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22-12-2024, 14:07
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#61
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 4,309
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by sailingharry
So, I've pulled out my notes.
First, I needed some high-end voltage considerations. The charge curve is very flat for most of the profile, and all that is really needed is to ensure that the alternator voltage is measurably over that voltage to ensure that effective charging occurs. Then, we need to know some data points.
These data come from various online tests/reports/etc.
* 95% - 3.3V -> 13.2V
* 97% - 3.3V -> 13.2V
* 99% - 3.4V -> 13.6V
* 100% - 3.5V -> 14.0V
The Eve data sheet has a few more data points.
* End of Charge - 3.65V -> 14.65V
* Max Charge - 3.8 -> 15.2V
It is also worth noting that I have a ~900Ah bank, and can realistically not maintain a charge rate over 150A. That means that I am charging at 150/900, or 17%/hour or .2% per minute, or 5 minutes to charge 1%.
So, here's my Balmar settings.
Bulk Voltage -- 14.0V
Bulk Time -- .2H, or 12 minutes
Absorption Voltage 13.6V
Absorption Time --- .2H
Float Voltage -- 13.0V
Float Time -- 6H
Here's what will (should) happen.
Turns on, starts charging at Absorption. This is charging to 100% (but given voltage losses and the fact that even LFP has a "charging voltage overage," it really is probably closer to 99%. Given that EVE specifies an "end of charge" of 14.65, I may end up raising my absorption voltage to 14.3 or 14.4. It gets to 100%, but because 14.0 is still 100%, it doesn't overcharge. Then after 12 minutes at 14.0, it backs off to a setting of 13.6 (which basically turns it off). After another 12 minutes, it backs down to 13.0 (truly off) for the next 6 hours. So essentially, I have turned it into a single-stage regulator -- set at 14.0 until reached, then shut off. Note that I have no desire for my alternator to REALLY reach 100%, if it only reaches 90 or 95%, that's no worry. My intention is for solar to get me to 100% on a fairly regular basis, and the only real reason to want to get to 100% is to reset the SOC meters.
Of course, my BMS will be monitoring individual cells for any outlier, and also for any anomalies in the regulator performance, and can shut down the regulator directly if necessary.
Even a ~2000 year Balmar does all that is needed. Note that charge sources are never based on SOC, but always on voltage. And even LFP have a fully charged voltage to reach, where all charge sources shut down.
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As soon as you have solar spare yourself and the system the danger of the alternator overcharging the cells and simply cut it at latest 99% SOC.
An alternator as well as wind gen and hydrogen are the worst charge sources for lifepo4 as they produces ripple voltage and these can in the knee easily overcharge and damage cells without the BMS been able to detect that. Surprise Non of these regulator manufacturer tell you as that’s bad for their business. So let these 3 charge sources do the bulk charge phase and disconnect them before they can do harm is the best advice, there is 1 till 2% of capacity so 3 to 6AH of a 300AH battery that you loose.
Solar is much better in absorption and you don‘t need much solar watts for the low current requirements to do the short absorption so cells can top balance. And if at night, don‘t absorb and let solar do it on the next day. KISS.
If you have an Electrodacus BMS like sailingharry and I do the balmar doesn‘t need to measure anything beside temp. The Electrodacus BMS measures SOC and cell voltages so I simply take an ExtIO (that it’s optocoppler that you can program) and program it as type 3 with 96% SOC so the BMS cuts with this optocoppler at 96% SOC+3% hystesis=99% SOC the brown wire of the balmar so before it goes into the knee and switches it on when 95% SOC is reached.
Program the Balmar to absorb of at 14.2V and float at 13.5V just in case the BMS fails to cut it.
So the balmar job is simply prevent the alternator from overheating and dail it back if needed and keep the voltage below 14.6V to not create an overvoltage disconnect. Nothing more. And a wakespeed or Zeus not of any additional value, actually the opposite as it’s complex install and bus dependencies can cause issues and bank shutdowns.
As sailingharry states correctly wakespeed and Zeus is need for niche applications like a big alternator on a small engine where you eg strongly derate it in idle/Tick tick and low RPMs as the engine would otherwise stall or run really badly which huge strain on cranckshaft bearings. The betas also need that on even big 50 and 60 hp engines as they are very sensitive to idle loads.
