|
Post by kris on Mar 7, 2021 13:19:55 GMT
So it was a crimping issue, I managed to tighten the crimp using the final death throes of my handheld hydraulic crimper. It’s dead now, only a cheap Chinese one but still it’s served me well and will need replacing. So anyway I can now charge my batteries with the battery charger. It’s a Sterling pro charger which has a lifepo4 setting, which is 13.8v high charge 13.8v float charge 13.2v maintenance charge. This charger does give the option of custom settings but I don’t know if you can turn the float off. So wondering if I should change them?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 7, 2021 13:33:23 GMT
So it was a crimping issue, I managed to tighten the crimp using the final death throes of my handheld hydraulic crimper. It’s dead now, only a cheap Chinese one but still it’s served me well and will need replacing. So anyway I can now charge my batteries with the battery charger. It’s a Sterling pro charger which has a lifepo4 setting, which is 13.8v high charge 13.8v float charge 13.2v maintenance charge. This charger does give the option of custom settings but I don’t know if you can turn the float off. So wondering if I should change them? Obviously take my advice with a large pinch of salt as I know basically nothing about these issues, but I would take into account whether you'll be cruising for 5 or 6 hours often, or mainly static and running the engine each day just to recharge. If you're cruising lots, then maybe a slightly lower float charge, just so that they dont get held at 13.8v for most of the day? But if they only get an hours engine charge each day then you want to bung in as much charge as you can asap, and they might not even get into the float phase every day. Do you have a lot of solar as well? That could put loads in during the summer- even today I was getting 17 amps- on a bright but slightly cloudy in early March. By June they could be giving me 30 amps for 8 hours of the day, and I'll hardly need to do any engine charging. My approach is to lower the voltage a bit for the second and third charging phases, and then see how it works out for a day or two- but to be fair I havent even had a chance to try it out yet!
|
|
|
Post by Telemachus on Mar 7, 2021 13:52:46 GMT
So it was a crimping issue, I managed to tighten the crimp using the final death throes of my handheld hydraulic crimper. It’s dead now, only a cheap Chinese one but still it’s served me well and will need replacing. So anyway I can now charge my batteries with the battery charger. It’s a Sterling pro charger which has a lifepo4 setting, which is 13.8v high charge 13.8v float charge 13.2v maintenance charge. This charger does give the option of custom settings but I don’t know if you can turn the float off. So wondering if I should change them? I think you will have to suck it and see, but what is to be avoided is holding the batteries up at 13.8v after the current has dropped of below 5% of capacity. At least with the BMV you will be able to see exactly what is going on.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 7, 2021 14:27:42 GMT
So it was a crimping issue, I managed to tighten the crimp using the final death throes of my handheld hydraulic crimper. It’s dead now, only a cheap Chinese one but still it’s served me well and will need replacing. So anyway I can now charge my batteries with the battery charger. It’s a Sterling pro charger which has a lifepo4 setting, which is 13.8v high charge 13.8v float charge 13.2v maintenance charge. This charger does give the option of custom settings but I don’t know if you can turn the float off. So wondering if I should change them? I think you will have to suck it and see, but what is to be avoided is holding the batteries up at 13.8v after the current has dropped of below 5% of capacity. At least with the BMV you will be able to see exactly what is going on. I've watched a couple of youtube videos (which obviously makes me a world authority), and something that struck me was that multi-stage charging is not needed for lithiums, because they are linear in behaviour. Lead acids need their 6 hour trickle charge to do the last 10% of charging, but lithiums dont- and yet the charging profiles all include the three traditional phases. The gist of what I've picked up is this: get the charge into them as quickly as is safe and healthy (too quickly will lower their life expectancy a bit), get them to 80 or 85% SoC, and then just stop. No conditoning, no floating. And when they go below (say) 70%, restart the charging. So during a day's cruise, you would allow a bit of cycling between 70-85% SoC, rather than hold them at a steady 85% all day. In Kris' case they seem to be taking this ON/OFF approach- its noticeable that bulk and float are both 13.8v, and then it drops off to 13.2, which is effectively not charging at all because the batteries will be above 13.2 for hours and hours.
