge better. NOW, if the discrepancy is always in the center, it could mean the interconnects are too thin for the ampere you're pushing through. OR, a loose bolt / nut, corrosion, etc When you have some time, take them all off, make sure there's no corrosion (clean with baking soda and hot water + wire brush) and re-tighten them. You should actually feel if one of the bolts are too loose as well.
January 17, 20179 yr 2 hours ago, incagarcilaso said: Yes, and if balancing solves the problem than that's great. I was also trying to find out exactly why this happens, although it now seems that it is not uncommon. If it's just a question of balancing that's find but if it's a bad cell I certainly don't know which one because there are all showing a very similar voltage. It's true that the readings show one or two tenths of a voltage lower across the board on the 12 that are not charging so high, which adds up to the 1.4 volts difference between the two banks. What confused me is why it didn't always show this, only on the last bit of the charge and only if the charging amps were high. Here is a snapshot of what's happening today. Not much voltage input when reaching almost fully charged so the difference between the top and bottom is not so high. But if there was sufficient charge to push them up to the 56.4 bulk charge level the mid-point deviation jumps to 3.5%. About 8 months ago the worst mid-point deviation reading was 2.3%, so they are getting worse. Batteries go out of balance due to small dissimilarities in each cell due to manufacturing, ageing differently, loss of electrolyte. There are probably dozens of reasons. You can treat you batteries with the utmost care and these discrepancies creep in. It is unavoidable. However treat your batteries badly and you accelerate the process. A deviation of 0.7% is the top end of what I would consider acceptable. Anything above 1% for a 48V system is something to be concerned about (2% for a 24V system).
January 17, 20179 yr Of course the balancers can work on 2V cells... well obviously not literally on a cell-by-cell basis but you can group your cells into 12V groups and balance over those. So let's say you balance over groups of 6 (ie you make up your own little 12V batteries internally), and you push the voltage to 56V, or 14V for each group. The balancers now forces each group to be roughly 14V, so imbalances are now restricted to groups of 6 rather than across all 24. In some ways it is a bit like tuning a piano to so-called equal temperament. There is a slight error in tuning which is rather technical and which I don't understand myself, so what tuners do is spread the error so that across the 12 notes making up an octave each note is off just a tad so that the errors adds up and by the time you hit the upper end of the scale you are "back in tune". This has interesting effects, the third always sounds high and the fifth always sounds flat (in equal temperament). Aaaanyway... so the same thing happens if you stick your balancers across groups. When you hit the 6th cell you are "back in tune" and all errors are accounted for inside that 6. Makes it easier to stick a multimeter on individual cells inside the group and check them out. Not sure how the balancers work, I know some of them flash a LED when they bypass, so the high cells should have their LEDs on more of the time than the low cells, which immediately indicates the neighbourhood of the poorer cells. If it turns out that you have a number of poorer cells inhabiting the same group -- measuring the SG with a hydrometer will help here-- you can spread them to other groups. to get things back into balance.
January 18, 20179 yr 9 hours ago, plonkster said: Of course the balancers can work on 2V cells... well obviously not literally on a cell-by-cell basis but you can group your cells into 12V groups and balance over those. I was thinking one could pair cells or have groups of 3 so that the "octave" so to speak was smaller.
January 18, 20179 yr I was thinking one could pair cells or have groups of 3 so that the "octave" so to speak was smaller. Exactly. If the 2.4V number is right, you can go to just two cells in a group, but of course you're going to need at least 3 of those balancers.Sent from my GT-I9195 using Tapatalk
January 18, 20179 yr 2 minutes ago, plonkster said: Exactly. If the 2.4V number is right, you can go to just two cells in a group, but of course you're going to need at least 3 of those balancers. Having spent a small fortune on 2V cells 3 balancers or 7 balancers is not really going to worry.
January 18, 20179 yr 16 hours ago, SilverNodashi said: NOW, if the discrepancy is always in the center, it could mean the interconnects are too thin for the ampere you're pushing through. OR, a loose bolt / nut, corrosion, etc When you have some time, take them all off, make sure there's no corrosion (clean with baking soda and hot water + wire brush) and re-tighten them. You should actually feel if one of the bolts are too loose as well. I think we have covered this enough now, if it is one serial string, as in this case, corrosion, thin interlinks, bad connections etc. etc. will not affect only certain cells in the string. The same amount of current will flow through everything in the string, so if there is a bad connection somewhere and less current flows, that same lower amount of current will flow everywhere in the serial string. He either has a bad cell or two or they are just not balanced (charged to the same state)
January 18, 20179 yr 1 hour ago, superdiy said: will not affect only certain cells in the string. It depends where you're doing the midpoint monitoring of course. In the simple case where I have two batteries with a bad interlink between them, and if we use round numbers just to make the example simple, you might get under load that battery1 is at 12V, battery 2 is at 12V, and there is a 1V drop over the bad linterlink, so the total "string voltage" sits at 25V under charging. Now depending on where you decided to measure the midpoint (on the left or the right of that interlink), it is going to look like one half is at 12V and the other half at 13V. That's a very simplistic case of course, it is certainly true that one bad interlink on this end of the bank is not going to cause strange readings on the other end of the bank. It would strictly affect only that part of the string where the bad link is located.