Another use case for wakespeed and Zeus is of advantage for eg motorboats and trawler with only engine and alternator as only charge source as this must do absorption and float, so absorption voltages and current need to be very precise not to harm the cells as you have nothing else to do this otherwise. Well I would put one 200W solar panel with an MPPT instead that should fit on any of these trawlers and motorboats and keep the alternator away from the knee.
A very good article to read about lifepo4 charging is from Eric Bertscher/Nordkyn Design that also describes how you can overcharge even with absorption voltages considered by many to be safe. A real eye opener.
https://nordkyndesign.com/charging-m...battery-banks/
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22-12-2024, 17:01
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#62
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Registered User
Join Date: Jun 2015
Location: Victoria, BC Canada
Boat: Nordic Tug 37
Posts: 150
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Re: The external regulator we've all been waiting for!
Unless your regulator monitors and responds to SOC, you risk overcharging your LFP cells.
With LFP batteries, Voltage and SOC are poorly correlated as per the Nordkyn design article. Even lower voltages applied for long enough time can over charge your LFP cells.
You can monitor SOC and modify the charging input manually (ie turn the charging off when the cells are full) but if you don't want to do that, you need a regulator that will...thus the reason that the Zeus or Wakespeed regulators exist. The Balmar will not do this for you.
Anyways, go ahead and install your system with a good shunt so that you can follow the SOC in real-time and you will quickly realize that the circa 2000-era Time / voltage Balmar protocols will not do the job.
__________________
MV TUGAWAY
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22-12-2024, 17:42
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#63
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Registered User
Join Date: Nov 2018
Location: San Diego
Boat: Shannon 50 Ketch
Posts: 744
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by eheffa
How do you get your Balmar regulators to respond to SOC instead of simple battery Voltage as their "time to change mode" indicator?
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Quote:
Originally Posted by eheffa
Unless your regulator monitors and responds to SOC, you risk overcharging your LFP cells.
You can monitor SOC and modify the charging input manually (ie turn the charging off when the cells are full) but if you don't want to do that, you need a regulator that will...thus the reason that the Zeus or Wakespeed regulators exist. The Balmar will not do this for you.
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I have the Balmar 712 wired directly to my (LFP) house bank. Here's how I've set up my system to respond to SOC%.
I mounted a Victron SolidSwitch 104 next to the Balmar and I ran the ignition wire so it goes through the SolidSwitch and THEN to the Balmar (before it was wired directly to the Balmar so when the engine power was turned on, power also turned on the Balmar).
The ignition wire connects to the Bat+ terminal on the SolidSwitch and then another wire (preferably brown) is run from Load on the SS to the Balmar ignition switch terminal.
Next, I ran a wire from my CerboGX, mounted at the nav station, to the compartment where my Balmar 712 is mounted and I connected that to the RemoteH terminal on the SolidSwitch. (almost done, I connected a batter negative line to the Bat- terminal on the SS).
Finally, I program the CerboGX Generator Start/Stop to "turn on the generator" at a specific SOC% and conversely, shut it down when the SOC% reaches as specific state, for example on=60% off=75%, or whatever you prefer.
Now, based on the example numbers above, whenever you turn on your engine ignition switch, if the SOC% on the Cerbo is below 60%, the signal is sent to the relay and the voltage regulator is energized and begins to operate as normal. Conversely, when the SOC% on the Cerbo reaches 75% the signal is disabled which shuts off the SolidSwitch relay and removes power from the regulator - this is totally safe, I've been doing it for 4 years and the system works perfectly.
Note: I also installed an override switch with wiring to bypass the SolidSwitch and force the alternator to charge even if I am not below the trigger threshold. Additionally, I have a relay wired also connected to my LFP BMS which is the "always on" kind of relay, a warning signal from the BMS (due to low voltage, over voltage, over temp, etc.) which is fired before BMS shutdown will close this relay and shut down the alternator in time before the BMS does, possibly even preventing the BMS from doing the shutdown.
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22-12-2024, 17:51
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#64
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Registered User
Join Date: Jun 2015
Location: Victoria, BC Canada
Boat: Nordic Tug 37
Posts: 150
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Re: The external regulator we've all been waiting for!
That makes sense. Your system is properly set up to respond to SOC values but this is not dependent on a Balmar protocol which would be voltage & time based.
__________________
MV TUGAWAY
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22-12-2024, 18:22
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#65
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Registered User
Join Date: Jun 2009
Location: Annapolis, MD
Boat: Sabre 34-1 (sold) and Saga 43
Posts: 2,794
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Re: The external regulator we've all been waiting for!