|
|
|
Post by kris on Mar 7, 2021 14:29:17 GMT
So it was a crimping issue, I managed to tighten the crimp using the final death throes of my handheld hydraulic crimper. It’s dead now, only a cheap Chinese one but still it’s served me well and will need replacing. So anyway I can now charge my batteries with the battery charger. It’s a Sterling pro charger which has a lifepo4 setting, which is 13.8v high charge 13.8v float charge 13.2v maintenance charge. This charger does give the option of custom settings but I don’t know if you can turn the float off. So wondering if I should change them? I think you will have to suck it and see, but what is to be avoided is holding the batteries up at 13.8v after the current has dropped of below 5% of capacity. At least with the BMV you will be able to see exactly what is going on. Yes that’s true , the reason l like these Sterling chargers is they have a voltmeter and an amp meter so at least with lead acids I could telll exactly when they where charged. It’s a matter of learning what that looks like for the lifepo4’s.
|
|
|
Post by Telemachus on Mar 7, 2021 15:06:44 GMT
I think you will have to suck it and see, but what is to be avoided is holding the batteries up at 13.8v after the current has dropped of below 5% of capacity. At least with the BMV you will be able to see exactly what is going on. I've watched a couple of youtube videos (which obviously makes me a world authority), and something that struck me was that multi-stage charging is not needed for lithiums, because they are linear in behaviour. Lead acids need their 6 hour trickle charge to do the last 10% of charging, but lithiums dont- and yet the charging profiles all include the three traditional phases. The gist of what I've picked up is this: get the charge into them as quickly as is safe and healthy (too quickly will lower their life expectancy a bit), get them to 80 or 85% SoC, and then just stop. No conditoning, no floating. And when they go below (say) 70%, restart the charging. So during a day's cruise, you would allow a bit of cycling between 70-85% SoC, rather than hold them at a steady 85% all day. In Kris' case they seem to be taking this ON/OFF approach- its noticeable that bulk and float are both 13.8v, and then it drops off to 13.2, which is effectively not charging at all because the batteries will be above 13.2 for hours and hours. The perceived wisdom seems to be CC CV charging, ie 2 stages. But in reality it depends on how fast you are charging them. If you charge at 1C (say 400 amps for a 400Ah battery) then when the voltage gets to your limiting voltage, say 14.4v, there is still 400A going in and if you stop then, the SoC will still be quite low. You need the CV stage (holding the voltage at 14.4 whilst the current decreases) for perhaps 30mins or so to get near 100%SoC. But then, when the current falls to 5% of capacity, it is important to stop charging and not hold the cells at a high voltage. At the other extreme, when I have been charging 4 of my cells (200Ah) at home, using my 5A power supply ie C/40, when the voltage hits 13.8v the cells are at 99% or more and one needs to stop charging immediately. In other words, the voltage reached during charge isn’t a guide to anything unless you factor in the current. In a boating scenario one will be somewhere between these two extremes and the detail will depend on charging current vs capacity. So one solution is to have the on/off solution but of course that is adding cycles to the battery. The solution I’m going for, when we are cruising for a day, is to take the alternator charge voltage down so that it matches the rested voltage of the cells at say 80 or 90% SoC, which is quite a low voltage such as 13.2v. So although you are in theory “floating” them, in practice with zero current flowing into the batteries they have no idea they are being “floated”, meanwhile the charging source can supply any loads arising from the boat’s systems. Matching the alternator voltage to the battery voltage will probably be a bit of a dynamic thing but fortunately the alternator controller will know exactly what is going on - cell voltages, charge current etc - so will be able to adjust its “float voltage” to give zero current in or out of the battery. When we leave the boat in the marina for a long time, there are continuous loads of about 30mA (the Empirbus system and the GSM remote receiver) so I will probably still leave the batteries on “float” but at perhaps 13.1v so the SoC can settle in the mid range. I will need to ensure temperature compensation is turned off on the Combi, it doesn’t have a Li setting so I will probably just have to disconnect the temperature sensor. The Combi does have a “fixed float” setting so it won’t try to do any refresher charges etc that would be desirable for LA.