January 26, 20179 yr Author On 17/1/2017 at 7:51 PM, plonkster said: Of course the balancers can work on 2V cells... well obviously not literally on a cell-by-cell basis but you can group your cells into 12V groups and balance over those. OK, I follow this. So if I get the HA02s that have been mentioned in this thread I can use them on pairs, groups of 3, 4 or 6 batteries? The HA02s will work in this case? If I do this to try and equalize them out and identify the area of the problem cells I can eventually get the whole bank of 24 back into better, even if not perfect, balance? I have looked at available info on the HA02s and it looks like they are primarily designed for balancing 4 x 12V batteries in a 48V system - that is probably the most common system. From what I can make out you can just connect 2 cells and leave the other 2 connections on the HA02 unused without it affecting the way it equalizes, although this is not completely clear (what I have been able to find is that you can leave one connection unused and connect to just 3 cells). I now think I understand that with these, as each one can work with up to 4 cells, I could use 6 to balance the cells in groups of 2, but if I want to fine tune a little less (following that analogy) I can connect each HA02 to, say, the positive and negative over a sequence of 3 cells. Or is it that I can use one HA02 on 4 sets of 2 cells each? But I can't work out if I do that how it will affect the ultimate goal which is to balance the two groups of 12 cells (that is where I have the deviation). Edited January 26, 20179 yr by incagarcilaso Update
January 26, 20179 yr Author On 18/1/2017 at 5:58 AM, plonkster said: Exactly. If the 2.4V number is right, you can go to just two cells in a group, but of course you're going to need at least 3 of those balancers. Sent from my GT-I9195 using Tapatalk So if I work with pairs I suppose I will need 12 balancers?
January 26, 20179 yr Author On 18/1/2017 at 6:02 AM, Chris Hobson said: Having spent a small fortune on 2V cells 3 balancers or 7 balancers is not really going to worry. Exactly! I am trying to find a way to save the investment. When you say 7 balancers is that for working in pairs? Are you thinking of doing one bank of 12 first and then the other? You'll have to be patient, I'm not an electrician.:-)
January 26, 20179 yr Author On 17/1/2017 at 3:11 PM, Chris Rossouw said: The HA02 series of battery equalisers cannot work on 2v cells. Sorry guys. I would think that one should be able to use them over 2 x 2v cells, but I think either Chris or Plonkster must help here! Hi Chris, Yes, 18 pcs HA02 are available, you can check the updated invoice please. The HA02 equalizer cannot work with 2v batteries, the smallest voltage is 2.4V. We are still trying to develop equalizer that can balance 2V battery, I can inform you if there is any updated news. Best regards, Iris Thanks for the update and confirmation Chris.
January 26, 20179 yr Being a cautious sort of guy I would group the 2V cells in groups of 3 to emulate a 6V battery. We assume that 4V will work but it is not it not explicitly stated in the literature. I must admit the instructions must be classified as "Instructions Lite" when you compare them to what Victron produces. When the bank is in better shape Incagarcilaso can stop admiring his 1500 Ah bank and see whether paired batteries will work. So balancer A is connected as such 1st pair of wires on cell No1's positive and battery No3's negative 2nd pair of wires on battery No 4's positive and cell No6's negative 3rd pair of wires on cell No7's positive and cell No9's negative 4th pair of wires on cell No 10's positive and cell No12's negative and balancer B is connected 1st pair of wires on cell No 7's positive and cell No9's negative 2nd pair of wires on cell No 10's positive and cell No12's negative 3rd pair of wires on cell No13's positive and cell No15's negative 4th pair of wires on cell No 16's positive and cell No18's negative and the final balancer C in connected 1st pair of wires on cell No 13's positive and cell No15's negative 2nd pair of wires on cell No 16's positive and cell No18's negative 3rd pair of wires on cell No19's positive and cell No21's negative 4th pair of wires on cell No 21's positive and cell No24's negative After a while and having spent time balancing cells and monitoring during late absorb on can start identifying the weaker cells - the ones with highest voltage under charge and position them in the middle of the bank where there are two balancers acting on each group of cells. It is going to be quite a tall order to balance 1500Ah cells the balancer can shunt 5A but the charging current could be as high as 45A during late absorb. Balance is not going to be achieved easily it is going to take time. I would double up on balancers if you have spares so that on could shunt 10A for cells 1-6 and 19-24. One would be able to shunt 20A for cells 7-18. Edited: Replaced the incorrect term battery with the correct term cell.
January 26, 20179 yr Been reading this with interest. In the back of my mind I keep on wondering why the guys whom are off-grid, only generators as backup, using large Ah banks with 2v cells, who's banks last +-15 years. Why do none of them have balancers, and they do know about them. I know they do keep painstaking records of each cells gravity, and handle it when there is a discrepancy by equalising. Does anyone know if golf cart rental oaks, or forklift operators use balancers? For as per Paul, the forklift batteries are going to last X years, nothing you can do will make a difference. So I'm wondering, based on the above, why is that? Are they missing the finer details or are we going overboard by 0.1-0.5% (pun intended) with no real longterm impact on the expected life of the batteries? What if we are creating a problem in that we under use the batteries by not USING the banks down to +-50% every week, and by that I mean that at least once a week the bank must be full, re-charge every day at 10-15% and equalise regularly every 4 weeks or if there is an imbalance? Are we not creating a "balancing" issue when there are no real long term reward, therefor nitpicking at a 0.5v imbalance on a 48v bank? I would think the only real benchmark would be 2 identical setups, one using the batteries, one carefully nurturing them with balancing to see which bank last the longest ito Ah drawn out of them over their lifespan i.e one lasting 5 years at max Ah usage, the other 8-10 years with min Ah usage = waste of funds. What do you guys think?
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