As pointed out, pack voltage is only good for charging LFP when they are mostly in balance. A single runner can't be seen in pack voltage, and continuing to charge when that runner is already at max voltage leads to damage. Basic stuff -- it's why a BMS monitors individual cells to watch for that.
However, SOC is absolutely the worst possible way to monitor/control charging. Sure, it's an excellent way to dial back if you want to, but it's kind of pointless. SOC is nothing more than counting beans. You look at electrons flowing out when discharging, and then look at electrons flowing in. You can lose an electron here or there, a cell can get the flu, who knows what all can happen. SOC is really useful, but is at best an approximation. If you charge to 99% every day, and discharge to 80% every night, and repeat, and never get to 100%, you can easily have SOC off by 10% or more after a few weeks. I think Rivet has claimed it's more like a few days -- and I'm willing to accept that. It's an APPROXIMATION nothing more.
Charging MUST continue until you reach 100% full, as determined by all cells are at a voltage above your target of choice. My plan is 3.5, or 14V. Your choices may be different. If you don't get all cells above your target voltage, you can't re-zero your SOC meter. And nothing knows cell voltage but the BMS. It can share that info, but it is the source of that info.
So, in the case of a Balmar, all you need is for your BMS to shut it down at some point before you exceed a damaging voltage. My Balmar will be programed to hold at 14V. That's enough to get the battery to 100%, and reset the SOC meter. On a good day, that's all that happens. But what if there is a runner? What if one cell is at 3.8, and the others are at 3.4? You are sitting at 14.0V, and still charging (well, no, you just stopped, but let's say you are still charging). The Balmar sees 14.0, so no worries. But with that one cell at 3.8, you are on the edge of damage. The BMS knows this -- and it already shut down charging (gracefully, by opening the ignition wire to the Balmar) when that cell got to 3.7, and is working to resolve the imbalance. As balance is restored, it will reactivate the charge sources to work all cells up to 3.5.
What does a Zeus do differently? It has no idea what the cell voltages are (unless your BMS shares it). It has no idea what the SOC is (unless your BMS shares it) and as discussed, SOC is a horrible way to manage charging. I'm about 99.99% sure your MPPT controllers don't know SOC or cell voltage -- how do you handle them?
Finally, it is possible to have the BMS share this data to your regulator. But why would you want to set all those charge parameters in both the BMS and the regulator? Cell voltage limits, SOC parameters (repeat my opinion on that!), etc. Far better to set target voltage, and charge to it -- with the caveat that the BMS can call for disaster relief in an off-plan excursion.
Curious for those who use a Zeus -- what cell voltage parameters have you set? What SOC level do you charge to? What, specifically, do you have your Zeus do that a Balmar doesn't? Or do you understand the black box well enough to explain it?
And for those that think that spending a grand or two to save 20 minutes doing a one-time programming a Balmar is money well spent, well, you did well in life. I still change my oil because paying someone a couple hundred to do something I can do in 20 minutes doesn't fit my budget.
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22-12-2024, 19:54
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#66
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 4,309
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by eheffa
That makes sense. Your system is properly set up to respond to SOC values but this is not dependent on a Balmar protocol which would be voltage & time based.
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Problem SOC will fade over time, especially when your bank doesn't reach 100% for some time which is completely OK with LFP, if not even better for lifespan.
It's a simple thing made complex.
The most simple thing is let the BMS steer it, if 3.4V is reached cut it off. Simple without any problems. No cerbo, DVCC or whatever complex stuff. 3.4V reach, cut and job done.
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22-12-2024, 20:04
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#67
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 4,309
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by sailingharry
As pointed out, pack voltage is only good for charging LFP when they are mostly in balance. A single runner can't be seen in pack voltage, and continuing to charge when that runner is already at max voltage leads to damage. Basic stuff -- it's why a BMS monitors individual cells to watch for that.
However, SOC is absolutely the worst possible way to monitor/control charging. Sure, it's an excellent way to dial back if you want to, but it's kind of pointless. SOC is nothing more than counting beans. You look at electrons flowing out when discharging, and then look at electrons flowing in. You can lose an electron here or there, a cell can get the flu, who knows what all can happen. SOC is really useful, but is at best an approximation. If you charge to 99% every day, and discharge to 80% every night, and repeat, and never get to 100%, you can easily have SOC off by 10% or more after a few weeks. I think Rivet has claimed it's more like a few days -- and I'm willing to accept that. It's an APPROXIMATION nothing more.