|
|
|
Post by kris on Mar 7, 2021 15:49:06 GMT
My battery charger does offer an alternative lifepo4’ setting that’s is high charge 14.6v float charge 14.6v and maintenance voltage. I suppose this is the rapid charging setting and the other setting of high charge13.8v float charge 13.8v maintenance 13.2v is a slower charge setting?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 7, 2021 16:58:32 GMT
The perceived wisdom seems to be CC CV charging, ie 2 stages. But in reality it depends on how fast you are charging them. If you charge at 1C (say 400 amps for a 400Ah battery) then when the voltage gets to your limiting voltage, say 14.4v, there is still 400A going in and if you stop then, the SoC will still be quite low. You need the CV stage (holding the voltage at 14.4 whilst the current decreases) for perhaps 30mins or so to get near 100%SoC. But then, when the current falls to 5% of capacity, it is important to stop charging and not hold the cells at a high voltage. At the other extreme, when I have been charging 4 of my cells (200Ah) at home, using my 5A power supply ie C/40, when the voltage hits 13.8v the cells are at 99% or more and one needs to stop charging immediately. In other words, the voltage reached during charge isn’t a guide to anything unless you factor in the current. In a boating scenario one will be somewhere between these two extremes and the detail will depend on charging current vs capacity. So one solution is to have the on/off solution but of course that is adding cycles to the battery. The solution I’m going for, when we are cruising for a day, is to take the alternator charge voltage down so that it matches the rested voltage of the cells at say 80 or 90% SoC, which is quite a low voltage such as 13.2v. So although you are in theory “floating” them, in practice with zero current flowing into the batteries they have no idea they are being “floated”, meanwhile the charging source can supply any loads arising from the boat’s systems. Matching the alternator voltage to the battery voltage will probably be a bit of a dynamic thing but fortunately the alternator controller will know exactly what is going on - cell voltages, charge current etc - so will be able to adjust its “float voltage” to give zero current in or out of the battery. When we leave the boat in the marina for a long time, there are continuous loads of about 30mA (the Empirbus system and the GSM remote receiver) so I will probably still leave the batteries on “float” but at perhaps 13.1v so the SoC can settle in the mid range. I will need to ensure temperature compensation is turned off on the Combi, it doesn’t have a Li setting so I will probably just have to disconnect the temperature sensor. The Combi does have a “fixed float” setting so it won’t try to do any refresher charges etc that would be desirable for LA. Apologies, you've pointed this out a couple of times, but I'd mentally sidelined the link between the charging current level and the rate of increase of the SoC, because in my case the charging current is almost a constant- its usually going to be 40 amps, maybe going up to 50 or 60 on a good solar day. At my level of charge current, I think the batteries are around 80% full when they get to 13.7, and 90% or more at 13.8v. That is a guess, but it seems to be borne out by the fact that the charging current tails off down to 6 amps or less after they go above 13.8v, so my assumption then is that they are nearing 100%. Its very early days, but I'm hoping the approach I'm taking means I dont need to adjust any settings whether its a cruising day or a static day. My goal is that whatever the sun is doing, and however long I run the engine, both solar and engine charging will stop when the batteries get to about 80-90% SoC (or in my case 13.8v), and that the voltage will never get above 13.9v. So that's two important ticks. My next goal will be to manage the SoC so that it doesnt stay at 85% for too long, but I'm still working on the first objectives at the moment. Your plan of lowering the alternator voltage on cruising days sounds great- and if you forget, you'll spot any charging issues on the victron app without going back into the cabin. For me, leaving the boat alone for 2 weeks needs to be thought out.
|
|
|
Post by Telemachus on Mar 7, 2021 17:00:09 GMT
My battery charger does offer an alternative lifepo4’ setting that’s is high charge 14.6v float charge 14.6v and maintenance voltage. I suppose this is the rapid charging setting and the other setting of high charge13.8v float charge 13.8v maintenance 13.2v is a slower charge setting? My view is that Charles Sterling doesn’t know much about Li batteries. Not too surprising really, neither did Mastervolt or Victron when they first started offering (very expensive) drop in Li replacements for LA. I had a look at the pro charge ultra manual, it doesn’t give much of a clue about the charging profiles or the terminology. But 14.6 float or 13.8 float is far too high. But probably Charles’ “float” is every one else’s “absorption” and his “maintenance” is everyone else’s “float”. 13.2 as a float voltage is certainly OK, it just depends how long it takes to get there (ie how long it remains at 13.8 or 14.6 after the battery is fully charged. I think you will just have to experiment but I would be disinclined to let the voltage stay at 14.6 for more than a few minutes once the current has subsided a bit.
|
|
|
Post by kris on Mar 7, 2021 17:12:04 GMT
I agree about Charles Sterling, these battery chargers are the only Sterling product I’ve ever liked. I don’t intend to take my batteries to 14.6v at all if I can help it. But that raises the question of how to synchronise to the bmv. It would be good to have reasonably accurate soc readings.
|
|
|
Post by Telemachus on Mar 7, 2021 18:00:34 GMT
I agree about Charles Sterling, these battery chargers are the only Sterling product I’ve ever liked. I don’t intend to take my batteries to 14.6v at all if I can help it. But that raises the question of how to synchronise to the bmv. It would be good to have reasonably accurate soc readings. It’s not so much about the instantaneous voltage (within reason), it just about the SoC, ie it’s about cramming all the Li ions onto the one electrode. If you hold a Li battery at 13.4v for long enough, it will get to 100%SoC. So actually that reveals an interesting point, perhaps it is better to charge to 100% fairly quickly, ie at a higher voltage, so that overall it spends less time very close to 100%. But anyway it is pretty easy to get very near 100% even at 13.8v, once the current has fallen to perhaps 10% you will be at least 95%. You don’t have to get the BMV to auto-synchronise, you can do it manually by the “synchronise” option on the App, or by manually setting say 95% (again, using the App). So once you have a feel for SoC vs voltage vs current so that you can identify say 95% SoC, you don’t need to go higher, you just manually set the SoC to 95. And probably what you want is consistency, rather than absolute accuracy. If what you thought was 95% turned out to be 90%, does it really matter?
|
|
|
Post by kris on Mar 7, 2021 18:05:46 GMT
That’s interesting about manually setting the soc, I’ll look into that. Now I’ve sorted the battery charger out I’d like to charge them up to maybe 13.8-13.9v which I suppose should be about 80-85%. As you I’ll just have to monitor them and see.
|
|
|
Post by Telemachus on Mar 7, 2021 18:17:33 GMT
That’s interesting about manually setting the soc, I’ll look into that. Now I’ve sorted the battery charger out I’d like to charge them up to maybe 13.8-13.9v which I suppose should be about 80-85%. As you I’ll just have to monitor them and see. I think you need to rethink the concept of relating charge voltage to SoC. If you apply 13.8v to your batteries, they will reach 100% SoC after a while, albeit somewhat slower than if you charged at 14.4v etc. So it is less about what voltage you charge to, more about what current you stop charging at. If you apply 13.8v at a high current, and stop as soon as the voltage reaches that, you will have a much lower SoC than if you apply 13.8v at a low current and stop charging as soon as 13.8v is reached. I can’t remember how much capacity you have but say it’s 400Ah and you are charging at 60A, that is relatively slow and once the battery voltage gets to 13.8v I suspect the SoC will be over 90%. But you will get a better idea of that than me, I am only theorising and relating to my experiences of charging 200Ah at 5A. I found (charging slowly) that once the voltage got to 13.6v there was virtually nothing left, ie SoC at 99%. Very shortly afterwards the voltage would be off up the knee because the batteries couldn’t take any more charge.