Charging MUST continue until you reach 100% full, as determined by all cells are at a voltage above your target of choice. My plan is 3.5, or 14V. Your choices may be different. If you don't get all cells above your target voltage, you can't re-zero your SOC meter. And nothing knows cell voltage but the BMS. It can share that info, but it is the source of that info.
So, in the case of a Balmar, all you need is for your BMS to shut it down at some point before you exceed a damaging voltage. My Balmar will be programed to hold at 14V. That's enough to get the battery to 100%, and reset the SOC meter. On a good day, that's all that happens. But what if there is a runner? What if one cell is at 3.8, and the others are at 3.4? You are sitting at 14.0V, and still charging (well, no, you just stopped, but let's say you are still charging). The Balmar sees 14.0, so no worries. But with that one cell at 3.8, you are on the edge of damage. The BMS knows this -- and it already shut down charging (gracefully, by opening the ignition wire to the Balmar) when that cell got to 3.7, and is working to resolve the imbalance. As balance is restored, it will reactivate the charge sources to work all cells up to 3.5.
What does a Zeus do differently? It has no idea what the cell voltages are (unless your BMS shares it). It has no idea what the SOC is (unless your BMS shares it) and as discussed, SOC is a horrible way to manage charging. I'm about 99.99% sure your MPPT controllers don't know SOC or cell voltage -- how do you handle them?
Finally, it is possible to have the BMS share this data to your regulator. But why would you want to set all those charge parameters in both the BMS and the regulator? Cell voltage limits, SOC parameters (repeat my opinion on that!), etc. Far better to set target voltage, and charge to it -- with the caveat that the BMS can call for disaster relief in an off-plan excursion.
Curious for those who use a Zeus -- what cell voltage parameters have you set? What SOC level do you charge to? What, specifically, do you have your Zeus do that a Balmar doesn't? Or do you understand the black box well enough to explain it?
And for those that think that spending a grand or two to save 20 minutes doing a one-time programming a Balmar is money well spent, well, you did well in life. I still change my oil because paying someone a couple hundred to do something I can do in 20 minutes doesn't fit my budget.
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Charging must be 100% full, why??? With lead yes but LFP doesn't need that at all.
Good banks actually need it all 3 month or even 6month is fine for 1p banks to correct top balance and that's best done with solar, alternator is one of the worst as mentioned. So don't hold it at 14V, cut it off at 13.6V and you are good...read Bertschers article 14V over longer periode and you get overcharged cells.
That's what ElectrodacusBMS is doing, steering the charge sources based on cell voltage and SOC and not let the alternator reach 14V. That's how the electrodacus works and it's it philosophy.
Yes SoC is approximation but the good thing is if BMS shows soc is 80% but it's 98% that doesn't matter the alternator can still charge and nothing happens. If it reaches 81 but its 99% nothing happens and then at 100% it corrects/resets soc and disconnects alternator immediately. But that's very very rarely the case. Mostly it's the opposite and SoC is shown at 80 but you are at 60%. If you cut alternator with soc you cut it earlier then needed which doesn't harm battery. If you cut at 99% you Can never cut it too late as in best it's precise and 99 is 3.4V and if not you cut at 3.3V but again nothing can happen. You don't need 100% full, 80 is enough because we all have a big buffer in capacity.
Let solar do the 100% as thats best controllable and saver for the cells.
Cell voltage is enough to steer clear of the knee for the alternator. Neither a Zeus nor a wakespeed is needed for that.
That why I actually like internally temp protected alternator, just let the agm regulator do it's job in bulk and cut it off by BMS via its sense wire if one cell reaches 3.4V.
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22-12-2024, 21:02
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#68
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Senior Cruiser

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 13,100
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by JPK
If you want to get pedantic, 24/7/365 = 0.00939335 
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Darn mathematics majors.
__________________
Non illigitamus carborundum
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23-12-2024, 03:47
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#69
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Senior Cruiser

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 51,843
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by newhaul
Darn mathematics majors.
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Mathematics is like sex:
You add the bed, subtract the clothes, and divide the legs — then hope you don't multiply. And, you don't get extra points, for being fast.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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23-12-2024, 05:56
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#70
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Registered User
Join Date: Jun 2009
Location: Annapolis, MD
Boat: Sabre 34-1 (sold) and Saga 43
Posts: 2,794
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by CaptainRivet
Charging must be 100% full, why??? With lead yes but LFP doesn't need that at all.