|
|
|
Post by kris on Mar 7, 2021 18:31:10 GMT
Yes I understand what you are talking about, which is why I like these battery chargers you see the amps and the voltage. I’ve 1040 amp/hrs but unfortunately only have 60amps of battery charging available at the min. When it’s all set up I plan to get another 120amp battery charger. But not yet, probably after I upgrade the solar.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 7, 2021 18:54:47 GMT
That’s interesting about manually setting the soc, I’ll look into that. Now I’ve sorted the battery charger out I’d like to charge them up to maybe 13.8-13.9v which I suppose should be about 80-85%. As you I’ll just have to monitor them and see. I think you need to rethink the concept of relating charge voltage to SoC. If you apply 13.8v to your batteries, they will reach 100% SoC after a while, albeit somewhat slower than if you charged at 14.4v etc. So it is less about what voltage you charge to, more about what current you stop charging at. If you apply 13.8v at a high current, and stop as soon as the voltage reaches that, you will have a much lower SoC than if you apply 13.8v at a low current and stop charging as soon as 13.8v is reached. I can’t remember how much capacity you have but say it’s 400Ah and you are charging at 60A, that is relatively slow and once the battery voltage gets to 13.8v I suspect the SoC will be over 90%. But you will get a better idea of that than me, I am only theorising and relating to my experiences of charging 200Ah at 5A. I found (charging slowly) that once the voltage got to 13.6v there was virtually nothing left, ie SoC at 99%. Very shortly afterwards the voltage would be off up the knee because the batteries couldn’t take any more charge. Can I ask your opinion on this issue Nick: On most days in the Winter months I wont be cruising (maybe 2 cruising days out of 5), and so on most days I will want to charge to 85% SoC as quickly as my limited setup allows. I am hoping to use the minimum amount of diesel that will deliver an acceptable charge (say 100Ah for a day). I'll normally be charging every day, but sometimes I'll leave it for 2 days and have 200+Ah to put back into the batteries. On many days the charge might be a bit fragmentary- an hour here and there perhaps, depending on whether I have boats close by, or how flat the batteries are first thing in the morning. On work days I dont like having the engine running between 9am and 5pm if possible. With that objective in mind of getting from (say) 50% to 85% with as little diesel used as possible, and within the scenario of snatching an hour here or there to do the charging, is there a case for creating a charging profile for the winter months, with the following characteristics: 1. a higher bulk voltage (say 14.4v) to speed things up (and would the 85% SoC target be reached more quickly than it would be if charging at say 13.8v?) 2. zero time spent at the target voltage, once it has been reached (on my Sterling there is a setting to control that). Bear in mind on most winter days, within the 90 mins engine running, I wont get to the target voltage anyway. 3. Second charge phase is set at 13.7v. The thinking here is that if the batteries have reached 14.2v in the first phase (at my low charge current), they will be brim full, so let them discharge a bit. But (as is more likely) if they havent gotten above 13.7v in the bulk charging phase, then they will get a further chance in the second phase to pick up a decent amount of charge One of the complicating factors in summer (not so much in winter) seems to be that the measurement of battery voltage during daylight is confused by the fact that they are constantly being charged by the solar, and I've noticed that when under charge, their voltage is not the same as it is when measured with no charge (I think you called this 'resting'). So when its sunny, the B2B is reading a charging voltage, but when its crappy weather, its reading what seems more like a resting voltage, and the thresholds and trigger voltages that it works with are more difficult to be certain about.
|
|