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100% isn't really a "thing" in the battery (we just pick some number up in the knee and call it that -- it's not like a gas tank where full can be measured to 6 significant figures). The battery doesn't want to get to 100%, or even really near it, for the batteries sake -- as you say, that's a lead thing. BUT, here's the big one, SOC is reset to 100% ONLY when you are at 100%. So, you tell your SOC meter "When we are above 14V for more than 1 minute with less than 1A of charge rate, set SOC to 100%." Numbers may vary, the concept doesn't. If you don't get to 100%, you can't reset the SOC meter, and things get out of alignment fast.
You've said it before, and you said it 2 posts above -- the SOC gets out of sync. How do you get your SOC back into sync without getting to 100%?
For sure, it's not the high priority thing it was with lead. And even on lead (which with Peukert and charge efficiency issues has more challenges with SOC calculations), I could go several days without reaching 100%, and would hit 100% with only maybe 5% error in the SOC meter. Since SOC is nothing more than a really useful guide, having it within even 10% is still really useful (really, how accurately can you read your car gas gauge, and yet it still does the job!). From an operational standpoint, I suspect I'd be happy getting to 100% at least once a week.
All that said, I still think charging should go to 100%. Not that I would leave the engine running just to get there -- but I certainly would NOT shut off charging sources at 85%, just to keep from getting charged. And, I am going to play with settings and see if I can get my BMS to hit 100% and then shut off till tomorrow (I think the 'Dacus can do that, but I'm not certain and don't have it in hand yet) so that it spends only minutes a day at "full."
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23-12-2024, 06:24
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#71
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Senior Cruiser

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 13,100
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by GordMay
Mathematics is like sex:
You add the bed, subtract the clothes, and divide the legs — then hope you don't multiply. And, you don't get extra points, for being fast.
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One word :. Sarcasm
__________________
Non illigitamus carborundum
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23-12-2024, 06:33
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#72
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 4,309
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by sailingharry
100% isn't really a "thing" in the battery (we just pick some number up in the knee and call it that -- it's not like a gas tank where full can be measured to 6 significant figures). The battery doesn't want to get to 100%, or even really near it, for the batteries sake -- as you say, that's a lead thing. BUT, here's the big one, SOC is reset to 100% ONLY when you are at 100%. So, you tell your SOC meter "When we are above 14V for more than 1 minute with less than 1A of charge rate, set SOC to 100%." Numbers may vary, the concept doesn't. If you don't get to 100%, you can't reset the SOC meter, and things get out of alignment fast.
You've said it before, and you said it 2 posts above -- the SOC gets out of sync. How do you get your SOC back into sync without getting to 100%?
For sure, it's not the high priority thing it was with lead. And even on lead (which with Peukert and charge efficiency issues has more challenges with SOC calculations), I could go several days without reaching 100%, and would hit 100% with only maybe 5% error in the SOC meter. Since SOC is nothing more than a really useful guide, having it within even 10% is still really useful (really, how accurately can you read your car gas gauge, and yet it still does the job!). From an operational standpoint, I suspect I'd be happy getting to 100% at least once a week.
All that said, I still think charging should go to 100%. Not that I would leave the engine running just to get there -- but I certainly would NOT shut off charging sources at 85%, just to keep from getting charged. And, I am going to play with settings and see if I can get my BMS to hit 100% and then shut off till tomorrow (I think the 'Dacus can do that, but I'm not certain and don't have it in hand yet) so that it spends only minutes a day at "full."
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SOC is just a helper, when a cell hits 3.4V it's basically full and charge can stop, no need for SOC. The knee is just to make sure all cells in series take the load as even as possible. With a a good SOC measurement like electrodacus or the BMV712 the SOC differs by about 10-15% from reality after 2month not in the knee, that's still fully enough to optimize load and charge means start the dump load waterheater when at 90% SOC, if it then 80 doesn't matter battery is with 80 or 90 close to being fully charged and it still burns to much solar into hot water. That's what SOC is for as in the flat curve you cannot steer that on voltage.
But in the beginning of the knee starting from 3.0V and 3.4V you can and should steer via voltage and don't need SOC.
Electrodacus just turns on or off charger based on cell voltage or SOC depending how you set Extio. If you set SOC it's either the SOC value you adjusted or the voltage set in the parameters which occurs first. So if you set shut off at 96%+3% hystesis=99%SOC or eof at 3.5V then the SBMS cuts it when SOc shows 99 if right or wrong but it cuts latest at 3.5V.
And you set charge sources parameter of eg Balmar outside of that so they don't interfere with the BMS and only come into play when the cutoff by SBMS fails as first line of defense. It's a different philosophy then all the other BMS!!! That's what you bought so adjust to it, if you don't that ends not well, seen that too often.
That's why I clearly stated what it does and how it operates, so people know that before they buy.
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23-12-2024, 07:17
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#73
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 4,309
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by jordanbigel
I have the Balmar 712 wired directly to my (LFP) house bank. Here's how I've set up my system to respond to SOC%.
I mounted a Victron SolidSwitch 104 next to the Balmar and I ran the ignition wire so it goes through the SolidSwitch and THEN to the Balmar (before it was wired directly to the Balmar so when the engine power was turned on, power also turned on the Balmar).
The ignition wire connects to the Bat+ terminal on the SolidSwitch and then another wire (preferably brown) is run from Load on the SS to the Balmar ignition switch terminal.
Next, I ran a wire from my CerboGX, mounted at the nav station, to the compartment where my Balmar 712 is mounted and I connected that to the RemoteH terminal on the SolidSwitch. (almost done, I connected a batter negative line to the Bat- terminal on the SS).
Finally, I program the CerboGX Generator Start/Stop to "turn on the generator" at a specific SOC% and conversely, shut it down when the SOC% reaches as specific state, for example on=60% off=75%, or whatever you prefer.
Now, based on the example numbers above, whenever you turn on your engine ignition switch, if the SOC% on the Cerbo is below 60%, the signal is sent to the relay and the voltage regulator is energized and begins to operate as normal. Conversely, when the SOC% on the Cerbo reaches 75% the signal is disabled which shuts off the SolidSwitch relay and removes power from the regulator - this is totally safe, I've been doing it for 4 years and the system works perfectly.
Note: I also installed an override switch with wiring to bypass the SolidSwitch and force the alternator to charge even if I am not below the trigger threshold. Additionally, I have a relay wired also connected to my LFP BMS which is the "always on" kind of relay, a warning signal from the BMS (due to low voltage, over voltage, over temp, etc.) which is fired before BMS shutdown will close this relay and shut down the alternator in time before the BMS does, possibly even preventing the BMS from doing the shutdown.
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The point here is SOC is not that precise to be able to do steering relaibly like you do here unless a) 100% SOC is really 100%, how do you figure and calibrate that ?( see the article from nordkyn) and b) hit that 100% SOC minimum all 3 days so it doesn't fade.
That's the parameters game Eric pointed out in the article you will always loose in the end....
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23-12-2024, 17:18
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#74
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Registered User
Join Date: Nov 2018
Location: San Diego
Boat: Shannon 50 Ketch
Posts: 744
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by eheffa
That makes sense. Your system is properly set up to respond to SOC values but this is not dependent on a Balmar protocol which would be voltage & time based.
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First, but you can configure the balmar voltage, and second there is no "time" component, when the system is on or off is controlled by the SOC% meter and the relay on the CerboGX.
When the relay activates, voltage regulator powers on and goes into bulk mode and stays there -- it never reaches the voltage set to begin absorption (which is like 14.5vdc on mine) the SOC% relay shuts it off before that happens, when we reach our target SOC%, well below 100% and thus well below 14.5vdc.
Lastly, I agree this is not dependent on a Balmar protocol, this approach will work with any brand voltage regulator, they can all be shut off and turned on by energizing the ignition circuit.
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23-12-2024, 17:22
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#75
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Registered User
Join Date: Nov 2018
Location: San Diego
Boat: Shannon 50 Ketch
Posts: 744
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Re: The external regulator we've all been waiting for!
Quote:
Originally Posted by CaptainRivet
Problem SOC will fade over time, especially when your bank doesn't reach 100% for some time which is completely OK with LFP, if not even better for lifespan.
It's a simple thing made complex.
The most simple thing is let the BMS steer it, if 3.4V is reached cut it off. Simple without any problems. No cerbo, DVCC or whatever complex stuff. 3.4V reach, cut and job done.
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Agree 100%. this is an issue. I attempt to address this issue by overriding my SOC% relay and forcing a full 100% charge program to allow for top balancing time. I try to do this every 3 months.
My goal is mainly to prevent damage and increase lifespan by not overcharging. I can accept knowing that the SOC% is an approximation. At worst I am undercharged sometimes, but LFP likes that fine. Right?
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